/*
* Copyright (C) 2011 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 "mutex.h"
#include <errno.h>
#include <sys/time.h>
#include "android-base/stringprintf.h"
#include "base/atomic.h"
#include "base/logging.h"
#include "base/systrace.h"
#include "base/time_utils.h"
#include "base/value_object.h"
#include "mutex-inl.h"
#include "scoped_thread_state_change-inl.h"
#include "thread-inl.h"
namespace art {
using android::base::StringPrintf;
static Atomic<Locks::ClientCallback*> safe_to_call_abort_callback(nullptr);
Mutex* Locks::abort_lock_ = nullptr;
Mutex* Locks::alloc_tracker_lock_ = nullptr;
Mutex* Locks::allocated_monitor_ids_lock_ = nullptr;
Mutex* Locks::allocated_thread_ids_lock_ = nullptr;
ReaderWriterMutex* Locks::breakpoint_lock_ = nullptr;
ReaderWriterMutex* Locks::classlinker_classes_lock_ = nullptr;
Mutex* Locks::deoptimization_lock_ = nullptr;
ReaderWriterMutex* Locks::heap_bitmap_lock_ = nullptr;
Mutex* Locks::instrument_entrypoints_lock_ = nullptr;
Mutex* Locks::intern_table_lock_ = nullptr;
Mutex* Locks::jni_function_table_lock_ = nullptr;
Mutex* Locks::jni_libraries_lock_ = nullptr;
Mutex* Locks::logging_lock_ = nullptr;
Mutex* Locks::modify_ldt_lock_ = nullptr;
MutatorMutex* Locks::mutator_lock_ = nullptr;
Mutex* Locks::profiler_lock_ = nullptr;
ReaderWriterMutex* Locks::verifier_deps_lock_ = nullptr;
ReaderWriterMutex* Locks::oat_file_manager_lock_ = nullptr;
Mutex* Locks::host_dlopen_handles_lock_ = nullptr;
Mutex* Locks::reference_processor_lock_ = nullptr;
Mutex* Locks::reference_queue_cleared_references_lock_ = nullptr;
Mutex* Locks::reference_queue_finalizer_references_lock_ = nullptr;
Mutex* Locks::reference_queue_phantom_references_lock_ = nullptr;
Mutex* Locks::reference_queue_soft_references_lock_ = nullptr;
Mutex* Locks::reference_queue_weak_references_lock_ = nullptr;
Mutex* Locks::runtime_shutdown_lock_ = nullptr;
Mutex* Locks::cha_lock_ = nullptr;
Mutex* Locks::subtype_check_lock_ = nullptr;
Mutex* Locks::thread_list_lock_ = nullptr;
ConditionVariable* Locks::thread_exit_cond_ = nullptr;
Mutex* Locks::thread_suspend_count_lock_ = nullptr;
Mutex* Locks::trace_lock_ = nullptr;
Mutex* Locks::unexpected_signal_lock_ = nullptr;
Mutex* Locks::user_code_suspension_lock_ = nullptr;
Uninterruptible Roles::uninterruptible_;
ReaderWriterMutex* Locks::jni_globals_lock_ = nullptr;
Mutex* Locks::jni_weak_globals_lock_ = nullptr;
ReaderWriterMutex* Locks::dex_lock_ = nullptr;
Mutex* Locks::native_debug_interface_lock_ = nullptr;
std::vector<BaseMutex*> Locks::expected_mutexes_on_weak_ref_access_;
Atomic<const BaseMutex*> Locks::expected_mutexes_on_weak_ref_access_guard_;
struct AllMutexData {
// A guard for all_mutexes_ that's not a mutex (Mutexes must CAS to acquire and busy wait).
Atomic<const BaseMutex*> all_mutexes_guard;
// All created mutexes guarded by all_mutexes_guard_.
std::set<BaseMutex*>* all_mutexes;
AllMutexData() : all_mutexes(nullptr) {}
};
static struct AllMutexData gAllMutexData[kAllMutexDataSize];
#if ART_USE_FUTEXES
static bool ComputeRelativeTimeSpec(timespec* result_ts, const timespec& lhs, const timespec& rhs) {
const int32_t one_sec = 1000 * 1000 * 1000; // one second in nanoseconds.
result_ts->tv_sec = lhs.tv_sec - rhs.tv_sec;
result_ts->tv_nsec = lhs.tv_nsec - rhs.tv_nsec;
if (result_ts->tv_nsec < 0) {
result_ts->tv_sec--;
result_ts->tv_nsec += one_sec;
} else if (result_ts->tv_nsec > one_sec) {
result_ts->tv_sec++;
result_ts->tv_nsec -= one_sec;
}
return result_ts->tv_sec < 0;
}
#endif
// Wait for an amount of time that roughly increases in the argument i.
// Spin for small arguments and yield/sleep for longer ones.
static void BackOff(uint32_t i) {
static constexpr uint32_t kSpinMax = 10;
static constexpr uint32_t kYieldMax = 20;
if (i <= kSpinMax) {
// TODO: Esp. in very latency-sensitive cases, consider replacing this with an explicit
// test-and-test-and-set loop in the caller. Possibly skip entirely on a uniprocessor.
volatile uint32_t x = 0;
const uint32_t spin_count = 10 * i;
for (uint32_t spin = 0; spin < spin_count; ++spin) {
++x; // Volatile; hence should not be optimized away.
}
// TODO: Consider adding x86 PAUSE and/or ARM YIELD here.
} else if (i <= kYieldMax) {
sched_yield();
} else {
NanoSleep(1000ull * (i - kYieldMax));
}
}
class ScopedAllMutexesLock FINAL {
public:
explicit ScopedAllMutexesLock(const BaseMutex* mutex) : mutex_(mutex) {
for (uint32_t i = 0;
!gAllMutexData->all_mutexes_guard.CompareAndSetWeakAcquire(0, mutex);
++i) {
BackOff(i);
}
}
~ScopedAllMutexesLock() {
DCHECK_EQ(gAllMutexData->all_mutexes_guard.LoadRelaxed(), mutex_);
gAllMutexData->all_mutexes_guard.StoreRelease(0);
}
private:
const BaseMutex* const mutex_;
};
class Locks::ScopedExpectedMutexesOnWeakRefAccessLock FINAL {
public:
explicit ScopedExpectedMutexesOnWeakRefAccessLock(const BaseMutex* mutex) : mutex_(mutex) {
for (uint32_t i = 0;
!Locks::expected_mutexes_on_weak_ref_access_guard_.CompareAndSetWeakAcquire(0, mutex);
++i) {
BackOff(i);
}
}
~ScopedExpectedMutexesOnWeakRefAccessLock() {
DCHECK_EQ(Locks::expected_mutexes_on_weak_ref_access_guard_.LoadRelaxed(), mutex_);
Locks::expected_mutexes_on_weak_ref_access_guard_.StoreRelease(0);
}
private:
const BaseMutex* const mutex_;
};
// Scoped class that generates events at the beginning and end of lock contention.
