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Migrate PostTask+Wait to BlockingCall to avoid deadlock in DegradedCall.

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The deadlock happens when the WebRtcCombinedNetworkAndWorkerThread
experiment is running because the worker thread doing the PostTask is
the same thread as the network thread. When using BlockingCall instead
this method will avoid the PostTask and just execute in-line instead
if the experiment is running and otherwise do what the old path did.

As per webrtc:15099, we do not want to increase uses of rtc::Thread in
general, and adding more block-invokes in is also discouraged
(webrtc:12649) so instead of adding new methods to TaskQueueBase we
simply do a static_cast<rtc::Thread*>.

When WebRtcCombinedNetworkAndWorkerThread has launched the blocking
call can be removed because then we're on a single thread always.

Bug: webrtc:15098
Change-Id: I6dcc09bcf6ee0ad12e4beffef3b206989265540b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/301880
Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39894}
This commit is contained in:
Henrik Boström 2023-04-19 10:30:04 +02:00 committed by WebRTC LUCI CQ
parent 2c0689ffad
commit f9ffd68d8e
2 changed files with 6 additions and 8 deletions
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1
call/BUILD.gn
View File

@ -328,6 +328,7 @@ rtc_library("call") {
"../rtc_base:rtc_task_queue",
"../rtc_base:safe_minmax",
"../rtc_base:stringutils",
"../rtc_base:threading",
"../rtc_base:timeutils",
"../rtc_base/experiments:field_trial_parser",
"../rtc_base/network:sent_packet",

13
call/degraded_call.cc
View File

@ -16,7 +16,7 @@
#include "absl/strings/string_view.h"
#include "api/sequence_checker.h"
#include "modules/rtp_rtcp/source/rtp_util.h"
#include "rtc_base/event.h"
#include "rtc_base/thread.h"
namespace webrtc {
@ -172,13 +172,10 @@ DegradedCall::~DegradedCall() {
// Otherwise, when the `DegradedCall` object is destroyed but
// `SetNotAlive` has not yet been called,
// another Closure guarded by `call_alive_` may be called.
rtc::Event event;
call_->network_thread()->PostTask(
[flag = std::move(call_alive_), &event]() mutable {
flag->SetNotAlive();
event.Set();
});
event.Wait(rtc::Event::kForever);
// TODO(https://crbug.com/webrtc/12649): Remove this block-invoke.
static_cast<rtc::Thread*>(call_->network_thread())
->BlockingCall(
[flag = std::move(call_alive_)]() mutable { flag->SetNotAlive(); });
}
AudioSendStream* DegradedCall::CreateAudioSendStream(