Use SingleThreadedTaskQueue in DirectTransport
DirectTransport has so far used its own thread, which led to a different threading-model for in the unit-tests than is used in actual WebRTC. Because of that, some critical-sections that weren't truly necessary in WebRTC could not be replaced with thread-checks, because those checks failed in unit-tests.
This CL introduces SingleThreadedTaskQueue - a TaskQueue which guarantees to run all of its tasks on the same thread (rtc::TaskQueue doesn't guarantee that on Mac) - and uses that for DirectTransport. CLs based on top of this will uncomment thread-checks which had to be commented out before, and remove unnecessary critical-sections.
Future work would probably replace the thread-checkers by more sophisticated serialized-access checks, allowing us to move from the SingleThreadedTaskQueue to a normal TaskQueue.
Related implementation notes:
* This CL has made DirectTransport::StopSending() superfluous, and so it was deleted.
BUG=webrtc:8113, webrtc:7405, webrtc:8056, webrtc:8116
Review-Url: https://codereview.webrtc.org/2998923002
Cr-Commit-Position: refs/heads/master@{#19445}
diff --git a/webrtc/test/single_threaded_task_queue_unittest.cc b/webrtc/test/single_threaded_task_queue_unittest.cc
new file mode 100644
index 0000000..8ad8b4f
--- /dev/null
+++ b/webrtc/test/single_threaded_task_queue_unittest.cc
@@ -0,0 +1,364 @@
+/*
+ * Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ * Use of this source code is governed by a BSD-style license
+ * that can be found in the LICENSE file in the root of the source
+ * tree. An additional intellectual property rights grant can be found
+ * in the file PATENTS. All contributing project authors may
+ * be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/test/single_threaded_task_queue.h"
+
+#include <atomic>
+#include <memory>
+#include <vector>
+
+#include "webrtc/rtc_base/event.h"
+#include "webrtc/rtc_base/ptr_util.h"
+#include "webrtc/test/gtest.h"
+
+namespace webrtc {
+namespace test {
+
+namespace {
+
+using TaskId = SingleThreadedTaskQueueForTesting::TaskId;
+
+// Test should not rely on the object under test not being faulty. If the task
+// queue ever blocks forever, we want the tests to fail, rather than hang.
+constexpr int kMaxWaitTimeMs = 10000;
+
+TEST(SingleThreadedTaskQueueForTestingTest, SanityConstructionDestruction) {
+ SingleThreadedTaskQueueForTesting task_queue("task_queue");
+}
+
+TEST(SingleThreadedTaskQueueForTestingTest, ExecutesPostedTasks) {
+ SingleThreadedTaskQueueForTesting task_queue("task_queue");
+
+ std::atomic<bool> executed(false);
+ rtc::Event done(true, false);
+
+ task_queue.PostTask([&executed, &done]() {
+ executed.store(true);
+ done.Set();
+ });
+ ASSERT_TRUE(done.Wait(kMaxWaitTimeMs));
+
+ EXPECT_TRUE(executed.load());
+}
+
+TEST(SingleThreadedTaskQueueForTestingTest,
+ PostMultipleTasksFromSameExternalThread) {
+ SingleThreadedTaskQueueForTesting task_queue("task_queue");
+
+ constexpr size_t kCount = 3;
+ std::atomic<bool> executed[kCount];
+ for (std::atomic<bool>& exec : executed) {
+ exec.store(false);
+ }
+
+ std::vector<std::unique_ptr<rtc::Event>> done_events;
+ for (size_t i = 0; i < kCount; i++) {
+ done_events.emplace_back(rtc::MakeUnique<rtc::Event>(false, false));
+ }
+
+ // To avoid the tasks which comprise the actual test from running before they
+ // have all be posted, which could result in only one task ever being in the
+ // queue at any given time, post one waiting task that would block the
+ // task-queue, and unblock only after all tasks have been posted.
+ rtc::Event rendezvous(true, false);
+ task_queue.PostTask([&rendezvous]() {
+ ASSERT_TRUE(rendezvous.Wait(kMaxWaitTimeMs));
+ });
+
+ // Post the tasks which comprise the test.
+ for (size_t i = 0; i < kCount; i++) {
+ task_queue.PostTask([&executed, &done_events, i]() { // |i| by value.
+ executed[i].store(true);
+ done_events[i]->Set();
+ });
+ }
+
+ rendezvous.Set(); // Release the task-queue.
+
+ // Wait until the task queue has executed all the tasks.
