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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.
*/
#ifndef ART_RUNTIME_THREAD_INL_H_
#define ART_RUNTIME_THREAD_INL_H_
#include "thread.h"
#include "base/mutex-inl.h"
#include "cutils/atomic-inline.h"
namespace art {
inline ThreadState Thread::SetState(ThreadState new_state) {
// Cannot use this code to change into Runnable as changing to Runnable should fail if
// old_state_and_flags.suspend_request is true.
DCHECK_NE(new_state, kRunnable);
DCHECK_EQ(this, Thread::Current());
union StateAndFlags old_state_and_flags = state_and_flags_;
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 {
#ifdef NDEBUG
UNUSED(check_locks); // Keep GCC happy about unused parameters.
#else
CHECK_EQ(0u, no_thread_suspension_) << 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_.
if (i != kMutatorLock) {
BaseMutex* held_mutex = GetHeldMutex(static_cast<LockLevel>(i));
if (held_mutex != NULL) {
LOG(ERROR) << "holding \"" << held_mutex->GetName()
<< "\" at point where thread suspension is expected";
bad_mutexes_held = true;
}
}
}
CHECK(!bad_mutexes_held);
}
#endif
}
inline void Thread::TransitionFromRunnableToSuspended(ThreadState new_state) {
AssertThreadSuspensionIsAllowable();
DCHECK_NE(new_state, kRunnable);
DCHECK_EQ(this, Thread::Current());
// Change to non-runnable state, thereby appearing suspended to the system.
DCHECK_EQ(GetState(), kRunnable);
union StateAndFlags old_state_and_flags;
union StateAndFlags new_state_and_flags;
do {
old_state_and_flags = state_and_flags_;
// Copy over flags and try to clear the checkpoint bit if it is set.
new_state_and_flags.as_struct.flags = old_state_and_flags.as_struct.flags & ~kCheckpointRequest;
new_state_and_flags.as_struct.state = new_state;
// CAS the value without a memory barrier, that will occur in the unlock below.
} while (UNLIKELY(android_atomic_cas(old_state_and_flags.as_int, new_state_and_flags.as_int,
&state_and_flags_.as_int) != 0));
// If we toggled the checkpoint flag we must have cleared it.
uint16_t flag_change = new_state_and_flags.as_struct.flags ^ old_state_and_flags.as_struct.flags;
if (UNLIKELY((flag_change & kCheckpointRequest) != 0)) {
RunCheckpointFunction();
}
// Release share on mutator_lock_.
Locks::mutator_lock_->SharedUnlock(this);
}
inline ThreadState Thread::TransitionFromSuspendedToRunnable() {
bool done = false;
union StateAndFlags old_state_and_flags = state_and_flags_;
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 = state_and_flags_;
DCHECK_EQ(old_state_and_flags.as_struct.state, old_state);
if (UNLIKELY((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 = state_and_flags_;
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 = state_and_flags_;
DCHECK_EQ(old_state_and_flags.as_struct.state, old_state);
}
DCHECK_EQ(GetSuspendCount(), 0);
}
// Re-acquire shared mutator_lock_ access.
Locks::mutator_lock_->SharedLock(this);
// Atomically change from suspended to runnable if no suspend request pending.
old_state_and_flags = state_and_flags_;
DCHECK_EQ(old_state_and_flags.as_struct.state, old_state);
if (LIKELY((old_state_and_flags.as_struct.flags & kSuspendRequest) == 0)) {
union StateAndFlags new_state_and_flags = old_state_and_flags;
new_state_and_flags.as_struct.state = kRunnable;
// CAS the value without a memory barrier, that occurred in the lock above.
done = android_atomic_cas(old_state_and_flags.as_int, new_state_and_flags.as_int,
&state_and_flags_.as_int) == 0;
}
if (UNLIKELY(!done)) {
// Failed to transition to Runnable. Release shared mutator_lock_ access and try again.
Locks::mutator_lock_->SharedUnlock(this);
}
} while (UNLIKELY(!done));
return static_cast<ThreadState>(old_state);
}
inline void Thread::VerifyStack() {
gc::Heap* heap = Runtime::Current()->GetHeap();
if (heap->IsObjectValidationEnabled()) {
VerifyStackImpl();
}
}
} // namespace art
#endif // ART_RUNTIME_THREAD_INL_H_
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