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P2PTransportChannel::OnCandidateResolved: fix resolver leak.

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This change fixes a problem where the eventual destruction of a
completed resolver sometimes doesn't happen. This is because the
destruction is posted to the network thread, and if it's destroyed
before the closure is executed, the resolver is leaked.

The fix is in three parts:
1. The resolver->Destroy call is performed on closure destruction
   to make sure it will always run.
2. The closure is executed with task queue. This because the
   RTC_DCHECK on thread:140 fires with the invoker_.
3. It's not possible to guarantee the context Destroy is called on due
   to TaskQueue semantics. Therefore SignalThread::Destroy was changed
   to accept any calling context and only requiring it's the last
   public call to the object.

For unknown reasons, this leak doesn't trigger the leak checker, see
referred bugs for further investigation.

Bug: webrtc:7723, webrtc:11605, chromium:905542
Change-Id: I2681ff1d2416ccbc564974a65ac84781a9ed7aee
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/176125
Commit-Queue: Markus Handell <handellm@webrtc.org>
Reviewed-by: Tommi <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31359}
This commit is contained in:
Markus Handell 2020-05-26 18:22:24 +02:00 committed by Commit Bot
parent b7c63ab83a
commit ff84d86d9c
5 changed files with 25 additions and 11 deletions
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1
p2p/BUILD.gn
View File

@ -107,6 +107,7 @@ rtc_library("rtc_p2p") {
"../rtc_base/memory:fifo_buffer",
"../rtc_base/network:sent_packet",
"../rtc_base/system:rtc_export",
"../rtc_base/task_utils:to_queued_task",
"../rtc_base/third_party/base64",
"../rtc_base/third_party/sigslot",
"../system_wrappers:field_trial",

6
p2p/base/p2p_transport_channel.cc
View File

@ -30,6 +30,7 @@
#include "rtc_base/net_helper.h"
#include "rtc_base/net_helpers.h"
#include "rtc_base/string_encode.h"
#include "rtc_base/task_utils/to_queued_task.h"
#include "rtc_base/time_utils.h"
#include "system_wrappers/include/field_trial.h"
#include "system_wrappers/include/metrics.h"
@ -1223,9 +1224,8 @@ void P2PTransportChannel::OnCandidateResolved(
Candidate candidate = p->candidate_;
resolvers_.erase(p);
AddRemoteCandidateWithResolver(candidate, resolver);
invoker_.AsyncInvoke<void>(
RTC_FROM_HERE, thread(),
rtc::Bind(&rtc::AsyncResolverInterface::Destroy, resolver, false));
thread()->PostTask(
webrtc::ToQueuedTask([] {}, [resolver] { resolver->Destroy(false); }));
}
void P2PTransportChannel::AddRemoteCandidateWithResolver(

