TaskGraphRunner refactor

cc/raster/single_thread_task_graph_runner.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "cc/raster/single_thread_task_graph_runner.h"
+
+#include <string>
+
+#include "base/threading/simple_thread.h"
+#include "base/threading/thread_restrictions.h"
+#include "base/trace_event/trace_event.h"
+
+namespace cc {
+
+SingleThreadTaskGraphRunner::SingleThreadTaskGraphRunner()
+    : lock_(),
+      has_ready_to_run_tasks_cv_(&lock_),
+      has_namespaces_with_finished_running_tasks_cv_(&lock_),
+      shutdown_(false) {}
+
+SingleThreadTaskGraphRunner::~SingleThreadTaskGraphRunner() {}
+
+void SingleThreadTaskGraphRunner::Start(
+    const std::string& thread_name,
+    const base::SimpleThread::Options& thread_options) {
+  thread_.reset(
+      new base::DelegateSimpleThread(this, thread_name, thread_options));
+  thread_->Start();
+}
+
+void SingleThreadTaskGraphRunner::Shutdown() {
+  {
+    base::AutoLock lock(lock_);
+
+    DCHECK(!work_queue_.HasReadyToRunTasks());
+    DCHECK(!work_queue_.HasAnyNamespaces());
+
+    DCHECK(!shutdown_);
+    shutdown_ = true;
+
+    // Wake up the worker so it knows it should exit.
+    has_ready_to_run_tasks_cv_.Signal();
+  }
+  thread_->Join();
+}
+
+NamespaceToken SingleThreadTaskGraphRunner::GetNamespaceToken() {
+  base::AutoLock lock(lock_);
+  return work_queue_.GetNamespaceToken();
+}
+
+void SingleThreadTaskGraphRunner::ScheduleTasks(NamespaceToken token,
+                                                TaskGraph* graph) {
+  TRACE_EVENT2("cc", "SingleThreadTaskGraphRunner::ScheduleTasks", "num_nodes",
+               graph->nodes.size(), "num_edges", graph->edges.size());
+
+  DCHECK(token.IsValid());
+  DCHECK(!TaskGraphWorkQueue::DependencyMismatch(graph));
+
+  {
+    base::AutoLock lock(lock_);
+
+    DCHECK(!shutdown_);
+
+    work_queue_.ScheduleTasks(token, graph);
+
+    // If there is more work available, wake up the worker thread.
+    if (work_queue_.HasReadyToRunTasks())
+      has_ready_to_run_tasks_cv_.Signal();
+  }
+}
+
+void SingleThreadTaskGraphRunner::WaitForTasksToFinishRunning(
+    NamespaceToken token) {
+  TRACE_EVENT0("cc",
+               "SingleThreadTaskGraphRunner::WaitForTasksToFinishRunning");
+
+  DCHECK(token.IsValid());
+
+  {
+    base::AutoLock lock(lock_);
+    base::ThreadRestrictions::ScopedAllowWait allow_wait;
+
+    auto* task_namespace = work_queue_.GetNamespaceForToken(token);
+
+    if (!task_namespace)
+      return;
+
+    while (!work_queue_.HasFinishedRunningTasksInNamespace(task_namespace))
+      has_namespaces_with_finished_running_tasks_cv_.Wait();
+
+    // There may be other namespaces that have finished running tasks, so wake
+    // up another origin thread.
+    has_namespaces_with_finished_running_tasks_cv_.Signal();
+  }
+}
+
+void SingleThreadTaskGraphRunner::CollectCompletedTasks(
+    NamespaceToken token,
+    Task::Vector* completed_tasks) {
+  TRACE_EVENT0("cc", "SingleThreadTaskGraphRunner::CollectCompletedTasks");
+
+  DCHECK(token.IsValid());
+
+  {
+    base::AutoLock lock(lock_);
+    work_queue_.CollectCompletedTasks(token, completed_tasks);
+  }
+}
+
+void SingleThreadTaskGraphRunner::Run() {
+  base::AutoLock lock(lock_);
+
+  while (true) {
+    if (!work_queue_.HasReadyToRunTasks()) {
+      // Exit when shutdown is set and no more tasks are pending.
+      if (shutdown_)
+        break;
+
+      // Wait for more tasks.
+      has_ready_to_run_tasks_cv_.Wait();
+      continue;
+    }
+
+    RunTaskWithLockAcquired();
+  }
+}
+
+void SingleThreadTaskGraphRunner::RunTaskWithLockAcquired() {
+  TRACE_EVENT0("toplevel",
+               "SingleThreadTaskGraphRunner::RunTaskWithLockAcquired");
+
+  lock_.AssertAcquired();
+
+  auto prioritized_task = work_queue_.GetNextTaskToRun();
+  Task* task = prioritized_task.task;
+
+  // Call WillRun() before releasing |lock_| and running task.
+  task->WillRun();
+
+  {
+    base::AutoUnlock unlock(lock_);
+    task->RunOnWorkerThread();
+  }
+
+  // This will mark task as finished running.
+  task->DidRun();
+
+  work_queue_.CompleteTask(prioritized_task);
+
+  // If namespace has finished running all tasks, wake up origin thread.
+  if (work_queue_.HasFinishedRunningTasksInNamespace(
+          prioritized_task.task_namespace))
+    has_namespaces_with_finished_running_tasks_cv_.Signal();
+}
+
+}  // namespace cc