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authorUlrich Drepper <drepper@redhat.com>2002-01-29 07:54:51 +0000
committerUlrich Drepper <drepper@redhat.com>2002-01-29 07:54:51 +0000
commitfa8d436c87f156d18208df3819fecee9fc1dbd9e (patch)
treee22f5754d69c0144f0945a26727c3984008f9d37 /malloc/arena.c
parentdb2ebcef2428cb568315895f8fe3ef19d41735bc (diff)
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Update.
2002-01-18 Wolfram Gloger <wg@malloc.de> * malloc/malloc.c: Rewrite, adapted from Doug Lea's malloc-2.7.0.c. * malloc/malloc.h: Likewise. * malloc/arena.c: New file. * malloc/hooks.c: New file. * malloc/tst-mallocstate.c: New file. * malloc/Makefile: Add new testcase tst-mallocstate. Add arena.c and hooks.c to distribute. Fix commented CPPFLAGS. 2002-01-28 Ulrich Drepper <drepper@redhat.com> * stdlib/msort.c: Remove last patch. The optimization violates the same rule which qsort.c had problems with. 2002-01-27 Paul Eggert <eggert@twinsun.com> * stdlib/qsort.c (_quicksort): Do not apply the comparison function to a pivot element that lies outside the array to be sorted, as ISO C99 requires that the comparison function be called only with addresses of array elements [PR libc/2880].
Diffstat (limited to 'malloc/arena.c')
-rw-r--r--malloc/arena.c746
1 files changed, 746 insertions, 0 deletions
diff --git a/malloc/arena.c b/malloc/arena.c
new file mode 100644
index 0000000..8324b68
--- /dev/null
+++ b/malloc/arena.c
@@ -0,0 +1,746 @@
+/* Malloc implementation for multiple threads without lock contention.
+ Copyright (C) 2001 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Wolfram Gloger <wg@malloc.de>, 2001.
+
+ 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. */
+
+/* $Id$ */
+
+/* Compile-time constants. */
+
+#define HEAP_MIN_SIZE (32*1024)
+#ifndef HEAP_MAX_SIZE
+#define HEAP_MAX_SIZE (1024*1024) /* must be a power of two */
+#endif
+
+/* 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. */
+
+/***************************************************************************/
+
+#define top(ar_ptr) ((ar_ptr)->top)
+
+/* A heap is a single contiguous memory region holding (coalesceable)
+ malloc_chunks. It is allocated with mmap() and always starts at an
+ address aligned to HEAP_MAX_SIZE. Not used unless compiling with
+ USE_ARENAS. */
+
+typedef struct _heap_info {
+ mstate ar_ptr; /* Arena for this heap. */
+ struct _heap_info *prev; /* Previous heap. */
+ size_t size; /* Current size in bytes. */
+ size_t pad; /* Make sure the following data is properly aligned. */
+} heap_info;
+
+/* Thread specific data */
+
+static tsd_key_t arena_key;
+static mutex_t list_lock;
+
+#if THREAD_STATS
+static int stat_n_heaps;
+#define THREAD_STAT(x) x
+#else
+#define THREAD_STAT(x) do ; while(0)
+#endif
+
+/* Mapped memory in non-main arenas (reliable only for NO_THREADS). */
+static unsigned long arena_mem;
+
+/**************************************************************************/
+
+#if USE_ARENAS
+
+/* 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
+ once over the circularly linked list of arenas. If no arena is
+ readily available, create a new one. In this latter case, `size'
+ is just a hint as to how much memory will be required immediately
+ in the new arena. */
+
+#define arena_get(ptr, size) do { \
+ Void_t *vptr = NULL; \
+ ptr = (mstate)tsd_getspecific(arena_key, vptr); \
