Fixing a couple cases that cause ProcessAllMessageQueues to hang.
The two situations are:
1. A thread is in the process of shutting down, so it won't handle any
more messages.
2. A message queue is cleared before it has a chance to process pending
messages.
In both of those cases, we should consider processing done at that
point.
R=honghaiz@webrtc.org, pthatcher@webrtc.org
Review URL: https://codereview.webrtc.org/2319303004 .
Cr-Commit-Position: refs/heads/master@{#14245}
diff --git a/webrtc/base/messagequeue.cc b/webrtc/base/messagequeue.cc
index ebf98f5..503d5af 100644
--- a/webrtc/base/messagequeue.cc
+++ b/webrtc/base/messagequeue.cc
@@ -126,17 +126,34 @@
}
void MessageQueueManager::ProcessAllMessageQueuesInternal() {
- // Post a delayed message at the current time and wait for it to be dispatched
- // on all queues, which will ensure that all messages that came before it were
- // also dispatched.
- volatile int queues_not_done;
- auto functor = [&queues_not_done] { AtomicOps::Decrement(&queues_not_done); };
- FunctorMessageHandler<void, decltype(functor)> handler(functor);
+ // This works by posting a delayed message at the current time and waiting
+ // for it to be dispatched on all queues, which will ensure that all messages
+ // that came before it were also dispatched.
+ volatile int queues_not_done = 0;
+
+ // This class is used so that whether the posted message is processed, or the
+ // message queue is simply cleared, queues_not_done gets decremented.
+ class ScopedIncrement : public MessageData {
+ public:
+ ScopedIncrement(volatile int* value) : value_(value) {
+ AtomicOps::Increment(value_);
+ }
+ ~ScopedIncrement() override { AtomicOps::Decrement(value_); }
+
+ private:
+ volatile int* value_;
+ };
+
{
DebugNonReentrantCritScope cs(&crit_, &locked_);
- queues_not_done = static_cast<int>(message_queues_.size());
for (MessageQueue* queue : message_queues_) {
- queue->PostDelayed(RTC_FROM_HERE, 0, &handler);
+ if (queue->IsQuitting()) {
+ // If the queue is quitting, it's done processing messages so it can
+ // be ignored. If we tried to post a message to it, it would be dropped.
+ continue;
+ }
+ queue->PostDelayed(RTC_FROM_HERE, 0, nullptr, MQID_DISPOSE,
+ new ScopedIncrement(&queues_not_done));
}
}
// Note: One of the message queues may have been on this thread, which is why
diff --git a/webrtc/base/messagequeue_unittest.cc b/webrtc/base/messagequeue_unittest.cc
index fc3a8f7..8834ab5 100644
--- a/webrtc/base/messagequeue_unittest.cc
+++ b/webrtc/base/messagequeue_unittest.cc
@@ -10,7 +10,11 @@
#include "webrtc/base/messagequeue.h"
+#include <functional>
+
+#include "webrtc/base/atomicops.h"
#include "webrtc/base/bind.h"
+#include "webrtc/base/event.h"
#include "webrtc/base/gunit.h"
#include "webrtc/base/logging.h"
#include "webrtc/base/thread.h"
@@ -140,3 +144,74 @@
EXPECT_TRUE(deleted);
EXPECT_FALSE(MessageQueueManager::IsInitialized());
}
+
+// Ensure that ProcessAllMessageQueues does its essential function; process
+// all messages (both delayed and non delayed) up until the current time, on
+// all registered message queues.
+TEST(MessageQueueManager, ProcessAllMessageQueues) {
+ Event entered_process_all_message_queues(true, false);
+ Thread a;
+ Thread b;
+ a.Start();
+ b.Start();
+
+ volatile int messages_processed = 0;
+ FunctorMessageHandler<void, std::function<void()>> incrementer(
+ [&messages_processed, &entered_process_all_message_queues] {
+ // Wait for event as a means to ensure Increment doesn't occur outside
+ // of ProcessAllMessageQueues. The event is set by a message posted to
+ // the main thread, which is guaranteed to be handled inside
+ // ProcessAllMessageQueues.
+ entered_process_all_message_queues.Wait(Event::kForever);
+ AtomicOps::Increment(&messages_processed);
+ });
+ FunctorMessageHandler<void, std::function<void()>> event_signaler(
+ [&entered_process_all_message_queues] {
+ entered_process_all_message_queues.Set();
+ });
+
+ // Post messages (both delayed and non delayed) to both threads.
+ a.Post(RTC_FROM_HERE, &incrementer);
+ b.Post(RTC_FROM_HERE, &incrementer);
+ a.PostDelayed(RTC_FROM_HERE, 0, &incrementer);
+ b.PostDelayed(RTC_FROM_HERE, 0, &incrementer);
+ rtc::Thread::Current()->Post(RTC_FROM_HERE, &event_signaler);
+
+ MessageQueueManager::ProcessAllMessageQueues();
+ EXPECT_EQ(4, AtomicOps::AcquireLoad(&messages_processed));
+}
+
+// Test that ProcessAllMessageQueues doesn't hang if a thread is quitting.
+TEST(MessageQueueManager, ProcessAllMessageQueuesWithQuittingThread) {
+ Thread t;
+ t.Start();
+ t.Quit();
+ MessageQueueManager::ProcessAllMessageQueues();
+}
+
+// Test that ProcessAllMessageQueues doesn't hang if a queue clears its
+// messages.
+TEST(MessageQueueManager, ProcessAllMessageQueuesWithClearedQueue) {
+ Event entered_process_all_message_queues(true, false);
+ Thread t;
+ t.Start();
+
+ FunctorMessageHandler<void, std::function<void()>> clearer(
+ [&entered_process_all_message_queues] {
+ // Wait for event as a means to ensure Clear doesn't occur outside of
+ // ProcessAllMessageQueues. The event is set by a message posted to the
+ // main thread, which is guaranteed to be handled inside
+ // ProcessAllMessageQueues.
+ entered_process_all_message_queues.Wait(Event::kForever);
+ rtc::Thread::Current()->Clear(nullptr);
+ });
+ FunctorMessageHandler<void, std::function<void()>> event_signaler(
+ [&entered_process_all_message_queues] {
+ entered_process_all_message_queues.Set();
+ });
+
+ // Post messages (both delayed and non delayed) to both threads.
+ t.Post(RTC_FROM_HERE, &clearer);
+ rtc::Thread::Current()->Post(RTC_FROM_HERE, &event_signaler);
+ MessageQueueManager::ProcessAllMessageQueues();
+}