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diff --git a/malloc/malloc.c b/malloc/malloc.c new file mode 100644 index 0000000..ed24d5d --- /dev/null +++ b/malloc/malloc.c @@ -0,0 +1,3443 @@ +/* Malloc implementation for multiple threads without lock contention. + Copyright (C) 1996 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Wolfram Gloger <wmglo@dent.med.uni-muenchen.de>, 1996. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +/* VERSION 2.6.4-pt Wed Dec 4 00:35:54 MET 1996 + + This work is mainly derived from malloc-2.6.4 by Doug Lea + <dl@cs.oswego.edu>, which is available from: + + ftp://g.oswego.edu/pub/misc/malloc.c + + Most of the original comments are reproduced in the code below. + +* Why use this malloc? + + This is not the fastest, most space-conserving, most portable, or + most tunable malloc ever written. However it is among the fastest + while also being among the most space-conserving, portable and tunable. + Consistent balance across these factors results in a good general-purpose + allocator. For a high-level description, see + http://g.oswego.edu/dl/html/malloc.html + + On many systems, the standard malloc implementation is by itself not + thread-safe, and therefore wrapped with a single global lock around + all malloc-related functions. In some applications, especially with + multiple available processors, this can lead to contention problems + and bad performance. This malloc version was designed with the goal + to avoid waiting for locks as much as possible. Statistics indicate + that this goal is achieved in many cases. + +* Synopsis of public routines + + (Much fuller descriptions are contained in the program documentation below.) + + ptmalloc_init(); + Initialize global configuration. When compiled for multiple threads, + this function must be called once before any other function in the + package. It is not required otherwise. It is called automatically + in the Linux/GNU C libray. + malloc(size_t n); + Return a pointer to a newly allocated chunk of at least n bytes, or null + if no space is available. + free(Void_t* p); + Release the chunk of memory pointed to by p, or no effect if p is null. + realloc(Void_t* p, size_t n); + Return a pointer to a chunk of size n that contains the same data + as does chunk p up to the minimum of (n, p's size) bytes, or null + if no space is available. The returned pointer may or may not be + the same as p. If p is null, equivalent to malloc. Unless the + #define REALLOC_ZERO_BYTES_FREES below is set, realloc with a + size argument of zero (re)allocates a minimum-sized chunk. + memalign(size_t alignment, size_t n); + Return a pointer to a newly allocated chunk of n bytes, aligned + in accord with the alignment argument, which must be a power of + two. + valloc(size_t n); + Equivalent to memalign(pagesize, n), where pagesize is the page + size of the system (or as near to this as can be figured out from + all the includes/defines below.) + pvalloc(size_t n); + Equivalent to valloc(minimum-page-that-holds(n)), that is, + round up n to nearest pagesize. + calloc(size_t unit, size_t quantity); + Returns a pointer to quantity * unit bytes, with all locations + set to zero. + cfree(Void_t* p); + Equivalent to free(p). + malloc_trim(size_t pad); + Release all but pad bytes of freed top-most memory back + to the system. Return 1 if successful, else 0. + malloc_usable_size(Void_t* p); + Report the number usable allocated bytes associated with allocated + chunk p. This may or may not report more bytes than were requested, + due to alignment and minimum size constraints. + malloc_stats(); + Prints brief summary statistics on stderr. + mallinfo() + Returns (by copy) a struct containing various summary statistics. + mallopt(int parameter_number, int parameter_value) + Changes one of the tunable parameters described below. Returns + 1 if successful in changing the parameter, else 0. + +* Vital statistics: + + Alignment: 8-byte + 8 byte alignment is currently hardwired into the design. This + seems to suffice for all current machines and C compilers. + + Assumed pointer representation: 4 or 8 bytes + Code for 8-byte pointers is untested by me but has worked + reliably by Wolfram Gloger, who contributed most of the + changes supporting this. + + Assumed size_t representation: 4 or 8 bytes + Note that size_t is allowed to be 4 bytes even if pointers are 8. + + Minimum overhead per allocated chunk: 4 or 8 bytes + Each malloced chunk has a hidden overhead of 4 bytes holding size + and status information. + + Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead) + 8-byte ptrs: 24/32 bytes (including, 4/8 overhead) + + When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte + ptrs but 4 byte size) or 24 (for 8/8) additional bytes are + needed; 4 (8) for a trailing size field + and 8 (16) bytes for free list pointers. Thus, the minimum + allocatable size is 16/24/32 bytes. + + Even a request for zero bytes (i.e., malloc(0)) returns a + pointer to something of the minimum allocatable size. + + Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes + 8-byte size_t: 2^63 - 16 bytes + + It is assumed that (possibly signed) size_t bit values suffice to + represent chunk sizes. `Possibly signed' is due to the fact + that `size_t' may be defined on a system as either a signed or + an unsigned type. To be conservative, values that would appear + as negative numbers are avoided. + Requests for sizes with a negative sign bit will return a + minimum-sized chunk. + + Maximum overhead wastage per allocated chunk: normally 15 bytes + + Alignnment demands, plus the minimum allocatable size restriction + make the normal worst-case wastage 15 bytes (i.e., up to 15 + more bytes will be allocated than were requested in malloc), with + two exceptions: + 1. Because requests for zero bytes allocate non-zero space, + the worst case wastage for a request of zero bytes is 24 bytes. + 2. For requests >= mmap_threshold that are serviced via + mmap(), the worst case wastage is 8 bytes plus the remainder + from a system page (the minimal mmap unit); typically 4096 bytes. + +* Limitations + + Here are some features that are NOT currently supported + + * No user-definable hooks for callbacks and the like. + * No automated mechanism for fully checking that all accesses + to malloced memory stay within their bounds. + * No support for compaction. + +* Synopsis of compile-time options: + + People have reported using previous versions of this malloc on all + versions of Unix, sometimes by tweaking some of the defines + below. It has been tested most extensively on Solaris and + Linux. People have also reported adapting this malloc for use in + stand-alone embedded systems. + + The implementation is in straight, hand-tuned ANSI C. Among other + consequences, it uses a lot of macros. Because of this, to be at + all usable, this code should be compiled using an optimizing compiler + (for example gcc -O2) that can simplify expressions and control + paths. + + __STD_C (default: derived from C compiler defines) + Nonzero if using ANSI-standard C compiler, a C++ compiler, or + a C compiler sufficiently close to ANSI to get away with it. + MALLOC_DEBUG (default: NOT defined) + Define to enable debugging. Adds fairly extensive assertion-based + checking to help track down memory errors, but noticeably slows down + execution. + REALLOC_ZERO_BYTES_FREES (default: NOT defined) + Define this if you think that realloc(p, 0) should be equivalent + to free(p). Otherwise, since malloc returns a unique pointer for + malloc(0), so does realloc(p, 0). + HAVE_MEMCPY (default: defined) + Define if you are not otherwise using ANSI STD C, but still + have memcpy and memset in your C library and want to use them. + Otherwise, simple internal versions are supplied. + USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise) + Define as 1 if you want the C library versions of memset and + memcpy called in realloc and calloc (otherwise macro versions are used). + At least on some platforms, the simple macro versions usually + outperform libc versions. + HAVE_MMAP (default: defined as 1) + Define to non-zero to optionally make malloc() use mmap() to + allocate very large blocks. + HAVE_MREMAP (default: defined as 0 unless Linux libc set) + Define to non-zero to optionally make realloc() use mremap() to + reallocate very large blocks. + malloc_getpagesize (default: derived from system #includes) + Either a constant or routine call returning the system page size. + HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined) + Optionally define if you are on a system with a /usr/include/malloc.h + that declares struct mallinfo. It is not at all necessary to + define this even if you do, but will ensure consistency. + INTERNAL_SIZE_T (default: size_t) + Define to a 32-bit type (probably `unsigned int') if you are on a + 64-bit machine, yet do not want or need to allow malloc requests of + greater than 2^31 to be handled. This saves space, especially for + very small chunks. + _LIBC (default: NOT defined) + Defined only when compiled as part of the Linux libc/glibc. + Also note that there is some odd internal name-mangling via defines + (for example, internally, `malloc' is named `mALLOc') needed + when compiling in this case. These look funny but don't otherwise + affect anything. + LACKS_UNISTD_H (default: undefined) + Define this if your system does not have a <unistd.h>. + MORECORE (default: sbrk) + The name of the routine to call to obtain more memory from the system. + MORECORE_FAILURE (default: -1) + The value returned upon failure of MORECORE. + MORECORE_CLEARS (default 1) + True (1) if the routine mapped to MORECORE zeroes out memory (which + holds for sbrk). + DEFAULT_TRIM_THRESHOLD + DEFAULT_TOP_PAD + DEFAULT_MMAP_THRESHOLD + DEFAULT_MMAP_MAX + Default values of tunable parameters (described in detail below) + controlling interaction with host system routines (sbrk, mmap, etc). + These values may also be changed dynamically via mallopt(). The + preset defaults are those that give best performance for typical + programs/systems. + + +*/ + +/* + +* Compile-time options for multiple threads: + + USE_PTHREADS, USE_THR, USE_SPROC + Define one of these as 1 to select the thread interface: + POSIX threads, Solaris threads or SGI sproc's, respectively. + If none of these is defined as non-zero, you get a `normal' + malloc implementation which is not thread-safe. Support for + multiple threads requires HAVE_MMAP=1. As an exception, when + compiling for GNU libc, i.e. when _LIBC is defined, then none of + the USE_... symbols have to be defined. + + HEAP_MIN_SIZE + HEAP_MAX_SIZE + When thread support is enabled, additional `heap's are created + with mmap calls. These are limited in size; HEAP_MIN_SIZE should + be a multiple of the page size, while HEAP_MAX_SIZE must be a power + of two for alignment reasons. HEAP_MAX_SIZE should be at least + twice as large as the mmap threshold. + THREAD_STATS + When this is defined as non-zero, some statistics on mutex locking + are computed. + +*/ + + + + +/* Macros for handling mutexes and thread-specific data. This is + included first, because some thread-related header files (such as + pthread.h) should be included before any others. */ +#include "thread-m.h" + + +/* Preliminaries */ + +#ifndef __STD_C +#if defined (__STDC__) +#define __STD_C 1 +#else +#if __cplusplus +#define __STD_C 1 +#else +#define __STD_C 0 +#endif /*__cplusplus*/ +#endif /*__STDC__*/ +#endif /*__STD_C*/ + +#ifndef Void_t +#if __STD_C +#define Void_t void +#else +#define Void_t char +#endif +#endif /*Void_t*/ + +#if __STD_C +#include <stddef.h> /* for size_t */ +#else +#include <sys/types.h> +#endif + +#ifdef __cplusplus +extern "C" { +#endif + +#include <stdio.h> /* needed for malloc_stats */ + + +/* + Compile-time options +*/ + + +/* + Debugging: + + Because freed chunks may be overwritten with link fields, this + malloc will often die when freed memory is overwritten by user + programs. This can be very effective (albeit in an annoying way) + in helping track down dangling pointers. + + If you compile with -DMALLOC_DEBUG, a number of assertion checks are + enabled that will catch more memory errors. You probably won't be + able to make much sense of the actual assertion errors, but they + should help you