+ if(ptr && !mutex_trylock(&ptr->mutex)) { \
+ THREAD_STAT(++(ptr->stat_lock_direct)); \
+ } else \
+ ptr = arena_get2(ptr, (size)); \
+} while(0)
+
+/* 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_chunk(ptr) \
+ (chunk_non_main_arena(ptr) ? heap_for_ptr(ptr)->ar_ptr : &main_arena)
+
+#else /* !USE_ARENAS */
+
+/* There is only one arena, main_arena. */
+
+#if THREAD_STATS
+#define arena_get(ar_ptr, sz) do { \
+ ar_ptr = &main_arena; \
+ if(!mutex_trylock(&ar_ptr->mutex)) \
+ ++(ar_ptr->stat_lock_direct); \
+ else { \
+ (void)mutex_lock(&ar_ptr->mutex); \
+ ++(ar_ptr->stat_lock_wait); \
+ } \
+} while(0)
+#else
+#define arena_get(ar_ptr, sz) do { \
+ ar_ptr = &main_arena; \
+ (void)mutex_lock(&ar_ptr->mutex); \
+} while(0)
+#endif
+#define arena_for_chunk(ptr) (&main_arena)
+
+#endif /* USE_ARENAS */
+
+/**************************************************************************/
+
+#ifndef NO_THREADS
+
+/* atfork support. */
+
+static __malloc_ptr_t (*save_malloc_hook) __MALLOC_P ((size_t __size,
+ __const __malloc_ptr_t));
+static void (*save_free_hook) __MALLOC_P ((__malloc_ptr_t __ptr,
+ __const __malloc_ptr_t));
+static Void_t* save_arena;
+
+/* Magic value for the thread-specific arena pointer when
+ malloc_atfork() is in use. */
+
+#define ATFORK_ARENA_PTR ((Void_t*)-1)
+
+/* The following hooks are used while the `atfork' handling mechanism
+ is active. */
+
+static Void_t*
+malloc_atfork(size_t sz, const Void_t *caller)
+{
+ Void_t *vptr = NULL;
+ Void_t *victim;
+
+ tsd_getspecific(arena_key, vptr);
+ if(vptr == ATFORK_ARENA_PTR) {
+ /* We are the only thread that may allocate at all. */
+ if(save_malloc_hook != malloc_check) {
+ return _int_malloc(&main_arena, sz);
+ } else {
+ if(top_check()<0)
+ return 0;
+ victim = _int_malloc(&main_arena, sz+1);
+ return mem2mem_check(victim, sz);
+ }
+ } else {
+ /* Suspend the thread until the `atfork' handlers have completed.
+ By that time, the hooks will have been reset as well, so that
+ mALLOc() can be used again. */
+ (void)mutex_lock(&list_lock);
+ (void)mutex_unlock(&list_lock);
+ return public_mALLOc(sz);
+ }
+}
+
+static void
+free_atfork(Void_t* mem, const Void_t *caller)
+{
+ Void_t *vptr = NULL;
+ mstate ar_ptr;
+ mchunkptr p; /* chunk corresponding to mem */
+
+ if (mem == 0) /* free(0) has no effect */
+ return;
+
+ p = mem2chunk(mem); /* do not bother to replicate free_check here */
+
+#if HAVE_MMAP
+ if (chunk_is_mmapped(p)) /* release mmapped memory. */
+ {
+ munmap_chunk(p);
+ return;
+ }
+#endif
+
+ ar_ptr = arena_for_chunk(p);
+ tsd_getspecific(arena_key, vptr);
+ if(vptr != ATFORK_ARENA_PTR)
+ (void)mutex_lock(&ar_ptr->mutex);
+ _int_free(ar_ptr, mem);
+ if(vptr != ATFORK_ARENA_PTR)
+ (void)mutex_unlock(&ar_ptr->mutex);
+}
+
+/* The following two functions are registered via thread_atfork() to
+ make sure that the mutexes remain in a consistent state in the
+ fork()ed version of a thread. Also adapt the malloc and free hooks
+ temporarily, because the `atfork' handler mechanism may use
+ malloc/free internally (e.g. in LinuxThreads). */
+
+static void
+ptmalloc_lock_all __MALLOC_P((void))
+{
+ mstate ar_ptr;
+
+ (void)mutex_lock(&list_lock);
+ for(ar_ptr = &main_arena;;) {
+ (void)mutex_lock(&ar_ptr->mutex);
+ ar_ptr = ar_ptr->next;
+ if(ar_ptr == &main_arena) break;
+ }
+ save_malloc_hook = __malloc_hook;
