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/*
* 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 "locks.h"
#include <errno.h>
#include <sys/time.h>
#include "android-base/logging.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 {
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::custom_tls_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::runtime_thread_pool_lock_ = nullptr;
Mutex* Locks::cha_lock_ = nullptr;
Mutex* Locks::jit_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;
Mutex* Locks::dex_cache_lock_ = nullptr;
ReaderWriterMutex* Locks::dex_lock_ = nullptr;
Mutex* Locks::native_debug_interface_lock_ = nullptr;
ReaderWriterMutex* Locks::jni_id_lock_ = nullptr;
std::vector<BaseMutex*> Locks::expected_mutexes_on_weak_ref_access_;
Atomic<const BaseMutex*> Locks::expected_mutexes_on_weak_ref_access_guard_;
// 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 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(nullptr,
mutex);
++i) {
BackOff(i);
}
}
~ScopedExpectedMutexesOnWeakRefAccessLock() {
DCHECK_EQ(Locks::expected_mutexes_on_weak_ref_access_guard_.load(std::memory_order_relaxed),
mutex_);
Locks::expected_mutexes_on_weak_ref_access_guard_.store(nullptr, std::memory_order_release);
}
private:
const BaseMutex* const mutex_;
};
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(custom_tls_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(jit_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);
DCHECK(jni_id_lock_ != nullptr);
DCHECK(runtime_thread_pool_lock_ != nullptr);
} else {
// Create global locks in level order from highest lock level to lowest.
LockLevel current_lock_level = kUserCodeSuspensionLock;
DCHECK(user_code_suspension_lock_ == nullptr);
user_code_suspension_lock_ = new Mutex("user code suspension 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(kInstrumentEntrypointsLock);
DCHECK(instrument_entrypoints_lock_ == nullptr);
instrument_entrypoints_lock_ = new Mutex("instrument entrypoint 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(kRuntimeThreadPoolLock);
DCHECK(runtime_thread_pool_lock_ == nullptr);
runtime_thread_pool_lock_ = new Mutex("runtime thread pool 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(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(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(kDexCacheLock);
DCHECK(dex_cache_lock_ == nullptr);
dex_cache_lock_ = new Mutex("DexCache 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(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(kCustomTlsLock);
DCHECK(custom_tls_lock_ == nullptr);
custom_tls_lock_ = new Mutex("Thread::custom_tls_ lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kJitCodeCacheLock);
DCHECK(jit_lock_ == nullptr);
jit_lock_ = new Mutex("Jit code cache", 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(kNativeDebugInterfaceLock);
DCHECK(native_debug_interface_lock_ == nullptr);
native_debug_interface_lock_ = new Mutex("Native debug interface lock", current_lock_level);
UPDATE_CURRENT_LOCK_LEVEL(kJniIdLock);
DCHECK(jni_id_lock_ == nullptr);
jni_id_lock_ = new ReaderWriterMutex("JNI id map 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.store(safe_to_call_abort_cb, std::memory_order_release);
}
// Helper to allow checking shutdown while ignoring locking requirements.
bool Locks::IsSafeToCallAbortRacy() {
Locks::ClientCallback* safe_to_call_abort_cb =
safe_to_call_abort_callback.load(std::memory_order_acquire);
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