locate incorrectly overwritten memory. The + checking is fairly extensive, and will slow down execution + noticeably. Calling malloc_stats or mallinfo with MALLOC_DEBUG set will + attempt to check every non-mmapped allocated and free chunk in the + course of computing the summmaries. (By nature, mmapped regions + cannot be checked very much automatically.) + + Setting MALLOC_DEBUG may also be helpful if you are trying to modify + this code. The assertions in the check routines spell out in more + detail the assumptions and invariants underlying the algorithms. + +*/ + +#if MALLOC_DEBUG +#include <assert.h> +#else +#define assert(x) ((void)0) +#endif + + +/* + INTERNAL_SIZE_T is the word-size used for internal bookkeeping + of chunk sizes. On a 64-bit machine, you can reduce malloc + overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int' + at the expense of not being able to handle requests greater than + 2^31. This limitation is hardly ever a concern; you are encouraged + to set this. However, the default version is the same as size_t. +*/ + +#ifndef INTERNAL_SIZE_T +#define INTERNAL_SIZE_T size_t +#endif + +/* + REALLOC_ZERO_BYTES_FREES should be set if a call to + realloc with zero bytes should be the same as a call to free. + Some people think it should. Otherwise, since this malloc + returns a unique pointer for malloc(0), so does realloc(p, 0). +*/ + + +/* #define REALLOC_ZERO_BYTES_FREES */ + + +/* + HAVE_MEMCPY should be defined if you are not otherwise using + ANSI STD C, but still have memcpy and memset in your C library + and want to use them in calloc and realloc. Otherwise simple + macro versions are defined here. + + USE_MEMCPY should be defined as 1 if you actually want to + have memset and memcpy called. People report that the macro + versions are often enough faster than libc versions on many + systems that it is better to use them. + +*/ + +#define HAVE_MEMCPY + +#ifndef USE_MEMCPY +#ifdef HAVE_MEMCPY +#define USE_MEMCPY 1 +#else +#define USE_MEMCPY 0 +#endif +#endif + +#if (__STD_C || defined(HAVE_MEMCPY)) + +#if __STD_C +void* memset(void*, int, size_t); +void* memcpy(void*, const void*, size_t); +#else +Void_t* memset(); +Void_t* memcpy(); +#endif +#endif + +#if USE_MEMCPY + +/* The following macros are only invoked with (2n+1)-multiples of + INTERNAL_SIZE_T units, with a positive integer n. This is exploited + for fast inline execution when n is small. */ + +#define MALLOC_ZERO(charp, nbytes) \ +do { \ + INTERNAL_SIZE_T mzsz = (nbytes); \ + if(mzsz <= 9*sizeof(mzsz)) { \ + INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \ + if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \ + *mz++ = 0; \ + if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \ + *mz++ = 0; \ + if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \ + *mz++ = 0; }}} \ + *mz++ = 0; \ + *mz++ = 0; \ + *mz = 0; \ + } else memset((charp), 0, mzsz); \ +} while(0) + +#define MALLOC_COPY(dest,src,nbytes) \ +do { \ + INTERNAL_SIZE_T mcsz = (nbytes); \ + if(mcsz <= 9*sizeof(mcsz)) { \ + INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \ + INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \ + if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ + *mcdst++ = *mcsrc++; \ + if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ + *mcdst++ = *mcsrc++; \ + if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ + *mcdst++ = *mcsrc++; }}} \ + *mcdst++ = *mcsrc++; \ + *mcdst++ = *mcsrc++; \ + *mcdst = *mcsrc ; \ + } else memcpy(dest, src, mcsz); \ +} while(0) + +#else /* !USE_MEMCPY */ + +/* Use Duff's device for good zeroing/copying performance. */ + +#define MALLOC_ZERO(charp, nbytes) \ +do { \ + INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \ + long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \ + if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \ + switch (mctmp) { \ + case 0: for(;;) { *mzp++ = 0; \ + case 7: *mzp++ = 0; \ + case 6: *mzp++ = 0; \ + case 5: *mzp++ = 0; \ + case 4: *mzp++ = 0; \ + case 3: *mzp++ = 0; \ + case 2: *mzp++ = 0; \ + case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \ + } \ +} while(0) + +#define MALLOC_COPY(dest,src,nbytes) \ +do { \ + INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \ + INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \ + long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \ + if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \ + switch (mctmp) { \ + case 0: for(;;) { *mcdst++ = *mcsrc++; \ + case 7: *mcdst++ = *mcsrc++; \ + case 6: *mcdst++ = *mcsrc++; \ + case 5: *mcdst++ = *mcsrc++; \ + case 4: *mcdst++ = *mcsrc++; \ + case 3: *mcdst++ = *mcsrc++; \ + case 2: *mcdst++ = *mcsrc++; \ + case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \ + } \ +} while(0) + +#endif + + +/* + Define HAVE_MMAP to optionally make malloc() use mmap() to + allocate very large blocks. These will be returned to the + operating system immediately after a free(). +*/ + +#ifndef HAVE_MMAP +#define HAVE_MMAP 1 +#endif + +/* + Define HAVE_MREMAP to make realloc() use mremap() to re-allocate + large blocks. This is currently only possible on Linux with + kernel versions newer than 1.3.77. +*/ + +#ifndef HAVE_MREMAP +#define HAVE_MREMAP defined(__linux__) +#endif + +#if HAVE_MMAP + +#include <unistd.h> +#include <fcntl.h> +#include <sys/mman.h> + +#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON) +#define MAP_ANONYMOUS MAP_ANON +#endif + +#endif /* HAVE_MMAP */ + +/* + Access to system page size. To the extent possible, this malloc + manages memory from the system in page-size units. + + The following mechanics for getpagesize were adapted from + bsd/gnu getpagesize.h +*/ + +#ifndef LACKS_UNISTD_H +# include <unistd.h> +#endif + +#ifndef malloc_getpagesize +# ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */ +# ifndef _SC_PAGE_SIZE +# define _SC_PAGE_SIZE _SC_PAGESIZE +# endif +# endif +# ifdef _SC_PAGE_SIZE +# define malloc_getpagesize sysconf(_SC_PAGE_SIZE) +# else +# if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE) + extern size_t getpagesize(); +# define malloc_getpagesize getpagesize() +# else +# include <sys/param.h> +# ifdef EXEC_PAGESIZE +# define malloc_getpagesize EXEC_PAGESIZE +# else +# ifdef NBPG +# ifndef CLSIZE +# define malloc_getpagesize NBPG +# else +# define malloc_getpagesize (NBPG * CLSIZE) +# endif +# else +# ifdef NBPC +# define malloc_getpagesize NBPC +# else +# ifdef PAGESIZE +# define malloc_getpagesize PAGESIZE +# else +# define malloc_getpagesize (4096) /* just guess */ +# endif +# endif +# endif +# endif +# endif +# endif +#endif + + + +/* + + This version of malloc supports the standard SVID/XPG mallinfo + routine that returns a struct containing the same kind of + information you can get from malloc_stats. It should work on + any SVID/XPG compliant system that has a /usr/include/malloc.h + defining struct mallinfo. (If you'd like to install such a thing + yourself, cut out the preliminary declarations as described above + and below and save them in a malloc.h file. But there's no + compelling reason to bother to do this.) + + The main declaration needed is the mallinfo struct that is returned + (by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a + bunch of fields, most of which are not even meaningful in this + version of malloc. Some of these fields are are instead filled by + mallinfo() with other numbers that might possibly be of interest. + + HAVE_USR_INCLUDE_MALLOC_H should be set if you have a + /usr/include/malloc.h file that includes a declaration of struct + mallinfo. If so, it is included; else an SVID2/XPG2 compliant + version is declared below. These must be precisely the same for + mallinfo() to work. + +*/ + +/* #define HAVE_USR_INCLUDE_MALLOC_H */ + +#if HAVE_USR_INCLUDE_MALLOC_H +#include "/usr/include/malloc.h" +#else +#include "malloc.h" +#endif + + + +#ifndef DEFAULT_TRIM_THRESHOLD +#define DEFAULT_TRIM_THRESHOLD (128 * 1024) +#endif + +/* + M_TRIM_THRESHOLD is the maximum amount of unused top-most memory + to keep before releasing via malloc_trim in free(). + + Automatic trimming is mainly useful in long-lived programs. + Because trimming via sbrk can be slow on some systems, and can + sometimes be wasteful (in cases where programs immediately + afterward allocate more large chunks) the value should be high + enough so that your overall system performance would improve by + releasing. + + The trim threshold and the mmap control parameters (see below) + can be traded off with one another. Trimming and mmapping are + two different ways of releasing unused memory back to the + system. Between these two, it is often possible to keep + system-level demands of a long-lived program down to a bare + minimum. For example, in one test suite of sessions measuring + the XF86 X server on Linux, using a trim threshold of 128K and a + mmap threshold of 192K led to near-minimal long term resource + consumption. + + If you are using this malloc in a long-lived program, it should + pay to experiment with these values. As a rough guide, you + might set to a value close to the average size of a process + (program) running on your system. Releasing this much memory + would allow such a process to run in memory. Generally, it's + worth it to tune for trimming rather tham memory mapping when a + program undergoes phases where several large chunks are + allocated and released in ways that can reuse each other's + storage, perhaps mixed with phases where there are no such + chunks at all. And in well-behaved long-lived programs, + controlling release of large blocks via trimming versus mapping + is usually faster. + + However, in most programs, these parameters serve mainly as + protection against the system-level effects of carrying around + massive amounts of unneeded memory. Since frequent calls to + sbrk, mmap, and munmap otherwise degrade performance, the default + parameters are set to relatively high values that serve only as + safeguards. + + The default trim value is high enough to cause trimming only in + fairly extreme (by current memory consumption standards) cases. + It must be greater than page size to have any useful effect. To + disable trimming completely, you can set to (unsigned long)(-1); + + +*/ + + +#ifndef DEFAULT_TOP_PAD +#define DEFAULT_TOP_PAD (0) +#endif + +/* + M_TOP_PAD is the amount of extra `padding' space to allocate or + retain whenever sbrk is called. It is used in two ways internally: + + * When sbrk is called to extend the top of the arena to satisfy + a new malloc request, this much padding is added to the sbrk + request. + + * When malloc_trim is called automatically from free(), + it is used as the `pad' argument. + + In both cases, the actual amount of padding is rounded + so that the end of the arena is always a system page boundary. + + The main reason for using padding is to avoid calling sbrk so + often. Having even a small pad greatly reduces the likelihood + that nearly every malloc request during program start-up (or + after trimming) will invoke sbrk, which needlessly wastes + time. + + Automatic rounding-up to page-size units is normally sufficient + to avoid measurable overhead, so the default is 0. However, in + systems where sbrk is relatively slow, it can pay to increase + this value, at the expense of carrying around more memory than + the program needs. + +*/ + + +#ifndef DEFAULT_MMAP_THRESHOLD +#define DEFAULT_MMAP_THRESHOLD (128 * 1024) +#endif + +/* + + M_MMAP_THRESHOLD is the request size threshold for using mmap() + to service a request. Requests of at least this size that cannot + be allocated using already-existing space will be serviced via mmap. + (If enough normal freed space already exists it is used instead.) + + Using mmap segregates relatively large chunks of memory so that + they can be individually obtained and released from the host + system. A request serviced through mmap is never reused by any + other request (at least not directly; the system may just so + happen to remap successive requests to the same locations). + + Segregating space in this way has the benefit that mmapped space + can ALWAYS be individually released back to the system, which + helps keep the system level memory demands of a long-lived + program low. Mapped memory can never become `locked' between + other chunks, as can happen with