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Diffstat (limited to 'libjava/java/lang/natObject.cc')
| -rw-r--r-- | libjava/java/lang/natObject.cc | 1457 |
1 files changed, 0 insertions, 1457 deletions
diff --git a/libjava/java/lang/natObject.cc b/libjava/java/lang/natObject.cc deleted file mode 100644 index 1a66640..0000000 --- a/libjava/java/lang/natObject.cc +++ /dev/null @@ -1,1457 +0,0 @@ -// natObject.cc - Implementation of the Object class. - -/* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2005 Free Software Foundation - - This file is part of libgcj. - -This software is copyrighted work licensed under the terms of the -Libgcj License. Please consult the file "LIBGCJ_LICENSE" for -details. */ - -#include <config.h> -#include <platform.h> - -#include <string.h> - -#pragma implementation "Object.h" - -#include <gcj/cni.h> -#include <jvm.h> -#include <java/lang/Object.h> -#include <java-threads.h> -#include <java-signal.h> -#include <java/lang/CloneNotSupportedException.h> -#include <java/lang/IllegalArgumentException.h> -#include <java/lang/IllegalMonitorStateException.h> -#include <java/lang/InterruptedException.h> -#include <java/lang/NullPointerException.h> -#include <java/lang/Class.h> -#include <java/lang/Cloneable.h> -#include <java/lang/Thread.h> - -#ifdef LOCK_DEBUG -# include <stdio.h> -#endif - - - -using namespace java::lang; - -// This is used to represent synchronization information. -struct _Jv_SyncInfo -{ -#if defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) - // We only need to keep track of initialization state if we can - // possibly finalize this object. - bool init; -#endif - _Jv_ConditionVariable_t condition; - _Jv_Mutex_t mutex; -}; - - - -jclass -java::lang::Object::getClass (void) -{ - _Jv_VTable **dt = (_Jv_VTable **) this; - return (*dt)->clas; -} - -jint -java::lang::Object::hashCode (void) -{ - return _Jv_HashCode (this); -} - -jobject -java::lang::Object::clone (void) -{ - jclass klass = getClass (); - jobject r; - jint size; - - // We also clone arrays here. If we put the array code into - // __JArray, then we'd have to figure out a way to find the array - // vtbl when creating a new array class. This is easier, if uglier. - if (klass->isArray()) - { - __JArray *array = (__JArray *) this; - jclass comp = getClass()->getComponentType(); - jint eltsize; - if (comp->isPrimitive()) - { - r = _Jv_NewPrimArray (comp, array->length); - eltsize = comp->size(); - } - else - { - r = _Jv_NewObjectArray (array->length, comp, NULL); - eltsize = sizeof (jobject); - } - // We can't use sizeof on __JArray because we must account for - // alignment of the element type. - size = (_Jv_GetArrayElementFromElementType (array, comp) - (char *) array - + array->length * eltsize); - } - else - { - if (! java::lang::Cloneable::class$.isAssignableFrom(klass)) - throw new CloneNotSupportedException; - - size = klass->size(); - r = _Jv_AllocObject (klass); - } - - memcpy ((void *) r, (void *) this, size); -#ifndef JV_HASH_SYNCHRONIZATION - // Guarantee that the locks associated to the two objects are - // distinct. - r->sync_info = NULL; -#endif - return r; -} - -void -_Jv_FinalizeObject (jobject obj) -{ - // Ignore exceptions. From section 12.6 of the Java Language Spec. - try - { - obj->finalize (); - } - catch (java::lang::Throwable *t) - { - // Ignore. - } -} - - -// -// Synchronization code. -// - -#ifndef JV_HASH_SYNCHRONIZATION -// This global is used to make sure that only one thread sets an -// object's `sync_info' field. -static _Jv_Mutex_t sync_mutex; - -// This macro is used to see if synchronization initialization is -// needed. -#if defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) -# define INIT_NEEDED(Obj) (! (Obj)->sync_info \ - || ! ((_Jv_SyncInfo *) ((Obj)->sync_info))->init) -#else -# define INIT_NEEDED(Obj) (! (Obj)->sync_info) -#endif - -#if defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) -// If we have to run a destructor for a sync_info member, then this -// function is registered as a finalizer for the sync_info. -static void -finalize_sync_info (jobject obj) -{ - _Jv_SyncInfo *si = (_Jv_SyncInfo *) obj; -#if defined (_Jv_HaveCondDestroy) - _Jv_CondDestroy (&si->condition); -#endif -#if defined (_Jv_HaveMutexDestroy) - _Jv_MutexDestroy (&si->mutex); -#endif - si->init = false; -} -#endif - -// This is called to initialize the sync_info element of an object. -void -java::lang::Object::sync_init (void) -{ - _Jv_MutexLock (&sync_mutex); - // Check again to see if initialization is needed now that we have - // the lock. - if (INIT_NEEDED (this)) - { - // We assume there are no pointers in the sync_info - // representation. - _Jv_SyncInfo *si; - // We always create a new sync_info, even if there is already - // one available. Any given object can only be finalized once. - // If we get here and sync_info is not null, then it has already - // been finalized. So if we just reinitialize the old one, - // we'll never be able to (re-)destroy the mutex and/or - // condition variable. - si = (_Jv_SyncInfo *) _Jv_AllocBytes (sizeof (_Jv_SyncInfo)); - _Jv_MutexInit (&si->mutex); - _Jv_CondInit (&si->condition); -#if defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) - // Register a finalizer. - si->init = true; - _Jv_RegisterFinalizer (si, finalize_sync_info); -#endif - sync_info = (jobject) si; - } - _Jv_MutexUnlock (&sync_mutex); -} - -void -java::lang::Object::notify (void) -{ - if (__builtin_expect (INIT_NEEDED (this), false)) - sync_init (); - _Jv_SyncInfo *si = (_Jv_SyncInfo *) sync_info; - if (__builtin_expect (_Jv_CondNotify (&si->condition, &si->mutex), false)) - throw new IllegalMonitorStateException(JvNewStringLatin1 - ("current thread not owner")); -} - -void -java::lang::Object::notifyAll (void) -{ - if (__builtin_expect (INIT_NEEDED (this), false)) - sync_init (); - _Jv_SyncInfo *si = (_Jv_SyncInfo *) sync_info; - if (__builtin_expect (_Jv_CondNotifyAll (&si->condition, &si->mutex), false)) - throw new IllegalMonitorStateException(JvNewStringLatin1 - ("current thread not owner")); -} - -void -java::lang::Object::wait (jlong timeout, jint nanos) -{ - if (__builtin_expect (INIT_NEEDED (this), false)) - sync_init (); - if (__builtin_expect (timeout < 0 || nanos < 0 || nanos > 999999, false)) - throw new IllegalArgumentException; - _Jv_SyncInfo *si = (_Jv_SyncInfo *) sync_info; - switch (_Jv_CondWait (&si->condition, &si->mutex, timeout, nanos)) - { - case _JV_NOT_OWNER: - throw new IllegalMonitorStateException (JvNewStringLatin1 - ("current thread not owner")); - case _JV_INTERRUPTED: - if (Thread::interrupted ()) - throw new InterruptedException; - } -} - -// -// Some runtime code. -// - -// This function is called at system startup to initialize the -// `sync_mutex'. -void -_Jv_InitializeSyncMutex (void) -{ - _Jv_MutexInit (&sync_mutex); -} - -void -_Jv_MonitorEnter (jobject obj) -{ -#ifndef HANDLE_SEGV - if (__builtin_expect (! obj, false)) - throw new java::lang::NullPointerException; -#endif - if (__builtin_expect (INIT_NEEDED (obj), false)) - obj->sync_init (); - _Jv_SyncInfo *si = (_Jv_SyncInfo *) obj->sync_info; - _Jv_MutexLock (&si->mutex); - // FIXME: In the Windows case, this can return a nonzero error code. - // We should turn that into some exception ... -} - -void -_Jv_MonitorExit (jobject obj) -{ - JvAssert (obj); - JvAssert (! INIT_NEEDED (obj)); - _Jv_SyncInfo *si = (_Jv_SyncInfo *) obj->sync_info; - if (__builtin_expect (_Jv_MutexUnlock (&si->mutex), false)) - throw new java::lang::IllegalMonitorStateException; -} - -bool -_Jv_ObjectCheckMonitor (jobject obj) -{ - if (__builtin_expect (INIT_NEEDED (obj), false)) - obj->sync_init (); - _Jv_SyncInfo *si = (_Jv_SyncInfo *) obj->sync_info; - return _Jv_MutexCheckMonitor (&si->mutex); -} - -#else /* JV_HASH_SYNCHRONIZATION */ - -// FIXME: We shouldn't be calling GC_register_finalizer directly. -#ifndef HAVE_BOEHM_GC -# error Hash synchronization currently requires boehm-gc -// That's actually a bit of a lie: It should also work with the null GC, -// probably even better than the alternative. -// To really support alternate GCs here, we would need to widen the -// interface to finalization, since we sometimes have to register a -// second finalizer for an object that already has one. -// We might also want to move the GC interface to a .h file, since -// the number of procedure call levels involved in some of these -// operations is already ridiculous, and would become worse if we -// went through the proper intermediaries. -#else -# ifdef LIBGCJ_GC_DEBUG -# define GC_DEBUG -# endif -# include "gc.h" -#endif - -// What follows currenly assumes a Linux-like platform. -// Some of it specifically assumes X86 or IA64 Linux, though that -// should be easily fixable. - -// A Java monitor implemention based on a table of locks. -// Each entry in the table describes -// locks held for objects that hash to that location. -// This started out as a reimplementation of the technique used in SGIs JVM, -// for which we obtained permission from SGI. -// But in fact, this ended up quite different, though some ideas are -// still shared with the original. -// It was also influenced by some of the published IBM work, -// though it also differs in many ways from that. -// We could speed this up if we had a way to atomically update -// an entire cache entry, i.e. 2 contiguous words of memory. -// That would usually be the case with a 32 bit ABI on a 64 bit processor. -// But we don't currently go out of our way to target those. -// I don't know how to do much better with a N bit ABI on a processor -// that can atomically update only N bits at a time. -// Author: Hans-J. Boehm (Hans_Boehm@hp.com, boehm@acm.org) - -#include <limits.h> -#include <unistd.h> // for usleep, sysconf. -#include <gcj/javaprims.h> -#include <sysdep/locks.h> -#include <java/lang/Thread.h> - -// Try to determine whether we are on a multiprocessor, i.e. whether -// spinning may be profitable. -// This should really use a suitable autoconf macro. -// False is the conservative answer, though the right one is much better. -static bool -is_mp() -{ -#ifdef _SC_NPROCESSORS_ONLN - long nprocs = sysconf(_SC_NPROCESSORS_ONLN); - return (nprocs > 1); -#else - return false; -#endif -} - -// A call to keep_live(p) forces p to be accessible to the GC -// at this point. -inline static void -keep_live(obj_addr_t p) -{ - __asm__ __volatile__("" : : "rm"(p) : "memory"); -} - -// Each hash table entry holds a single preallocated "lightweight" lock. -// In addition, it holds a chain of "heavyweight" locks. Lightweight -// locks do not support Object.wait(), and are converted to heavyweight -// status in response to contention. Unlike the SGI scheme, both -// ligtweight and heavyweight locks in one hash entry can be simultaneously -// in use. (The SGI scheme requires that we be able to acquire a heavyweight -// lock on behalf of another thread, and can thus convert a lock we don't -// hold to heavyweight status. Here we don't insist on that, and thus -// let the original holder of the lighweight lock keep it.) - -struct heavy_lock { - void * reserved_for_gc; - struct heavy_lock *next; // Hash chain link. - // Traced by GC. - void * old_client_data; // The only other field traced by GC. - GC_finalization_proc old_finalization_proc; - obj_addr_t address; // Object to which this lock corresponds. - // Should not be traced by GC. - // Cleared as heavy_lock is destroyed. - // Together with the rest of the heavy lock - // chain, this is protected by the lock - // bit in the hash table entry to which - // the chain is attached. - _Jv_SyncInfo si; - // The remaining fields save prior finalization info for - // the object, which we needed to replace in