/* * Copyright (C) 2008 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include "monitor.h" #include #include #include #include #include #include #include #include "class_linker.h" #include "mutex.h" #include "object.h" #include "object_utils.h" #include "scoped_thread_list_lock.h" #include "stl_util.h" #include "thread.h" #include "thread_list.h" namespace art { /* * Every Object has a monitor associated with it, but not every Object is * actually locked. Even the ones that are locked do not need a * full-fledged monitor until a) there is actual contention or b) wait() * is called on the Object. * * For Android, we have implemented a scheme similar to the one described * in Bacon et al.'s "Thin locks: featherweight synchronization for Java" * (ACM 1998). Things are even easier for us, though, because we have * a full 32 bits to work with. * * The two states of an Object's lock are referred to as "thin" and * "fat". A lock may transition from the "thin" state to the "fat" * state and this transition is referred to as inflation. Once a lock * has been inflated it remains in the "fat" state indefinitely. * * The lock value itself is stored in Object.lock. The LSB of the * lock encodes its state. When cleared, the lock is in the "thin" * state and its bits are formatted as follows: * * [31 ---- 19] [18 ---- 3] [2 ---- 1] [0] * lock count thread id hash state 0 * * When set, the lock is in the "fat" state and its bits are formatted * as follows: * * [31 ---- 3] [2 ---- 1] [0] * pointer hash state 1 * * For an in-depth description of the mechanics of thin-vs-fat locking, * read the paper referred to above. * * Monitors provide: * - mutually exclusive access to resources * - a way for multiple threads to wait for notification * * In effect, they fill the role of both mutexes and condition variables. * * Only one thread can own the monitor at any time. There may be several * threads waiting on it (the wait call unlocks it). One or more waiting * threads may be getting interrupted or notified at any given time. * * TODO: the various members of monitor are not SMP-safe. */ /* * Monitor accessor. Extracts a monitor structure pointer from a fat * lock. Performs no error checking. */ #define LW_MONITOR(x) \ ((Monitor*)((x) & ~((LW_HASH_STATE_MASK << LW_HASH_STATE_SHIFT) | LW_SHAPE_MASK))) /* * Lock recursion count field. Contains a count of the number of times * a lock has been recursively acquired. */ #define LW_LOCK_COUNT_MASK 0x1fff #define LW_LOCK_COUNT_SHIFT 19 #define LW_LOCK_COUNT(x) (((x) >> LW_LOCK_COUNT_SHIFT) & LW_LOCK_COUNT_MASK) bool (*Monitor::is_sensitive_thread_hook_)() = NULL; uint32_t Monitor::lock_profiling_threshold_ = 0; bool Monitor::IsSensitiveThread() { if (is_sensitive_thread_hook_ != NULL) { return (*is_sensitive_thread_hook_)(); } return false; } void Monitor::Init(uint32_t lock_profiling_threshold, bool (*is_sensitive_thread_hook)()) { lock_profiling_threshold_ = lock_profiling_threshold; is_sensitive_thread_hook_ = is_sensitive_thread_hook; } Monitor::Monitor(Object* obj) : owner_(NULL), lock_count_(0), obj_(obj), wait_set_(NULL), lock_("a monitor lock"), locking_method_(NULL), locking_pc_(0) { } Monitor::~Monitor() { DCHECK(obj_ != NULL); DCHECK_EQ(LW_SHAPE(*obj_->GetRawLockWordAddress()), LW_SHAPE_FAT); } /* * Links a thread into a monitor's wait set. The monitor lock must be * held by the caller of this routine. */ void Monitor::AppendToWaitSet(Thread* thread) { DCHECK(owner_ == Thread::Current()); DCHECK(thread != NULL); DCHECK(thread->wait_next_ == NULL) << thread->wait_next_; if (wait_set_ == NULL) { wait_set_ = thread; return; } // push_back. Thread* t = wait_set_; while (t->wait_next_ != NULL) { t = t->wait_next_; } t->wait_next_ = thread; } /* * Unlinks a thread from a monitor's wait set. The monitor lock must * be held by the caller of this routine. */ void Monitor::RemoveFromWaitSet(Thread *thread) { DCHECK(owner_ == Thread::Current()); DCHECK(thread != NULL); if (wait_set_ == NULL) { return; } if (wait_set_ == thread) { wait_set_ = thread->wait_next_; thread->wait_next_ = NULL; return; } Thread* t = wait_set_; while (t->wait_next_ != NULL) { if (t->wait_next_ == thread) { t->wait_next_ = thread->wait_next_; thread->wait_next_ = NULL; return; } t = t->wait_next_; } } Object* Monitor::GetObject() { return obj_; } void Monitor::Lock(Thread* self) { if (owner_ == self) { lock_count_++; return; } uint64_t waitStart, waitEnd; if (!lock_.TryLock()) { uint32_t wait_threshold = lock_profiling_threshold_; const Method* current_locking_method = NULL; uintptr_t current_locking_pc = 0; { ScopedThreadStateChange tsc(self, Thread::kBlocked); if (wait_threshold != 0) { waitStart = NanoTime() / 1000; } current_locking_method = locking_method_; current_locking_pc = locking_pc_; lock_.Lock(); if (wait_threshold != 0) { waitEnd = NanoTime() / 1000; } } if (wait_threshold != 0) { uint64_t wait_ms = (waitEnd - waitStart) / 1000; uint32_t sample_percent; if (wait_ms >= wait_threshold) { sample_percent = 100; } else { sample_percent = 100 * wait_ms / wait_threshold; } if (sample_percent != 0 && (static_cast(rand() % 100) < sample_percent)) { const char* current_locking_filename; uint32_t current_locking_line_number; TranslateLocation(current_locking_method, current_locking_pc, current_locking_filename, current_locking_line_number); LogContentionEvent(self, wait_ms, sample_percent, current_locking_filename, current_locking_line_number); } } } owner_ = self; DCHECK_EQ(lock_count_, 0); // When debugging, save the current monitor holder for future // acquisition failures to use in sampled logging. if (lock_profiling_threshold_ != 0) { locking_method_ = self->GetCurrentMethod(&locking_pc_); } } static void ThrowIllegalMonitorStateExceptionF(const char* fmt, ...) __attribute__((format(printf, 1, 2))); static void ThrowIllegalMonitorStateExceptionF(const char* fmt, ...) { va_list args; va_start(args, fmt); Thread::Current()->ThrowNewExceptionV("Ljava/lang/IllegalMonitorStateException;", fmt, args); va_end(args); } static std::string ThreadToString(Thread* thread) { if (thread == NULL) { return "NULL"; } std::ostringstream oss; // TODO: alternatively, we could just return the thread's name. oss << *thread; return oss.str(); } void Monitor::FailedUnlock(Object* o, Thread* expected_owner, Thread* found_owner, Monitor* monitor) { Thread* current_owner = NULL; std::string current_owner_string; std::string expected_owner_string; std::string found_owner_string; { // TODO: isn't this too late to prevent threads from disappearing? // Acquire thread list lock so threads won't disappear from under us. ScopedThreadListLock thread_list_lock; // Re-read owner now that we hold lock. current_owner = (monitor != NULL) ? monitor->owner_ : NULL; // Get short descriptions of the threads involved. current_owner_string = ThreadToString(current_owner); expected_owner_string = ThreadToString(expected_owner); found_owner_string = ThreadToString(found_owner); } if (current_owner == NULL) { if (found_owner == NULL) { ThrowIllegalMonitorStateExceptionF("unlock of unowned monitor on object of type '%s'" " on thread '%s'", PrettyTypeOf(o).c_str(), expected_owner_string.c_str()); } else { // Race: the original read found an owner but now there is none ThrowIllegalMonitorStateExceptionF("unlock of monitor owned by '%s' on object of type '%s'" " (where now the monitor appears unowned) on thread '%s'", found_owner_string.c_str(), PrettyTypeOf(o).c_str(), expected_owner_string.c_str()); } } else { if (found_owner == NULL) { // Race: originally there was no owner, there is now ThrowIllegalMonitorStateExceptionF("unlock of monitor owned by '%s' on object of type '%s'" " (originally believed to be unowned) on thread '%s'", current_owner_string.c_str(), PrettyTypeOf(o).c_str(), expected_owner_string.c_str()); } else { if (found_owner != current_owner) { // Race: originally found and current owner have changed ThrowIllegalMonitorStateExceptionF("unlock of monitor originally owned by '%s' (now" " owned by '%s') on object of type '%s' on thread '%s'", found_owner_string.c_str(), current_owner_string.c_str(), PrettyTypeOf(o).c_str(), expected_owner_string.c_str()); } else { ThrowIllegalMonitorStateExceptionF("unlock of monitor owned by '%s' on object of type '%s'" " on thread '%s", current_owner_string.c_str(), PrettyTypeOf(o).c_str(), expected_owner_string.c_str()); } } } } bool Monitor::Unlock(Thread* self) { DCHECK(self != NULL); Thread* owner = owner_; if (owner == self) { // We own the monitor, so nobody else can be in here. if (lock_count_ == 0) { owner_ = NULL; locking_method_ = NULL; locking_pc_ = 0; lock_.Unlock(); } else { --lock_count_; } } else { // We don't own this, so we're not allowed to unlock it. // The JNI spec says that we should throw IllegalMonitorStateException // in this case. FailedUnlock(obj_, self, owner, this); return false; } return true; } /* * Converts the given relative waiting time into an absolute time. */ static void ToAbsoluteTime(int64_t ms, int32_t ns, struct timespec *ts) { int64_t endSec; #ifdef HAVE_TIMEDWAIT_MONOTONIC clock_gettime(CLOCK_MONOTONIC, ts); #else { struct timeval tv; gettimeofday(&tv, NULL); ts->tv_sec = tv.tv_sec; ts->tv_nsec = tv.tv_usec * 1000; } #endif endSec = ts->tv_sec + ms / 1000; if (endSec >= 0x7fffffff) { LOG(INFO) << "Note: end time exceeds epoch"; endSec = 0x7ffffffe; } ts->tv_sec = endSec; ts->tv_nsec = (ts->tv_nsec + (ms % 1000) * 1000000) + ns; // Catch rollover. if (ts->tv_nsec >= 1000000000L) { ts->tv_sec++; ts->tv_nsec -= 1000000000L; } } /* * Wait on a monitor until timeout, interrupt, or notification. Used for * Object.wait() and (somewhat indirectly) Thread.sleep() and Thread.join(). * * If another thread calls Thread.interrupt(), we throw InterruptedException * and return immediately if one of the following are true: * - blocked in wait(), wait(long), or wait(long, int) methods of Object * - blocked in join(), join(long), or join(long, int) methods of Thread * - blocked in sleep(long), or sleep(long, int) methods of Thread * Otherwise, we set the "interrupted" flag. * * Checks to make sure that "ns" is in the range 0-999999 * (i.e. fractions of a millisecond) and throws the appropriate * exception if it isn't. * * The spec allows "spurious wakeups", and recommends that all code using * Object.wait() do so in a loop. This appears to derive from concerns * about pthread_cond_wait() on multiprocessor systems. Some commentary * on the web casts doubt on whether these can/should occur. * * Since we're allowed to wake up "early", we clamp extremely long durations * to return at the end of the 32-bit time epoch. */ void Monitor::Wait(Thread* self, int64_t ms, int32_t ns, bool interruptShouldThrow) { DCHECK(self != NULL); // Make sure that we hold the lock. if (owner_ != self) { ThrowIllegalMonitorStateExceptionF("object not locked by thread before wait()"); return; } // Enforce the timeout range. if (ms < 0 || ns < 0 || ns > 999999) { Thread::Current()->ThrowNewExceptionF("Ljava/lang/IllegalArgumentException;", "timeout arguments out of range: ms=%lld ns=%d", ms, ns); return; } // Compute absolute wakeup time, if necessary. struct timespec ts; bool timed = false; if (ms != 0 || ns != 0) { ToAbsoluteTime(ms, ns, &ts); timed = true; } /* * Add ourselves to the set of threads waiting on this monitor, and * release our hold. We need to let it go even if we're a few levels * deep in a recursive lock, and we need to restore that later. * * We append to the wait set ahead of clearing the count and owner * fields so the subroutine can check that the calling thread owns * the monitor. Aside from that, the order of member updates is * not order sensitive as we hold the pthread mutex. */ AppendToWaitSet(self); int prevLockCount = lock_count_; lock_count_ = 0; owner_ = NULL; const Method* savedMethod = locking_method_; locking_method_ = NULL; uintptr_t savedPc = locking_pc_; locking_pc_ = 0; /* * Update thread status. If the GC wakes up, it'll ignore us, knowing * that we won't touch any references in this state, and we'll check * our suspend mode before we transition out. */ if (timed) { self->SetState(Thread::kTimedWaiting); } else { self->SetState(Thread::kWaiting); } self->wait_mutex_->Lock(); /* * Set wait_monitor_ to the monitor object we will be waiting on. * When wait_monitor_ is non-NULL a notifying or interrupting thread * must signal the thread's wait_cond_ to wake it up. */ DCHECK(self->wait_monitor_ == NULL); self->wait_monitor_ = this; /* * Handle the case where the thread was interrupted before we called * wait(). */ bool wasInterrupted = false; if (self->interrupted_) { wasInterrupted = true; self->wait_monitor_ = NULL; self->wait_mutex_->Unlock(); goto done; } /* * Release the monitor lock and wait for a notification or * a timeout to occur. */ lock_.Unlock(); if (!timed) { self->wait_cond_->Wait(*self->wait_mutex_); } else { self->wait_cond_->TimedWait(*self->wait_mutex_, ts); } if (self->interrupted_) { wasInterrupted = true; } self->interrupted_ = false; self->wait_monitor_ = NULL; self->wait_mutex_->Unlock(); // Reacquire the monitor lock. Lock(self); done: /* * We remove our thread from wait set after restoring the count * and owner fields so the subroutine can check that the calling * thread owns the monitor. Aside from that, the order of member * updates is not order sensitive as we hold the pthread mutex. */ owner_ = self; lock_count_ = prevLockCount; locking_method_ = savedMethod; locking_pc_ = savedPc; RemoveFromWaitSet(self); /* set self->status back to Thread::kRunnable, and self-suspend if needed */ self->SetState(Thread::kRunnable); if (wasInterrupted) { /* * We were interrupted while waiting, or somebody interrupted an * un-interruptible thread earlier and we're bailing out immediately. * * The doc sayeth: "The interrupted status of the current thread is * cleared when this exception is thrown." */ self->interrupted_ = false; if (interruptShouldThrow) { Thread::Current()->ThrowNewException("Ljava/lang/InterruptedException;", NULL); } } } void Monitor::Notify(Thread* self) { DCHECK(self != NULL); // Make sure that we hold the lock. if (owner_ != self) { ThrowIllegalMonitorStateExceptionF("object not locked by thread before notify()"); return; } // Signal the first waiting thread in the wait set. while (wait_set_ != NULL) { Thread* thread = wait_set_; wait_set_ = thread->wait_next_; thread->wait_next_ = NULL; // Check to see if the thread is still waiting. MutexLock mu(*thread->wait_mutex_); if (thread->wait_monitor_ != NULL) { thread->wait_cond_->Signal(); return; } } } void Monitor::NotifyAll(Thread* self) { DCHECK(self != NULL); // Make sure that we hold the lock. if (owner_ != self) { ThrowIllegalMonitorStateExceptionF("object not locked by thread before notifyAll()"); return; } // Signal all threads in the wait set. while (wait_set_ != NULL) { Thread* thread = wait_set_; wait_set_ = thread->wait_next_; thread->wait_next_ = NULL; thread->Notify(); } } /* * Changes the shape of a monitor from thin to fat, preserving the * internal lock state. The calling thread must own the lock. */ void Monitor::Inflate(Thread* self, Object* obj) { DCHECK(self != NULL); DCHECK(obj != NULL); DCHECK_EQ(LW_SHAPE(*obj->GetRawLockWordAddress()), LW_SHAPE_THIN); DCHECK_EQ(LW_LOCK_OWNER(*obj->GetRawLockWordAddress()), static_cast(self->GetThinLockId())); // Allocate and acquire a new monitor. Monitor* m = new Monitor(obj); VLOG(monitor) << "monitor: thread " << self->GetThinLockId() << " created monitor " << m << " for object " << obj; Runtime::Current()->GetMonitorList()->Add(m); m->Lock(self); // Propagate the lock state. uint32_t thin = *obj->GetRawLockWordAddress(); m->lock_count_ = LW_LOCK_COUNT(thin); thin &= LW_HASH_STATE_MASK << LW_HASH_STATE_SHIFT; thin |= reinterpret_cast(m) | LW_SHAPE_FAT; // Publish the updated lock word. android_atomic_release_store(thin, obj->GetRawLockWordAddress()); } void Monitor::MonitorEnter(Thread* self, Object* obj) { volatile int32_t* thinp = obj->GetRawLockWordAddress(); struct timespec tm; long sleepDelayNs; long minSleepDelayNs = 1000000; /* 1 millisecond */ long maxSleepDelayNs = 1000000000; /* 1 second */ uint32_t thin, newThin; DCHECK(self != NULL); DCHECK(obj != NULL); uint32_t threadId = self->GetThinLockId(); retry: thin = *thinp; if (LW_SHAPE(thin) == LW_SHAPE_THIN) { /* * The lock is a thin lock. The owner field is used to * determine the acquire method, ordered by cost. */ if (LW_LOCK_OWNER(thin) == threadId) { /* * The calling thread owns the lock. Increment the * value of the recursion count field. */ *thinp += 1 << LW_LOCK_COUNT_SHIFT; if (LW_LOCK_COUNT(*thinp) == LW_LOCK_COUNT_MASK) { /* * The reacquisition limit has been reached. Inflate * the lock so the next acquire will not overflow the * recursion count field. */ Inflate(self, obj); } } else if (LW_LOCK_OWNER(thin) == 0) { /* * The lock is unowned. Install the thread id of the * calling thread into the owner field. This is the * common case. In performance critical code the JIT * will have tried this before calling out to the VM. */ newThin = thin | (threadId << LW_LOCK_OWNER_SHIFT); if (android_atomic_acquire_cas(thin, newThin, thinp) != 0) { // The acquire failed. Try again. goto retry; } } else { VLOG(monitor) << StringPrintf("monitor: thread %d spin on lock %p (a %s) owned by %d", threadId, thinp, PrettyTypeOf(obj).c_str(), LW_LOCK_OWNER(thin)); // The lock is owned by another thread. Notify the VM that we are about to wait. self->monitor_enter_object_ = obj; Thread::State oldStatus = self->SetState(Thread::kBlocked); // Spin until the thin lock is released or inflated. sleepDelayNs = 0; for (;;) { thin = *thinp; // Check the shape of the lock word. Another thread // may have inflated the lock while we were waiting. if (LW_SHAPE(thin) == LW_SHAPE_THIN) { if (LW_LOCK_OWNER(thin) == 0) { // The lock has been released. Install the thread id of the // calling thread into the owner field. newThin = thin | (threadId << LW_LOCK_OWNER_SHIFT); if (android_atomic_acquire_cas(thin, newThin, thinp) == 0) { // The acquire succeed. Break out of the loop and proceed to inflate the lock. break; } } else { // The lock has not been released. Yield so the owning thread can run. if (sleepDelayNs == 0) { sched_yield(); sleepDelayNs = minSleepDelayNs; } else { tm.tv_sec = 0; tm.tv_nsec = sleepDelayNs; nanosleep(&tm, NULL); // Prepare the next delay value. Wrap to avoid once a second polls for eternity. if (sleepDelayNs < maxSleepDelayNs / 2) { sleepDelayNs *= 2; } else { sleepDelayNs = minSleepDelayNs; } } } } else { // The thin lock was inflated by another thread. Let the VM know we are no longer // waiting and try again. VLOG(monitor) << "monitor: thread " << threadId << " found lock " << (void*) thinp << " surprise-fattened by another thread"; self->monitor_enter_object_ = NULL; self->SetState(oldStatus); goto retry; } } VLOG(monitor) << StringPrintf("monitor: thread %d spin on lock %p done", threadId, thinp); // We have acquired the thin lock. Let the VM know that we are no longer waiting. self->monitor_enter_object_ = NULL; self->SetState(oldStatus); // Fatten the lock. Inflate(self, obj); VLOG(monitor) << StringPrintf("monitor: thread %d fattened lock %p", threadId, thinp); } } else { // The lock is a fat lock. VLOG(monitor) << StringPrintf("monitor: thread %d locking fat lock %p (%p) %p on a %s", threadId, thinp, LW_MONITOR(*thinp), (void*)*thinp, PrettyTypeOf(obj).c_str()); DCHECK(LW_MONITOR(*thinp) != NULL); LW_MONITOR(*thinp)->Lock(self); } } bool Monitor::MonitorExit(Thread* self, Object* obj) { volatile int32_t* thinp = obj->GetRawLockWordAddress(); DCHECK(self != NULL); //DCHECK_EQ(self->GetState(), Thread::kRunnable); DCHECK(obj != NULL); /* * Cache the lock word as its value can change while we are * examining its state. */ uint32_t thin = *thinp; if (LW_SHAPE(thin) == LW_SHAPE_THIN) { /* * The lock is thin. We must ensure that the lock is owned * by the given thread before unlocking it. */ if (LW_LOCK_OWNER(thin) == self->GetThinLockId()) { /* * We are the lock owner. It is safe to update the lock * without CAS as lock ownership guards the lock itself. */ if (LW_LOCK_COUNT(thin) == 0) { /* * The lock was not recursively acquired, the common * case. Unlock by clearing all bits except for the * hash state. */ thin &= (LW_HASH_STATE_MASK << LW_HASH_STATE_SHIFT); android_atomic_release_store(thin, thinp); } else { /* * The object was recursively acquired. Decrement the * lock recursion count field. */ *thinp -= 1 << LW_LOCK_COUNT_SHIFT; } } else { /* * We do not own the lock. The JVM spec requires that we * throw an exception in this case. */ FailedUnlock(obj, self, NULL, NULL); return false; } } else { /* * The lock is fat. We must check to see if Unlock has * raised any exceptions before continuing. */ DCHECK(LW_MONITOR(*thinp) != NULL); if (!LW_MONITOR(*thinp)->Unlock(self)) { // An exception has been raised. Do not fall through. return false; } } return true; } /* * Object.wait(). Also called for class init. */ void Monitor::Wait(Thread* self, Object *obj, int64_t ms, int32_t ns, bool interruptShouldThrow) { volatile int32_t* thinp = obj->GetRawLockWordAddress(); // If the lock is still thin, we need to fatten it. uint32_t thin = *thinp; if (LW_SHAPE(thin) == LW_SHAPE_THIN) { // Make sure that 'self' holds the lock. if (LW_LOCK_OWNER(thin) != self->GetThinLockId()) { ThrowIllegalMonitorStateExceptionF("object not locked by thread before wait()"); return; } /* This thread holds the lock. We need to fatten the lock * so 'self' can block on it. Don't update the object