normally allocated chunks, which + menas that even trimming via malloc_trim would not release them. + + However, it has the disadvantages that: + + 1. The space cannot be reclaimed, consolidated, and then + used to service later requests, as happens with normal chunks. + 2. It can lead to more wastage because of mmap page alignment + requirements + 3. It causes malloc performance to be more dependent on host + system memory management support routines which may vary in + implementation quality and may impose arbitrary + limitations. Generally, servicing a request via normal + malloc steps is faster than going through a system's mmap. + + All together, these considerations should lead you to use mmap + only for relatively large requests. + + +*/ + + + +#ifndef DEFAULT_MMAP_MAX +#if HAVE_MMAP +#define DEFAULT_MMAP_MAX (1024) +#else +#define DEFAULT_MMAP_MAX (0) +#endif +#endif + +/* + M_MMAP_MAX is the maximum number of requests to simultaneously + service using mmap. This parameter exists because: + + 1. Some systems have a limited number of internal tables for + use by mmap. + 2. In most systems, overreliance on mmap can degrade overall + performance. + 3. If a program allocates many large regions, it is probably + better off using normal sbrk-based allocation routines that + can reclaim and reallocate normal heap memory. Using a + small value allows transition into this mode after the + first few allocations. + + Setting to 0 disables all use of mmap. If HAVE_MMAP is not set, + the default value is 0, and attempts to set it to non-zero values + in mallopt will fail. +*/ + + + +#define HEAP_MIN_SIZE (32*1024) +#define HEAP_MAX_SIZE (1024*1024) /* must be a power of two */ + +/* HEAP_MIN_SIZE and HEAP_MAX_SIZE limit the size of mmap()ed heaps + that are dynamically created for multi-threaded programs. The + maximum size must be a power of two, for fast determination of + which heap belongs to a chunk. It should be much larger than + the mmap threshold, so that requests with a size just below that + threshold can be fulfilled without creating too many heaps. +*/ + + + +#ifndef THREAD_STATS +#define THREAD_STATS 0 +#endif + +/* If THREAD_STATS is non-zero, some statistics on mutex locking are + computed. */ + + +/* + + Special defines for the Linux/GNU C library. + +*/ + + +#ifdef _LIBC + +#if __STD_C + +Void_t * __default_morecore (ptrdiff_t); +static Void_t *(*__morecore)(ptrdiff_t) = __default_morecore; + +#else + +Void_t * __default_morecore (); +static Void_t *(*__morecore)() = __default_morecore; + +#endif + +#define MORECORE (*__morecore) +#define MORECORE_FAILURE 0 +#define MORECORE_CLEARS 1 + +#else /* _LIBC */ + +#if __STD_C +extern Void_t* sbrk(ptrdiff_t); +#else +extern Void_t* sbrk(); +#endif + +#ifndef MORECORE +#define MORECORE sbrk +#endif + +#ifndef MORECORE_FAILURE +#define MORECORE_FAILURE -1 +#endif + +#ifndef MORECORE_CLEARS +#define MORECORE_CLEARS 1 +#endif + +#endif /* _LIBC */ + +#if 0 && defined(_LIBC) + +#define cALLOc __libc_calloc +#define fREe __libc_free +#define mALLOc __libc_malloc +#define mEMALIGn __libc_memalign +#define rEALLOc __libc_realloc +#define vALLOc __libc_valloc +#define pvALLOc __libc_pvalloc +#define mALLINFo __libc_mallinfo +#define mALLOPt __libc_mallopt + +#pragma weak calloc = __libc_calloc +#pragma weak free = __libc_free +#pragma weak cfree = __libc_free +#pragma weak malloc = __libc_malloc +#pragma weak memalign = __libc_memalign +#pragma weak realloc = __libc_realloc +#pragma weak valloc = __libc_valloc +#pragma weak pvalloc = __libc_pvalloc +#pragma weak mallinfo = __libc_mallinfo +#pragma weak mallopt = __libc_mallopt + +#else + +#define cALLOc calloc +#define fREe free +#define mALLOc malloc +#define mEMALIGn memalign +#define rEALLOc realloc +#define vALLOc valloc +#define pvALLOc pvalloc +#define mALLINFo mallinfo +#define mALLOPt mallopt + +#endif + +/* Public routines */ + +#if __STD_C + +#ifndef _LIBC +void ptmalloc_init(void); +#endif +Void_t* mALLOc(size_t); +void fREe(Void_t*); +Void_t* rEALLOc(Void_t*, size_t); +Void_t* mEMALIGn(size_t, size_t); +Void_t* vALLOc(size_t); +Void_t* pvALLOc(size_t); +Void_t* cALLOc(size_t, size_t); +void cfree(Void_t*); +int malloc_trim(size_t); +size_t malloc_usable_size(Void_t*); +void malloc_stats(void); +int mALLOPt(int, int); +struct mallinfo mALLINFo(void); +#else +#ifndef _LIBC +void ptmalloc_init(); +#endif +Void_t* mALLOc(); +void fREe(); +Void_t* rEALLOc(); +Void_t* mEMALIGn(); +Void_t* vALLOc(); +Void_t* pvALLOc(); +Void_t* cALLOc(); +void cfree(); +int malloc_trim(); +size_t malloc_usable_size(); +void malloc_stats(); +int mALLOPt(); +struct mallinfo mALLINFo(); +#endif + + +#ifdef __cplusplus +}; /* end of extern "C" */ +#endif + +#if !defined(NO_THREADS) && !HAVE_MMAP +"Can't have threads support without mmap" +#endif + + +/* + Type declarations +*/ + + +struct malloc_chunk +{ + INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */ + INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */ + struct malloc_chunk* fd; /* double links -- used only if free. */ + struct malloc_chunk* bk; +}; + +typedef struct malloc_chunk* mchunkptr; + +/* + + malloc_chunk details: + + (The following includes lightly edited explanations by Colin Plumb.) + + Chunks of memory are maintained using a `boundary tag' method as + described in e.g., Knuth or Standish. (See the paper by Paul + Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a + survey of such techniques.) Sizes of free chunks are stored both + in the front of each chunk and at the end. This makes + consolidating fragmented chunks into bigger chunks very fast. The + size fields also hold bits representing whether chunks are free or + in use. + + An allocated chunk looks like this: + + + chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Size of previous chunk, if allocated | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Size of chunk, in bytes |P| + mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | User data starts here... . + . . + . (malloc_usable_space() bytes) . + . | +nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Size of chunk | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + + Where "chunk" is the front of the chunk for the purpose of most of + the malloc code, but "mem" is the pointer that is returned to the + user. "Nextchunk" is the beginning of the next contiguous chunk. + + Chunks always begin on even word boundries, so the mem portion + (which is returned to the user) is also on an even word boundary, and + thus double-word aligned. + + Free chunks are stored in circular doubly-linked lists, and look like this: + + chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Size of previous chunk | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + `head:' | Size of chunk, in bytes |P| + mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Forward pointer to next chunk in list | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Back pointer to previous chunk in list | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Unused space (may be 0 bytes long) . + . . + . | +nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + `foot:' | Size of chunk, in bytes | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + The P (PREV_INUSE) bit, stored in the unused low-order bit of the + chunk size (which is always a multiple of two words), is an in-use + bit for the *previous* chunk. If that bit is *clear*, then the + word before the current chunk size contains the previous chunk + size, and can be used to find the front of the previous chunk. + (The very first chunk allocated always has this bit set, + preventing access to non-existent (or non-owned) memory.) + + Note that the `foot' of the current chunk is actually represented + as the prev_size of the NEXT chunk. (This makes it easier to + deal with alignments etc). + + The two exceptions to all this are + + 1. The special chunk `top', which doesn't bother using the + trailing size field since there is no + next contiguous chunk that would have to index off it. (After + initialization, `top' is forced to always exist. If it would + become less than MINSIZE bytes long, it is replenished via + malloc_extend_top.) + + 2. Chunks allocated via mmap, which have the second-lowest-order + bit (IS_MMAPPED) set in their size fields. Because they are + never merged or traversed from any other chunk, they have no + foot size or inuse information. + + Available chunks are kept in any of several places (all declared below): + + * `av': An array of chunks serving as bin headers for consolidated + chunks. Each bin is doubly linked. The bins are approximately + proportionally (log) spaced. There are a lot of these bins + (128). This may look excessive, but works very well in + practice. All procedures maintain the invariant that no + consolidated chunk physically borders another one. Chunks in + bins are kept in size order, with ties going to the + approximately least recently used chunk. + + The chunks in each bin are maintained in decreasing sorted order by + size. This is irrelevant for the small bins, which all contain + the same-sized chunks, but facilitates best-fit allocation for + larger chunks. (These lists are just sequential. Keeping them in + order almost never requires enough traversal to warrant using + fancier ordered data structures.) Chunks of the same size are + linked with the most recently freed at the front, and allocations + are taken from the back. This results in LRU or FIFO allocation + order, which tends to give each chunk an equal opportunity to be + consolidated with adjacent freed chunks, resulting in larger free + chunks and less fragmentation. + + * `top': The top-most available chunk (i.e., the one bordering the + end of available memory) is treated specially. It is never + included in any bin, is used only if no other chunk is + available, and is released back to the system if it is very + large (see M_TRIM_THRESHOLD). + + * `last_remainder': A bin holding only the remainder of the + most recently split (non-top) chunk. This bin is checked + before other non-fitting chunks, so as to provide better + locality for runs of sequentially allocated chunks. + + * Implicitly, through the host system's memory mapping tables. + If supported, requests greater than a threshold are usually + serviced via calls to mmap, and then later released via munmap. + +*/ + +/* + Bins + + The bins are an array of pairs of pointers serving as the + heads of (initially empty) doubly-linked lists of chunks, laid out + in a way so that each pair can be treated as if it were in a + malloc_chunk. (This way, the fd/bk offsets for linking bin heads + and chunks are the same). + + Bins for sizes < 512 bytes contain chunks of all the same size, spaced + 8 bytes apart. Larger bins are approximately logarithmically + spaced. (See the table below.) + + Bin layout: + + 64 bins of size 8 + 32 bins of size 64 + 16 bins of size 512 + 8 bins of size 4096 + 4 bins of size 32768 + 2 bins of size 262144 + 1 bin of size what's left + + There is actually a little bit of slop in the numbers in bin_index + for the sake of speed. This makes no difference elsewhere. + + The special chunks `top' and `last_remainder' get their own bins, + (this is implemented via yet more trickery with the av array), + although `top' is never properly linked to its bin since it is + always handled specially. + +*/ + +#define NAV 128 /* number of bins */ + +typedef struct malloc_chunk* mbinptr; + +/* An arena is a configuration of malloc_chunks together with an array + of bins. With multiple threads, it must be locked via a mutex + before changing its data structures. One or more `heaps' are + associated with each arena, except for the main_arena, which is + associated only with the `main heap', i.e. the conventional free + store obtained with calls to MORECORE() (usually sbrk). The `av' + array is never mentioned directly in the code, but instead used via + bin access macros. */ + +typedef struct _arena { + mbinptr av[2*NAV + 2]; + struct _arena *next; + mutex_t mutex; +} arena; + + +/* A heap is a single contiguous memory region holding (coalescable) + malloc_chunks. It is allocated with mmap() and always starts at an + address aligned to HEAP_MAX_SIZE. Not used unless compiling for + multiple threads. */ + +typedef struct _heap_info { + arena *ar_ptr; + size_t size; +} heap_info; + + +/* + Static functions (forward declarations) +*/ + +#if __STD_C +static void chunk_free(arena *ar_ptr, mchunkptr p); +static mchunkptr chunk_alloc(arena *ar_ptr, INTERNAL_SIZE_T size); +static int arena_trim(arena *ar_ptr, size_t pad); +#else +static void chunk_free(); +static mchunkptr chunk_alloc(); +static int arena_trim(); +#endif + + + +/* sizes, alignments */ + +#define SIZE_SZ (sizeof(INTERNAL_SIZE_T)) +#define MALLOC_ALIGNMENT (SIZE_SZ + SIZE_SZ) +#define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1) +#define MINSIZE (sizeof(struct malloc_chunk)) + +/* conversion from malloc headers to user pointers, and back */ + +#define chunk2mem(p) ((Void_t*)((char*)(p) + 2*SIZE_SZ)) +#define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ)) + +/* pad request bytes into a usable size */ + +#define request2size(req) \ + (((long)((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) < \ + (long)(MINSIZE + MALLOC_ALIGN_MASK)) ? MINSIZE : \ + (((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) & ~(MALLOC_ALIGN_MASK))) + +/* Check if m has acceptable alignment */ + +#define aligned_OK(m) (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0) + + + + +/* + Physical chunk operations +*/ + + +/* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */ + +#define PREV_INUSE 0x1 + +/* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */ + +#define IS_MMAPPED 0x2 + +/* Bits to mask off when extracting size */ + +#define SIZE_BITS (PREV_INUSE|IS_MMAPPED) + + +/* Ptr to next physical malloc_chunk. */ + +#define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~PREV_INUSE) )) + +/* Ptr to previous physical malloc_chunk */ + +#define prev_chunk(p) ((mchunkptr)( ((char*)(p)) - ((p)->prev_size) )) + + +/* Treat space at ptr + offset as a chunk */ + +#define chunk_at_offset(p, s) ((mchunkptr)(((char*)(p)) + (s))) + + + + +/* + Dealing with use bits +*/ + +/* extract p's inuse bit */ + +#define inuse(p) \ + ((((mchunkptr)(((char*)(p))+((p)->size & ~PREV_INUSE)))->size) & PREV_INUSE) + +/* extract inuse bit of previous chunk */ + +#define prev_inuse(p) ((p)->size & PREV_INUSE) + +/* check for mmap()'ed chunk */ + +#define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED) + +/* set/clear chunk as in use without otherwise disturbing */ + +#define set_inuse(p) \ + ((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size |= PREV_INUSE + +#define clear_inuse(p) \ + ((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size &= ~(PREV_INUSE) + +/* check/set/clear inuse bits in known places */ + +#define inuse_bit_at_offset(p, s)\ + (((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE) + +#define set_inuse_bit_at_offset(p, s)\ + (((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE) + +#define clear_inuse_bit_at_offset(p, s)\ + (((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE)) + + + + +/* + Dealing with size fields +*/ + +/* Get size, ignoring use bits */ + +#define chunksize(p) ((p)->size & ~(SIZE_BITS)) + +/* Set size at head, without disturbing its use bit */ + +#define set_head_size(p, s) ((p)->size = (((p)->size & PREV_INUSE) | (s))) + +/* Set size/use ignoring previous bits in header */ + +#define set_head(p, s) ((p)->size = (s)) + +/* Set size at footer (only when chunk is not in use) */ + +#define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_size = (s)) + + + + + +/* access macros */ + +#define bin_at(a, i) ((mbinptr)((char*)&(((a)->av)[2*(i) + 2]) - 2*SIZE_SZ)) +#define init_bin(a, i) ((a)->av[2*i+2] = (a)->av[2*i+3] = bin_at((a), i)) +#define next_bin(b) ((mbinptr)((char*)(b) + 2 * sizeof(mbinptr))) +#define prev_bin(b) ((mbinptr)((char*)(b) - 2 * sizeof(mbinptr))) + +/* + The first 2 bins are never indexed. The corresponding av cells are instead + used for bookkeeping. This is not to save space, but to simplify + indexing, maintain locality, and avoid some initialization tests. +*/ + +#define binblocks(a) (bin_at(a,0)->size)/* bitvector of nonempty blocks */ +#define top(a) (bin_at(a,0)->fd) /* The topmost chunk */ +#define last_remainder(a) (bin_at(a,1)) /* remainder from last split */ + +/* + Because top initially points to its own bin with initial + zero size, thus forcing extension on the first malloc request, + we avoid having any special code in malloc to check whether + it even exists yet. But we still need to in malloc_extend_top. +*/ + +#define initial_top(a) ((mchunkptr)bin_at(a, 0)) + + + +/* field-extraction macros */ + +#define first(b) ((b)->fd) +#define last(b) ((b)->bk) + +/* + Indexing into bins +*/ + +#define bin_index(sz) \ +(((((unsigned long)(sz)) >> 9) == 0) ? (((unsigned long)(sz)) >> 3): \ + ((((unsigned long)(sz)) >> 9) <= 4) ? 56 + (((unsigned long)(sz)) >> 6): \ + ((((unsigned long)(sz)) >> 9) <= 20) ? 91 + (((unsigned long)(sz)) >> 9): \ + ((((unsigned long)(sz)) >> 9) <= 84) ? 110 + (((unsigned long)(sz)) >> 12): \ + ((((unsigned long)(sz)) >> 9) <= 340) ? 119 + (((unsigned long)(sz)) >> 15): \ + ((((unsigned long)(sz)) >> 9) <= 1364) ? 124 + (((unsigned long)(sz)) >> 18): \ + 126) +/* + bins for chunks < 512 are all spaced 8 bytes apart, and hold + identically sized chunks. This is exploited in malloc. +*/ + +#define MAX_SMALLBIN 63 +#define MAX_SMALLBIN_SIZE 512 +#define SMALLBIN_WIDTH 8 + +#define smallbin_index(sz) (((unsigned long)(sz)) >> 3) + +/* + Requests are `small' if both the corresponding and the next bin are small +*/ + +#define is_small_request(nb) ((nb) < MAX_SMALLBIN_SIZE - SMALLBIN_WIDTH) + + + +/* + To help compensate for the large number of bins, a one-level index + structure is used for bin-by-bin searching. `binblocks' is a + one-word bitvector recording whether groups of BINBLOCKWIDTH bins + have any (possibly) non-empty bins, so they can be skipped over + all at once during during traversals. The bits are NOT always + cleared as soon as all bins in a block are empty, but instead only + when all are noticed to be empty during traversal in malloc. +*/ + +#define BINBLOCKWIDTH 4 /* bins per block */ + +/* bin<->block macros */ + +#define idx2binblock(ix) ((unsigned)1 << ((ix) / BINBLOCKWIDTH)) +#define mark_binblock(a, ii) (binblocks(a) |= idx2binblock(ii)) +#define clear_binblock(a, ii) (binblocks(a) &= ~(idx2binblock(ii))) + + + + +/* Static bookkeeping data */ + +/* Helper macro to initialize bins */ +#define IAV(i) bin_at(&main_arena, i), bin_at(&main_arena, i) + +static arena main_arena = { + { + 0, 0, + IAV(0), IAV(1), IAV(2), IAV(3), IAV(4), IAV(5), IAV(6), IAV(7), + IAV(8), IAV(9), IAV(10), IAV(11), IAV(12), IAV(13), IAV(14), IAV(15), + IAV(16), IAV(17), IAV(18), IAV(19), IAV(20), IAV(21), IAV(22), IAV(23), + IAV(24), IAV(25), IAV(26), IAV(27), IAV(28), IAV(29), IAV(30), IAV(31), + IAV(32), IAV(33), IAV(34), IAV(35), IAV(36), IAV(37), IAV(38), IAV(39), + IAV(40), IAV(41), IAV(42), IAV(43), IAV(44), IAV(45), IAV(46), IAV(47), + IAV(48), IAV(49), IAV(50), IAV(51), IAV(52), IAV(53), IAV(54), IAV(55), + IAV(56), IAV(57), IAV(58), IAV(59), IAV(60), IAV(61), IAV(62), IAV(63), + IAV(64), IAV(65), IAV(66), IAV(67), IAV(68), IAV(69), IAV(70), IAV(71), + IAV(72), IAV(73), IAV(74), IAV(75), IAV(76), IAV(77), IAV(78), IAV(79), + IAV(80), IAV(81), IAV(82), IAV(83), IAV(84), IAV(85), IAV(86), IAV(87), + IAV(88), IAV(89), IAV(90), IAV(91), IAV(92), IAV(93), IAV(94), IAV(95), + IAV(96), IAV(97), IAV(98), IAV(99), IAV(100), IAV(101), IAV(102), IAV(103), + IAV(104), IAV(105), IAV(106), IAV(107), IAV(108), IAV(109), IAV(110), IAV(111), + IAV(112), IAV(113), IAV(114), IAV(115), IAV(116), IAV(117), IAV(118), IAV(119), + IAV(120), IAV(121), IAV(122), IAV(123), IAV(124), IAV(125), IAV(126), IAV(127) + }, + NULL, /* next */ + MUTEX_INITIALIZER /* mutex */ +}; + +#undef IAV + +/* Thread specific data */ + +static tsd_key_t arena_key; +static mutex_t list_lock = MUTEX_INITIALIZER; + +#if THREAD_STATS +static int stat_n_arenas = 0; +static int stat_n_heaps = 0; +static long stat_lock_direct = 0; +static long stat_lock_loop = 0; +#define THREAD_STAT(x) x +#else +#define THREAD_STAT(x) do ; while(0) +#endif + +/* variables holding tunable values */ + +static unsigned long trim_threshold = DEFAULT_TRIM_THRESHOLD; +static unsigned long top_pad = DEFAULT_TOP_PAD; +static unsigned int n_mmaps_max = DEFAULT_MMAP_MAX; +static unsigned long mmap_threshold = DEFAULT_MMAP_THRESHOLD; + +/* The first value returned from sbrk */ +static char* sbrk_base = (char*)(-1); + +/* The maximum memory obtained from system via sbrk */ +static unsigned long max_sbrked_mem = 0; + +/* The maximum via either sbrk or mmap */ +static unsigned long max_total_mem = 0; + +/* internal working copy of mallinfo */ +static struct mallinfo current_mallinfo = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; + +/* The total memory obtained from system via sbrk */ +#define sbrked_mem (current_mallinfo.arena) + +/* Tracking mmaps */ + +static unsigned int n_mmaps = 0; +static unsigned int max_n_mmaps = 0; +static unsigned long mmapped_mem = 0; +static unsigned long max_mmapped_mem = 0; + + + + + +/* Initialization routine. */ +#if defined(_LIBC) +static void ptmalloc_init __MALLOC_P ((void)) __attribute__ ((constructor)); + +static void +ptmalloc_init __MALLOC_P((void)) +#else +void +ptmalloc_init __MALLOC_P((void)) +#endif +{ + static int first = 1; + +#if defined(_LIBC) + /* Initialize the pthread. */ + if (__pthread_initialize != NULL) + __pthread_initialize (); +#endif + + if(first) { + first = 0; + mutex_init(&main_arena.mutex); + mutex_init(&list_lock); + tsd_key_create(&arena_key, NULL); + tsd_setspecific(arena_key, (Void_t *)&main_arena); + } +} + + + + + +/* Routines dealing with mmap(). */ + +#if HAVE_MMAP + +#ifndef MAP_ANONYMOUS + +static int dev_zero_fd = -1; /* Cached file descriptor for /dev/zero. */ + +#define MMAP(size, prot) ((dev_zero_fd < 0) ? \ + (dev_zero_fd = open("/dev/zero", O_RDWR), \ + mmap(0, (size), (prot), MAP_PRIVATE, dev_zero_fd, 0)) : \ + mmap(0, (size), (prot), MAP_PRIVATE, dev_zero_fd, 0)) + +#else + +#define MMAP(size, prot) \ + (mmap(0, (size), (prot), MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)) + +#endif + +#if __STD_C +static mchunkptr mmap_chunk(size_t size) +#else +static mchunkptr mmap_chunk(size) size_t size; +#endif +{ + size_t page_mask = malloc_getpagesize - 1; + mchunkptr p; + + if(n_mmaps >= n_mmaps_max) return 0; /* too many regions */ + + /* For mmapped chunks, the overhead is one SIZE_SZ unit larger, because + * there is no following chunk whose prev_size field could be used. + */ + size = (size + SIZE_SZ + page_mask) & ~page_mask; + + p = (mchunkptr)MMAP(size, PROT_READ|PROT_WRITE); + if(p == (mchunkptr)-1) return 0; + + n_mmaps++; + if (n_mmaps > max_n_mmaps) max_n_mmaps = n_mmaps; + + /* We demand that eight bytes into a page must be 8-byte aligned. */ + assert(aligned_OK(chunk2mem(p))); + + /* The offset to the start of the mmapped region is stored + * in the prev_size field of the chunk; normally it is zero, + * but that can be changed in memalign(). + */ + p->prev_size = 0; + set_head(p, size|IS_MMAPPED); + + mmapped_mem += size; + if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem) + max_mmapped_mem = mmapped_mem; + if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem) + max_total_mem = mmapped_mem + sbrked_mem; + return p; +} + +#if __STD_C +static void munmap_chunk(mchunkptr p) +#else +static void munmap_chunk(p) mchunkptr p; +#endif +{ + INTERNAL_SIZE_T size = chunksize(p); + int ret; + + assert (chunk_is_mmapped(p)); + assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem)); + assert((n_mmaps > 0)); + assert(((p->prev_size + size) & (malloc_getpagesize-1)) == 0); + + n_mmaps--; + mmapped_mem -= (size + p->prev_size); + + ret = munmap((char *)p - p->prev_size, size + p->prev_size); + + /* munmap returns non-zero on failure */ + assert(ret == 0); +} + +#if HAVE_MREMAP + +#if __STD_C +static mchunkptr mremap_chunk(mchunkptr p, size_t new_size) +#else +static mchunkptr mremap_chunk(p, new_size) mchunkptr p; size_t new_size; +#endif +{ + size_t page_mask = malloc_getpagesize - 1; + INTERNAL_SIZE_T offset = p->prev_size; + INTERNAL_SIZE_T size = chunksize(p); + char *cp; + + assert (chunk_is_mmapped(p)); + assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem)); + assert((n_mmaps > 0)); + assert(((size + offset) & (malloc_getpagesize-1)) == 