class ScopedContentionRecorder FINAL : public ValueObject {
public:
ScopedContentionRecorder(BaseMutex* mutex, uint64_t blocked_tid, uint64_t owner_tid)
: mutex_(kLogLockContentions ? mutex : nullptr),
blocked_tid_(kLogLockContentions ? blocked_tid : 0),
owner_tid_(kLogLockContentions ? owner_tid : 0),
start_nano_time_(kLogLockContentions ? NanoTime() : 0) {
if (ATRACE_ENABLED()) {
std::string msg = StringPrintf("Lock contention on %s (owner tid: %" PRIu64 ")",
mutex->GetName(), owner_tid);
ATRACE_BEGIN(msg.c_str());
}
}
~ScopedContentionRecorder() {
ATRACE_END();
if (kLogLockContentions) {
uint64_t end_nano_time = NanoTime();
mutex_->RecordContention(blocked_tid_, owner_tid_, end_nano_time - start_nano_time_);
}
}
private:
BaseMutex* const mutex_;
const uint64_t blocked_tid_;
const uint64_t owner_tid_;
const uint64_t start_nano_time_;
};
BaseMutex::BaseMutex(const char* name, LockLevel level)
: level_(level),
name_(name),
should_respond_to_empty_checkpoint_request_(false) {
if (kLogLockContentions) {
ScopedAllMutexesLock mu(this);
std::set<BaseMutex*>** all_mutexes_ptr = &gAllMutexData->all_mutexes;
if (*all_mutexes_ptr == nullptr) {
// We leak the global set of all mutexes to avoid ordering issues in global variable
// construction/destruction.
*all_mutexes_ptr = new std::set<BaseMutex*>();
}
(*all_mutexes_ptr)->insert(this);
}
}
BaseMutex::~BaseMutex() {
if (kLogLockContentions) {
ScopedAllMutexesLock mu(this);
gAllMutexData->all_mutexes->erase(this);
}
}
void BaseMutex::DumpAll(std::ostream& os) {
if (kLogLockContentions) {
os << "Mutex logging:\n";
ScopedAllMutexesLock mu(reinterpret_cast<const BaseMutex*>(-1));
std::set<BaseMutex*>* all_mutexes = gAllMutexData->all_mutexes;
if (all_mutexes == nullptr) {
// No mutexes have been created yet during at startup.
return;
}
typedef std::set<BaseMutex*>::const_iterator It;
os << "(Contended)\n";
for (It it = all_mutexes->begin(); it != all_mutexes->end(); ++it) {
BaseMutex* mutex = *it;
if (mutex->HasEverContended()) {
mutex->Dump(os);
os << "\n";
}
}
os << "(Never contented)\n";
for (It it = all_mutexes->begin(); it != all_mutexes->end(); ++it) {
BaseMutex* mutex = *it;
if (!mutex->HasEverContended()) {
mutex->Dump(os);
os << "\n";
}
}
}
}
void BaseMutex::CheckSafeToWait(Thread* self) {
if (self == nullptr) {
CheckUnattachedThread(level_);
return;
}
if (kDebugLocking) {
CHECK(self->GetHeldMutex(level_) == this || level_ == kMonitorLock)
<< "Waiting on unacquired mutex: " << name_;
bool bad_mutexes_held = false;
for (int i = kLockLevelCount - 1; i >= 0; --i) {
if (i != level_) {
BaseMutex* held_mutex = self->GetHeldMutex(static_cast<LockLevel>(i));
// We allow the thread to wait even if the user_code_suspension_lock_ is held so long as we
// are some thread's resume_cond_ (level_ == kThreadSuspendCountLock). This just means that
// gc or some other internal process is suspending the thread while it is trying to suspend
// some other thread. So long as the current thread is not being suspended by a
// SuspendReason::kForUserCode (which needs the user_code_suspension_lock_ to clear) this is
// fine.
if (held_mutex == Locks::user_code_suspension_lock_ && level_ == kThreadSuspendCountLock) {
// No thread safety analysis is fine since we have both the user_code_suspension_lock_
// from the line above and the ThreadSuspendCountLock since it is our level_. We use this
// lambda to avoid having to annotate the whole function as NO_THREAD_SAFETY_ANALYSIS.
auto is_suspending_for_user_code = [self]() NO_THREAD_SAFETY_ANALYSIS {
return self->GetUserCodeSuspendCount() != 0;
};
if (is_suspending_for_user_code()) {
LOG(ERROR) << "Holding \"" << held_mutex->name_ << "\" "
<< "(level " << LockLevel(i) << ") while performing wait on "
<< "\"" << name_ << "\" (level " << level_ << ") "
<< "with SuspendReason::kForUserCode pending suspensions";
bad_mutexes_held = true;
}
} else if (held_mutex != nullptr) {
LOG(ERROR) << "Holding \"" << held_mutex->name_ << "\" "
<< "(level " << LockLevel(i) << ") while performing wait on "
<< "\"" << name_ << "\" (level " << level_ << ")";
bad_mutexes_held = true;
}
}
}
if (gAborting == 0) { // Avoid recursive aborts.
CHECK(!bad_mutexes_held) << this;
}
}
}
void BaseMutex::ContentionLogData::AddToWaitTime(uint64_t value) {
if (kLogLockContentions) {
// Atomically add value to wait_time.
wait_time.FetchAndAddSequentiallyConsistent(value);
}
}
void BaseMutex::RecordContention(uint64_t blocked_tid,
uint64_t owner_tid,
uint64_t nano_time_blocked) {
if (kLogLockContentions) {
ContentionLogData* data = contention_log_data_;
++(data->contention_count);
data->AddToWaitTime(nano_time_blocked);
ContentionLogEntry* log = data->contention_log;
// This code is intentionally racy as it is only used for diagnostics.
