/*
* 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.
*/
#ifndef ART_RUNTIME_THREAD_INL_H_
#define ART_RUNTIME_THREAD_INL_H_
#include "thread.h"
#ifdef __ANDROID__
#include <bionic_tls.h> // Access to our own TLS slot.
#endif
#include <pthread.h>
#include "base/casts.h"
#include "base/mutex-inl.h"
#include "gc/heap.h"
#include "jni_env_ext.h"
#include "thread_pool.h"
namespace art {
// Quickly access the current thread from a JNIEnv.
static inline Thread* ThreadForEnv(JNIEnv* env) {
JNIEnvExt* full_env(down_cast<JNIEnvExt*>(env));
return full_env->self;
}
inline Thread* Thread::Current() {
// We rely on Thread::Current returning null for a detached thread, so it's not obvious
// that we can replace this with a direct %fs access on x86.
if (!is_started_) {
return nullptr;
} else {
#ifdef __ANDROID__
void* thread = __get_tls()[TLS_SLOT_ART_THREAD_SELF];
#else
void* thread = pthread_getspecific(Thread::pthread_key_self_);
#endif
return reinterpret_cast<Thread*>(thread);
}
}
inline void Thread::AllowThreadSuspension() {
DCHECK_EQ(Thread::Current(), this);
if (UNLIKELY(TestAllFlags())) {
CheckSuspend();
}
}
inline void Thread::CheckSuspend() {
DCHECK_EQ(Thread::Current(), this);
for (;;) {
if (ReadFlag(kCheckpointRequest)) {
RunCheckpointFunction();
} else if (ReadFlag(kSuspendRequest)) {
FullSuspendCheck();
} else {
break;
}
}
}
inline ThreadState Thread::SetState(ThreadState new_state) {
// Should only be used to change between suspended states.
// Cannot use this code to change into or from Runnable as changing to Runnable should
// fail if old_state_and_flags.suspend_request is true and changing from Runnable might
// miss passing an active suspend barrier.
DCHECK_NE(new_state, kRunnable);
if (kIsDebugBuild && this != Thread::Current()) {
std::string name;
GetThreadName(name);
LOG(FATAL) << "Thread \"" << name << "\"(" << this << " != Thread::Current()="
<< Thread::Current() << ") changing state to " << new_state;
}
union StateAndFlags old_state_and_flags;
old_state_and_flags.as_int = tls32_.state_and_flags.as_int;
CHECK_NE(old_state_and_flags.as_struct.state, kRunnable);
tls32_.state_and_flags.as_struct.state = new_state;
return static_cast<ThreadState>(old_state_and_flags.as_struct.state);
}
inline void Thread::AssertThreadSuspensionIsAllowable(bool check_locks) const {
if (kIsDebugBuild) {
if (gAborting == 0) {
CHECK_EQ(0u, tls32_.no_thread_suspension) << tlsPtr_.last_no_thread_suspension_cause;
}
if (check_locks) {
bool bad_mutexes_held = false;
for (int i = kLockLevelCount - 1; i >= 0; --i) {
// We expect no locks except the mutator_lock_ or thread list suspend thread lock.
if (i != kMutatorLock) {
BaseMutex* held_mutex = GetHeldMutex(static_cast<LockLevel>(i));
if (held_mutex != nullptr) {
LOG(ERROR) << "holding \"" << held_mutex->GetName()
<< "\" at point where thread suspension is expected";
bad_mutexes_held = true;
}
}
}
if (gAborting == 0) {
CHECK(!bad_mutexes_held);
}
}
}
}
inline void Thread::TransitionToSuspendedAndRunCheckpoints(ThreadState new_state) {
DCHECK_NE(new_state, kRunnable);
DCHECK_EQ(GetState(), kRunnable);
union StateAndFlags old_state_and_flags;
union StateAndFlags new_state_and_flags;
while (true) {
old_state_and_flags.as_int = tls32_.state_and_flags.as_int;
if (UNLIKELY((old_state_and_flags.as_struct.flags & kCheckpointRequest) != 0)) {
RunCheckpointFunction();
continue;
}
// Change the state but keep the current flags (kCheckpointRequest is clear).
DCHECK_EQ((old_state_and_flags.as_struct.flags & kCheckpointRequest), 0);
new_state_and_flags.as_struct.flags = old_state_and_flags.as_struct.flags;
new_state_and_flags.as_struct.state = new_state;
// CAS the value with a memory ordering.
bool done =
tls32_.state_and_flags.as_atomic_int.CompareExchangeWeakRelease(old_state_and_flags.as_int,
new_state_and_flags.as_int);
if (LIKELY(done)) {
break;
}
}
}
inline void Thread::PassActiveSuspendBarriers() {
while (true) {
uint16_t current_flags = tls32_.state_and_flags.as_struct.flags;
if (LIKELY((current_flags & (kCheckpointRequest | kActiveSuspendBarrier)) == 0)) {
break;
} else if ((current_flags & kActiveSuspendBarrier) != 0) {
PassActiveSuspendBarriers(this);
} else {
// Impossible
LOG(FATAL) << "Fatal, thread transitioned into suspended without running the checkpoint";
}
}
}
inline void Thread::TransitionFromRunnableToSuspended(ThreadState new_state) {
AssertThreadSuspensionIsAllowable();
DCHECK_EQ(this, Thread::Current());
// Change to non-runnable state, thereby appearing suspended to the system.
TransitionToSuspendedAndRunCheckpoints(new_state);
// Mark the release of the share of the mutator_lock_.