order to arrange - // for cleanup of the lock structure. -}; - -#ifdef LOCK_DEBUG -void -print_hl_list(heavy_lock *hl) -{ - heavy_lock *p = hl; - for (; 0 != p; p = p->next) - fprintf (stderr, "(hl = %p, addr = %p)", p, (void *)(p -> address)); -} -#endif /* LOCK_DEBUG */ - -#if defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) -// If we have to run a destructor for a sync_info member, then this -// function could be registered as a finalizer for the sync_info. -// In fact, we now only invoke it explicitly. -static inline void -heavy_lock_finalization_proc (heavy_lock *hl) -{ -#if defined (_Jv_HaveCondDestroy) - _Jv_CondDestroy (&hl->si.condition); -#endif -#if defined (_Jv_HaveMutexDestroy) - _Jv_MutexDestroy (&hl->si.mutex); -#endif - hl->si.init = false; -} -#endif /* defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) */ - -// We convert the lock back to lightweight status when -// we exit, so that a single contention episode doesn't doom the lock -// forever. But we also need to make sure that lock structures for dead -// objects are eventually reclaimed. We do that in a an additional -// finalizer on the underlying object. -// Note that if the corresponding object is dead, it is safe to drop -// the heavy_lock structure from its list. It is not necessarily -// safe to deallocate it, since the unlock code could still be running. - -struct hash_entry { - volatile obj_addr_t address; // Address of object for which lightweight - // k is held. - // We assume the 3 low order bits are zero. - // With the Boehm collector and bitmap - // allocation, objects of size 4 bytes are - // broken anyway. Thus this is primarily - // a constraint on statically allocated - // objects used for synchronization. - // This allows us to use the low order - // bits as follows: -# define LOCKED 1 // This hash entry is locked, and its - // state may be invalid. - // The lock protects both the hash_entry - // itself (except for the light_count - // and light_thr_id fields, which - // are protected by the lightweight - // lock itself), and any heavy_monitor - // structures attached to it. -# define HEAVY 2 // Heavyweight locks associated with this - // hash entry may be held. - // The lightweight entry is still valid, - // if the leading bits of the address - // field are nonzero. - // If the LOCKED bit is clear, then this is - // set exactly when heavy_count is > 0 . - // Stored redundantly so a single - // compare-and-swap works in the easy case. - // If HEAVY is not set, it is safe to use - // an available lightweight lock entry - // without checking if there is an existing - // heavyweight lock for the same object. - // (There may be one, but it won't be held - // or waited for.) -# define REQUEST_CONVERSION 4 // The lightweight lock is held. But - // one or more other threads have tried - // to acquire the lock, and hence request - // conversion to heavyweight status. - // The heavyweight lock is already allocated. - // Threads requesting conversion are - // waiting on the condition variable associated - // with the heavyweight lock. - // Not used for conversion due to - // Object.wait() calls. -# define FLAGS (LOCKED | HEAVY | REQUEST_CONVERSION) - volatile _Jv_ThreadId_t light_thr_id; - // Thr_id of holder of lightweight lock. - // Only updated by lightweight lock holder. - // Must be recognizably invalid if the - // lightweight lock is not held. -# define INVALID_THREAD_ID 0 // Works for Linux? - // If zero doesn't work, we have to - // initialize lock table. - volatile unsigned short light_count; - // Number of times the lightweight lock - // is held minus one. Zero if lightweight - // lock is not held. Only updated by - // lightweight lock holder or, in one - // case, while holding the LOCKED bit in - // a state in which there can be no - // lightweight lock holder. - unsigned short heavy_count; // Total number of times heavyweight locks - // associated with this hash entry are held - // or waiting to be acquired. - // Threads in wait() are included eventhough - // they have temporarily released the lock. - // Protected by LOCKED bit. - // Threads requesting conversion to heavyweight - // status are also included. - struct heavy_lock * heavy_locks; - // Chain of heavy locks. Protected - // by lockbit for he. Locks may - // remain allocated here even if HEAVY - // is not set and heavy_count is 0. - // If a lightweight and heavyweight lock - // correspond to the same address, the - // lightweight lock is the right one. -}; - -#ifndef JV_SYNC_TABLE_SZ -# define JV_SYNC_TABLE_SZ 2048 // Must be power of 2. -#endif - -hash_entry light_locks[JV_SYNC_TABLE_SZ]; - -#define JV_SYNC_HASH(p) (((long)p ^ ((long)p >> 10)) & (JV_SYNC_TABLE_SZ-1)) - -// Note that the light_locks table is scanned conservatively by the -// collector. It is essential the the heavy_locks field is scanned. -// Currently the address field may or may not cause the associated object -// to be retained, depending on whether flag bits are set. -// This means that we can conceivable get an unexpected deadlock if -// 1) Object at address A is locked. -// 2) The client drops A without unlocking it. -// 3) Flag bits in the address entry are set, so the collector reclaims -// the object at A. -// 4) A is reallocated, and an attempt is made to lock the result. -// This could be fixed by scanning light_locks in a more customized -// manner that ignores the flag bits. But it can only happen with hand -// generated semi-illegal .class files, and then it doesn't present a -// security hole. - -#ifdef LOCK_DEBUG - void print_he(hash_entry *he) - { - fprintf(stderr, "lock hash entry = %p, index = %d, address = 0x%lx\n" - "\tlight_thr_id = 0x%lx, light_count = %d, " - "heavy_count = %d\n\theavy_locks:", he, - he - light_locks, (unsigned long)(he -> address), - (unsigned long)(he -> light_thr_id), - he -> light_count, he -> heavy_count); - print_hl_list(he -> heavy_locks); - fprintf(stderr, "\n"); - } -#endif /* LOCK_DEBUG */ - -#ifdef LOCK_LOG - // Log locking operations. For debugging only. - // Logging is intended to be as unintrusive as possible. - // Log calls are made after an operation completes, and hence - // may not completely reflect actual synchronization ordering. - // The choice of events to log is currently a bit haphazard. - // The intent is that if we have to track down any other bugs - // inthis code, we extend the logging as appropriate. - typedef enum - { - ACQ_LIGHT, ACQ_LIGHT2, ACQ_HEAVY, ACQ_HEAVY2, PROMOTE, REL_LIGHT, - REL_HEAVY, REQ_CONV, PROMOTE2, WAIT_START, WAIT_END, NOTIFY, NOTIFY_ALL - } event_type; - - struct lock_history - { - event_type tp; - obj_addr_t addr; // Often includes flags. - _Jv_ThreadId_t thr; - }; - - const int LOG_SIZE = 128; // Power of 2. - - lock_history lock_log[LOG_SIZE]; - - volatile obj_addr_t log_next = 0; - // Next location in lock_log. - // Really an int, but we need compare_and_swap. - - static void add_log_entry(event_type t, obj_addr_t a, _Jv_ThreadId_t th) - { - obj_addr_t my_entry; - obj_addr_t next_entry; - do - { - my_entry = log_next; - next_entry = ((my_entry + 1) & (LOG_SIZE - 1)); - } - while (!compare_and_swap(&log_next, my_entry, next_entry)); - lock_log[my_entry].tp = t; - lock_log[my_entry].addr = a; - lock_log[my_entry].thr = th; - } - -# define LOG(t, a, th) add_log_entry(t, a, th) -#else /* !LOCK_LOG */ -# define LOG(t, a, th) -#endif - -static bool mp = false; // Known multiprocesssor. - -// Wait for roughly 2^n units, touching as little memory as possible. -static void -spin(unsigned n) -{ - const unsigned MP_SPINS = 10; - const unsigned YIELDS = 4; - const unsigned SPINS_PER_UNIT = 30; - const unsigned MIN_SLEEP_USECS = 2001; // Shorter times spin under Linux. - const unsigned MAX_SLEEP_USECS = 200000; - static unsigned spin_limit = 0; - static unsigned yield_limit = YIELDS; - static bool spin_initialized = false; - - if (!spin_initialized) - { - mp = is_mp(); - if (mp) - { - spin_limit = MP_SPINS; - yield_limit = MP_SPINS + YIELDS; - } - spin_initialized = true; - } - if (n < spin_limit) - { - unsigned i = SPINS_PER_UNIT << n; - for (; i > 0; --i) - __asm__ __volatile__(""); - } - else if (n < yield_limit) - { - _Jv_ThreadYield(); - } - else - { - unsigned duration = MIN_SLEEP_USECS << (n - yield_limit); - if (n >= 15 + yield_limit || duration > MAX_SLEEP_USECS) - duration = MAX_SLEEP_USECS; - _Jv_platform_usleep(duration); - } -} - -// Wait for a hash entry to become unlocked. -static void -wait_unlocked (hash_entry *he) -{ - unsigned i = 0; - while (he -> address & LOCKED) - spin (i++); -} - -// Return the heavy lock for addr if it was already allocated. -// The client passes in the appropriate hash_entry. -// We hold the lock for he. -static inline heavy_lock * -find_heavy (obj_addr_t addr, hash_entry *he) -{ - heavy_lock *hl = he -> heavy_locks; - while (hl != 0 && hl -> address != addr) hl = hl -> next; - return hl; -} - -// Unlink the heavy lock for the given address from its hash table chain. -// Dies miserably and conspicuously if it's not there, since that should -// be impossible. -static inline void -unlink_heavy (obj_addr_t addr, hash_entry *he) -{ - heavy_lock **currentp = &(he -> heavy_locks); - while ((*currentp) -> address != addr) - currentp = &((*currentp) -> next); - *currentp = (*currentp) -> next; -} - -// Finalization procedure for objects that have associated heavy-weight -// locks. This may replace the real finalization procedure. -static void -heavy_lock_obj_finalization_proc (void *obj, void *cd) -{ - heavy_lock *hl = (heavy_lock *)cd; - -// This only addresses misalignment of statics, not heap objects. It -// works only because registering statics for finalization is a noop, -// no matter what the least significant bits are. -#ifdef JV_LINKER_CANNOT_8BYTE_ALIGN_STATICS - obj_addr_t addr = (obj_addr_t)obj & ~((obj_addr_t)0x7); -#else - obj_addr_t addr = (obj_addr_t)obj; -#endif - hash_entry *he = light_locks + JV_SYNC_HASH(addr); - obj_addr_t he_address = (he -> address & ~LOCKED); - - // Acquire lock bit immediately. It's possible that the hl was already - // destroyed while we were waiting for the finalizer to run. If it - // was, the address field was set to zero. The address filed access is - // protected by the lock bit to ensure that we do this exactly once. - // The lock bit also protects updates to the objects finalizer. - while (!compare_and_swap(&(he -> address), he_address, he_address|LOCKED )) - { - // Hash table entry is currently locked. We can't safely - // touch the list of heavy locks. - wait_unlocked(he); - he_address = (he -> address & ~LOCKED); - } - if (0 == hl -> address) - { - // remove_all_heavy destroyed hl, and took care of the real finalizer. - release_set(&(he -> address), he_address); - return; - } - JvAssert(hl -> address == addr); - GC_finalization_proc old_finalization_proc = hl -> old_finalization_proc; - if (old_finalization_proc != 0) - { - // We still need to run a real finalizer. In an idealized - // world, in which people write thread-safe finalizers, that is - // likely to require synchronization. Thus we reregister - // ourselves as the only finalizer, and simply run the real one. - // Thus we don't clean up the lock yet, but we're likely to do so - // on the next GC cycle. - // It's OK if remove_all_heavy actually destroys the heavy lock, - // since we've updated old_finalization_proc, and thus the user's - // finalizer won't be rerun. - void * old_client_data = hl -> old_client_data; - hl -> old_finalization_proc = 0; - hl -> old_client_data = 0; -# ifdef HAVE_BOEHM_GC - GC_REGISTER_FINALIZER_NO_ORDER(obj, heavy_lock_obj_finalization_proc, cd, 0, 0); -# endif - release_set(&(he -> address), he_address); - old_finalization_proc(obj, old_client_data); - } - else - { - // The object is really dead, although it's conceivable that - // some thread may still be in the process of releasing the - // heavy lock. Unlink it and, if necessary, register a finalizer - // to destroy sync_info. - unlink_heavy(addr, he); - hl -> address = 0; // Don't destroy it again. - release_set(&(he -> address), he_address); -# if defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) - // Make sure lock is not held and then destroy condvar and mutex. - _Jv_MutexLock(&(hl->si.mutex)); - _Jv_MutexUnlock(&(hl->si.mutex)); - heavy_lock_finalization_proc (hl); -# endif - } -} - -// We hold the lock on he, and heavy_count is 0. -// Release the lock by replacing the address with new_address_val. -// Remove all heavy locks on the list. Note that the only possible way -// in which a lock may still be in use is if it's in the process of -// being unlocked. -// FIXME: Why does this unlock the hash entry? I think that -// could now be done more cleanly in MonitorExit. -static void -remove_all_heavy (hash_entry *he, obj_addr_t new_address_val) -{ - JvAssert(he -> heavy_count == 0); - JvAssert(he -> address & LOCKED); - heavy_lock *hl = he -> heavy_locks; - he -> heavy_locks = 0; - // We would really like to release the lock bit here. Unfortunately, that - // Creates a race between or finalizer removal, and the potential - // reinstallation of a new finalizer as a new heavy lock is created. - // This may need to be revisited. - for(; 0 != hl; hl = hl->next) - { - obj_addr_t obj = hl -> address; - JvAssert(0 != obj); // If this was previously finalized, it should no - // longer appear on our list. - hl -> address = 0; // Finalization proc might still see it after we - // finish. - GC_finalization_proc old_finalization_proc = hl -> old_finalization_proc; - void * old_client_data = hl -> old_client_data; -# ifdef HAVE_BOEHM_GC - // Remove our finalization procedure. - // Reregister the clients if applicable. - GC_REGISTER_FINALIZER_NO_ORDER((GC_PTR)obj, old_finalization_proc, - old_client_data, 0, 0); - // Note that our old finalization procedure may have been - // previously determined to be runnable, and may still run. - // FIXME - direct dependency on boehm GC. -# endif -# if defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) - // Wait for a possible lock holder to finish unlocking it. - // This is only an issue if we have to explicitly destroy the mutex - // or possibly if we have to destroy a condition variable that is - // still being notified. - _Jv_MutexLock(&(hl->si.mutex)); - _Jv_MutexUnlock(&(hl->si.mutex)); - heavy_lock_finalization_proc (hl); -# endif - } - release_set(&(he -> address), new_address_val); -} - -// We hold the lock on he and heavy_count is 0. -// We release it by replacing the address field with new_address_val. -// Remove all heavy locks on the list if the list is sufficiently long. -// This is called periodically to avoid very long lists of heavy locks. -// This seems to otherwise become an issue with SPECjbb, for example. -static inline void -maybe_remove_all_heavy (hash_entry *he, obj_addr_t new_address_val) -{ - static const int max_len = 5; - heavy_lock *hl = he -> heavy_locks; - - for (int i = 0; i < max_len; ++i) - { - if (0 == hl) - { - release_set(&(he -> address), new_address_val); - return; - } - hl = hl -> next; - } - remove_all_heavy(he, new_address_val); -} - -// Allocate a new heavy lock for addr, returning its address. -// Assumes we already have the hash_entry locked, and there -// is currently no lightweight or allocated lock for addr. -// We register a finalizer for addr, which is responsible for -// removing the heavy lock when addr goes away, in addition -// to the responsibilities of any prior finalizer. -// This unfortunately holds the lock bit for the hash entry while it -// allocates two objects (on for the finalizer). -// It would be nice to avoid that somehow ... -static heavy_lock * -alloc_heavy(obj_addr_t addr, hash_entry *he) -{ - heavy_lock * hl = (heavy_lock *) _Jv_AllocTraceTwo(sizeof (heavy_lock)); - - hl -> address = addr; - _Jv_MutexInit (&(hl -> si.mutex)); - _Jv_CondInit (&(hl -> si.condition)); -# if defined (_Jv_HaveCondDestroy) || defined (_Jv_HaveMutexDestroy) - hl->si.init = true; // needed ? -# endif - hl -> next = he -> heavy_locks; - he -> heavy_locks = hl; - // FIXME: The only call that cheats and goes directly to the GC interface. -# ifdef HAVE_BOEHM_GC - GC_REGISTER_FINALIZER_NO_ORDER( - (void *)addr, heavy_lock_obj_finalization_proc, - hl, &hl->old_finalization_proc, - &hl->old_client_data); -# endif /* HAVE_BOEHM_GC */ - return hl; -} - -// Return the heavy lock for addr, allocating if necessary. -// Assumes we have the cache entry locked, and there is no lightweight -// lock for addr. -static heavy_lock * -get_heavy(obj_addr_t addr, hash_entry *he) -{ - heavy_lock *hl = find_heavy(addr, he); - if (0 == hl) - hl = alloc_heavy(addr, he); - return hl; -} - -void -_Jv_MonitorEnter (jobject obj) -{ -#ifdef JV_LINKER_CANNOT_8BYTE_ALIGN_STATICS - obj_addr_t addr = (obj_addr_t)obj & ~((obj_addr_t)FLAGS); -#else - obj_addr_t addr = (obj_addr_t)obj; -#endif - obj_addr_t address; - unsigned hash = JV_SYNC_HASH(addr); - hash_entry * he = light_locks + hash; - _Jv_ThreadId_t self = _Jv_ThreadSelf(); - unsigned count; - const unsigned N_SPINS = 18; - - // We need to somehow check that addr is not NULL on the fast path. - // A very predictable - // branch on a register value is probably cheaper than dereferencing addr. - // We could also permanently lock the NULL entry in the hash table. - // But it's not clear that's cheaper either. - if (__builtin_expect(!addr, false)) - throw new java::lang::NullPointerException; - - JvAssert(!