uint32_t slot = data->cur_content_log_entry.LoadRelaxed();
if (log[slot].blocked_tid == blocked_tid &&
log[slot].owner_tid == blocked_tid) {
++log[slot].count;
} else {
uint32_t new_slot;
do {
slot = data->cur_content_log_entry.LoadRelaxed();
new_slot = (slot + 1) % kContentionLogSize;
} while (!data->cur_content_log_entry.CompareAndSetWeakRelaxed(slot, new_slot));
log[new_slot].blocked_tid = blocked_tid;
log[new_slot].owner_tid = owner_tid;
log[new_slot].count.StoreRelaxed(1);
}
}
}
void BaseMutex::DumpContention(std::ostream& os) const {
if (kLogLockContentions) {
const ContentionLogData* data = contention_log_data_;
const ContentionLogEntry* log = data->contention_log;
uint64_t wait_time = data->wait_time.LoadRelaxed();
uint32_t contention_count = data->contention_count.LoadRelaxed();
if (contention_count == 0) {
os << "never contended";
} else {
os << "contended " << contention_count
<< " total wait of contender " << PrettyDuration(wait_time)
<< " average " << PrettyDuration(wait_time / contention_count);
SafeMap<uint64_t, size_t> most_common_blocker;
SafeMap<uint64_t, size_t> most_common_blocked;
for (size_t i = 0; i < kContentionLogSize; ++i) {
uint64_t blocked_tid = log[i].blocked_tid;
uint64_t owner_tid = log[i].owner_tid;
uint32_t count = log[i].count.LoadRelaxed();
if (count > 0) {
auto it = most_common_blocked.find(blocked_tid);
if (it != most_common_blocked.end()) {
most_common_blocked.Overwrite(blocked_tid, it->second + count);
} else {
most_common_blocked.Put(blocked_tid, count);
}
it = most_common_blocker.find(owner_tid);
if (it != most_common_blocker.end()) {
most_common_blocker.Overwrite(owner_tid, it->second + count);
} else {
most_common_blocker.Put(owner_tid, count);
}
}
}
uint64_t max_tid = 0;
size_t max_tid_count = 0;
for (const auto& pair : most_common_blocked) {
if (pair.second > max_tid_count) {
max_tid = pair.first;
max_tid_count = pair.second;
}
}
if (max_tid != 0) {
os << " sample shows most blocked tid=" << max_tid;
}
max_tid = 0;
max_tid_count = 0;
for (const auto& pair : most_common_blocker) {
if (pair.second > max_tid_count) {
max_tid = pair.first;
max_tid_count = pair.second;
}
}
if (max_tid != 0) {
os << " sample shows tid=" << max_tid << " owning during this time";
}
}
}
}
Mutex::Mutex(const char* name, LockLevel level, bool recursive)
: BaseMutex(name, level), exclusive_owner_(0), recursive_(recursive), recursion_count_(0) {
#if ART_USE_FUTEXES
DCHECK_EQ(0, state_.LoadRelaxed());
DCHECK_EQ(0, num_contenders_.LoadRelaxed());
#else
CHECK_MUTEX_CALL(pthread_mutex_init, (&mutex_, nullptr));
#endif
}
// Helper to allow checking shutdown while locking for thread safety.
static bool IsSafeToCallAbortSafe() {
MutexLock mu(Thread::Current(), *Locks::runtime_shutdown_lock_);
return Locks::IsSafeToCallAbortRacy();
}
Mutex::~Mutex() {
bool safe_to_call_abort = Locks::IsSafeToCallAbortRacy();
#if ART_USE_FUTEXES
if (state_.LoadRelaxed() != 0) {
LOG(safe_to_call_abort ? FATAL : WARNING)
<< "destroying mutex with owner: " << GetExclusiveOwnerTid();
} else {
if (GetExclusiveOwnerTid() != 0) {
LOG(safe_to_call_abort ? FATAL : WARNING)
<< "unexpectedly found an owner on unlocked mutex " << name_;
}
if (num_contenders_.LoadSequentiallyConsistent() != 0) {
LOG(safe_to_call_abort ? FATAL : WARNING)
<< "unexpectedly found a contender on mutex " << name_;
}
}
#else
// We can't use CHECK_MUTEX_CALL here because on shutdown a suspended daemon thread
// may still be using locks.
int rc = pthread_mutex_destroy(&mutex_);
if (rc != 0) {
errno = rc;
PLOG(safe_to_call_abort ? FATAL : WARNING)
<< "pthread_mutex_destroy failed for " << name_;
}
#endif
}
void Mutex::ExclusiveLock(Thread* self) {
DCHECK(self == nullptr || self == Thread::Current());
if (kDebugLocking && !recursive_) {
AssertNotHeld(self);
}
if (!recursive_ || !IsExclusiveHeld(self)) {
#if ART_USE_FUTEXES
bool done = false;
do {
int32_t cur_state = state_.LoadRelaxed();
if (LIKELY(cur_state == 0)) {
// Change state from 0 to 1 and impose load/store ordering appropriate for lock acquisition.
done = state_.CompareAndSetWeakAcquire(0 /* cur_state */, 1 /* new state */);
} else {
// Failed to acquire, hang up.
ScopedContentionRecorder scr(this, SafeGetTid(self), GetExclusiveOwnerTid());
num_contenders_++;
if (UNLIKELY(should_respond_to_empty_checkpoint_request_)) {
self->CheckEmptyCheckpointFromMutex();
}
if (futex(state_.Address(), FUTEX_WAIT, 1, nullptr, nullptr, 0) != 0) {
// EAGAIN and EINTR both indicate a spurious failure, try again from the beginning.
// We don't use TEMP_FAILURE_RETRY so we can intentionally retry to acquire the lock.
if ((errno != EAGAIN) && (errno != EINTR)) {
PLOG(FATAL) << "futex wait failed for " << name_;
}
}
num_contenders_--;
}
} while (!done);
DCHECK_EQ(state_.LoadRelaxed(), 1);
#else
CHECK_MUTEX_CALL(pthread_mutex_lock, (&mutex_));
#endif
DCHECK_EQ(GetExclusiveOwnerTid(), 0);
exclusive_owner_.StoreRelaxed(SafeGetTid(self));
RegisterAsLocked(self);
}
recursion_count_++;
if (kDebugLocking) {
CHECK(recursion_count_ == 1 || recursive_) << "Unexpected recursion count on mutex: "
<< name_ << " " << recursion_count_;
AssertHeld(self);
}
}
bool Mutex::ExclusiveTryLock(Thread* self) {
DCHECK(self == nullptr || self == Thread::Current());
if (kDebugLocking && !recursive_) {
AssertNotHeld(self);
}
if (!recursive_ || !IsExclusiveHeld(self)) {
#if ART_USE_FUTEXES
bool done = false;
do {
int32_t cur_state = state_.LoadRelaxed();
if (cur_state == 0) {
// Change state from 0 to 1 and impose load/store ordering appropriate for lock acquisition.
