Add heap task processor
The heap task processor processes async tasks which may be delayed.
The motivation for this change is preventing deadlocks which
can occur when the daemon threads get suspended by GetThreadStack.
Other improvements, reduces daemon thread count by one.
Cleaner pending transition VS heap trimming logic.
Bug: 18739541
Change-Id: Idab52b2d9661a6385cada74b93ff297ddc55fc78
diff --git a/runtime/gc/task_processor.cc b/runtime/gc/task_processor.cc
new file mode 100644
index 0000000..1a3c6f5
--- /dev/null
+++ b/runtime/gc/task_processor.cc
@@ -0,0 +1,125 @@
+/*
+ * 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 "scoped_thread_state_change.h"
+
+namespace art {
+namespace gc {
+
+TaskProcessor::TaskProcessor()
+ : lock_(new Mutex("Task processor lock", kReferenceProcessorLock)), is_running_(false) {
+ // Piggyback off the reference processor lock level.
+ cond_.reset(new ConditionVariable("Task processor condition", *lock_));
+}
+
+TaskProcessor::~TaskProcessor() {
+ delete lock_;
+}
+
+void TaskProcessor::AddTask(Thread* self, HeapTask* task) {
+ ScopedThreadStateChange tsc(self, kBlocked);
+ MutexLock mu(self, *lock_);
+ tasks_.insert(task);
+ cond_->Signal(self);
+}
+
+HeapTask* TaskProcessor::GetTask(Thread* self) {
+ ScopedThreadStateChange tsc(self, kBlocked);
+ 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 untl 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();
+ return nullptr;
+}
+
+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_;
+}
+
+void TaskProcessor::Stop(Thread* self) {
+ MutexLock mu(self, *lock_);
+ is_running_ = false;
+ cond_->Broadcast(self);
+}
+
+void TaskProcessor::Start(Thread* self) {
+ MutexLock mu(self, *lock_);
+ is_running_ = true;
+}
+
+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