(addr & FLAGS)); -retry: - if (__builtin_expect(compare_and_swap(&(he -> address), - 0, addr),true)) - { - JvAssert(he -> light_thr_id == INVALID_THREAD_ID); - JvAssert(he -> light_count == 0); - he -> light_thr_id = self; - // Count fields are set correctly. Heavy_count was also zero, - // but can change asynchronously. - // This path is hopefully both fast and the most common. - LOG(ACQ_LIGHT, addr, self); - return; - } - address = he -> address; - if ((address & ~(HEAVY | REQUEST_CONVERSION)) == addr) - { - if (he -> light_thr_id == self) - { - // We hold the lightweight lock, and it's for the right - // address. - count = he -> light_count; - if (count == USHRT_MAX) - { - // I think most JVMs don't check for this. - // But I'm not convinced I couldn't turn this into a security - // hole, even with a 32 bit counter. - throw new java::lang::IllegalMonitorStateException( - JvNewStringLatin1("maximum monitor nesting level exceeded")); - } - he -> light_count = count + 1; - return; - } - else - { - JvAssert(!(address & LOCKED)); - // Lightweight lock is held, but by somone else. - // Spin a few times. This avoids turning this into a heavyweight - // lock if the current holder is about to release it. - // FIXME: Does this make sense on a uniprocessor, where - // it actually yields? It's probably cheaper to convert. - for (unsigned int i = 0; i < N_SPINS; ++i) - { - if ((he -> address & ~LOCKED) != address) goto retry; - spin(i); - } - if (!compare_and_swap(&(he -> address), address, address | LOCKED )) - { - wait_unlocked(he); - goto retry; - } - heavy_lock *hl = get_heavy(addr, he); - ++ (he -> heavy_count); - // The hl lock acquisition can't block for long, since it can - // only be held by other threads waiting for conversion, and - // they, like us, drop it quickly without blocking. - _Jv_MutexLock(&(hl->si.mutex)); - JvAssert(he -> address == (address | LOCKED)); - release_set(&(he -> address), (address | REQUEST_CONVERSION | HEAVY)); - // release lock on he - LOG(REQ_CONV, (address | REQUEST_CONVERSION | HEAVY), self); - // If _Jv_CondWait is interrupted, we ignore the interrupt, but - // restore the thread's interrupt status flag when done. - jboolean interrupt_flag = false; - while ((he -> address & ~FLAGS) == (address & ~FLAGS)) - { - // Once converted, the lock has to retain heavyweight - // status, since heavy_count > 0. - int r = _Jv_CondWait (&(hl->si.condition), &(hl->si.mutex), 0, 0); - if (r == _JV_INTERRUPTED) - { - interrupt_flag = true; - Thread::currentThread()->interrupt_flag = false; - } - } - if (interrupt_flag) - Thread::currentThread()->interrupt_flag = interrupt_flag; - keep_live(addr); - // Guarantee that hl doesn't get unlinked by finalizer. - // This is only an issue if the client fails to release - // the lock, which is unlikely. - JvAssert(he -> address & HEAVY); - // Lock has been converted, we hold the heavyweight lock, - // heavy_count has been incremented. - return; - } - } - obj_addr_t was_heavy = (address & HEAVY); - if ((address & LOCKED) || - !compare_and_swap(&(he -> address), address, address | LOCKED )) - { - wait_unlocked(he); - goto retry; - } - if ((address & ~(HEAVY | REQUEST_CONVERSION)) == 0) - { - // Either was_heavy is true, or something changed out from under us, - // since the initial test for 0 failed. - JvAssert(!(address & REQUEST_CONVERSION)); - // Can't convert a nonexistent lightweight lock. - heavy_lock *hl; - hl = (was_heavy? find_heavy(addr, he) : 0); - // The CAS succeeded, so was_heavy is still accurate. - if (0 == hl) - { - // It is OK to use the lighweight lock, since either the - // heavyweight lock does not exist, or none of the - // heavyweight locks are currently in use. Future threads - // trying to acquire the lock will see the lightweight - // one first and use that. - he -> light_thr_id = self; // OK, since nobody else can hold - // light lock or do this at the same time. - JvAssert(he -> light_count == 0); - JvAssert(was_heavy == (he -> address & HEAVY)); - release_set(&(he -> address), (addr | was_heavy)); - LOG(ACQ_LIGHT2, addr | was_heavy, self); - } - else - { - // Must use heavy lock. - ++ (he -> heavy_count); - JvAssert(0 == (address & ~HEAVY)); - release_set(&(he -> address), HEAVY); - LOG(ACQ_HEAVY, addr | was_heavy, self); - _Jv_MutexLock(&(hl->si.mutex)); - keep_live(addr); - } - return; - } - // Lightweight lock is held, but does not correspond to this object. - // We hold the lock on the hash entry, and he -> address can't - // change from under us. Neither can the chain of heavy locks. - { - JvAssert(0 == he -> heavy_count || (address & HEAVY)); - heavy_lock *hl = get_heavy(addr, he); - ++ (he -> heavy_count); - release_set(&(he -> address), address | HEAVY); - LOG(ACQ_HEAVY2, address | HEAVY, self); - _Jv_MutexLock(&(hl->si.mutex)); - keep_live(addr); - } -} - - -void -_Jv_MonitorExit (jobject obj) -{ -#ifdef JV_LINKER_CANNOT_8BYTE_ALIGN_STATICS - obj_addr_t addr = (obj_addr_t)obj & ~((obj_addr_t)FLAGS); -#else - obj_addr_t addr = (obj_addr_t)obj; -#endif - _Jv_ThreadId_t self = _Jv_ThreadSelf(); - unsigned hash = JV_SYNC_HASH(addr); - hash_entry * he = light_locks + hash; - _Jv_ThreadId_t light_thr_id; - unsigned count; - obj_addr_t address; - -retry: - light_thr_id = he -> light_thr_id; - // Unfortunately, it turns out we always need to read the address - // first. Even if we are going to update it with compare_and_swap, - // we need to reset light_thr_id, and that's not safe unless we know - // that we hold the lock. - address = he -> address; - // First the (relatively) fast cases: - if (__builtin_expect(light_thr_id == self, true)) - // Above must fail if addr == 0 . - { - count = he -> light_count; - if (__builtin_expect((address & ~HEAVY) == addr, true)) - { - if (count != 0) - { - // We held the lightweight lock all along. Thus the values - // we saw for light_thr_id and light_count must have been valid. - he -> light_count = count - 1; - return; - } - else - { - // We hold the