done = state_.CompareAndSetWeakAcquire(0 /* cur_state */, 1 /* new state */);
} else {
return false;
}
} while (!done);
DCHECK_EQ(state_.LoadRelaxed(), 1);
#else
int result = pthread_mutex_trylock(&mutex_);
if (result == EBUSY) {
return false;
}
if (result != 0) {
errno = result;
PLOG(FATAL) << "pthread_mutex_trylock failed for " << name_;
}
#endif
DCHECK_EQ(GetExclusiveOwnerTid(), 0);
exclusive_owner_.StoreRelaxed(SafeGetTid(self));
RegisterAsLocked(self);
}
recursion_count_++;
if (kDebugLocking) {
CHECK(recursion_count_ == 1 || recursive_) << "Unexpected recursion count on mutex: "
<< name_ << " " << recursion_count_;
AssertHeld(self);
}
return true;
}
void Mutex::ExclusiveUnlock(Thread* self) {
if (kIsDebugBuild && self != nullptr && self != Thread::Current()) {
std::string name1 = "<null>";
std::string name2 = "<null>";
if (self != nullptr) {
self->GetThreadName(name1);
}
if (Thread::Current() != nullptr) {
Thread::Current()->GetThreadName(name2);
}
LOG(FATAL) << GetName() << " level=" << level_ << " self=" << name1
<< " Thread::Current()=" << name2;
}
AssertHeld(self);
DCHECK_NE(GetExclusiveOwnerTid(), 0);
recursion_count_--;
if (!recursive_ || recursion_count_ == 0) {
if (kDebugLocking) {
CHECK(recursion_count_ == 0 || recursive_) << "Unexpected recursion count on mutex: "
<< name_ << " " << recursion_count_;
}
RegisterAsUnlocked(self);
#if ART_USE_FUTEXES
bool done = false;
do {
int32_t cur_state = state_.LoadRelaxed();
if (LIKELY(cur_state == 1)) {
// We're no longer the owner.
exclusive_owner_.StoreRelaxed(0);
// Change state to 0 and impose load/store ordering appropriate for lock release.
// Note, the relaxed loads below mustn't reorder before the CompareAndSet.
// TODO: the ordering here is non-trivial as state is split across 3 fields, fix by placing
// a status bit into the state on contention.
done = state_.CompareAndSetWeakSequentiallyConsistent(cur_state, 0 /* new state */);
if (LIKELY(done)) { // Spurious fail?
// Wake a contender.
if (UNLIKELY(num_contenders_.LoadRelaxed() > 0)) {
futex(state_.Address(), FUTEX_WAKE, 1, nullptr, nullptr, 0);
}
}
} else {
// Logging acquires the logging lock, avoid infinite recursion in that case.
if (this != Locks::logging_lock_) {
LOG(FATAL) << "Unexpected state_ in unlock " << cur_state << " for " << name_;
} else {
LogHelper::LogLineLowStack(__FILE__,
__LINE__,
::android::base::FATAL_WITHOUT_ABORT,
StringPrintf("Unexpected state_ %d in unlock for %s",
cur_state, name_).c_str());
_exit(1);
}
}
} while (!done);
#else
exclusive_owner_.StoreRelaxed(0);
CHECK_MUTEX_CALL(pthread_mutex_unlock, (&mutex_));
#endif
}
}
void Mutex::Dump(std::ostream& os) const {
os << (recursive_ ? "recursive " : "non-recursive ")
<< name_
<< " level=" << static_cast<int>(level_)
<< " rec=" << recursion_count_
<< " owner=" << GetExclusiveOwnerTid() << " ";
DumpContention(os);
}
std::ostream& operator<<(std::ostream& os, const Mutex& mu) {
mu.Dump(os);
return os;
}
void Mutex::WakeupToRespondToEmptyCheckpoint() {
#if ART_USE_FUTEXES
// Wake up all the waiters so they will respond to the emtpy checkpoint.
DCHECK(should_respond_to_empty_checkpoint_request_);
if (UNLIKELY(num_contenders_.LoadRelaxed() > 0)) {
futex(state_.Address(), FUTEX_WAKE, -1, nullptr, nullptr, 0);
}
#else
LOG(FATAL) << "Non futex case isn't supported.";
#endif
}
ReaderWriterMutex::ReaderWriterMutex(const char* name, LockLevel level)
: BaseMutex(name, level)
#if ART_USE_FUTEXES
, state_(0), num_pending_readers_(0), num_pending_writers_(0)
#endif
{
#if !ART_USE_FUTEXES
CHECK_MUTEX_CALL(pthread_rwlock_init, (&rwlock_, nullptr));
#endif
exclusive_owner_.StoreRelaxed(0);
}
ReaderWriterMutex::~ReaderWriterMutex() {
#if ART_USE_FUTEXES
CHECK_EQ(state_.LoadRelaxed(), 0);
CHECK_EQ(GetExclusiveOwnerTid(), 0);
CHECK_EQ(num_pending_readers_.LoadRelaxed(), 0);
CHECK_EQ(num_pending_writers_.LoadRelaxed(), 0);
#else
// We can't use CHECK_MUTEX_CALL here because on shutdown a suspended daemon thread
// may still be using locks.
int rc = pthread_rwlock_destroy(&rwlock_);
if (rc != 0) {
errno = rc;
bool is_safe_to_call_abort = IsSafeToCallAbortSafe();
PLOG(is_safe_to_call_abort ? FATAL : WARNING) << "pthread_rwlock_destroy failed for " << name_;
}
#endif
}
void ReaderWriterMutex::ExclusiveLock(Thread* self) {
DCHECK(self == nullptr || self == Thread::Current());
AssertNotExclusiveHeld(self);
#if ART_USE_FUTEXES
bool done = false;
do {
int32_t cur_state = state_.LoadRelaxed();
if (LIKELY(cur_state == 0)) {
// Change state from 0 to -1 and impose load/store ordering appropriate for lock acquisition.
done = state_.CompareAndSetWeakAcquire(0 /* cur_state*/, -1 /* new state */);
} else {
// Failed to acquire, hang up.
ScopedContentionRecorder scr(this, SafeGetTid(self), GetExclusiveOwnerTid());
++num_pending_writers_;
if (UNLIKELY(should_respond_to_empty_checkpoint_request_)) {
self->CheckEmptyCheckpointFromMutex();
}
if (futex(state_.Address(), FUTEX_WAIT, cur_state, nullptr, nullptr, 0) != 0) {
// EAGAIN and EINTR both indicate a spurious failure, try again from the beginning.
// We don't use TEMP_FAILURE_RETRY so we can intentionally retry to acquire the lock.
if ((errno != EAGAIN) && (errno != EINTR)) {
PLOG(FATAL) << "futex wait failed for " << name_;
}
}
--num_pending_writers_;
}
} while (!done);
DCHECK_EQ(state_.LoadRelaxed(), -1);
#else
CHECK_MUTEX_CALL(pthread_rwlock_wrlock, (&rwlock_));
#endif
DCHECK_EQ(GetExclusiveOwnerTid(), 0);
exclusive_owner_.StoreRelaxed(SafeGetTid(self));
RegisterAsLocked(self);
AssertExclusiveHeld(self);
}
void ReaderWriterMutex::ExclusiveUnlock(Thread* self) {
DCHECK(self == nullptr || self == Thread::Current());
AssertExclusiveHeld(self);
RegisterAsUnlocked(self);
DCHECK_NE(GetExclusiveOwnerTid(), 0);
#if ART_USE_FUTEXES
bool done = false;
do {
int32_t cur_state = state_.LoadRelaxed();
if (LIKELY(cur_state == -1)) {
// We're no longer the owner.
exclusive_owner_.StoreRelaxed(0);
// Change state from -1 to 0 and impose load/store ordering appropriate for lock release.