+ save_free_hook = __free_hook;
+ __malloc_hook = malloc_atfork;
+ __free_hook = free_atfork;
+ /* Only the current thread may perform malloc/free calls now. */
+ tsd_getspecific(arena_key, save_arena);
+ tsd_setspecific(arena_key, ATFORK_ARENA_PTR);
+}
+
+static void
+ptmalloc_unlock_all __MALLOC_P((void))
+{
+ mstate ar_ptr;
+
+ tsd_setspecific(arena_key, save_arena);
+ __malloc_hook = save_malloc_hook;
+ __free_hook = save_free_hook;
+ for(ar_ptr = &main_arena;;) {
+ (void)mutex_unlock(&ar_ptr->mutex);
+ ar_ptr = ar_ptr->next;
+ if(ar_ptr == &main_arena) break;
+ }
+ (void)mutex_unlock(&list_lock);
+}
+
+#ifdef __linux__
+
+/* In LinuxThreads, unlocking a mutex in the child process after a
+ fork() is currently unsafe, whereas re-initializing it is safe and
+ does not leak resources. Therefore, a special atfork handler is
+ installed for the child. */
+
+static void
+ptmalloc_unlock_all2 __MALLOC_P((void))
+{
+ mstate ar_ptr;
+
+#if defined _LIBC || defined MALLOC_HOOKS
+ tsd_setspecific(arena_key, save_arena);
+ __malloc_hook = save_malloc_hook;
+ __free_hook = save_free_hook;
+#endif
+ for(ar_ptr = &main_arena;;) {
+ (void)mutex_init(&ar_ptr->mutex);
+ ar_ptr = ar_ptr->next;
+ if(ar_ptr == &main_arena) break;
+ }
+ (void)mutex_init(&list_lock);
+}
+
+#else
+
+#define ptmalloc_unlock_all2 ptmalloc_unlock_all
+
+#endif
+
+#endif /* !defined NO_THREADS */
+
+/* Already initialized? */
+int __malloc_initialized = -1;
+
+/* Initialization routine. */
+#ifdef _LIBC
+#include <string.h>
+extern char **_environ;
+
+static char *
+internal_function
+next_env_entry (char ***position)
+{
+ char **current = *position;
+ char *result = NULL;
+
+ while (*current != NULL)
+ {
+ if (__builtin_expect ((*current)[0] == 'M', 0)
+ && (*current)[1] == 'A'
+ && (*current)[2] == 'L'
+ && (*current)[3] == 'L'
+ && (*current)[4] == 'O'
+ && (*current)[5] == 'C'
+ && (*current)[6] == '_')
+ {
+ result = &(*current)[7];
+
+ /* Save current position for next visit. */
+ *position = ++current;
+
+ break;
+ }
+
+ ++current;
+ }
+
+ return result;
+}
+#endif /* _LIBC */
+
+static void
+ptmalloc_init __MALLOC_P((void))
+{
+#if __STD_C
+ const char* s;
+#else
+ char* s;
+#endif
+ int secure = 0;
+
+ if(__malloc_initialized >= 0) return;
+ __malloc_initialized = 0;
+
+ mp_.top_pad = DEFAULT_TOP_PAD;
+ mp_.n_mmaps_max = DEFAULT_MMAP_MAX;
+ mp_.mmap_threshold = DEFAULT_MMAP_THRESHOLD;
+ mp_.trim_threshold = DEFAULT_TRIM_THRESHOLD;
+ mp_.pagesize = malloc_getpagesize;
+
+#ifndef NO_THREADS
+ /* With some threads implementations, creating thread-specific data
+ or initializing a mutex may call malloc() itself. Provide a
+ simple starter version (realloc() won't work). */
+ save_malloc_hook = __malloc_hook;
+ save_free_hook = __free_hook;
+ __malloc_hook = malloc_starter;
+ __free_hook = free_starter;
+#ifdef _LIBC
+ /* Initialize the pthreads interface. */
+ if (__pthread_initialize != NULL)
+ __pthread_initialize();
+#endif
+#endif /* !defined NO_THREADS */
+ mutex_init(&main_arena.mutex);
+ main_arena.next = &main_arena;
+
+ mutex_init(&list_lock);
+ tsd_key_create(&arena_key, NULL);
+ tsd_setspecific(arena_key, (Void_t *)&main_arena);
+ thread_atfork(ptmalloc_lock_all, ptmalloc_unlock_all, ptmalloc_unlock_all2);
+#ifndef NO_THREADS
+ __malloc_hook = save_malloc_hook;
+ __free_hook = save_free_hook;
+#endif
+#ifdef _LIBC