+ for (size_t i = 0; i < kCount; i++) {
+ ASSERT_TRUE(done_events[i]->Wait(kMaxWaitTimeMs));
+ }
+
+ for (size_t i = 0; i < kCount; i++) {
+ EXPECT_TRUE(executed[i].load());
+ }
+}
+
+TEST(SingleThreadedTaskQueueForTestingTest, PostToTaskQueueFromOwnThread) {
+ SingleThreadedTaskQueueForTesting task_queue("task_queue");
+
+ std::atomic<bool> executed(false);
+ rtc::Event done(true, false);
+
+ auto internally_posted_task = [&executed, &done]() {
+ executed.store(true);
+ done.Set();
+ };
+
+ auto externally_posted_task = [&task_queue, &internally_posted_task]() {
+ task_queue.PostTask(internally_posted_task);
+ };
+
+ task_queue.PostTask(externally_posted_task);
+
+ ASSERT_TRUE(done.Wait(kMaxWaitTimeMs));
+ EXPECT_TRUE(executed.load());
+}
+
+TEST(SingleThreadedTaskQueueForTestingTest, TasksExecutedInSequence) {
+ SingleThreadedTaskQueueForTesting task_queue("task_queue");
+
+ // The first task would perform:
+ // accumulator = 10 * accumulator + i
+ // Where |i| is 1, 2 and 3 for the 1st, 2nd and 3rd tasks, respectively.
+ // The result would be 123 if and only iff the tasks were executed in order.
+ size_t accumulator = 0;
+ size_t expected_value = 0; // Updates to the correct value.
+
+ // Prevent the chain from being set in motion before we've had time to
+ // schedule it all, lest the queue only contain one task at a time.
+ rtc::Event rendezvous(true, false);
+ task_queue.PostTask([&rendezvous]() {
+ ASSERT_TRUE(rendezvous.Wait(kMaxWaitTimeMs));
+ });
+
+ for (size_t i = 0; i < 3; i++) {
+ task_queue.PostTask([&accumulator, i]() { // |i| passed by value.
+ accumulator = 10 * accumulator + i;
+ });
+ expected_value = 10 * expected_value + i;
+ }
+
+ // The test will wait for the task-queue to finish.
+ rtc::Event done(true, false);
+ task_queue.PostTask([&done]() {
+ done.Set();
+ });
+
+ rendezvous.Set(); // Set the chain in motion.
+
+ ASSERT_TRUE(done.Wait(kMaxWaitTimeMs));
+
+ EXPECT_EQ(accumulator, expected_value);
+}
+
+TEST(SingleThreadedTaskQueueForTestingTest, ExecutesPostedDelayedTask) {
+ SingleThreadedTaskQueueForTesting task_queue("task_queue");
+
+ std::atomic<bool> executed(false);
+ rtc::Event done(true, false);
+
+ constexpr int64_t delay_ms = 20;
+ static_assert(delay_ms < kMaxWaitTimeMs / 2, "Delay too long for tests.");
+
+ task_queue.PostDelayedTask([&executed, &done]() {
+ executed.store(true);
+ done.Set();
+ }, delay_ms);
+ ASSERT_TRUE(done.Wait(kMaxWaitTimeMs));
+
+ EXPECT_TRUE(executed.load());
+}
+
+TEST(SingleThreadedTaskQueueForTestingTest, DoesNotExecuteDelayedTaskTooSoon) {
+ SingleThreadedTaskQueueForTesting task_queue("task_queue");
+
+ std::atomic<bool> executed(false);
+
+ constexpr int64_t delay_ms = 2000;
+ static_assert(delay_ms < kMaxWaitTimeMs / 2, "Delay too long for tests.");
+
+ task_queue.PostDelayedTask([&executed]() {
+ executed.store(true);
+ }, delay_ms);
+
+ // Wait less than is enough, make sure the task was not yet executed.
+ rtc::Event not_done(true, false);
+ ASSERT_FALSE(not_done.Wait(delay_ms / 2));
+ EXPECT_FALSE(executed.load());
+}
+
+TEST(SingleThreadedTaskQueueForTestingTest,
+ TaskWithLesserDelayPostedAfterFirstDelayedTaskExectuedBeforeFirst) {
+ SingleThreadedTaskQueueForTesting task_queue("task_queue");
+
+ std::atomic<bool> earlier_executed(false);
+ constexpr int64_t earlier_delay_ms = 500;
+
+ std::atomic<bool> later_executed(false);
+ constexpr int64_t later_delay_ms = 1000;
+
+ static_assert(earlier_delay_ms + later_delay_ms < kMaxWaitTimeMs / 2,
+ "Delay too long for tests.");
+
+ rtc::Event done(true, false);
+
+ auto earlier_task = [&earlier_executed, &later_executed]() {
+ EXPECT_FALSE(later_executed.load());
+ earlier_executed.store(true);
+ };
+
+ auto later_task = [&earlier_executed, &later_executed, &done]() {
+ EXPECT_TRUE(earlier_executed.load());
+ later_executed.store(true);
+ done.Set();
+ };
+
+ task_queue.PostDelayedTask(later_task, later_delay_ms);
+ task_queue.PostDelayedTask(earlier_task, earlier_delay_ms);
+
+ ASSERT_TRUE(done.Wait(kMaxWaitTimeMs));
+ ASSERT_TRUE(earlier_executed);
+ ASSERT_TRUE(later_executed);
+}
+
+TEST(SingleThreadedTaskQueueForTestingTest,
+ TaskWithGreaterDelayPostedAfterFirstDelayedTaskExectuedAfterFirst) {
+ SingleThreadedTaskQueueForTesting task_queue("task_queue");
+
+ std::atomic<bool> earlier_executed(false);
+ constexpr int64_t earlier_delay_ms = 500;
+
+ std::atomic<bool> later_executed(false);
+ constexpr int64_t later_delay_ms = 1000;
+
+ static_assert(earlier_delay_ms + later_delay_ms < kMaxWaitTimeMs / 2,
+ "Delay too long for tests.");
+
+ rtc::Event done(true, false);
+
+ auto earlier_task = [&earlier_executed, &later_executed]() {
+ EXPECT_FALSE(later_executed.load());
+ earlier_executed.store(true);
+ };
+
+ auto later_task = [&earlier_executed, &later_executed, &done]() {
+ EXPECT_TRUE(earlier_executed.load());
+ later_executed.store(true);
+ done.Set();
+ };
+
+ task_queue.PostDelayedTask(earlier_task, earlier_delay_ms);
+ task_queue.PostDelayedTask(later_task, later_delay_ms);
+
+ ASSERT_TRUE(done.Wait(kMaxWaitTimeMs));
+ ASSERT_TRUE(earlier_executed);
+ ASSERT_TRUE(later_executed);
+}
+
+TEST(SingleThreadedTaskQueueForTestingTest, ExternalThreadCancelsTask) {
+ SingleThreadedTaskQueueForTesting task_queue("task_queue");
+
+ rtc::Event done(true, false);
+
+ // Prevent the to-be-cancelled task from being executed before we've had
+ // time to cancel it.