// Note, the relaxed loads below musn't reorder before the CompareAndSet.
// TODO: the ordering here is non-trivial as state is split across 3 fields, fix by placing
// a status bit into the state on contention.
done = state_.CompareAndSetWeakSequentiallyConsistent(-1 /* cur_state*/, 0 /* new state */);
if (LIKELY(done)) { // Weak CAS may fail spuriously.
// Wake any waiters.
if (UNLIKELY(num_pending_readers_.LoadRelaxed() > 0 ||
num_pending_writers_.LoadRelaxed() > 0)) {
futex(state_.Address(), FUTEX_WAKE, -1, nullptr, nullptr, 0);
}
}
} else {
LOG(FATAL) << "Unexpected state_:" << cur_state << " for " << name_;
}
} while (!done);
#else
exclusive_owner_.StoreRelaxed(0);
CHECK_MUTEX_CALL(pthread_rwlock_unlock, (&rwlock_));
#endif
}
#if HAVE_TIMED_RWLOCK
bool ReaderWriterMutex::ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32_t ns) {
DCHECK(self == nullptr || self == Thread::Current());
#if ART_USE_FUTEXES
bool done = false;
timespec end_abs_ts;
InitTimeSpec(true, CLOCK_MONOTONIC, ms, ns, &end_abs_ts);
do {
int32_t cur_state = state_.LoadRelaxed();
if (cur_state == 0) {
// Change state from 0 to -1 and impose load/store ordering appropriate for lock acquisition.
done = state_.CompareAndSetWeakAcquire(0 /* cur_state */, -1 /* new state */);
} else {
// Failed to acquire, hang up.
timespec now_abs_ts;
InitTimeSpec(true, CLOCK_MONOTONIC, 0, 0, &now_abs_ts);
timespec rel_ts;
if (ComputeRelativeTimeSpec(&rel_ts, end_abs_ts, now_abs_ts)) {
return false; // Timed out.
}
ScopedContentionRecorder scr(this, SafeGetTid(self), GetExclusiveOwnerTid());
++num_pending_writers_;
if (UNLIKELY(should_respond_to_empty_checkpoint_request_)) {
self->CheckEmptyCheckpointFromMutex();
}
if (futex(state_.Address(), FUTEX_WAIT, cur_state, &rel_ts, nullptr, 0) != 0) {
if (errno == ETIMEDOUT) {
--num_pending_writers_;
return false; // Timed out.
} else if ((errno != EAGAIN) && (errno != EINTR)) {
// EAGAIN and EINTR both indicate a spurious failure,
// recompute the relative time out from now and try again.
// We don't use TEMP_FAILURE_RETRY so we can recompute rel_ts;
PLOG(FATAL) << "timed futex wait failed for " << name_;
}
}
--num_pending_writers_;
}
} while (!done);
#else
timespec ts;
InitTimeSpec(true, CLOCK_REALTIME, ms, ns, &ts);
int result = pthread_rwlock_timedwrlock(&rwlock_, &ts);
if (result == ETIMEDOUT) {
return false;
}
if (result != 0) {
errno = result;
PLOG(FATAL) << "pthread_rwlock_timedwrlock failed for " << name_;
}
#endif
exclusive_owner_.StoreRelaxed(SafeGetTid(self));
RegisterAsLocked(self);
AssertSharedHeld(self);
return true;
}
#endif
#if ART_USE_FUTEXES
void ReaderWriterMutex::HandleSharedLockContention(Thread* self, int32_t cur_state) {
// Owner holds it exclusively, hang up.
ScopedContentionRecorder scr(this, SafeGetTid(self), GetExclusiveOwnerTid());
++num_pending_readers_;
if (UNLIKELY(should_respond_to_empty_checkpoint_request_)) {
self->CheckEmptyCheckpointFromMutex();
}
if (futex(state_.Address(), FUTEX_WAIT, cur_state, nullptr, nullptr, 0) != 0) {
if (errno != EAGAIN && errno != EINTR) {
PLOG(FATAL) << "futex wait failed for " << name_;
}
}
--num_pending_readers_;
}
#endif
bool ReaderWriterMutex::SharedTryLock(Thread* self) {
DCHECK(self == nullptr || self == Thread::Current());
#if ART_USE_FUTEXES
bool done = false;
do {
int32_t cur_state = state_.LoadRelaxed();
if (cur_state >= 0) {
// Add as an extra reader and impose load/store ordering appropriate for lock acquisition.
done = state_.CompareAndSetWeakAcquire(cur_state, cur_state + 1);
} else {
// Owner holds it exclusively.
return false;
}
} while (!done);
#else
int result = pthread_rwlock_tryrdlock(&rwlock_);
if (result == EBUSY) {
return false;
}
if (result != 0) {
errno = result;
PLOG(FATAL) << "pthread_mutex_trylock failed for " << name_;
}
#endif
RegisterAsLocked(self);
AssertSharedHeld(self);
return true;
}
bool ReaderWriterMutex::IsSharedHeld(const Thread* self) const {
DCHECK(self == nullptr || self == Thread::Current());
bool result;
if (UNLIKELY(self == nullptr)) { // Handle unattached threads.
result = IsExclusiveHeld(self); // TODO: a better best effort here.
} else {
result = (self->GetHeldMutex(level_) == this);
}
return result;
}
void ReaderWriterMutex::Dump(std::ostream& os) const {
os << name_
<< " level=" << static_cast<int>(level_)
<< " owner=" << GetExclusiveOwnerTid()
#if ART_USE_FUTEXES
<< " state=" << state_.LoadSequentiallyConsistent()
<< " num_pending_writers=" << num_pending_writers_.LoadSequentiallyConsistent()
<< " num_pending_readers=" << num_pending_readers_.LoadSequentiallyConsistent()
#endif
<< " ";
DumpContention(os);
}
std::ostream& operator<<(std::ostream& os, const ReaderWriterMutex& mu) {
mu.Dump(os);
return os;
}
std::ostream& operator<<(std::ostream& os, const MutatorMutex& mu) {
mu.Dump(os);
return os;
}
void ReaderWriterMutex::WakeupToRespondToEmptyCheckpoint() {
#if ART_USE_FUTEXES
// Wake up all the waiters so they will respond to the emtpy checkpoint.