+ secure = __libc_enable_secure;
+ s = NULL;
+ {
+ char **runp = _environ;
+ char *envline;
+
+ while (__builtin_expect ((envline = next_env_entry (&runp)) != NULL,
+ 0))
+ {
+ size_t len = strcspn (envline, "=");
+
+ if (envline[len] != '=')
+ /* This is a "MALLOC_" variable at the end of the string
+ without a '=' character. Ignore it since otherwise we
+ will access invalid memory below. */
+ continue;
+
+ switch (len)
+ {
+ case 6:
+ if (memcmp (envline, "CHECK_", 6) == 0)
+ s = &envline[7];
+ break;
+ case 8:
+ if (! secure && memcmp (envline, "TOP_PAD_", 8) == 0)
+ mALLOPt(M_TOP_PAD, atoi(&envline[9]));
+ break;
+ case 9:
+ if (! secure && memcmp (envline, "MMAP_MAX_", 9) == 0)
+ mALLOPt(M_MMAP_MAX, atoi(&envline[10]));
+ break;
+ case 15:
+ if (! secure)
+ {
+ if (memcmp (envline, "TRIM_THRESHOLD_", 15) == 0)
+ mALLOPt(M_TRIM_THRESHOLD, atoi(&envline[16]));
+ else if (memcmp (envline, "MMAP_THRESHOLD_", 15) == 0)
+ mALLOPt(M_MMAP_THRESHOLD, atoi(&envline[16]));
+ }
+ break;
+ default:
+ break;
+ }
+ }
+ }
+#else
+ if (! secure)
+ {
+ if((s = getenv("MALLOC_TRIM_THRESHOLD_")))
+ mALLOPt(M_TRIM_THRESHOLD, atoi(s));
+ if((s = getenv("MALLOC_TOP_PAD_")))
+ mALLOPt(M_TOP_PAD, atoi(s));
+ if((s = getenv("MALLOC_MMAP_THRESHOLD_")))
+ mALLOPt(M_MMAP_THRESHOLD, atoi(s));
+ if((s = getenv("MALLOC_MMAP_MAX_")))
+ mALLOPt(M_MMAP_MAX, atoi(s));
+ }
+ s = getenv("MALLOC_CHECK_");
+#endif
+ if(s) {
+ if(s[0]) mALLOPt(M_CHECK_ACTION, (int)(s[0] - '0'));
+ __malloc_check_init();
+ }
+ if(__malloc_initialize_hook != NULL)
+ (*__malloc_initialize_hook)();
+ __malloc_initialized = 1;
+}
+
+/* There are platforms (e.g. Hurd) with a link-time hook mechanism. */
+#ifdef thread_atfork_static
+thread_atfork_static(ptmalloc_lock_all, ptmalloc_unlock_all, \
+ ptmalloc_unlock_all2)
+#endif
+
+
+
+/* Managing heaps and arenas (for concurrent threads) */
+
+#if USE_ARENAS
+
+#if MALLOC_DEBUG > 1
+
+/* Print the complete contents of a single heap to stderr. */
+
+static void
+#if __STD_C
+dump_heap(heap_info *heap)
+#else
+dump_heap(heap) heap_info *heap;
+#endif
+{
+ char *ptr;
+ mchunkptr p;
+
+ fprintf(stderr, "Heap %p, size %10lx:\n", heap, (long)heap->size);
+ ptr = (heap->ar_ptr != (mstate)(heap+1)) ?
+ (char*)(heap + 1) : (char*)(heap + 1) + sizeof(struct malloc_state);
+ p = (mchunkptr)(((unsigned long)ptr + MALLOC_ALIGN_MASK) &
+ ~MALLOC_ALIGN_MASK);
+ for(;;) {
+ fprintf(stderr, "chunk %p size %10lx", p, (long)p->size);
+ if(p == top(heap->ar_ptr)) {
+ fprintf(stderr, " (top)\n");
+ break;
+ } else if(p->size == (0|PREV_INUSE)) {
+ fprintf(stderr, " (fence)\n");
+ break;
+ }
+ fprintf(stderr, "\n");
+ p = next_chunk(p);
+ }
+}
+
+#endif /* MALLOC_DEBUG > 1 */
+
+/* Create a new heap. size is automatically rounded up to a multiple
+ of the page size. */
+
+static heap_info *
+internal_function
+#if __STD_C
+new_heap(size_t size, size_t top_pad)
+#else
+new_heap(size, top_pad) size_t size, top_pad;
+#endif
+{
+ size_t page_mask = malloc_getpagesize - 1;
+ char *p1, *p2;
+ unsigned long ul;
+ heap_info *h;
+
+ if(size+top_pad < HEAP_MIN_SIZE)
+ size = HEAP_MIN_SIZE;
+ else if(size+top_pad <= HEAP_MAX_SIZE)
+ size += top_pad;
+ else if(size > HEAP_MAX_SIZE)
+ return 0;
+ else
+ size = HEAP_MAX_SIZE;
+ size = (size + page_mask) & ~page_mask;
+
+ /* A memory region aligned to a multiple of HEAP_MAX_SIZE is needed.