13
p2p/base/p2p_transport_channel_unittest.cc
View File

@ -4844,10 +4844,13 @@ TEST_F(P2PTransportChannelTest,
// address after the resolution completes.
TEST_F(P2PTransportChannelTest,
PeerReflexiveCandidateDuringResolvingHostCandidateWithMdnsName) {
NiceMock<rtc::MockAsyncResolver> mock_async_resolver;
auto mock_async_resolver = new NiceMock<rtc::MockAsyncResolver>();
ON_CALL(*mock_async_resolver, Destroy).WillByDefault([mock_async_resolver] {
delete mock_async_resolver;
});
webrtc::MockAsyncResolverFactory mock_async_resolver_factory;
EXPECT_CALL(mock_async_resolver_factory, Create())
.WillOnce(Return(&mock_async_resolver));
.WillOnce(Return(mock_async_resolver));
// ep1 and ep2 will only gather host candidates with addresses
// kPublicAddrs[0] and kPublicAddrs[1], respectively.
@ -4874,7 +4877,7 @@ TEST_F(P2PTransportChannelTest,
bool mock_async_resolver_started = false;
// Not signaling done yet, and only make sure we are in the process of
// resolution.
EXPECT_CALL(mock_async_resolver, Start(_))
EXPECT_CALL(*mock_async_resolver, Start(_))
.WillOnce(InvokeWithoutArgs([&mock_async_resolver_started]() {
mock_async_resolver_started = true;
}));
@ -4887,7 +4890,7 @@ TEST_F(P2PTransportChannelTest,
ResumeCandidates(1);
ASSERT_TRUE_WAIT(ep1_ch1()->selected_connection() != nullptr, kMediumTimeout);
// Let the mock resolver of ep2 receives the correct resolution.
EXPECT_CALL(mock_async_resolver, GetResolvedAddress(_, _))
EXPECT_CALL(*mock_async_resolver, GetResolvedAddress(_, _))
.WillOnce(DoAll(SetArgPointee<1>(local_address), Return(true)));
// Upon receiving a ping from ep1, ep2 adds a prflx candidate from the
// unknown address and establishes a connection.
@ -4899,7 +4902,7 @@ TEST_F(P2PTransportChannelTest,
ep2_ch1()->selected_connection()->remote_candidate().type());
// ep2 should also be able resolve the hostname candidate. The resolved remote
// host candidate should be merged with the prflx remote candidate.
mock_async_resolver.SignalDone(&mock_async_resolver);
mock_async_resolver->SignalDone(mock_async_resolver);
EXPECT_EQ_WAIT(LOCAL_PORT_TYPE,
ep2_ch1()->selected_connection()->remote_candidate().type(),
kMediumTimeout);

11
rtc_base/signal_thread.cc
View File

@ -31,11 +31,13 @@ SignalThread::SignalThread()
}
SignalThread::~SignalThread() {
rtc::CritScope lock(&cs_);
RTC_DCHECK(refcount_ == 0);
}
bool SignalThread::SetName(const std::string& name, const void* obj) {
EnterExit ee(this);
RTC_DCHECK(!destroy_called_);
RTC_DCHECK(main_->IsCurrent());
RTC_DCHECK(kInit == state_);
return worker_.SetName(name, obj);
@ -43,6 +45,7 @@ bool SignalThread::SetName(const std::string& name, const void* obj) {
void SignalThread::Start() {
EnterExit ee(this);
RTC_DCHECK(!destroy_called_);
RTC_DCHECK(main_->IsCurrent());
if (kInit == state_ || kComplete == state_) {
state_ = kRunning;
@ -55,7 +58,11 @@ void SignalThread::Start() {
void SignalThread::Destroy(bool wait) {
EnterExit ee(this);
RTC_DCHECK(main_->IsCurrent());
// Sometimes the caller can't guarantee which thread will call Destroy, only
// that it will be the last thing it does.
// RTC_DCHECK(main_->IsCurrent());
RTC_DCHECK(!destroy_called_);
destroy_called_ = true;
if ((kInit == state_) || (kComplete == state_)) {
refcount_--;
} else if (kRunning == state_ || kReleasing == state_) {
@ -78,6 +85,7 @@ void SignalThread::Destroy(bool wait) {
void SignalThread::Release() {
EnterExit ee(this);
RTC_DCHECK(!destroy_called_);
RTC_DCHECK(main_->IsCurrent());
if (kComplete == state_) {
refcount_--;
@ -91,6 +99,7 @@ void SignalThread::Release() {
bool SignalThread::ContinueWork() {
EnterExit ee(this);
RTC_DCHECK(!destroy_called_);
RTC_DCHECK(worker_.IsCurrent());
return worker_.ProcessMessages(0);
}

5
rtc_base/signal_thread.h
View File

@ -144,8 +144,9 @@ class SignalThread : public sigslot::has_slots<>, protected MessageHandler {
Thread* main_;
Worker worker_;
CriticalSection cs_;
State state_;
int refcount_;
State state_ RTC_GUARDED_BY(cs_);
int refcount_ RTC_GUARDED_BY(cs_);
bool destroy_called_ RTC_GUARDED_BY(cs_) = false;
RTC_DISALLOW_COPY_AND_ASSIGN(SignalThread);
};