DCHECK(should_respond_to_empty_checkpoint_request_);
if (UNLIKELY(num_pending_readers_.LoadRelaxed() > 0 ||
num_pending_writers_.LoadRelaxed() > 0)) {
futex(state_.Address(), FUTEX_WAKE, -1, nullptr, nullptr, 0);
}
#else
LOG(FATAL) << "Non futex case isn't supported.";
#endif
}
ConditionVariable::ConditionVariable(const char* name, Mutex& guard)
: name_(name), guard_(guard) {
#if ART_USE_FUTEXES
DCHECK_EQ(0, sequence_.LoadRelaxed());
num_waiters_ = 0;
#else
pthread_condattr_t cond_attrs;
CHECK_MUTEX_CALL(pthread_condattr_init, (&cond_attrs));
#if !defined(__APPLE__)
// Apple doesn't have CLOCK_MONOTONIC or pthread_condattr_setclock.
CHECK_MUTEX_CALL(pthread_condattr_setclock, (&cond_attrs, CLOCK_MONOTONIC));
#endif
CHECK_MUTEX_CALL(pthread_cond_init, (&cond_, &cond_attrs));
#endif
}
ConditionVariable::~ConditionVariable() {
#if ART_USE_FUTEXES
if (num_waiters_!= 0) {
bool is_safe_to_call_abort = IsSafeToCallAbortSafe();
LOG(is_safe_to_call_abort ? FATAL : WARNING)
<< "ConditionVariable::~ConditionVariable for " << name_
<< " called with " << num_waiters_ << " waiters.";
}
#else
// We can't use CHECK_MUTEX_CALL here because on shutdown a suspended daemon thread
// may still be using condition variables.
int rc = pthread_cond_destroy(&cond_);
if (rc != 0) {
errno = rc;
bool is_safe_to_call_abort = IsSafeToCallAbortSafe();
PLOG(is_safe_to_call_abort ? FATAL : WARNING) << "pthread_cond_destroy failed for " << name_;
}
#endif
}
void ConditionVariable::Broadcast(Thread* self) {
DCHECK(self == nullptr || self == Thread::Current());
// TODO: enable below, there's a race in thread creation that causes false failures currently.
// guard_.AssertExclusiveHeld(self);
DCHECK_EQ(guard_.GetExclusiveOwnerTid(), SafeGetTid(self));
#if ART_USE_FUTEXES
if (num_waiters_ > 0) {
sequence_++; // Indicate the broadcast occurred.
bool done = false;
do {
int32_t cur_sequence = sequence_.LoadRelaxed();
// Requeue waiters onto mutex. The waiter holds the contender count on the mutex high ensuring
// mutex unlocks will awaken the requeued waiter thread.
done = futex(sequence_.Address(), FUTEX_CMP_REQUEUE, 0,
reinterpret_cast<const timespec*>(std::numeric_limits<int32_t>::max()),
guard_.state_.Address(), cur_sequence) != -1;
if (!done) {
if (errno != EAGAIN && errno != EINTR) {
PLOG(FATAL) << "futex cmp requeue failed for " << name_;
}
}
} while (!done);
}
#else
CHECK_MUTEX_CALL(pthread_cond_broadcast, (&cond_));
#endif
}
void ConditionVariable::Signal(Thread* self) {
DCHECK(self == nullptr || self == Thread::Current());
guard_.AssertExclusiveHeld(self);
#if ART_USE_FUTEXES
if (num_waiters_ > 0) {
sequence_++; // Indicate a signal occurred.
// Futex wake 1 waiter who will then come and in contend on mutex. It'd be nice to requeue them
// to avoid this, however, requeueing can only move all waiters.
int num_woken = futex(sequence_.Address(), FUTEX_WAKE, 1, nullptr, nullptr, 0);
// Check something was woken or else we changed sequence_ before they had chance to wait.
CHECK((num_woken == 0) || (num_woken == 1));
}
#else
CHECK_MUTEX_CALL(pthread_cond_signal, (&cond_));
#endif
}
void ConditionVariable::Wait(Thread* self) {
guard_.CheckSafeToWait(self);
WaitHoldingLocks(self);
}
void ConditionVariable::WaitHoldingLocks(Thread* self) {
DCHECK(self == nullptr || self == Thread::Current());
guard_.AssertExclusiveHeld(self);
unsigned int old_recursion_count = guard_.recursion_count_;
#if ART_USE_FUTEXES
num_waiters_++;
// Ensure the Mutex is contended so that requeued threads are awoken.
guard_.num_contenders_++;
guard_.recursion_count_ = 1;
int32_t cur_sequence = sequence_.LoadRelaxed();
guard_.ExclusiveUnlock(self);
if (futex(sequence_.Address(), FUTEX_WAIT, cur_sequence, nullptr, nullptr, 0) != 0) {
// Futex failed, check it is an expected error.
// EAGAIN == EWOULDBLK, so we let the caller try again.
// EINTR implies a signal was sent to this thread.
if ((errno != EINTR) && (errno != EAGAIN)) {
PLOG(FATAL) << "futex wait failed for " << name_;
}
}
if (self != nullptr) {
JNIEnvExt* const env = self->GetJniEnv();
if (UNLIKELY(env != nullptr && env->IsRuntimeDeleted())) {
CHECK(self->IsDaemon());
// If the runtime has been deleted, then we cannot proceed. Just sleep forever. This may
// occur for user daemon threads that get a spurious wakeup. This occurs for test 132 with
// --host and --gdb.
// After we wake up, the runtime may have been shutdown, which means that this condition may
// have been deleted. It is not safe to retry the wait.
SleepForever();
}
}
guard_.ExclusiveLock(self);
CHECK_GE(num_waiters_, 0);
num_waiters_--;
// We awoke and so no longer require awakes from the guard_'s unlock.
CHECK_GE(guard_.num_contenders_.LoadRelaxed(), 0);
guard_.num_contenders_--;
#else
pid_t old_owner = guard_.GetExclusiveOwnerTid();
guard_.exclusive_owner_.StoreRelaxed(0);
guard_.recursion_count_ = 0;
CHECK_MUTEX_CALL(pthread_cond_wait, (&cond_, &guard_.mutex_));
guard_.exclusive_owner_.StoreRelaxed(old_owner);
#endif
guard_.recursion_count_ = old_recursion_count;
}
bool ConditionVariable::TimedWait(Thread* self, int64_t ms, int32_t ns) {
DCHECK(self == nullptr || self == Thread::Current());
bool timed_out = false;
guard_.AssertExclusiveHeld(self);
guard_.CheckSafeToWait(self);
unsigned int old_recursion_count = guard_.recursion_count_;
#if ART_USE_FUTEXES
timespec rel_ts;
InitTimeSpec(false, CLOCK_REALTIME, ms, ns, &rel_ts);
num_waiters_++;
// Ensure the Mutex is contended so that requeued threads are awoken.
guard_.num_contenders_++;
guard_.recursion_count_ = 1;
int32_t cur_sequence = sequence_.LoadRelaxed();
guard_.ExclusiveUnlock(self);
if (futex(sequence_.Address(), FUTEX_WAIT, cur_sequence, &rel_ts, nullptr, 0) != 0) {
if (errno == ETIMEDOUT) {
// Timed out we're done.
timed_out = true;
} else if ((errno == EAGAIN) || (errno == EINTR)) {
// A signal or ConditionVariable::Signal/Broadcast has come in.
