Test SequencedWorkerPool with redirection to the TaskScheduler.

base/threading/sequenced_worker_pool.cc

 // Copyright (c) 2012 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 "base/threading/sequenced_worker_pool.h"
 
 #include <stdint.h>
 
 #include <list>
 #include <map>
@@ skipping 36 matching lines @@
 #endif
 
 #if !defined(OS_NACL)
 #include "base/metrics/histogram_macros.h"
 #endif
 
 namespace base {
 
 namespace {
 
-// An enum representing the state of all pools. Any given process should only
-// ever transition from NONE_ACTIVE to the active states, transitions between
-// actives states are unexpected. The REDIRECTED_TO_TASK_SCHEDULER transition
-// occurs when RedirectSequencedWorkerPoolsToTaskSchedulerForProcess() is called
-// and the WORKER_CREATED transition occurs when a Worker needs to be created
-// because the first task was posted and the state is still NONE_ACTIVE.
+// An enum representing the state of all pools. Any given non-test process
+// should only ever transition from NONE_ACTIVE to the active states,

[danakj, 2016/09/16 20:29:36]

to one of the active states. Transitions between active states

(you have "actives states")

[fdoray, 2016/09/16 21:21:31]

Done.

+// transitions between actives states are unexpected. The
+// REDIRECTED_TO_TASK_SCHEDULER transition occurs when
+// RedirectToTaskSchedulerForProcess() is called. The WORKER_CREATED transition
+// occurs when a Worker needs to be created because the first task was posted
+// and the state is still NONE_ACTIVE. In a test process, a transition to
+// NONE_ACTIVE occurs when ResetRedirectToTaskSchedulerForProcessForTesting() is
+// called.
+//
 // |g_all_pools_state| uses relaxed atomic operations to ensure no data race
 // between reads/writes, strict memory ordering isn't required per no other
 // state being inferred from its value. Explicit synchronization (e.g. locks or
 // events) would be overkill (it's fine for other threads to still see
 // NONE_ACTIVE after the first Worker was created -- this is not possible for
 // REDIRECTED_TO_TASK_SCHEDULER per its API requesting to be invoked while no
 // other threads are active).
+//
 // TODO(gab): Remove this if http://crbug.com/622400 fails (SequencedWorkerPool
 // will be phased out completely otherwise).
 enum AllPoolsState : subtle::Atomic32 {
   NONE_ACTIVE,
   WORKER_CREATED,
   REDIRECTED_TO_TASK_SCHEDULER,
 };
 subtle::Atomic32 g_all_pools_state = AllPoolsState::NONE_ACTIVE;
 
 struct SequencedTask : public TrackingInfo  {
@@ skipping 815 matching lines @@
   } else {
     ThreadMap::const_iterator found =
         threads_.find(PlatformThread::CurrentId());
     return found != threads_.end() && found->second->is_processing_task() &&
            sequence_token.Equals(found->second->task_sequence_token());
   }
 }
 
 // See https://code.google.com/p/chromium/issues/detail?id=168415
 void SequencedWorkerPool::Inner::CleanupForTesting() {
+  DCHECK_NE(subtle::NoBarrier_Load(&g_all_pools_state),
+            AllPoolsState::REDIRECTED_TO_TASK_SCHEDULER);
   DCHECK(!RunsTasksOnCurrentThread());
   base::ThreadRestrictions::ScopedAllowWait allow_wait;
   AutoLock lock(lock_);
   CHECK_EQ(CLEANUP_DONE, cleanup_state_);
   if (shutdown_called_)
     return;
   if (pending_tasks_.empty() && waiting_thread_count_ == threads_.size())
     return;
   cleanup_state_ = CLEANUP_REQUESTED;
   cleanup_idlers_ = 0;
@@ skipping 527 matching lines @@
 scoped_refptr<SequencedWorkerPool>
 SequencedWorkerPool::GetWorkerPoolForCurrentThread() {
   Worker* worker = Worker::GetForCurrentThread();
   if (!worker)
     return nullptr;
 
   return worker->worker_pool();
 }
 
 // static
-void SequencedWorkerPool::
-    RedirectSequencedWorkerPoolsToTaskSchedulerForProcess() {
+void SequencedWorkerPool::RedirectToTaskSchedulerForProcess() {
   DCHECK(TaskScheduler::GetInstance());
   // Hitting this DCHECK indicates that a task was posted to a
   // SequencedWorkerPool before the TaskScheduler was initialized and
   // redirected, posting task to SequencedWorkerPools needs to at least be
   // delayed until after that point.
   DCHECK_EQ(AllPoolsState::NONE_ACTIVE,
             subtle::NoBarrier_Load(&g_all_pools_state));
   subtle::NoBarrier_Store(&g_all_pools_state,
                           AllPoolsState::REDIRECTED_TO_TASK_SCHEDULER);
 }
 
+// static
+void SequencedWorkerPool::ResetRedirectToTaskSchedulerForProcessForTesting() {
+  // This can be called when the current state is REDIRECTED_TO_TASK_SCHEDULER
+  // to stop redirecting tasks. It can also be called when the current state is
+  // WORKER_CREATED to allow RedirectToTaskSchedulerForProcess() to be called
+  // (can usually not be called after a worker has been created).

[gab, 2016/09/16 20:16:10]

"when current state is WORKER_CREATED" and "usually not after a worker has been
created" are contradictory, no?

[fdoray, 2016/09/16 21:21:31]

Made the comment clearer.

+  subtle::NoBarrier_Store(&g_all_pools_state, AllPoolsState::NONE_ACTIVE);
+}
+
 SequencedWorkerPool::SequencedWorkerPool(size_t max_threads,
                                          const std::string& thread_name_prefix,
                                          base::TaskPriority task_priority)
     : constructor_task_runner_(ThreadTaskRunnerHandle::Get()),
       inner_(new Inner(this,
                        max_threads,
                        thread_name_prefix,
                        task_priority,
                        NULL)) {}
 
@@ skipping 136 matching lines @@
 bool SequencedWorkerPool::IsShutdownInProgress() {
   return inner_->IsShutdownInProgress();
 }
 
 bool SequencedWorkerPool::IsRunningSequenceOnCurrentThread(
     SequenceToken sequence_token) const {
   return inner_->IsRunningSequenceOnCurrentThread(sequence_token);
 }
 
 }  // namespace base