lock * field yet, because 'self' needs to acquire the lock before * any other thread gets a chance. */ Inflate(self, obj); VLOG(monitor) << StringPrintf("monitor: thread %d fattened lock %p by wait()", self->GetThinLockId(), thinp); } LW_MONITOR(*thinp)->Wait(self, ms, ns, interruptShouldThrow); } void Monitor::Notify(Thread* self, Object *obj) { uint32_t thin = *obj->GetRawLockWordAddress(); // If the lock is still thin, there aren't any waiters; // waiting on an object forces lock fattening. if (LW_SHAPE(thin) == LW_SHAPE_THIN) { // Make sure that 'self' holds the lock. if (LW_LOCK_OWNER(thin) != self->GetThinLockId()) { ThrowIllegalMonitorStateExceptionF("object not locked by thread before notify()"); return; } // no-op; there are no waiters to notify. } else { // It's a fat lock. LW_MONITOR(thin)->Notify(self); } } void Monitor::NotifyAll(Thread* self, Object *obj) { uint32_t thin = *obj->GetRawLockWordAddress(); // If the lock is still thin, there aren't any waiters; // waiting on an object forces lock fattening. if (LW_SHAPE(thin) == LW_SHAPE_THIN) { // Make sure that 'self' holds the lock. if (LW_LOCK_OWNER(thin) != self->GetThinLockId()) { ThrowIllegalMonitorStateExceptionF("object not locked by thread before notifyAll()"); return; } // no-op; there are no waiters to notify. } else { // It's a fat lock. LW_MONITOR(thin)->NotifyAll(self); } } uint32_t Monitor::GetThinLockId(uint32_t raw_lock_word) { if (LW_SHAPE(raw_lock_word) == LW_SHAPE_THIN) { return LW_LOCK_OWNER(raw_lock_word); } else { Thread* owner = LW_MONITOR(raw_lock_word)->owner_; return owner ? owner->GetThinLockId() : 0; } } void Monitor::DescribeWait(std::ostream& os, const Thread* thread) { Thread::State state = thread->GetState(); Object* object = NULL; uint32_t lock_owner = ThreadList::kInvalidId; if (state == Thread::kWaiting || state == Thread::kTimedWaiting) { os << " - waiting on "; Monitor* monitor = thread->wait_monitor_; if (monitor != NULL) { object = monitor->obj_; } lock_owner = Thread::LockOwnerFromThreadLock(object); } else if (state == Thread::kBlocked) { os << " - waiting to lock "; object = thread->monitor_enter_object_; if (object != NULL) { lock_owner = object->GetThinLockId(); } } else { // We're not waiting on anything. return; } os << "<" << object << ">"; // - waiting on <0x613f83d8> (a java.lang.ThreadLock) held by thread 5 // - waiting on <0x6008c468> (a java.lang.Class) os << " (a " << PrettyTypeOf(object) << ")"; if (lock_owner != ThreadList::kInvalidId) { os << " held by thread " << lock_owner; } os << "\n"; } void Monitor::TranslateLocation(const Method* method, uint32_t pc, const char*& source_file, uint32_t& line_number) const { // If method is null, location is unknown if (method == NULL) { source_file = ""; line_number = 0; return; } MethodHelper mh(method); source_file = mh.GetDeclaringClassSourceFile(); if (source_file == NULL) { source_file = ""; } line_number = mh.GetLineNumFromNativePC(pc); } MonitorList::MonitorList() : lock_("MonitorList lock") { } MonitorList::~MonitorList() { MutexLock mu(lock_); STLDeleteElements(&list_); } void MonitorList::Add(Monitor* m) { MutexLock mu(lock_); list_.push_front(m); } void MonitorList::SweepMonitorList(Heap::IsMarkedTester is_marked, void* arg) { MutexLock mu(lock_); typedef std::list::iterator It; // TODO: C++0x auto It it = list_.begin(); while (it != list_.end()) { Monitor* m = *it; if (!is_marked(m->GetObject(), arg)) { VLOG(monitor) << "freeing monitor " << m << " belonging to unmarked object " << m->GetObject(); delete m; it = list_.erase(it); } else { ++it; } } } } // namespace art