} else {
PLOG(FATAL) << "timed futex wait failed for " << name_;
}
}
guard_.ExclusiveLock(self);
CHECK_GE(num_waiters_, 0);
num_waiters_--;
// We awoke and so no longer require awakes from the guard_'s unlock.
CHECK_GE(guard_.num_contenders_.LoadRelaxed(), 0);
guard_.num_contenders_--;
#else
#if !defined(__APPLE__)
int clock = CLOCK_MONOTONIC;
#else
int clock = CLOCK_REALTIME;
#endif
pid_t old_owner = guard_.GetExclusiveOwnerTid();
guard_.exclusive_owner_.StoreRelaxed(0);
guard_.recursion_count_ = 0;
timespec ts;
InitTimeSpec(true, clock, ms, ns, &ts);
int rc = TEMP_FAILURE_RETRY(pthread_cond_timedwait(&cond_, &guard_.mutex_, &ts));
if (rc == ETIMEDOUT) {
timed_out = true;
} else if (rc != 0) {
errno = rc;
PLOG(FATAL) << "TimedWait failed for " << name_;
}
guard_.exclusive_owner_.StoreRelaxed(old_owner);
#endif
guard_.recursion_count_ = old_recursion_count;
return timed_out;
}
void Locks::Init() {
if (logging_lock_ != nullptr) {
// Already initialized.
if (kRuntimeISA == InstructionSet::kX86 || kRuntimeISA == InstructionSet::kX86_64) {
DCHECK(modify_ldt_lock_ != nullptr);
} else {
DCHECK(modify_ldt_lock_ == nullptr);
}
DCHECK(abort_lock_ != nullptr);
DCHECK(alloc_tracker_lock_ != nullptr);
DCHECK(allocated_monitor_ids_lock_ != nullptr);
DCHECK(allocated_thread_ids_lock_ != nullptr);
DCHECK(breakpoint_lock_ != nullptr);
DCHECK(classlinker_classes_lock_ != nullptr);
DCHECK(deoptimization_lock_ != nullptr);
DCHECK(heap_bitmap_lock_ != nullptr);
DCHECK(oat_file_manager_lock_ != nullptr);
DCHECK(verifier_deps_lock_ != nullptr);
DCHECK(host_dlopen_handles_lock_ != nullptr);
DCHECK(intern_table_lock_ != nullptr);
DCHECK(jni_function_table_lock_ != nullptr);
DCHECK(jni_libraries_lock_ != nullptr);
DCHECK(logging_lock_ != nullptr);
DCHECK(mutator_lock_ != nullptr);
DCHECK(profiler_lock_ != nullptr);
DCHECK(cha_lock_ != nullptr);
DCHECK(subtype_check_lock_ != nullptr);
DCHECK(thread_list_lock_ != nullptr);
DCHECK(thread_suspend_count_lock_ != nullptr);
DCHECK(trace_lock_ != nullptr);
DCHECK(unexpected_signal_lock_ != nullptr);
DCHECK(user_code_suspension_lock_ != nullptr);
DCHECK(dex_lock_ != nullptr);
DCHECK(native_debug_interface_lock_ != nullptr);
} else {
// Create global locks in level order from highest lock level to lowest.
LockLevel current_lock_level = kInstrumentEntrypointsLock;
DCHECK(instrument_entrypoints_lock_ == nullptr);
instrument_entrypoints_lock_ = new Mutex("instrument entrypoint lock", current_lock_level);
#define UPDATE_CURRENT_LOCK_LEVEL(new_level) \
if ((new_level) >= current_lock_level) { \
/* Do not use CHECKs or FATAL here, abort_lock_ is not setup yet. */ \
fprintf(stderr, "New local level %d is not less than current level %d\n", \
new_level, current_lock_level); \
exit(1); \
} \
current_lock_level = new_level;
UPDATE_CURRENT_LOCK_LEVEL(kUserCodeSuspensionLock);
DCHECK(user_code_suspension_lock_ == nullptr);
user_code_suspension_lock_ = new Mutex("user code suspension lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kMutatorLock);
DCHECK(mutator_lock_ == nullptr);
mutator_lock_ = new MutatorMutex("mutator lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kHeapBitmapLock);
DCHECK(heap_bitmap_lock_ == nullptr);
heap_bitmap_lock_ = new ReaderWriterMutex("heap bitmap lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kTraceLock);
DCHECK(trace_lock_ == nullptr);
trace_lock_ = new Mutex("trace lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kRuntimeShutdownLock);
DCHECK(runtime_shutdown_lock_ == nullptr);
runtime_shutdown_lock_ = new Mutex("runtime shutdown lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kProfilerLock);
DCHECK(profiler_lock_ == nullptr);
profiler_lock_ = new Mutex("profiler lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kDeoptimizationLock);
DCHECK(deoptimization_lock_ == nullptr);
deoptimization_lock_ = new Mutex("Deoptimization lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kAllocTrackerLock);
DCHECK(alloc_tracker_lock_ == nullptr);
alloc_tracker_lock_ = new Mutex("AllocTracker lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kThreadListLock);
DCHECK(thread_list_lock_ == nullptr);
thread_list_lock_ = new Mutex("thread list lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kJniLoadLibraryLock);
DCHECK(jni_libraries_lock_ == nullptr);
jni_libraries_lock_ = new Mutex("JNI shared libraries map lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kBreakpointLock);
DCHECK(breakpoint_lock_ == nullptr);
breakpoint_lock_ = new ReaderWriterMutex("breakpoint lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kSubtypeCheckLock);
DCHECK(subtype_check_lock_ == nullptr);
subtype_check_lock_ = new Mutex("SubtypeCheck lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kCHALock);
DCHECK(cha_lock_ == nullptr);
cha_lock_ = new Mutex("CHA lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kClassLinkerClassesLock);
DCHECK(classlinker_classes_lock_ == nullptr);
classlinker_classes_lock_ = new ReaderWriterMutex("ClassLinker classes lock",
current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kMonitorPoolLock);
DCHECK(allocated_monitor_ids_lock_ == nullptr);
allocated_monitor_ids_lock_ = new Mutex("allocated monitor ids lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kAllocatedThreadIdsLock);
DCHECK(allocated_thread_ids_lock_ == nullptr);
allocated_thread_ids_lock_ = new Mutex("allocated thread ids lock", current_lock_level);
if (kRuntimeISA == InstructionSet::kX86 || kRuntimeISA == InstructionSet::kX86_64) {
UPDATE_CURRENT_LOCK_LEVEL(kModifyLdtLock);
DCHECK(modify_ldt_lock_ == nullptr);
modify_ldt_lock_ = new Mutex("modify_ldt lock", current_lock_level);
}
UPDATE_CURRENT_LOCK_LEVEL(kDexLock);
DCHECK(dex_lock_ == nullptr);