0); + + /* Note the extra SIZE_SZ overhead as in mmap_chunk(). */ + new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask; + + cp = (char *)mremap((char *)p - offset, size + offset, new_size, + MREMAP_MAYMOVE); + + if (cp == (char *)-1) return 0; + + p = (mchunkptr)(cp + offset); + + assert(aligned_OK(chunk2mem(p))); + + assert((p->prev_size == offset)); + set_head(p, (new_size - offset)|IS_MMAPPED); + + mmapped_mem -= size + offset; + mmapped_mem += new_size; + if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem) + max_mmapped_mem = mmapped_mem; + if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem) + max_total_mem = mmapped_mem + sbrked_mem; + return p; +} + +#endif /* HAVE_MREMAP */ + +#endif /* HAVE_MMAP */ + + + +/* Managing heaps and arenas (for concurrent threads) */ + +#ifndef NO_THREADS + +/* Create a new heap. size is automatically rounded up to a multiple + of the page size. */ + +static heap_info * +#if __STD_C +new_heap(size_t size) +#else +new_heap(size) size_t size; +#endif +{ + size_t page_mask = malloc_getpagesize - 1; + char *p1, *p2; + unsigned long ul; + heap_info *h; + + if(size < HEAP_MIN_SIZE) + size = HEAP_MIN_SIZE; + size = (size + page_mask) & ~page_mask; + if(size > HEAP_MAX_SIZE) + return 0; + p1 = (char *)MMAP(HEAP_MAX_SIZE<<1, PROT_NONE); + if(p1 == (char *)-1) + return 0; + p2 = (char *)(((unsigned long)p1 + HEAP_MAX_SIZE) & ~(HEAP_MAX_SIZE-1)); + ul = p2 - p1; + munmap(p1, ul); + munmap(p2 + HEAP_MAX_SIZE, HEAP_MAX_SIZE - ul); + if(mprotect(p2, size, PROT_READ|PROT_WRITE) != 0) { + munmap(p2, HEAP_MAX_SIZE); + return 0; + } + h = (heap_info *)p2; + h->size = size; + THREAD_STAT(stat_n_heaps++); + return h; +} + +/* Grow or shrink a heap. size is automatically rounded up to a + multiple of the page size. */ + +static int +#if __STD_C +grow_heap(heap_info *h, long diff) +#else +grow_heap(h, diff) heap_info *h; long diff; +#endif +{ + size_t page_mask = malloc_getpagesize - 1; + long new_size; + + if(diff >= 0) { + diff = (diff + page_mask) & ~page_mask; + new_size = (long)h->size + diff; + if(new_size > HEAP_MAX_SIZE) + return -1; + if(mprotect((char *)h + h->size, diff, PROT_READ|PROT_WRITE) != 0) + return -2; + } else { + new_size = (long)h->size + diff; + if(new_size < 0) + return -1; + if(mprotect((char *)h + new_size, -diff, PROT_NONE) != 0) + return -2; + } + h->size = new_size; + return 0; +} + +/* arena_get() acquires an arena and locks the corresponding mutex. + First, try the one last locked successfully by this thread. (This + is the common case and handled with a macro for speed.) Then, loop + over the singly linked list of arenas. If no arena is readily + available, create a new one. */ + +#define arena_get(ptr, size) do { \ + Void_t *vptr = NULL; \ + ptr = (arena *)tsd_getspecific(arena_key, vptr); \ + if(ptr && !mutex_trylock(&ptr->mutex)) { \ + THREAD_STAT(stat_lock_direct++); \ + } else { \ + ptr = arena_get2(ptr, (size)); \ + } \ +} while(0) + +static arena * +#if __STD_C +arena_get2(arena *a_tsd, size_t size) +#else +arena_get2(a_tsd, size) arena *a_tsd; size_t size; +#endif +{ + arena *a; + heap_info *h; + char *ptr; + int i; + unsigned long misalign; + + /* Check the list for unlocked arenas. */ + if(a_tsd) { + for(a = a_tsd->next; a; a = a->next) { + if(!mutex_trylock(&a->mutex)) + goto done; + } + for(a = &main_arena; a != a_tsd; a = a->next) { + if(!mutex_trylock(&a->mutex)) + goto done; + } + } else { + for(a = &main_arena; a; a = a->next) { + if(!mutex_trylock(&a->mutex)) + goto done; + } + } + + /* Nothing immediately available, so generate a new arena. */ + h = new_heap(size + (sizeof(*h) + sizeof(*a) + MALLOC_ALIGNMENT)); + if(!h) + return 0; + a = h->ar_ptr = (arena *)(h+1); + for(i=0; i<NAV; i++) + init_bin(a, i); + mutex_init(&a->mutex); + i = mutex_lock(&a->mutex); /* remember result */ + + /* Set up the top chunk, with proper alignment. */ + ptr = (char *)(a + 1); + misalign = (unsigned long)chunk2mem(ptr) & MALLOC_ALIGN_MASK; + if (misalign > 0) + ptr += MALLOC_ALIGNMENT - misalign; + top(a) = (mchunkptr)ptr; + set_head(top(a), (h->size - (ptr-(char*)h)) | PREV_INUSE); + + /* Add the new arena to the list. */ + (void)mutex_lock(&list_lock); + a->next = main_arena.next; + main_arena.next = a; + THREAD_STAT(stat_n_arenas++); + (void)mutex_unlock(&list_lock); + + if(i) /* locking failed; keep arena for further attempts later */ + return 0; + +done: + THREAD_STAT(stat_lock_loop++); + tsd_setspecific(arena_key, (Void_t *)a); + return a; +} + +/* find the heap and corresponding arena for a given ptr */ + +#define heap_for_ptr(ptr) \ + ((heap_info *)((unsigned long)(ptr) & ~(HEAP_MAX_SIZE-1))) +#define arena_for_ptr(ptr) \ + (((mchunkptr)(ptr) < top(&main_arena) && (char *)(ptr) >= sbrk_base) ? \ + &main_arena : heap_for_ptr(ptr)->ar_ptr) + +#else /* defined(NO_THREADS) */ + +/* Without concurrent threads, there is only one arena. */ + +#define arena_get(ptr, sz) (ptr = &main_arena) +#define arena_for_ptr(ptr) (&main_arena) + +#endif /* !defined(NO_THREADS) */ + + + +/* + Debugging support +*/ + +#if MALLOC_DEBUG + + +/* + These routines make a number of assertions about the states + of data structures that should be true at all times. If any + are not true, it's very likely that a user program has somehow + trashed memory. (It's also possible that there is a coding error + in malloc. In which case, please report it!) +*/ + +#if __STD_C +static void do_check_chunk(arena *ar_ptr, mchunkptr p) +#else +static void do_check_chunk(ar_ptr, p) arena *ar_ptr; mchunkptr p; +#endif +{ + INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE; + + /* No checkable chunk is mmapped */ + assert(!chunk_is_mmapped(p)); + +#ifndef NO_THREADS + if(ar_ptr != &main_arena) { + heap_info *heap = heap_for_ptr(p); + assert(heap->ar_ptr == ar_ptr); + assert((char *)p + sz <= (char *)heap + heap->size); + return; + } +#endif + + /* Check for legal address ... */ + assert((char*)p >= sbrk_base); + if (p != top(ar_ptr)) + assert((char*)p + sz <= (char*)top(ar_ptr)); + else + assert((char*)p + sz <= sbrk_base + sbrked_mem); + +} + + +#if __STD_C +static void do_check_free_chunk(arena *ar_ptr, mchunkptr p) +#else +static void do_check_free_chunk(ar_ptr, p) arena *ar_ptr; mchunkptr p; +#endif +{ + INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE; + mchunkptr next = chunk_at_offset(p, sz); + + do_check_chunk(ar_ptr, p); + + /* Check whether it claims to be free ... */ + assert(!inuse(p)); + + /* Unless a special marker, must have OK fields */ + if ((long)sz >= (long)MINSIZE) + { + assert((sz & MALLOC_ALIGN_MASK) == 0); + assert(aligned_OK(chunk2mem(p))); + /* ... matching footer field */ + assert(next->prev_size == sz); + /* ... and is fully consolidated */ + assert(prev_inuse(p)); + assert (next == top(ar_ptr) || inuse(next)); + + /* ... and has minimally sane links */ + assert(p->fd->bk == p); + assert(p->bk->fd == p); + } + else /* markers are always of size SIZE_SZ */ + assert(sz == SIZE_SZ); +} + +#if __STD_C +static void do_check_inuse_chunk(arena *ar_ptr, mchunkptr p) +#else +static void do_check_inuse_chunk(ar_ptr, p) arena *ar_ptr; mchunkptr p; +#endif +{ + mchunkptr next = next_chunk(p); + do_check_chunk(ar_ptr, p); + + /* Check whether it claims to be in use ... */ + assert(inuse(p)); + + /* ... and is surrounded by OK chunks. + Since more things can be checked with free chunks than inuse ones, + if an inuse chunk borders them and debug is on, it's worth doing them. + */ + if (!prev_inuse(p)) + { + mchunkptr prv = prev_chunk(p); + assert(next_chunk(prv) == p); + do_check_free_chunk(ar_ptr, prv); + } + if (next == top(ar_ptr)) + { + assert(prev_inuse(next)); + assert(chunksize(next) >= MINSIZE); + } + else if (!inuse(next)) + do_check_free_chunk(ar_ptr, next); + +} + +#if __STD_C +static void do_check_malloced_chunk(arena *ar_ptr, + mchunkptr p, INTERNAL_SIZE_T s) +#else +static void do_check_malloced_chunk(ar_ptr, p, s) +arena *ar_ptr; mchunkptr p; INTERNAL_SIZE_T s; +#endif +{ + INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE; + long room = sz - s; + + do_check_inuse_chunk(ar_ptr, p); + + /* Legal size ... */ + assert((long)sz >= (long)MINSIZE); + assert((sz & MALLOC_ALIGN_MASK) == 0); + assert(room >= 0); + assert(room < (long)MINSIZE); + + /* ... and alignment */ + assert(aligned_OK(chunk2mem(p))); + + + /* ... and was allocated at front of an available chunk */ + assert(prev_inuse(p)); + +} + + +#define check_free_chunk(A,P) do_check_free_chunk(A,P) +#define check_inuse_chunk(A,P) do_check_inuse_chunk(A,P) +#define check_chunk(A,P) do_check_chunk(A,P) +#define check_malloced_chunk(A,P,N) do_check_malloced_chunk(A,P,N) +#else +#define check_free_chunk(A,P) +#define check_inuse_chunk(A,P) +#define check_chunk(A,P) +#define check_malloced_chunk(A,P,N) +#endif + + + +/* + Macro-based internal utilities +*/ + + +/* + Linking chunks in bin lists. + Call these only with variables, not arbitrary expressions, as arguments. +*/ + +/* + Place chunk p of size s in its bin, in size order, + putting it ahead of others of same size. +*/ + + +#define frontlink(A, P, S, IDX, BK, FD) \ +{ \ + if (S < MAX_SMALLBIN_SIZE) \ + { \ + IDX = smallbin_index(S); \ + mark_binblock(A, IDX); \ + BK = bin_at(A, IDX); \ + FD = BK->fd; \ + P->bk = BK; \ + P->fd = FD; \ + FD->bk = BK->fd = P; \ + } \ + else \ + { \ + IDX = bin_index(S); \ + BK = bin_at(A, IDX); \ + FD = BK->fd; \ + if (FD == BK) mark_binblock(A, IDX); \ + else \ + { \ + while (FD != BK && S < chunksize(FD)) FD = FD->fd; \ + BK = FD->bk; \ + } \ + P->bk = BK; \ + P->fd = FD; \ + FD->bk = BK->fd = P; \ + } \ +} + + +/* take a chunk off a list */ + +#define unlink(P, BK, FD) \ +{ \ + BK = P->bk; \ + FD = P->fd; \ + FD->bk = BK; \ + BK->fd = FD; \ +} \ + +/* Place p as the last remainder */ + +#define link_last_remainder(A, P) \ +{ \ + last_remainder(A)->fd = last_remainder(A)->bk = P; \ + P->fd = P->bk = last_remainder(A); \ +} + +/* Clear the last_remainder bin */ + +#define clear_last_remainder(A) \ + (last_remainder(A)->fd = last_remainder(A)->bk = last_remainder(A)) + + + + + +/* + Extend the top-most chunk by obtaining memory from system. + Main interface to sbrk (but see also malloc_trim). +*/ + +#if __STD_C +static void malloc_extend_top(arena *ar_ptr, INTERNAL_SIZE_T nb) +#else +static void malloc_extend_top(ar_ptr, nb) arena *ar_ptr; INTERNAL_SIZE_T nb; +#endif +{ + unsigned long pagesz = malloc_getpagesize; + mchunkptr old_top = top(ar_ptr); /* Record state of old top */ + INTERNAL_SIZE_T old_top_size = chunksize(old_top); + INTERNAL_SIZE_T top_size; /* new size of top chunk */ + +#ifndef NO_THREADS + if(ar_ptr == &main_arena) { +#endif + + char* brk; /* return value from sbrk */ + INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of sbrked space */ + INTERNAL_SIZE_T correction; /* bytes for 2nd sbrk call */ + char* new_brk; /* return of 2nd sbrk call */ + char* old_end = (char*)(chunk_at_offset(old_top, old_top_size)); + + /* Pad request with top_pad plus minimal overhead */ + INTERNAL_SIZE_T sbrk_size = nb + top_pad + MINSIZE; + + /* If not the first time through, round to preserve page boundary */ + /* Otherwise, we need to correct to a page size below anyway. */ + /* (We also correct below if an intervening foreign sbrk call.) */ + + if (sbrk_base != (char*)(-1)) + sbrk_size = (sbrk_size + (pagesz - 1)) & ~(pagesz - 1); + + brk = (char*)(MORECORE (sbrk_size)); + + /* Fail if sbrk failed or if a foreign sbrk call killed our space */ + if (brk == (char*)(MORECORE_FAILURE) || + (brk < old_end && old_top != initial_top(&main_arena))) + return; + + sbrked_mem += sbrk_size; + + if (brk == old_end) { /* can just add bytes to current top */ + top_size = sbrk_size + old_top_size; + set_head(old_top, top_size | PREV_INUSE); + old_top = 0; /* don't free below */ + } else { + if (sbrk_base == (char*)(-1)) /* First time through. Record base */ + sbrk_base = brk; + else + /* Someone else called sbrk(). Count those bytes as sbrked_mem. */ + sbrked_mem += brk - (char*)old_end; + + /* Guarantee alignment of first new chunk made from this space */ + front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK; + if (front_misalign > 0) { + correction = (MALLOC_ALIGNMENT) - front_misalign; + brk += correction; + } else + correction = 0; + + /* Guarantee the next brk will be at a page boundary */ + correction += pagesz - ((unsigned long)(brk + sbrk_size) & (pagesz - 1)); + + /* Allocate correction */ + new_brk = (char*)(MORECORE (correction)); + if (new_brk == (char*)(MORECORE_FAILURE)) return; + + sbrked_mem += correction; + + top(&main_arena) = (mchunkptr)brk; + top_size = new_brk - brk + correction; + set_head(top(&main_arena), top_size | PREV_INUSE); + + if (old_top == initial_top(&main_arena)) + old_top = 0; /* don't free below */ + } + + if ((unsigned long)sbrked_mem > (unsigned long)max_sbrked_mem) + max_sbrked_mem = sbrked_mem; + if ((unsigned long)(mmapped_mem + sbrked_mem) > + (unsigned long)max_total_mem) + max_total_mem = mmapped_mem + sbrked_mem; + +#ifndef NO_THREADS + } else { /* ar_ptr != &main_arena */ + + heap_info *heap; + + if(old_top_size < MINSIZE) /* this should never happen */ + return; + + /* First try to extend the current heap. */ + if(MINSIZE + nb <= old_top_size) + return; + heap = heap_for_ptr(old_top); + if(grow_heap(heap, MINSIZE + nb - old_top_size) == 0) { + top_size = heap->size - ((char *)old_top - (char *)heap); + set_head(old_top, top_size | PREV_INUSE); + return; + } + + /* A new heap must be created. */ + heap = new_heap(nb + top_pad + (MINSIZE + sizeof(*heap))); + if(!heap) + return; + heap->ar_ptr = ar_ptr; + + /* Set up the new top, so we can safely use chunk_free() below. */ + top(ar_ptr) = chunk_at_offset(heap, sizeof(*heap)); + top_size = heap->size - sizeof(*heap); + set_head(top(ar_ptr), top_size | PREV_INUSE); + } +#endif /* !defined(NO_THREADS) */ + + /* We always land on a page boundary */ + assert(((unsigned long)((char*)top(ar_ptr) + top_size) & (pagesz-1)) == 0); + + /* Setup fencepost and free the old top chunk. */ + if(old_top) { + /* Keep size a multiple of MALLOC_ALIGNMENT. */ + old_top_size = (old_top_size - 3*SIZE_SZ) & ~MALLOC_ALIGN_MASK; + /* If possible, release the rest. */ + if (old_top_size >= MINSIZE) { + set_head(chunk_at_offset(old_top, old_top_size ), + SIZE_SZ|PREV_INUSE); + set_head(chunk_at_offset(old_top, old_top_size+SIZE_SZ), + SIZE_SZ|PREV_INUSE); + set_head_size(old_top, old_top_size); + chunk_free(ar_ptr, old_top); + } else { + set_head(old_top, SIZE_SZ|PREV_INUSE); + set_head(chunk_at_offset(old_top, SIZE_SZ), SIZE_SZ|PREV_INUSE); + } + } +} + + + + +/* Main public routines */ + + +/* + Malloc Algorthim: + + The requested size is first converted into a usable form, `nb'. + This currently means to add 4 bytes overhead plus possibly more to + obtain 8-byte alignment and/or to obtain a size of at least + MINSIZE (currently 16 bytes), the smallest allocatable size. + (All fits are considered `exact' if they are within MINSIZE bytes.) + + From there, the first successful of the following steps is taken: + + 1. The bin corresponding to the request size is scanned, and if + a chunk of exactly the right size is found, it is taken. + + 2. The most recently remaindered chunk is used if it is big + enough. This is a form of (roving) first fit, used only in + the absence of exact fits. Runs of consecutive requests use + the remainder of the chunk used for the previous such request + whenever possible. This limited use of a first-fit style + allocation strategy tends to give contiguous chunks + coextensive lifetimes, which improves locality and can reduce + fragmentation in the long run. + + 3. Other bins are scanned in increasing size order, using a + chunk big enough to fulfill the request, and splitting off + any remainder. This search is strictly by best-fit; i.e., + the smallest (with ties going to approximately the least + recently used) chunk that fits is selected. + + 4. If large enough, the chunk bordering the end of memory + (`top') is split off. (This use of `top' is in accord with + the best-fit search rule. In effect, `top' is treated as + larger (and thus less well fitting) than any other available + chunk since it can be extended to be as large as necessary + (up to system limitations). + + 5. If the request size meets the mmap threshold and the + system supports mmap, and there are few enough currently + allocated mmapped regions, and a call to mmap succeeds, + the request is allocated via direct memory mapping. + + 6. Otherwise, the top of memory is extended by + obtaining more space from the system (normally using sbrk, + but definable to anything else via the MORECORE macro). + Memory is gathered from the system (in system page-sized + units) in a way that allows chunks obtained across different + sbrk calls to be consolidated, but does not require + contiguous memory. Thus, it should be safe to intersperse + mallocs with other sbrk calls. + + + All allocations are made from the the `lowest' part of any found + chunk. (The implementation invariant is that prev_inuse is + always true of any allocated chunk; i.e., that each allocated + chunk borders either a previously allocated and still in-use chunk, + or the base of its memory arena.) + +*/ + +#if __STD_C +Void_t* mALLOc(size_t bytes) +#else +Void_t* mALLOc(bytes) size_t bytes; +#endif +{ + arena *ar_ptr; + INTERNAL_SIZE_T nb = request2size(bytes); /* padded request size; */ + mchunkptr victim; + + arena_get(ar_ptr, nb + top_pad); + if(!ar_ptr) + return 0; + victim = chunk_alloc(ar_ptr, nb); + (void)mutex_unlock(&ar_ptr->mutex); + return victim ? chunk2mem(victim) : 0; +} + +static mchunkptr +#if __STD_C +chunk_alloc(arena *ar_ptr, INTERNAL_SIZE_T nb) +#else +chunk_alloc(ar_ptr, nb) arena *ar_ptr; INTERNAL_SIZE_T nb; +#endif +{ + mchunkptr victim; /* inspected/selected chunk */ + INTERNAL_SIZE_T victim_size; /* its size */ + int idx; /* index for bin traversal */ + mbinptr bin; /* associated bin */ + mchunkptr remainder; /* remainder from a split */ + long remainder_size; /* its size */ + int remainder_index; /* its bin index */ + unsigned long block; /* block traverser bit */ + int startidx; /* first bin of a traversed block */ + mchunkptr fwd; /* misc temp for linking */ + mchunkptr bck; /* misc temp for linking */ + mbinptr q; /* misc temp */ + + + /* Check for exact match in a bin */ + + if (is_small_request(nb)) /* Faster version for small requests */ + { + idx = smallbin_index(nb); + + /* No traversal or size check necessary for small bins. */ + + q = bin_at(ar_ptr, idx); + victim = last(q); + + /* Also scan the next one, since it would have a remainder < MINSIZE */ + if (victim == q) + { + q = next_bin(q); + victim = last(q); + } + if (victim != q) + { + victim_size = chunksize(victim); + unlink(victim, bck, fwd); + set_inuse_bit_at_offset(victim, victim_size); + check_malloced_chunk(ar_ptr, victim, nb); + return victim; + } + + idx += 2; /* Set for bin scan below. We've already scanned 2 bins. */ + + } + else + { + idx = bin_index(nb); + bin = bin_at(ar_ptr, idx); + + for (victim = last(bin); victim != bin; victim = victim->bk) + { + victim_size = chunksize(victim); + remainder_size = victim_size - nb; + + if (remainder_size >= (long)MINSIZE) /* too big */ + { + --idx; /* adjust to rescan below after checking last remainder */ + break; + } + + else if (remainder_size >= 0) /* exact fit */ + { + unlink(victim, bck, fwd); + set_inuse_bit_at_offset(victim, victim_size); + check_malloced_chunk(ar_ptr, victim, nb); + return victim; + } + } + + ++idx; + + } + + /* Try to use the last split-off remainder */ + + if ( (victim = last_remainder(ar_ptr)->fd) != last_remainder(ar_ptr)) + { + victim_size = chunksize(victim); + remainder_size = victim_size - nb; + + if (remainder_size >= (long)MINSIZE) /* re-split */ + { + remainder = chunk_at_offset(victim, nb); + set_head(victim, nb | PREV_INUSE); + link_last_remainder(ar_ptr, remainder); + set_head(remainder, remainder_size | PREV_INUSE); + set_foot(remainder, remainder_size); + check_malloced_chunk(ar_ptr, victim, nb); + return victim; + } + + clear_last_remainder(ar_ptr); + + if (remainder_size >= 0) /* exhaust */ + { + set_inuse_bit_at_offset(victim, victim_size); + check_malloced_chunk(ar_ptr, victim, nb); + return victim; + } + + /* Else place in bin */ + + frontlink(ar_ptr, victim, victim_size, remainder_index, bck, fwd); + } + + /* + If there are any possibly nonempty big-enough blocks, + search for best fitting chunk by scanning bins in blockwidth units. + */ + + if ( (block = idx2binblock(idx)) <= binblocks(ar_ptr)) + { + + /* Get to the first marked block */ + + if ( (block & binblocks(ar_ptr)) == 0) + { + /* force to an even block boundary */ + idx = (idx & ~(BINBLOCKWIDTH - 1)) + BINBLOCKWIDTH; + block <<= 1; + while ((block & binblocks(ar_ptr)) == 0) + { + idx += BINBLOCKWIDTH; + block <<= 1; + } + } + + /* For each possibly nonempty block ... */ + for (;;) + { + startidx = idx; /* (track incomplete blocks) */ + q = bin = bin_at(ar_ptr, idx); + + /* For each bin in this block ... */ + do + { + /* Find and use first big enough chunk ... */ + + for (victim = last(bin); victim != bin; victim = victim->bk) + { + victim_size = chunksize(victim); + remainder_size = victim_size - nb; + + if (remainder_size >= (long)MINSIZE) /* split */ + { + remainder = chunk_at_offset(victim, nb); + set_head(victim, nb | PREV_INUSE); + unlink(victim, bck, fwd); + link_last_remainder(ar_ptr, remainder); + set_head(remainder, remainder_size | PREV_INUSE); + set_foot(remainder, remainder_size); + check_malloced_chunk(ar_ptr, victim, nb); + return victim; + } + + else if (remainder_size >= 0) /* take */ + { + set_inuse_bit_at_offset(victim, victim_size); + unlink(victim, bck, fwd); + check_malloced_chunk(ar_ptr, victim, nb); + return victim; + } + + } + + bin = next_bin(bin); + + } while ((++idx & (BINBLOCKWIDTH - 1)) != 0); + + /* Clear out the block bit. */ + + do /* Possibly backtrack to try to clear a partial block */ + { + if ((startidx & (BINBLOCKWIDTH - 1)) == 0) + { + binblocks(ar_ptr) &= ~block; + break; + } + --startidx; + q = prev_bin(q); + } while (first(q) == q); + + /* Get to the next possibly nonempty block */ + + if ( (block <<= 1) <= binblocks(ar_ptr) && (block != 0) ) + { + while ((block & binblocks(ar_ptr)) == 0) + { + idx += BINBLOCKWIDTH; + block <<= 1; + } + } + else + break; + } + } + + + /* Try to use top chunk */ + + /* Require that there be a remainder, ensuring top always exists */ + if ( (remainder_size = chunksize(top(ar_ptr)) - nb) < (long)MINSIZE) + { + +#if HAVE_MMAP + /* If big and would otherwise need to extend, try to use mmap instead */ + if ((unsigned long)nb >= (unsigned long)mmap_threshold && + (victim = mmap_chunk(nb)) != 0) + return victim; +#endif + + /* Try to extend */ + malloc_extend_top(ar_ptr, nb); + if ((remainder_size = chunksize(top(ar_ptr)) - nb) < (long)MINSIZE) + return 0; /* propagate failure */ + } + + victim = top(ar_ptr); + set_head(victim, nb | PREV_INUSE); + top(ar_ptr) = chunk_at_offset(victim, nb); + set_head(top(ar_ptr), remainder_size | PREV_INUSE); + check_malloced_chunk(ar_ptr, victim, nb); + return victim; + +} + + + + +/* + + free() algorithm : + + cases: + + 1. free(0) has no effect. + + 2. If the chunk was allocated via mmap, it is released via munmap(). + + 3. If a returned chunk borders the current high end of memory, + it is consolidated into the top, and if the total unused + topmost memory exceeds the trim threshold, malloc_trim is + called. + + 4. Other chunks are consolidated as they arrive, and + placed in corresponding bins. (This includes the case of + consolidating with the current `last_remainder'). + +*/ + + +#if __STD_C +void fREe(Void_t* mem) +#else +void fREe(mem) Void_t* mem; +#endif +{ + arena *ar_ptr; + mchunkptr p; /* chunk corresponding to mem */ + + if (mem == 0) /* free(0) has no effect */ + return; + + p = mem2chunk(mem); + +#if HAVE_MMAP + if (chunk_is_mmapped(p)) /* release mmapped memory. */ + { + munmap_chunk(p); + return; + } +#endif + + ar_ptr = arena_for_ptr(p); + (void)mutex_lock(&ar_ptr->mutex); + chunk_free(ar_ptr, p); + (void)mutex_unlock(&ar_ptr->mutex); +} + +static void +#if __STD_C +chunk_free(arena *ar_ptr, mchunkptr p) +#else +chunk_free(ar_ptr, p) arena *ar_ptr; mchunkptr p; +#endif +{ + INTERNAL_SIZE_T hd = p->size; /* its head field */ + INTERNAL_SIZE_T sz; /* its size */ + int idx; /* its bin index */ + mchunkptr next; /* next contiguous chunk */ + INTERNAL_SIZE_T nextsz; /* its size */ + INTERNAL_SIZE_T prevsz; /* size of previous contiguous chunk */ + mchunkptr bck; /* misc temp for linking */ + mchunkptr fwd; /* misc temp for linking */ + int islr; /* track whether merging with last_remainder */ + + check_inuse_chunk(ar_ptr, p); + + sz = hd & ~PREV_INUSE; + next = chunk_at_offset(p, sz); + nextsz = chunksize(next); + + if (next == top(ar_ptr)) /* merge with top */ + { + sz += nextsz; + + if (!