lightweight lock once. - he -> light_thr_id = INVALID_THREAD_ID; - if (compare_and_swap_release(&(he -> address), address, - address & HEAVY)) - { - LOG(REL_LIGHT, address & HEAVY, self); - return; - } - else - { - he -> light_thr_id = light_thr_id; // Undo prior damage. - goto retry; - } - } - } - // else lock is not for this address, conversion is requested, - // or the lock bit in the address field is set. - } - else - { - if (__builtin_expect(!addr, false)) - throw new java::lang::NullPointerException; - if ((address & ~(HEAVY | REQUEST_CONVERSION)) == addr) - { -# ifdef LOCK_DEBUG - fprintf(stderr, "Lightweight lock held by other thread\n\t" - "light_thr_id = 0x%lx, self = 0x%lx, " - "address = 0x%lx, heavy_count = %d, pid = %d\n", - light_thr_id, self, (unsigned long)address, - he -> heavy_count, getpid()); - print_he(he); - for(;;) {} -# endif - // Someone holds the lightweight lock for this object, and - // it can't be us. - throw new java::lang::IllegalMonitorStateException( - JvNewStringLatin1("current thread not owner")); - } - else - count = he -> light_count; - } - if (address & LOCKED) - { - wait_unlocked(he); - goto retry; - } - // Now the unlikely cases. - // We do know that: - // - Address is set, and doesn't contain the LOCKED bit. - // - If address refers to the same object as addr, then he -> light_thr_id - // refers to this thread, and count is valid. - // - The case in which we held the lightweight lock has been - // completely handled, except for the REQUEST_CONVERSION case. - // - if ((address & ~FLAGS) == addr) - { - // The lightweight lock is assigned to this object. - // Thus we must be in the REQUEST_CONVERSION case. - if (0 != count) - { - // Defer conversion until we exit completely. - he -> light_count = count - 1; - return; - } - JvAssert(he -> light_thr_id == self); - JvAssert(address & REQUEST_CONVERSION); - // Conversion requested - // Convert now. - if (!compare_and_swap(&(he -> address), address, address | LOCKED)) - goto retry; - heavy_lock *hl = find_heavy(addr, he); - JvAssert (0 != hl); - // Requestor created it. - he -> light_count = 0; - JvAssert(he -> heavy_count > 0); - // was incremented by requestor. - _Jv_MutexLock(&(hl->si.mutex)); - // Release the he lock after acquiring the mutex. - // Otherwise we can accidentally - // notify a thread that has already seen a heavyweight - // lock. - he -> light_thr_id = INVALID_THREAD_ID; - release_set(&(he -> address), HEAVY); - LOG(PROMOTE, address, self); - // lightweight lock now unused. - _Jv_CondNotifyAll(&(hl->si.condition), &(hl->si.mutex)); - _Jv_MutexUnlock(&(hl->si.mutex)); - // heavy_count was already incremented by original requestor. - keep_live(addr); - return; - } - // lightweight lock not for this object. - JvAssert(!(address & LOCKED)); - JvAssert((address & ~FLAGS) != addr); - if (!compare_and_swap(&(he -> address), address, address | LOCKED)) - goto retry; - heavy_lock *hl = find_heavy(addr, he); - if (NULL == hl) - { -# ifdef LOCK_DEBUG - fprintf(stderr, "Failed to find heavyweight lock for addr 0x%lx" - " pid = %d\n", addr, getpid()); - print_he(he); - for(;;) {} -# endif - release_set(&(he -> address), address); - throw new java::lang::IllegalMonitorStateException( - JvNewStringLatin1("current thread not owner")); - } - JvAssert(address & HEAVY); - count = he -> heavy_count; - JvAssert(count > 0); - --count; - he -> heavy_count = count; - if (0 == count) - { - const unsigned test_freq = 16; // Power of 2 - static volatile unsigned counter = 0; - unsigned my_counter = counter; - - counter = my_counter + 1; - if (my_counter%test_freq == 0) - { - // Randomize the interval length a bit. - counter = my_counter + (my_counter >> 4) % (test_freq/2); - // Unlock mutex first, to avoid self-deadlock, or worse. - _Jv_MutexUnlock(&(hl->si.mutex)); - maybe_remove_all_heavy(he, address &~HEAVY); - // release lock bit, preserving - // REQUEST_CONVERSION - // and object address. - } - else - { - release_set(&(he -> address), address &~HEAVY); - _Jv_MutexUnlock(&(hl->si.mutex)); - // Unlock after releasing the lock bit, so that - // we don't switch to another thread prematurely. - } - } - else - { - release_set(&(he -> address), address); - _Jv_MutexUnlock(&(hl->si.mutex)); - } - LOG(REL_HEAVY, addr, self); - keep_live(addr); -} - -// Return false if obj's monitor is held by the current thread -bool -_Jv_ObjectCheckMonitor (jobject obj) -{ -#ifdef JV_LINKER_CANNOT_8BYTE_ALIGN_STATICS - obj_addr_t addr = (obj_addr_t)obj & ~((obj_addr_t)FLAGS); -#else - obj_addr_t addr = (obj_addr_t)obj; -#endif - obj_addr_t address; - unsigned hash = JV_SYNC_HASH(addr); - hash_entry * he = light_locks + hash; - - JvAssert(!(addr & FLAGS)); - address = he -> address; - // Try it the easy way first: - if (address == 0) return true; - _Jv_ThreadId_t self = _Jv_ThreadSelf(); - if ((address & ~(HEAVY | REQUEST_CONVERSION)) == addr) - // Fails if entry is LOCKED. - // I can't asynchronously become or stop being the holder. - return he -> light_thr_id != self; -retry: - // Acquire the hash table entry lock - address &= ~LOCKED; - if (!compare_and_swap(&(he -> address), address, address | LOCKED)) - { - wait_unlocked(he); - goto retry; - } - - bool not_mine; - - if ((address & ~FLAGS) == addr) - not_mine = (he -> light_thr_id != self); - else - { - heavy_lock* hl = find_heavy(addr, he); - not_mine = hl ? _Jv_MutexCheckMonitor(&hl->si.mutex) : true; - } - - release_set(&(he -> address), address); // unlock hash entry - return not_mine; -} - -// The rest of these are moderately thin veneers on _Jv_Cond ops. -// The current version of Notify might be able to make the pthread -// call AFTER releasing the lock, thus saving some context switches?? - -void -java::lang::Object::wait (jlong timeout, jint nanos) -{ -#ifdef JV_LINKER_CANNOT_8BYTE_ALIGN_STATICS - obj_addr_t addr = (obj_addr_t)this & ~((obj_addr_t)FLAGS); -#else - obj_addr_t addr = (obj_addr_t)this; -#endif - _Jv_ThreadId_t self = _Jv_ThreadSelf(); - unsigned hash = JV_SYNC_HASH(addr); - hash_entry * he = light_locks + hash; - unsigned count; - obj_addr_t address; - heavy_lock *hl; - - if (__builtin_expect (timeout < 0 || nanos < 0 || nanos > 999999, false)) - throw new IllegalArgumentException; -retry: - address = he -> address; - address &= ~LOCKED; - if (!compare_and_swap(&(he -> address), address, address | LOCKED)) - { - wait_unlocked(he); - goto retry; - } - // address did not have the lock bit set. We now hold the lock on he. - if ((address & ~FLAGS) == addr) - { - // Convert to heavyweight. - if (he -> light_thr_id != self) - { -# ifdef LOCK_DEBUG - fprintf(stderr, "Found wrong lightweight lock owner in wait " - "address = 0x%lx pid = %d\n", address, getpid()); - print_he(he); - for(;;) {} -# endif - release_set(&(he -> address), address); - throw new IllegalMonitorStateException (JvNewStringLatin1 - ("current thread not owner")); - } - count = he -> light_count; - hl = get_heavy(addr, he); - he -> light_count = 0; - he -> heavy_count += count + 1; - for (unsigned i = 0; i <= count; ++i) - _Jv_MutexLock(&(hl->si.mutex)); - // Again release the he lock after acquiring the mutex. - he -> light_thr_id = INVALID_THREAD_ID; - release_set(&(he -> address), HEAVY); // lightweight lock now unused. - LOG(PROMOTE2, addr, self); - if (address & REQUEST_CONVERSION) - _Jv_CondNotifyAll (&(hl->si.condition), &(hl->si.mutex)); - // Since we do this before we do a CondWait, we guarantee that - // threads waiting on requested conversion are awoken before - // a real wait on the same condition variable. - // No other notification can occur in the interim, since - // we hold the heavy lock, and notifications are made - // without acquiring it. - } - else /* We should hold the heavyweight lock. */ - { - hl = find_heavy(addr, he); - release_set(&(he -> address), address); - if (0 == hl) - { -# ifdef LOCK_DEBUG - fprintf(stderr, "Couldn't find heavy lock in wait " - "addr = 0x%lx pid = %d\n", addr, getpid()); - print_he(he); - for(;;) {} -# endif - throw new IllegalMonitorStateException (JvNewStringLatin1 - ("current thread not owner")); - } - JvAssert(address & HEAVY); - } - LOG(WAIT_START, addr, self); - switch (_Jv_CondWait (&(hl->si.condition), &(hl->si.mutex), timeout, nanos)) - { - case _JV_NOT_OWNER: - throw new IllegalMonitorStateException (JvNewStringLatin1 - ("current thread not owner")); - case _JV_INTERRUPTED: - if (Thread::interrupted ()) - throw new InterruptedException; - } - LOG(WAIT_END, addr, self); -} - -void -java::lang::Object::notify (void) -{ -#ifdef JV_LINKER_CANNOT_8BYTE_ALIGN_STATICS - obj_addr_t addr = (obj_addr_t)this & ~((obj_addr_t)FLAGS); -#else - obj_addr_t addr = (obj_addr_t)this; -#endif - _Jv_ThreadId_t self = _Jv_ThreadSelf(); - unsigned hash = JV_SYNC_HASH(addr); - hash_entry * he = light_locks + hash; - heavy_lock *hl; - obj_addr_t address; - int result; - -retry: - address = ((he -> address) & ~LOCKED); - if (!compare_and_swap(&(he -> address), address, address | LOCKED)) - { - wait_unlocked(he); - goto retry; - } - if ((address & ~FLAGS) == addr && he -> light_thr_id == self) - { - // We hold lightweight lock. Since it has not - // been inflated, there are no waiters. - release_set(&(he -> address), address); // unlock - return; - } - hl = find_heavy(addr, he); - // Hl can't disappear since we point to the underlying object. - // It's important that we release the lock bit before the notify, since - // otherwise we will try to wake up the target while we still hold the - // bit. This results in lock bit contention, which we don't handle - // terribly well. - release_set(&(he -> address), address); // unlock - if (0 == hl) - { - throw new IllegalMonitorStateException(JvNewStringLatin1 - ("current thread not owner")); - return; - } - // We know that we hold the heavyweight lock at this point, - // and the lightweight lock is not in use. - result = _Jv_CondNotify(&(hl->si.condition), &(hl->si.mutex)); - LOG(NOTIFY, addr, self); - keep_live(addr); - if (__builtin_expect (result, 0)) - throw new IllegalMonitorStateException(JvNewStringLatin1 - ("current thread not owner")); -} - -void -java::lang::Object::notifyAll (void) -{ -#ifdef JV_LINKER_CANNOT_8BYTE_ALIGN_STATICS - obj_addr_t addr = (obj_addr_t)this & ~((obj_addr_t)FLAGS); -#else - obj_addr_t addr = (obj_addr_t)this; -#endif - _Jv_ThreadId_t self = _Jv_ThreadSelf(); - unsigned hash = JV_SYNC_HASH(addr); - hash_entry * he = light_locks + hash; - heavy_lock *hl; - obj_addr_t address; - int result; - -retry: - address = (he -> address) & ~LOCKED; - if (!compare_and_swap(&(he -> address), address, address | LOCKED)) - { - wait_unlocked(he); - goto retry; - } - hl = find_heavy(addr, he); - if ((address & ~FLAGS) == addr && he -> light_thr_id == self) - { - // We hold lightweight lock. Since it has not - // been inflated, there are no waiters. - release_set(&(he -> address), address); // unlock - return; - } - release_set(&(he -> address), address); // unlock - if (0 == hl) - { - throw new IllegalMonitorStateException(JvNewStringLatin1 - ("current thread not owner")); - } - result = _Jv_CondNotifyAll(&(hl->si.condition), &(hl->si.mutex)); - LOG(NOTIFY_ALL, addr, self); - if (__builtin_expect (result, 0)) - throw new IllegalMonitorStateException(JvNewStringLatin1 - ("current thread not owner")); -} - -// This is declared in Java code and in Object.h. -// It should never be called with JV_HASH_SYNCHRONIZATION -void -java::lang::Object::sync_init (void) -{ - throw new IllegalMonitorStateException(JvNewStringLatin1 - ("internal error: sync_init")); -} - -// This is called on startup and declared in Object.h. -// For now we just make it a no-op. -void -_Jv_InitializeSyncMutex (void) -{ -} - -#endif /* JV_HASH_SYNCHRONIZATION */ - |