+ No swap space needs to be reserved for the following large
+ mapping (on Linux, this is the case for all non-writable mappings
+ anyway). */
+ p1 = (char *)MMAP(0, HEAP_MAX_SIZE<<1, PROT_NONE, MAP_PRIVATE|MAP_NORESERVE);
+ if(p1 != MAP_FAILED) {
+ p2 = (char *)(((unsigned long)p1 + (HEAP_MAX_SIZE-1)) & ~(HEAP_MAX_SIZE-1));
+ ul = p2 - p1;
+ munmap(p1, ul);
+ munmap(p2 + HEAP_MAX_SIZE, HEAP_MAX_SIZE - ul);
+ } else {
+ /* Try to take the chance that an allocation of only HEAP_MAX_SIZE
+ is already aligned. */
+ p2 = (char *)MMAP(0, HEAP_MAX_SIZE, PROT_NONE, MAP_PRIVATE|MAP_NORESERVE);
+ if(p2 == MAP_FAILED)
+ return 0;
+ if((unsigned long)p2 & (HEAP_MAX_SIZE-1)) {
+ munmap(p2, HEAP_MAX_SIZE);
+ return 0;
+ }
+ }
+ 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 if it is positive. */
+
+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 < (long)sizeof(*h))
+ return -1;
+ /* Try to re-map the extra heap space freshly to save memory, and
+ make it inaccessible. */
+ if((char *)MMAP((char *)h + new_size, -diff, PROT_NONE,
+ MAP_PRIVATE|MAP_FIXED) == (char *) MAP_FAILED)
+ return -2;
+ /*fprintf(stderr, "shrink %p %08lx\n", h, new_size);*/
+ }
+ h->size = new_size;
+ return 0;
+}
+
+/* Delete a heap. */
+
+#define delete_heap(heap) munmap((char*)(heap), HEAP_MAX_SIZE)
+
+static int
+internal_function
+#if __STD_C
+heap_trim(heap_info *heap, size_t pad)
+#else
+heap_trim(heap, pad) heap_info *heap; size_t pad;
+#endif
+{
+ mstate ar_ptr = heap->ar_ptr;
+ unsigned long pagesz = mp_.pagesize;
+ mchunkptr top_chunk = top(ar_ptr), p, bck, fwd;
+ heap_info *prev_heap;
+ long new_size, top_size, extra;
+
+ /* Can this heap go away completely? */
+ while(top_chunk == chunk_at_offset(heap, sizeof(*heap))) {
+ prev_heap = heap->prev;
+ p = chunk_at_offset(prev_heap, prev_heap->size - (MINSIZE-2*SIZE_SZ));
+ assert(p->size == (0|PREV_INUSE)); /* must be fencepost */
+ p = prev_chunk(p);
+ new_size = chunksize(p) + (MINSIZE-2*SIZE_SZ);
+ assert(new_size>0 && new_size<(long)(2*MINSIZE));
+ if(!prev_inuse(p))
+ new_size += p->prev_size;
+ assert(new_size>0 && new_size<HEAP_MAX_SIZE);
+ if(new_size + (HEAP_MAX_SIZE - prev_heap->size) < pad + MINSIZE + pagesz)
+ break;
+ ar_ptr->system_mem -= heap->size;
+ arena_mem -= heap->size;
+ delete_heap(heap);
+ heap = prev_heap;
+ if(!prev_inuse(p)) { /* consolidate backward */
+ p = prev_chunk(p);
+ unlink(p, bck, fwd);
+ }
+ assert(((unsigned long)((char*)p + new_size) & (pagesz-1)) == 0);
+ assert( ((char*)p + new_size) == ((char*)heap + heap->size) );
+ top(ar_ptr) = top_chunk = p;
+ set_head(top_chunk, new_size | PREV_INUSE);
+ /*check_chunk(ar_ptr, top_chunk);*/
+ }
+ top_size = chunksize(top_chunk);
+ extra = ((top_size - pad - MINSIZE + (pagesz-1))/pagesz - 1) * pagesz;
+ if(extra < (long)pagesz)
+ return 0;
+ /* Try to shrink. */
+ if(grow_heap(heap, -extra) != 0)
+ return 0;