Locks::mutator_lock_->TransitionFromRunnableToSuspended(this);
// Once suspended - check the active suspend barrier flag
PassActiveSuspendBarriers();
}
inline ThreadState Thread::TransitionFromSuspendedToRunnable() {
union StateAndFlags old_state_and_flags;
old_state_and_flags.as_int = tls32_.state_and_flags.as_int;
int16_t old_state = old_state_and_flags.as_struct.state;
DCHECK_NE(static_cast<ThreadState>(old_state), kRunnable);
do {
Locks::mutator_lock_->AssertNotHeld(this); // Otherwise we starve GC..
old_state_and_flags.as_int = tls32_.state_and_flags.as_int;
DCHECK_EQ(old_state_and_flags.as_struct.state, old_state);
if (LIKELY(old_state_and_flags.as_struct.flags == 0)) {
// Optimize for the return from native code case - this is the fast path.
// Atomically change from suspended to runnable if no suspend request pending.
union StateAndFlags new_state_and_flags;
new_state_and_flags.as_int = old_state_and_flags.as_int;
new_state_and_flags.as_struct.state = kRunnable;
// CAS the value with a memory barrier.
if (LIKELY(tls32_.state_and_flags.as_atomic_int.CompareExchangeWeakAcquire(
old_state_and_flags.as_int,
new_state_and_flags.as_int))) {
// Mark the acquisition of a share of the mutator_lock_.
Locks::mutator_lock_->TransitionFromSuspendedToRunnable(this);
break;
}
} else if ((old_state_and_flags.as_struct.flags & kActiveSuspendBarrier) != 0) {
PassActiveSuspendBarriers(this);
} else if ((old_state_and_flags.as_struct.flags & kCheckpointRequest) != 0) {
// Impossible
LOG(FATAL) << "Transitioning to runnable with checkpoint flag, "
<< " flags=" << old_state_and_flags.as_struct.flags
<< " state=" << old_state_and_flags.as_struct.state;
} else if ((old_state_and_flags.as_struct.flags & kSuspendRequest) != 0) {
// Wait while our suspend count is non-zero.
MutexLock mu(this, *Locks::thread_suspend_count_lock_);
old_state_and_flags.as_int = tls32_.state_and_flags.as_int;
DCHECK_EQ(old_state_and_flags.as_struct.state, old_state);
while ((old_state_and_flags.as_struct.flags & kSuspendRequest) != 0) {
// Re-check when Thread::resume_cond_ is notified.
Thread::resume_cond_->Wait(this);
old_state_and_flags.as_int = tls32_.state_and_flags.as_int;
DCHECK_EQ(old_state_and_flags.as_struct.state, old_state);
}
DCHECK_EQ(GetSuspendCount(), 0);
}
} while (true);
// Run the flip function, if set.
Closure* flip_func = GetFlipFunction();
if (flip_func != nullptr) {
flip_func->Run(this);
}
return static_cast<ThreadState>(old_state);
}
inline void Thread::VerifyStack() {
if (kVerifyStack) {
if (Runtime::Current()->GetHeap()->IsObjectValidationEnabled()) {
VerifyStackImpl();
}
}
}
inline size_t Thread::TlabSize() const {
return tlsPtr_.thread_local_end - tlsPtr_.thread_local_pos;
}
inline mirror::Object* Thread::AllocTlab(size_t bytes) {
DCHECK_GE(TlabSize(), bytes);
++tlsPtr_.thread_local_objects;
mirror::Object* ret = reinterpret_cast<mirror::Object*>(tlsPtr_.thread_local_pos);
tlsPtr_.thread_local_pos += bytes;
return ret;
}
inline bool Thread::PushOnThreadLocalAllocationStack(mirror::Object* obj) {
DCHECK_LE(tlsPtr_.thread_local_alloc_stack_top, tlsPtr_.thread_local_alloc_stack_end);
if (tlsPtr_.thread_local_alloc_stack_top < tlsPtr_.thread_local_alloc_stack_end) {
// There's room.
DCHECK_LE(reinterpret_cast<uint8_t*>(tlsPtr_.thread_local_alloc_stack_top) +
sizeof(StackReference<mirror::Object>),
reinterpret_cast<uint8_t*>(tlsPtr_.thread_local_alloc_stack_end));
DCHECK(tlsPtr_.thread_local_alloc_stack_top->AsMirrorPtr() == nullptr);
tlsPtr_.thread_local_alloc_stack_top->Assign(obj);
++tlsPtr_.thread_local_alloc_stack_top;
return true;
}
return false;
}
inline void Thread::SetThreadLocalAllocationStack(StackReference<mirror::Object>* start,
StackReference<mirror::Object>* end) {
DCHECK(Thread::Current() == this) << "Should be called by self";
DCHECK(start != nullptr);
DCHECK(end != nullptr);
DCHECK_ALIGNED(start, sizeof(StackReference<mirror::Object>));
DCHECK_ALIGNED(end, sizeof(StackReference<mirror::Object>));
DCHECK_LT(start, end);
tlsPtr_.thread_local_alloc_stack_end = end;
tlsPtr_.thread_local_alloc_stack_top = start;
}
inline void Thread::RevokeThreadLocalAllocationStack() {
if (kIsDebugBuild) {
// Note: self is not necessarily equal to this thread since thread may be suspended.
Thread* self = Thread::Current();
DCHECK(this == self || IsSuspended() || GetState() == kWaitingPerformingGc)
<< GetState() << " thread " << this << " self " << self;
}
tlsPtr_.thread_local_alloc_stack_end = nullptr;
tlsPtr_.thread_local_alloc_stack_top = nullptr;
}
} // namespace art
#endif // ART_RUNTIME_THREAD_INL_H_