dex_lock_ = new ReaderWriterMutex("ClassLinker dex lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kOatFileManagerLock);
DCHECK(oat_file_manager_lock_ == nullptr);
oat_file_manager_lock_ = new ReaderWriterMutex("OatFile manager lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kVerifierDepsLock);
DCHECK(verifier_deps_lock_ == nullptr);
verifier_deps_lock_ = new ReaderWriterMutex("verifier deps lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kHostDlOpenHandlesLock);
DCHECK(host_dlopen_handles_lock_ == nullptr);
host_dlopen_handles_lock_ = new Mutex("host dlopen handles lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kInternTableLock);
DCHECK(intern_table_lock_ == nullptr);
intern_table_lock_ = new Mutex("InternTable lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kReferenceProcessorLock);
DCHECK(reference_processor_lock_ == nullptr);
reference_processor_lock_ = new Mutex("ReferenceProcessor lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kReferenceQueueClearedReferencesLock);
DCHECK(reference_queue_cleared_references_lock_ == nullptr);
reference_queue_cleared_references_lock_ = new Mutex("ReferenceQueue cleared references lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kReferenceQueueWeakReferencesLock);
DCHECK(reference_queue_weak_references_lock_ == nullptr);
reference_queue_weak_references_lock_ = new Mutex("ReferenceQueue cleared references lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kReferenceQueueFinalizerReferencesLock);
DCHECK(reference_queue_finalizer_references_lock_ == nullptr);
reference_queue_finalizer_references_lock_ = new Mutex("ReferenceQueue finalizer references lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kReferenceQueuePhantomReferencesLock);
DCHECK(reference_queue_phantom_references_lock_ == nullptr);
reference_queue_phantom_references_lock_ = new Mutex("ReferenceQueue phantom references lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kReferenceQueueSoftReferencesLock);
DCHECK(reference_queue_soft_references_lock_ == nullptr);
reference_queue_soft_references_lock_ = new Mutex("ReferenceQueue soft references lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kJniGlobalsLock);
DCHECK(jni_globals_lock_ == nullptr);
jni_globals_lock_ =
new ReaderWriterMutex("JNI global reference table lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kJniWeakGlobalsLock);
DCHECK(jni_weak_globals_lock_ == nullptr);
jni_weak_globals_lock_ = new Mutex("JNI weak global reference table lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kJniFunctionTableLock);
DCHECK(jni_function_table_lock_ == nullptr);
jni_function_table_lock_ = new Mutex("JNI function table lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kNativeDebugInterfaceLock);
DCHECK(native_debug_interface_lock_ == nullptr);
native_debug_interface_lock_ = new Mutex("Native debug interface lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kAbortLock);
DCHECK(abort_lock_ == nullptr);
abort_lock_ = new Mutex("abort lock", current_lock_level, true);
UPDATE_CURRENT_LOCK_LEVEL(kThreadSuspendCountLock);
DCHECK(thread_suspend_count_lock_ == nullptr);
thread_suspend_count_lock_ = new Mutex("thread suspend count lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kUnexpectedSignalLock);
DCHECK(unexpected_signal_lock_ == nullptr);
unexpected_signal_lock_ = new Mutex("unexpected signal lock", current_lock_level, true);
UPDATE_CURRENT_LOCK_LEVEL(kLoggingLock);
DCHECK(logging_lock_ == nullptr);
logging_lock_ = new Mutex("logging lock", current_lock_level, true);
#undef UPDATE_CURRENT_LOCK_LEVEL
// List of mutexes that we may hold when accessing a weak ref.
AddToExpectedMutexesOnWeakRefAccess(dex_lock_, /*need_lock*/ false);
AddToExpectedMutexesOnWeakRefAccess(classlinker_classes_lock_, /*need_lock*/ false);
AddToExpectedMutexesOnWeakRefAccess(jni_libraries_lock_, /*need_lock*/ false);
InitConditions();
}
}
void Locks::InitConditions() {
thread_exit_cond_ = new ConditionVariable("thread exit condition variable", *thread_list_lock_);
}
void Locks::SetClientCallback(ClientCallback* safe_to_call_abort_cb) {
safe_to_call_abort_callback.StoreRelease(safe_to_call_abort_cb);
}
// Helper to allow checking shutdown while ignoring locking requirements.
bool Locks::IsSafeToCallAbortRacy() {
Locks::ClientCallback* safe_to_call_abort_cb = safe_to_call_abort_callback.LoadAcquire();
return safe_to_call_abort_cb != nullptr && safe_to_call_abort_cb();
}
void Locks::AddToExpectedMutexesOnWeakRefAccess(BaseMutex* mutex, bool need_lock) {
if (need_lock) {
ScopedExpectedMutexesOnWeakRefAccessLock mu(mutex);
mutex->SetShouldRespondToEmptyCheckpointRequest(true);
expected_mutexes_on_weak_ref_access_.push_back(mutex);
} else {
mutex->SetShouldRespondToEmptyCheckpointRequest(true);
expected_mutexes_on_weak_ref_access_.push_back(mutex);
}
}
void Locks::RemoveFromExpectedMutexesOnWeakRefAccess(BaseMutex* mutex, bool need_lock) {
if (need_lock) {
ScopedExpectedMutexesOnWeakRefAccessLock mu(mutex);
mutex->SetShouldRespondToEmptyCheckpointRequest(false);
std::vector<BaseMutex*>& list = expected_mutexes_on_weak_ref_access_;
auto it = std::find(list.begin(), list.end(), mutex);
DCHECK(it != list.end());
list.erase(it);
} else {
mutex->SetShouldRespondToEmptyCheckpointRequest(false);
std::vector<BaseMutex*>& list = expected_mutexes_on_weak_ref_access_;
auto it = std::find(list.begin(), list.end(), mutex);
DCHECK(it != list.end());
list.erase(it);
}
}
bool Locks::IsExpectedOnWeakRefAccess(BaseMutex* mutex) {
ScopedExpectedMutexesOnWeakRefAccessLock mu(mutex);
std::vector<BaseMutex*>& list = expected_mutexes_on_weak_ref_access_;
return std::find(list.begin(), list.end(), mutex) != list.end();
}
} // namespace art