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Handle initialization race in TaskQueue on Windows, discovered by drmemory.

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The issue was that if the main entry routine of the thread would get called before the first APC, the thread would hang on a GetMessage() call and the APC sent to initialize the thread, would never run.

BUG=

Review-Url: https://codereview.webrtc.org/2139723003
Cr-Commit-Position: refs/heads/master@{#13438}
This commit is contained in:
tommi 2016-07-12 01:24:36 -07:00 committed by Commit bot
parent 913b70489d
commit b89257a51b
2 changed files with 29 additions and 12 deletions
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4
webrtc/base/task_queue.h
View File

@ -13,6 +13,7 @@
#include <list>
#include <memory>
#include <unordered_map>
#if defined(WEBRTC_MAC) && !defined(WEBRTC_BUILD_LIBEVENT)
#include <dispatch/dispatch.h>
@ -253,7 +254,10 @@ class LOCKABLE TaskQueue {
dispatch_queue_t queue_;
QueueContext* const context_;
#elif defined(WEBRTC_WIN)
typedef std::unordered_map<UINT_PTR, std::unique_ptr<QueuedTask>>
DelayedTasks;
static bool ThreadMain(void* context);
static bool ProcessQueuedMessages(DelayedTasks* delayed_tasks);
class WorkerThread : public PlatformThread {
public:

37
webrtc/base/task_queue_win.cc
View File

@ -11,7 +11,6 @@
#include "webrtc/base/task_queue.h"
#include <string.h>
#include <unordered_map>
#include "webrtc/base/checks.h"
#include "webrtc/base/logging.h"
@ -132,12 +131,26 @@ void TaskQueue::PostTaskAndReply(std::unique_ptr<QueuedTask> task,
// static
bool TaskQueue::ThreadMain(void* context) {
std::unordered_map<UINT_PTR, std::unique_ptr<QueuedTask>> delayed_tasks;
DelayedTasks delayed_tasks;
while (true) {
DWORD result = ::MsgWaitForMultipleObjectsEx(0, nullptr, INFINITE,
QS_ALLEVENTS, MWMO_ALERTABLE);
RTC_CHECK_NE(WAIT_FAILED, result);
if (result == WAIT_OBJECT_0) {
if (!ProcessQueuedMessages(&delayed_tasks))
break;
} else {
RTC_DCHECK_EQ(WAIT_IO_COMPLETION, result);
}
}
return false;
}
BOOL ret;
MSG msg;
while ((ret = GetMessage(&msg, nullptr, 0, 0)) != 0 && ret != -1) {
// static
bool TaskQueue::ProcessQueuedMessages(DelayedTasks* delayed_tasks) {
MSG msg = {};
while (PeekMessage(&msg, nullptr, 0, 0, PM_REMOVE) &&
msg.message != WM_QUIT) {
if (!msg.hwnd) {
switch (msg.message) {
case WM_RUN_TASK: {
@ -157,16 +170,16 @@ bool TaskQueue::ThreadMain(void* context) {
post_time > milliseconds ? 0 : milliseconds - post_time;
#endif
UINT_PTR timer_id = SetTimer(nullptr, 0, milliseconds, nullptr);
delayed_tasks.insert(std::make_pair(timer_id, task));
delayed_tasks->insert(std::make_pair(timer_id, task));
break;
}
case WM_TIMER: {
KillTimer(nullptr, msg.wParam);
auto found = delayed_tasks.find(msg.wParam);
RTC_DCHECK(found != delayed_tasks.end());
auto found = delayed_tasks->find(msg.wParam);
RTC_DCHECK(found != delayed_tasks->end());
if (!found->second->Run())
found->second.release();
delayed_tasks.erase(found);
delayed_tasks->erase(found);
break;
}
default:
@ -178,7 +191,7 @@ bool TaskQueue::ThreadMain(void* context) {
DispatchMessage(&msg);
}
}
return false;
return msg.message != WM_QUIT;
}
} // namespace rtc