(hd & PREV_INUSE)) /* consolidate backward */ + { + prevsz = p->prev_size; + p = chunk_at_offset(p, -prevsz); + sz += prevsz; + unlink(p, bck, fwd); + } + + set_head(p, sz | PREV_INUSE); + top(ar_ptr) = p; + if ((unsigned long)(sz) >= (unsigned long)trim_threshold) + arena_trim(ar_ptr, top_pad); + return; + } + + set_head(next, nextsz); /* clear inuse bit */ + + islr = 0; + + if (!(hd & PREV_INUSE)) /* consolidate backward */ + { + prevsz = p->prev_size; + p = chunk_at_offset(p, -prevsz); + sz += prevsz; + + if (p->fd == last_remainder(ar_ptr)) /* keep as last_remainder */ + islr = 1; + else + unlink(p, bck, fwd); + } + + if (!(inuse_bit_at_offset(next, nextsz))) /* consolidate forward */ + { + sz += nextsz; + + if (!islr && next->fd == last_remainder(ar_ptr)) + /* re-insert last_remainder */ + { + islr = 1; + link_last_remainder(ar_ptr, p); + } + else + unlink(next, bck, fwd); + } + + set_head(p, sz | PREV_INUSE); + set_foot(p, sz); + if (!islr) + frontlink(ar_ptr, p, sz, idx, bck, fwd); +} + + + + + +/* + + Realloc algorithm: + + Chunks that were obtained via mmap cannot be extended or shrunk + unless HAVE_MREMAP is defined, in which case mremap is used. + Otherwise, if their reallocation is for additional space, they are + copied. If for less, they are just left alone. + + Otherwise, if the reallocation is for additional space, and the + chunk can be extended, it is, else a malloc-copy-free sequence is + taken. There are several different ways that a chunk could be + extended. All are tried: + + * Extending forward into following adjacent free chunk. + * Shifting backwards, joining preceding adjacent space + * Both shifting backwards and extending forward. + * Extending into newly sbrked space + + Unless the #define REALLOC_ZERO_BYTES_FREES is set, realloc with a + size argument of zero (re)allocates a minimum-sized chunk. + + If the reallocation is for less space, and the new request is for + a `small' (<512 bytes) size, then the newly unused space is lopped + off and freed. + + The old unix realloc convention of allowing the last-free'd chunk + to be used as an argument to realloc is no longer supported. + I don't know of any programs still relying on this feature, + and allowing it would also allow too many other incorrect + usages of realloc to be sensible. + + +*/ + + +#if __STD_C +Void_t* rEALLOc(Void_t* oldmem, size_t bytes) +#else +Void_t* rEALLOc(oldmem, bytes) Void_t* oldmem; size_t bytes; +#endif +{ + arena *ar_ptr; + INTERNAL_SIZE_T nb; /* padded request size */ + + mchunkptr oldp; /* chunk corresponding to oldmem */ + INTERNAL_SIZE_T oldsize; /* its size */ + + mchunkptr newp; /* chunk to return */ + INTERNAL_SIZE_T newsize; /* its size */ + Void_t* newmem; /* corresponding user mem */ + + mchunkptr next; /* next contiguous chunk after oldp */ + INTERNAL_SIZE_T nextsize; /* its size */ + + mchunkptr prev; /* previous contiguous chunk before oldp */ + INTERNAL_SIZE_T prevsize; /* its size */ + + mchunkptr remainder; /* holds split off extra space from newp */ + INTERNAL_SIZE_T remainder_size; /* its size */ + + mchunkptr bck; /* misc temp for linking */ + mchunkptr fwd; /* misc temp for linking */ + +#ifdef REALLOC_ZERO_BYTES_FREES + if (bytes == 0) { fREe(oldmem); return 0; } +#endif + + + /* realloc of null is supposed to be same as malloc */ + if (oldmem == 0) return mALLOc(bytes); + + newp = oldp = mem2chunk(oldmem); + newsize = oldsize = chunksize(oldp); + + + nb = request2size(bytes); + +#if HAVE_MMAP + if (chunk_is_mmapped(oldp)) + { +#if HAVE_MREMAP + newp = mremap_chunk(oldp, nb); + if(newp) return chunk2mem(newp); +#endif + /* Note the extra SIZE_SZ overhead. */ + if(oldsize - SIZE_SZ >= nb) return oldmem; /* do nothing */ + /* Must alloc, copy, free. */ + newmem = mALLOc(bytes); + if (newmem == 0) return 0; /* propagate failure */ + MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ); + munmap_chunk(oldp); + return newmem; + } +#endif + + ar_ptr = arena_for_ptr(oldp); + (void)mutex_lock(&ar_ptr->mutex); + /* As in malloc(), remember this arena for the next allocation. */ + tsd_setspecific(arena_key, (Void_t *)ar_ptr); + + check_inuse_chunk(ar_ptr, oldp); + + if ((long)(oldsize) < (long)(nb)) + { + + /* Try expanding forward */ + + next = chunk_at_offset(oldp, oldsize); + if (next == top(ar_ptr) || !inuse(next)) + { + nextsize = chunksize(next); + + /* Forward into top only if a remainder */ + if (next == top(ar_ptr)) + { + if ((long)(nextsize + newsize) >= (long)(nb + MINSIZE)) + { + newsize += nextsize; + top(ar_ptr) = chunk_at_offset(oldp, nb); + set_head(top(ar_ptr), (newsize - nb) | PREV_INUSE); + set_head_size(oldp, nb); + (void)mutex_unlock(&ar_ptr->mutex); + return chunk2mem(oldp); + } + } + + /* Forward into next chunk */ + else if (((long)(nextsize + newsize) >= (long)(nb))) + { + unlink(next, bck, fwd); + newsize += nextsize; + goto split; + } + } + else + { + next = 0; + nextsize = 0; + } + + /* Try shifting backwards. */ + + if (!prev_inuse(oldp)) + { + prev = prev_chunk(oldp); + prevsize = chunksize(prev); + + /* try forward + backward first to save a later consolidation */ + + if (next != 0) + { + /* into top */ + if (next == top(ar_ptr)) + { + if ((long)(nextsize + prevsize + newsize) >= (long)(nb + MINSIZE)) + { + unlink(prev, bck, fwd); + newp = prev; + newsize += prevsize + nextsize; + newmem = chunk2mem(newp); + MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); + top(ar_ptr) = chunk_at_offset(newp, nb); + set_head(top(ar_ptr), (newsize - nb) | PREV_INUSE); + set_head_size(newp, nb); + (void)mutex_unlock(&ar_ptr->mutex); + return newmem; + } + } + + /* into next chunk */ + else if (((long)(nextsize + prevsize + newsize) >= (long)(nb))) + { + unlink(next, bck, fwd); + unlink(prev, bck, fwd); + newp = prev; + newsize += nextsize + prevsize; + newmem = chunk2mem(newp); + MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); + goto split; + } + } + + /* backward only */ + if (prev != 0 && (long)(prevsize + newsize) >= (long)nb) + { + unlink(prev, bck, fwd); + newp = prev; + newsize += prevsize; + newmem = chunk2mem(newp); + MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); + goto split; + } + } + + /* Must allocate */ + + newp = chunk_alloc (ar_ptr, nb); + + if (newp == 0) /* propagate failure */ + return 0; + + /* Avoid copy if newp is next chunk after oldp. */ + /* (This can only happen when new chunk is sbrk'ed.) */ + + if ( newp == next_chunk(oldp)) + { + newsize += chunksize(newp); + newp = oldp; + goto split; + } + + /* Otherwise copy, free, and exit */ + newmem = chunk2mem(newp); + MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); + chunk_free(ar_ptr, oldp); + (void)mutex_unlock(&ar_ptr->mutex); + return newmem; + } + + + split: /* split off extra room in old or expanded chunk */ + + if (newsize - nb >= MINSIZE) /* split off remainder */ + { + remainder = chunk_at_offset(newp, nb); + remainder_size = newsize - nb; + set_head_size(newp, nb); + set_head(remainder, remainder_size | PREV_INUSE); + set_inuse_bit_at_offset(remainder, remainder_size); + chunk_free(ar_ptr, remainder); + } + else + { + set_head_size(newp, newsize); + set_inuse_bit_at_offset(newp, newsize); + } + + check_inuse_chunk(ar_ptr, newp); + (void)mutex_unlock(&ar_ptr->mutex); + return chunk2mem(newp); +} + + + + +/* + + memalign algorithm: + + memalign requests more than enough space from malloc, finds a spot + within that chunk that meets the alignment request, and then + possibly frees the leading and trailing space. + + The alignment argument must be a power of two. This property is not + checked by memalign, so misuse may result in random runtime errors. + + 8-byte alignment is guaranteed by normal malloc calls, so don't + bother calling memalign with an argument of 8 or less. + + Overreliance on memalign is a sure way to fragment space. + +*/ + + +#if __STD_C +Void_t* mEMALIGn(size_t alignment, size_t bytes) +#else +Void_t* mEMALIGn(alignment, bytes) size_t alignment; size_t bytes; +#endif +{ + arena *ar_ptr; + INTERNAL_SIZE_T nb; /* padded request size */ + char* m; /* memory returned by malloc call */ + mchunkptr p; /* corresponding chunk */ + char* brk; /* alignment point within p */ + mchunkptr newp; /* chunk to return */ + INTERNAL_SIZE_T newsize; /* its size */ + INTERNAL_SIZE_T leadsize; /* leading space befor alignment point */ + mchunkptr remainder; /* spare room at end to split off */ + long remainder_size; /* its size */ + + /* If need less alignment than we give anyway, just relay to malloc */ + + if (alignment <= MALLOC_ALIGNMENT) return mALLOc(bytes); + + /* Otherwise, ensure that it is at least a minimum chunk size */ + + if (alignment < MINSIZE) alignment = MINSIZE; + + /* Call malloc with worst case padding to hit alignment. */ + + nb = request2size(bytes); + arena_get(ar_ptr, nb + alignment + MINSIZE); + if(!ar_ptr) + return 0; + p = chunk_alloc(ar_ptr, nb + alignment + MINSIZE); + + if (p == 0) { + (void)mutex_unlock(&ar_ptr->mutex); + return 0; /* propagate failure */ + } + + m = chunk2mem(p); + + if ((((unsigned long)(m)) % alignment) == 0) /* aligned */ + { +#if HAVE_MMAP + if(chunk_is_mmapped(p)) { + (void)mutex_unlock(&ar_ptr->mutex); + return chunk2mem(p); /* nothing more to do */ + } +#endif + } + else /* misaligned */ + { + /* + Find an aligned spot inside chunk. + Since we need to give back leading space in a chunk of at + least MINSIZE, if the first calculation places us at + a spot with less than MINSIZE leader, we can move to the + next aligned spot -- we've allocated enough total room so that + this is always possible. + */ + + brk = (char*)mem2chunk(((unsigned long)(m + alignment - 1)) & -alignment); + if ((long)(brk - (char*)(p)) < (long) MINSIZE) brk = brk + alignment; + + newp = (mchunkptr)brk; + leadsize = brk - (char*)(p); + newsize = chunksize(p) - leadsize; + +#if HAVE_MMAP + if(chunk_is_mmapped(p)) + { + newp->prev_size = p->prev_size + leadsize; + set_head(newp, newsize|IS_MMAPPED); + (void)mutex_unlock(&ar_ptr->mutex); + return chunk2mem(newp); + } +#endif + + /* give back leader, use the rest */ + + set_head(newp, newsize | PREV_INUSE); + set_inuse_bit_at_offset(newp, newsize); + set_head_size(p, leadsize); + chunk_free(ar_ptr, p); + p = newp; + + assert (newsize>=nb && (((unsigned long)(chunk2mem(p))) % alignment) == 0); + } + + /* Also give back spare room at the end */ + + remainder_size = chunksize(p) - nb; + + if (remainder_size >= (long)MINSIZE) + { + remainder = chunk_at_offset(p, nb); + set_head(remainder, remainder_size | PREV_INUSE); + set_head_size(p, nb); + chunk_free(ar_ptr, remainder); + } + + check_inuse_chunk(ar_ptr, p); + (void)mutex_unlock(&ar_ptr->mutex); + return chunk2mem(p); + +} + + + + +/* + valloc just invokes memalign with alignment argument equal + to the page size of the system (or as near to this as can + be figured out from all the includes/defines above.) +*/ + +#if __STD_C +Void_t* vALLOc(size_t bytes) +#else +Void_t* vALLOc(bytes) size_t bytes; +#endif +{ + return mEMALIGn (malloc_getpagesize, bytes); +} + +/* + pvalloc just invokes valloc for the nearest pagesize + that will accommodate request +*/ + + +#if __STD_C +Void_t* pvALLOc(size_t bytes) +#else +Void_t* pvALLOc(bytes) size_t bytes; +#endif +{ + size_t pagesize = malloc_getpagesize; + return mEMALIGn (pagesize, (bytes + pagesize - 1) & ~(pagesize - 1)); +} + +/* + + calloc calls malloc, then zeroes out the allocated chunk. + +*/ + +#if __STD_C +Void_t* cALLOc(size_t n, size_t elem_size) +#else +Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size; +#endif +{ + arena *ar_ptr; + mchunkptr p, oldtop; + INTERNAL_SIZE_T csz, oldtopsize; + Void_t* mem; + + INTERNAL_SIZE_T sz = request2size(n * elem_size); + + arena_get(ar_ptr, sz); + if(!ar_ptr) + return 0; + + /* check if expand_top called, in which case don't need to clear */ +#if MORECORE_CLEARS + oldtop = top(ar_ptr); + oldtopsize = chunksize(top(ar_ptr)); +#endif + p = chunk_alloc (ar_ptr, sz); + + /* Only clearing follows, so we can unlock early. */ + (void)mutex_unlock(&ar_ptr->mutex); + + if (p == 0) + return 0; + else + { + mem = chunk2mem(p); + + /* Two optional cases in which clearing not necessary */ + +#if HAVE_MMAP + if (chunk_is_mmapped(p)) return mem; +#endif + + csz = chunksize(p); + +#if MORECORE_CLEARS + if (p == oldtop && csz > oldtopsize) + { + /* clear only the bytes from non-freshly-sbrked memory */ + csz = oldtopsize; + } +#endif + + MALLOC_ZERO(mem, csz - SIZE_SZ); + return mem; + } +} + +/* + + cfree just calls free. It is needed/defined on some systems + that pair it with calloc, presumably for odd historical reasons. + +*/ + +#if !defined(_LIBC) +#if __STD_C +void cfree(Void_t *mem) +#else +void cfree(mem) Void_t *mem; +#endif +{ + free(mem); +} +#endif + + + +/* + + Malloc_trim gives memory back to the system (via negative + arguments to sbrk) if there is unused memory at the `high' end of + the malloc pool. You can call this after freeing large blocks of + memory to potentially reduce the system-level memory requirements + of a program. However, it cannot guarantee to reduce memory. Under + some allocation patterns, some large free blocks of memory will be + locked between two used chunks, so they cannot be given back to + the system. + + The `pad' argument to malloc_trim represents the amount of free + trailing space to leave untrimmed. If this argument is zero, + only the minimum amount of memory to maintain internal data + structures will be left (one page or less). Non-zero arguments + can be supplied to maintain enough trailing space to service + future expected allocations without having to re-obtain memory + from the system. + + Malloc_trim returns 1 if it actually released any memory, else 0. + +*/ + +#if __STD_C +int malloc_trim(size_t pad) +#else +int malloc_trim(pad) size_t pad; +#endif +{ + int res; + + (void)mutex_lock(&main_arena.mutex); + res = arena_trim(&main_arena, pad); + (void)mutex_unlock(&main_arena.mutex); + return res; +} + +static int +#if __STD_C +arena_trim(arena *ar_ptr, size_t pad) +#else +arena_trim(ar_ptr, pad) arena *ar_ptr; size_t pad; +#endif +{ + mchunkptr top_chunk; /* The current top chunk */ + long top_size; /* Amount of top-most memory */ + long extra; /* Amount to release */ + char* current_brk; /* address returned by pre-check sbrk call */ + char* new_brk; /* address returned by negative sbrk call */ + + unsigned long pagesz = malloc_getpagesize; + + top_chunk = top(ar_ptr); + top_size = chunksize(top_chunk); + extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz; + + if (extra < (long)pagesz) /* Not enough memory to release */ + return 0; + +#ifndef NO_THREADS + if(ar_ptr == &main_arena) { +#endif + + /* Test to make sure no one else called sbrk */ + current_brk = (char*)(MORECORE (0)); + if (current_brk != (char*)(top_chunk) + top_size) + return 0; /* Apparently we don't own memory; must fail */ + + new_brk = (char*)(MORECORE (-extra)); + + if (new_brk == (char*)(MORECORE_FAILURE)) { /* sbrk failed? */ + /* Try to figure out what we have */ + current_brk = (char*)(MORECORE (0)); + top_size = current_brk - (char*)top_chunk; + if (top_size >= (long)MINSIZE) /* if not, we are very very dead! */ + { + sbrked_mem = current_brk - sbrk_base; + set_head(top_chunk, top_size | PREV_INUSE); + } + check_chunk(ar_ptr, top_chunk); + return 0; + } + sbrked_mem -= extra; + +#ifndef NO_THREADS + } else { + if(grow_heap(heap_for_ptr(top_chunk), -extra) != 0) + return 0; + } +#endif + + /* Success. Adjust top accordingly. */ + set_head(top_chunk, (top_size - extra) | PREV_INUSE); + check_chunk(ar_ptr, top_chunk); + return 1; +} + + + +/* + malloc_usable_size: + + This routine tells you how many bytes you can actually use in an + allocated chunk, which may be more than you requested (although + often not). You can use this many bytes without worrying about + overwriting other allocated objects. Not a particularly great + programming practice, but still sometimes useful. + +*/ + +#if __STD_C +size_t malloc_usable_size(Void_t* mem) +#else +size_t malloc_usable_size(mem) Void_t* mem; +#endif +{ + mchunkptr p; + + if (mem == 0) + return 0; + else + { + p = mem2chunk(mem); + if(!chunk_is_mmapped(p)) + { + if (!inuse(p)) return 0; + check_inuse_chunk(arena_for_ptr(mem), p); + return chunksize(p) - SIZE_SZ; + } + return chunksize(p) - 2*SIZE_SZ; + } +} + + + + +/* Utility to update current_mallinfo for malloc_stats and mallinfo() */ + +static void malloc_update_mallinfo __MALLOC_P ((void)) +{ + arena *ar_ptr = &main_arena; + int i, navail; + mbinptr b; + mchunkptr p; +#if MALLOC_DEBUG + mchunkptr q; +#endif + INTERNAL_SIZE_T avail; + + (void)mutex_lock(&ar_ptr->mutex); + avail = chunksize(top(ar_ptr)); + navail = ((long)(avail) >= (long)MINSIZE)? 1 : 0; + + for (i = 1; i < NAV; ++i) + { + b = bin_at(ar_ptr, i); + for (p = last(b); p != b; p = p->bk) + { +#if MALLOC_DEBUG + check_free_chunk(ar_ptr, p); + for (q = next_chunk(p); + q < top(ar_ptr) && inuse(q) && (long)chunksize(q) >= (long)MINSIZE; + q = next_chunk(q)) + check_inuse_chunk(ar_ptr, q); +#endif + avail += chunksize(p); + navail++; + } + } + + current_mallinfo.ordblks = navail; + current_mallinfo.uordblks = sbrked_mem - avail; + current_mallinfo.fordblks = avail; + current_mallinfo.hblks = n_mmaps; + current_mallinfo.hblkhd = mmapped_mem; + current_mallinfo.keepcost = chunksize(top(ar_ptr)); + + (void)mutex_unlock(&ar_ptr->mutex); +} + + + +/* + + malloc_stats: + + Prints on stderr the amount of space obtain from the system (both + via sbrk and mmap), the maximum amount (which may be more than + current if malloc_trim and/or munmap got called), the maximum + number of simultaneous mmap regions used, and the current number + of bytes allocated via malloc (or realloc, etc) but not yet + freed. (Note that this is the number of bytes allocated, not the + number requested. It will be larger than the number requested + because of alignment and bookkeeping overhead.) + +*/ + +void malloc_stats() +{ + malloc_update_mallinfo(); + fprintf(stderr, "max system bytes = %10u\n", + (unsigned int)(max_total_mem)); + fprintf(stderr, "system bytes = %10u\n", + (unsigned int)(sbrked_mem + mmapped_mem)); + fprintf(stderr, "in use bytes = %10u\n", + (unsigned int)(current_mallinfo.uordblks + mmapped_mem)); +#if HAVE_MMAP + fprintf(stderr, "max mmap regions = %10u\n", + (unsigned int)max_n_mmaps); +#endif +#if THREAD_STATS + fprintf(stderr, "arenas created = %10d\n", stat_n_arenas); + fprintf(stderr, "heaps created = %10d\n", stat_n_heaps); + fprintf(stderr, "locked directly = %10ld\n", stat_lock_direct); + fprintf(stderr, "locked in loop = %10ld\n", stat_lock_loop); +#endif +} + +/* + mallinfo returns a copy of updated current mallinfo. +*/ + +struct mallinfo mALLINFo() +{ + malloc_update_mallinfo(); + return current_mallinfo; +} + + + + +/* + mallopt: + + mallopt is the general SVID/XPG interface to tunable parameters. + The format is to provide a (parameter-number, parameter-value) pair. + mallopt then sets the corresponding parameter to the argument + value if it can (i.e., so long as the value is meaningful), + and returns 1 if successful else 0. + + See descriptions of tunable parameters above. + +*/ + +#if __STD_C +int mALLOPt(int param_number, int value) +#else +int mALLOPt(param_number, value) int param_number; int value; +#endif +{ + switch(param_number) + { + case M_TRIM_THRESHOLD: + trim_threshold = value; return 1; + case M_TOP_PAD: + top_pad = value; return 1; + case M_MMAP_THRESHOLD: +#ifndef NO_THREADS + /* Forbid setting the threshold too high. */ + if((unsigned long)value > HEAP_MAX_SIZE/2) return 0; +#endif + mmap_threshold = value; return 1; + case M_MMAP_MAX: +#if HAVE_MMAP + n_mmaps_max = value; return 1; +#else + if (value != 0) return 0; else n_mmaps_max = value; return 1; +#endif + + default: + return 0; + } +} + +#if 0 && defined(_LIBC) +weak_alias (__libc_calloc, calloc) +weak_alias (__libc_free, cfree) +weak_alias (__libc_free, free) +weak_alias (__libc_malloc, malloc) +weak_alias (__libc_memalign, memalign) +weak_alias (__libc_realloc, realloc) +weak_alias (__libc_valloc, valloc) +weak_alias (__libc_pvalloc, pvalloc) +weak_alias (__libc_mallinfo, mallinfo) +weak_alias (__libc_mallopt, mallopt) +#endif + +/* + +History: + + V2.6.4-pt Wed Dec 4 1996 Wolfram Gloger (wmglo@dent.med.uni-muenchen.de) + * Very minor updates from the released 2.6.4 version. + * Trimmed include file down to exported data structures. + * Changes from H.J. Lu for glibc-2.0. + + V2.6.3i-pt Sep 16 1996 Wolfram Gloger (wmglo@dent.med.uni-muenchen.de) + * Many changes for multiple threads + * Introduced arenas and heaps + + V2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee) + * Added pvalloc, as recommended by H.J. Liu + * Added 64bit pointer support mainly from Wolfram Gloger + * Added anonymously donated WIN32 sbrk emulation + * Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen + * malloc_extend_top: fix mask error that caused wastage after + foreign sbrks + * Add linux mremap support code from HJ Liu + + V2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee) + * Integrated most documentation with the code. + * Add support for mmap, with help from + Wolfram Gloger (Gloger@lrz.uni-muenchen.de). + * Use last_remainder in more cases. + * Pack bins using idea from colin@nyx10.cs.du.edu + * Use ordered bins instead of best-fit threshhold + * Eliminate block-local decls to simplify tracing and debugging. + * Support another case of realloc via move into top + * Fix error occuring when initial sbrk_base not word-aligned. + * Rely on page size for units instead of SBRK_UNIT to + avoid surprises about sbrk alignment conventions. + * Add mallinfo, mallopt. Thanks to Raymond Nijssen + (raymond@es.ele.tue.nl) for the suggestion. + * Add `pad' argument to malloc_trim and top_pad mallopt parameter. + * More precautions for cases where other routines call sbrk, + courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de). + * Added macros etc., allowing use in linux libc from + H.J. Lu (hjl@gnu.ai.mit.edu) + * Inverted this history list + + V2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee) + * Re-tuned and fixed to behave more nicely with V2.6.0 changes. + * Removed all preallocation code since under current scheme + the work required to undo bad preallocations exceeds + the work saved in good cases for most test programs. + * No longer use return list or unconsolidated bins since + no scheme using them consistently outperforms those that don't + given above changes. + * Use best fit for very large chunks to prevent some worst-cases. + * Added some support for debugging + + V2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee) + * Removed footers when chunks are in use. Thanks to + Paul Wilson (wilson@cs.texas.edu) for the suggestion. + + V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee) + * Added malloc_trim, with help from Wolfram Gloger + (wmglo@Dent.MED.Uni-Muenchen.DE). + + V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g) + + V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g) + * realloc: try to expand in both directions + * malloc: swap order of clean-bin strategy; + * realloc: only conditionally expand backwards + * Try not to scavenge used bins + * Use bin counts as a guide to preallocation + * Occasionally bin return list chunks in first scan + * Add a few optimizations from colin@nyx10.cs.du.edu + + V2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g) + * faster bin computation & slightly different binning + * merged all consolidations to one part of malloc proper + (eliminating old malloc_find_space & malloc_clean_bin) + * Scan 2 returns chunks (not just 1) + * Propagate failure in realloc if malloc returns 0 + * Add stuff to allow compilation on non-ANSI compilers + from kpv@research.att.com + + V2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu) + * removed potential for odd address access in prev_chunk + * removed dependency on getpagesize.h + * misc cosmetics and a bit more internal documentation + * anticosmetics: mangled names in macros to evade debugger strangeness + * tested on sparc, hp-700, dec-mips, rs6000 + with gcc & native cc (hp, dec only) allowing + Detlefs & Zorn comparison study (in SIGPLAN Notices.) + + Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu) + * Based loosely on libg++-1.2X malloc. (It retains some of the overall + structure of old version, but most details differ.) + +*/ |