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/*
* Copyright (C) 2014 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 "task_processor.h"
#include "base/time_utils.h"
#include "scoped_thread_state_change-inl.h"
namespace art {
namespace gc {
TaskProcessor::TaskProcessor()
: lock_("Task processor lock", kReferenceProcessorLock),
cond_("Task processor condition", lock_),
is_running_(false),
running_thread_(nullptr) {
}
TaskProcessor::~TaskProcessor() {
if (!tasks_.empty()) {
LOG(WARNING) << "TaskProcessor: Finalizing " << tasks_.size() << " unprocessed tasks.";
for (HeapTask* task : tasks_) {
task->Finalize();
}
}
}
void TaskProcessor::AddTask(Thread* self, HeapTask* task) {
ScopedThreadStateChange tsc(self, ThreadState::kWaitingForTaskProcessor);
MutexLock mu(self, lock_);
tasks_.insert(task);
cond_.Signal(self);
}
HeapTask* TaskProcessor::GetTask(Thread* self) {
ScopedThreadStateChange tsc(self, ThreadState::kWaitingForTaskProcessor);
MutexLock mu(self, lock_);
while (true) {
if (tasks_.empty()) {
if (!is_running_) {
return nullptr;
}
cond_.Wait(self); // Empty queue, wait until we are signalled.
} else {
// Non empty queue, look at the top element and see if we are ready to run it.
const uint64_t current_time = NanoTime();
HeapTask* task = *tasks_.begin();
// If we are shutting down, return the task right away without waiting. Otherwise return the
// task if it is late enough.
uint64_t target_time = task->GetTargetRunTime();
if (!is_running_ || target_time <= current_time) {
tasks_.erase(tasks_.begin());
return task;
}
DCHECK_GT(target_time, current_time);
// Wait until we hit the target run time.
const uint64_t delta_time = target_time - current_time;
const uint64_t ms_delta = NsToMs(delta_time);
const uint64_t ns_delta = delta_time - MsToNs(ms_delta);
cond_.TimedWait(self, static_cast<int64_t>(ms_delta), static_cast<int32_t>(ns_delta));
}
}
UNREACHABLE();
}
void TaskProcessor::UpdateTargetRunTime(Thread* self, HeapTask* task, uint64_t new_target_time) {
MutexLock mu(self, lock_);
// Find the task.
auto range = tasks_.equal_range(task);
for (auto it = range.first; it != range.second; ++it) {
if (*it == task) {
// Check if the target time was updated, if so re-insert then wait.
if (new_target_time != task->GetTargetRunTime()) {
tasks_.erase(it);
task->SetTargetRunTime(new_target_time);
tasks_.insert(task);
// If we became the first task then we may need to signal since we changed the task that we
// are sleeping on.
if (*tasks_.begin() == task) {
cond_.Signal(self);
}
return;
}
}
}
}
bool TaskProcessor::IsRunning() const {
MutexLock mu(Thread::Current(), lock_);
return is_running_;
}
bool TaskProcessor::WaitForThread(Thread* self) {
// Waiting for too little time here may cause us to fail to get stack traces, since we can't
// safely do so without identifying a HeapTaskDaemon to avoid it. Waiting too long could
// conceivably deadlock if we somehow try to get a stack trace on the way to starting the
// HeapTaskDaemon. Under normal circumstances. this should terminate immediately, since
// HeapTaskDaemon should normally be running.
constexpr int kTotalWaitMillis = 100;
for (int i = 0; i < kTotalWaitMillis; ++i) {
if (is_running_) {
return true;
}
cond_.TimedWait(self, 1 /*msecs*/, 0 /*nsecs*/);
}
LOG(ERROR) << "No identifiable HeapTaskDaemon; unsafe to get thread stacks.";
return false;
}
bool TaskProcessor::IsRunningThread(Thread* t, bool wait) {
Thread* self = Thread::Current();
MutexLock mu(self, lock_);
if (wait && !WaitForThread(self)) {
// If Wait failed, either answer may be correct; in our case, true is safer.
return true;
}
return running_thread_ == t;
}
void TaskProcessor::Stop(Thread* self) {
MutexLock mu(self, lock_);
is_running_ = false;
running_thread_ = nullptr;
cond_.Broadcast(self);
}
void TaskProcessor::Start(Thread* self) {
MutexLock mu(self, lock_);
is_running_ = true;
running_thread_ = self;
}
void TaskProcessor::RunAllTasks(Thread* self) {
while (true) {
// Wait and get a task, may be interrupted.
HeapTask* task = GetTask(self);
if (task != nullptr) {
task->Run(self);
task->Finalize();
} else if (!IsRunning()) {
break;
}
}
}
} // namespace gc
} // namespace art
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