+ ar_ptr->system_mem -= extra;
+ arena_mem -= extra;
+
+ /* Success. Adjust top accordingly. */
+ set_head(top_chunk, (top_size - extra) | PREV_INUSE);
+ /*check_chunk(ar_ptr, top_chunk);*/
+ return 1;
+}
+
+static mstate
+internal_function
+#if __STD_C
+arena_get2(mstate a_tsd, size_t size)
+#else
+arena_get2(a_tsd, size) mstate a_tsd; size_t size;
+#endif
+{
+ mstate a;
+ int err;
+
+ if(!a_tsd)
+ a = a_tsd = &main_arena;
+ else {
+ a = a_tsd->next;
+ if(!a) {
+ /* This can only happen while initializing the new arena. */
+ (void)mutex_lock(&main_arena.mutex);
+ THREAD_STAT(++(main_arena.stat_lock_wait));
+ return &main_arena;
+ }
+ }
+
+ /* Check the global, circularly linked list for available arenas. */
+ repeat:
+ do {
+ if(!mutex_trylock(&a->mutex)) {
+ THREAD_STAT(++(a->stat_lock_loop));
+ tsd_setspecific(arena_key, (Void_t *)a);
+ return a;
+ }
+ a = a->next;
+ } while(a != a_tsd);
+
+ /* If not even the list_lock can be obtained, try again. This can
+ happen during `atfork', or for example on systems where thread
+ creation makes it temporarily impossible to obtain _any_
+ locks. */
+ if(mutex_trylock(&list_lock)) {
+ a = a_tsd;
+ goto repeat;
+ }
+ (void)mutex_unlock(&list_lock);
+
+ /* Nothing immediately available, so generate a new arena. */
+ a = _int_new_arena(size);
+ if(!a)
+ return 0;
+
+ tsd_setspecific(arena_key, (Void_t *)a);
+ mutex_init(&a->mutex);
+ err = mutex_lock(&a->mutex); /* remember result */
+
+ /* Add the new arena to the global list. */
+ (void)mutex_lock(&list_lock);
+ a->next = main_arena.next;
+ main_arena.next = a;
+ (void)mutex_unlock(&list_lock);
+
+ if(err) /* locking failed; keep arena for further attempts later */
+ return 0;
+
+ THREAD_STAT(++(a->stat_lock_loop));
+ return a;
+}
+
+/* Create a new arena with initial size "size". */
+
+mstate
+_int_new_arena(size_t size)
+{
+ mstate a;
+ heap_info *h;
+ char *ptr;
+ unsigned long misalign;
+
+ h = new_heap(size + (sizeof(*h) + sizeof(*a) + MALLOC_ALIGNMENT),
+ mp_.top_pad);
+ if(!h) {
+ /* Maybe size is too large to fit in a single heap. So, just try
+ to create a minimally-sized arena and let _int_malloc() attempt
+ to deal with the large request via mmap_chunk(). */
+ h = new_heap(sizeof(*h) + sizeof(*a) + MALLOC_ALIGNMENT, mp_.top_pad);
+ if(!h)
+ return 0;
+ }
+ a = h->ar_ptr = (mstate)(h+1);
+ malloc_init_state(a);
+ /*a->next = NULL;*/
+ a->system_mem = a->max_system_mem = h->size;
+ arena_mem += h->size;
+#ifdef NO_THREADS
+ if((unsigned long)(mp_.mmapped_mem + arena_mem + main_arena.system_mem) >
+ mp_.max_total_mem)
+ mp_.max_total_mem = mp_.mmapped_mem + arena_mem + main_arena.system_mem;
+#endif
+
+ /* 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), (((char*)h + h->size) - ptr) | PREV_INUSE);
+
+ return a;
+}
+
+#endif /* USE_ARENAS */
+
+/*
+ * Local variables:
+ * c-basic-offset: 2
+ * End:
+ */