+ rtc::Event rendezvous(true, false);
+ task_queue.PostTask([&rendezvous]() {
+ ASSERT_TRUE(rendezvous.Wait(kMaxWaitTimeMs));
+ });
+
+ TaskId cancelled_task_id = task_queue.PostTask([]() {
+ EXPECT_TRUE(false);
+ });
+ task_queue.PostTask([&done]() {
+ done.Set();
+ });
+
+ task_queue.CancelTask(cancelled_task_id);
+
+ // Set the tasks in motion; the cancelled task does not run (otherwise the
+ // test would fail). The last task ends the test, showing that the queue
+ // progressed beyond the cancelled task.
+ rendezvous.Set();
+ ASSERT_TRUE(done.Wait(kMaxWaitTimeMs));
+}
+
+// In this test, we'll set off a chain where the first task cancels the second
+// task, then a third task runs (showing that we really cancelled the task,
+// rather than just halted the task-queue).
+TEST(SingleThreadedTaskQueueForTestingTest, InternalThreadCancelsTask) {
+ SingleThreadedTaskQueueForTesting task_queue("task_queue");
+
+ rtc::Event done(true, false);
+
+ // Prevent the chain from being set-off before we've set everything up.
+ rtc::Event rendezvous(true, false);
+ task_queue.PostTask([&rendezvous]() {
+ ASSERT_TRUE(rendezvous.Wait(kMaxWaitTimeMs));
+ });
+
+ // This is the canceller-task. It takes cancelled_task_id by reference,
+ // because the ID will only become known after the cancelled task is
+ // scheduled.
+ TaskId cancelled_task_id;
+ auto canceller_task = [&task_queue, &cancelled_task_id]() {
+ task_queue.CancelTask(cancelled_task_id);
+ };
+ task_queue.PostTask(canceller_task);
+
+ // This task will be cancelled by the task before it.
+ auto cancelled_task = []() {
+ EXPECT_TRUE(false);
+ };
+ cancelled_task_id = task_queue.PostTask(cancelled_task);
+
+ // When this task runs, it will allow the test to be finished.
+ auto completion_marker_task = [&done]() {
+ done.Set();
+ };
+ task_queue.PostTask(completion_marker_task);
+
+ rendezvous.Set(); // Set the chain in motion.
+
+ ASSERT_TRUE(done.Wait(kMaxWaitTimeMs));
+}
+
+TEST(SingleThreadedTaskQueueForTestingTest, SendTask) {
+ SingleThreadedTaskQueueForTesting task_queue("task_queue");
+
+ std::atomic<bool> executed(false);
+
+ task_queue.SendTask([&executed]() {
+ // Intentionally delay, so that if SendTask didn't block, the sender thread
+ // would have time to read |executed|.
+ rtc::Event delay(true, false);
+ ASSERT_FALSE(delay.Wait(1000));
+ executed.store(true);
+ });
+
+ EXPECT_TRUE(executed);
+}
+
+TEST(SingleThreadedTaskQueueForTestingTest,
+ DestructTaskQueueWhileTasksPending) {
+ auto task_queue =
+ rtc::MakeUnique<SingleThreadedTaskQueueForTesting>("task_queue");
+
+ std::atomic<size_t> counter(0);
+
+ constexpr size_t tasks = 10;
+ for (size_t i = 0; i < tasks; i++) {
+ task_queue->PostTask([&counter]() {
+ std::atomic_fetch_add(&counter, static_cast<size_t>(1));
+ rtc::Event delay(true, false);
+ ASSERT_FALSE(delay.Wait(500));
+ });
+ }
+
+ task_queue.reset();
+
+ EXPECT_LT(counter, tasks);
+}
+
+} // namespace
+} // namespace test
+} // namespace webrtc