Reland "[PeerConnection] Use an OperationsChain in PeerConnection for async ops."
This is a reland of 1dddaa1a84330091ca083c950ef2e24a85a48fc8
The regression that caused the original CL to be reverted was the fact that
invoking SetLocalDescription() inside of the CreateOffer() callback was no
longer executing synchronously and immediately.
In this CL, the original CL is patched so that the CreateOffer() operation
is marked as completed just before invoking the CreateOffer() callback
(versus doing it just afterwards). This ensures that the OperationsChain is
popped before the callback runs. The same applies for CreateAnswer().
See diff between Patch Set 1 (Original CL) and the latest Patch Set.
Original change's description:
> [PeerConnection] Use an OperationsChain in PeerConnection for async ops.
>
> For background, motivation, requirements and implementation notes, see
> https://docs.google.com/document/d/1XLwNN2kUIGGTwz9LQ0NwJNkcybi9oKnynUEZB1jGA14/edit?usp=sharing
>
> Using the OperationsChain will unblock future CLs from chaining multiple
> operations together such as implementing parameterless
> setLocalDescription().
>
> In this CL, the OperationsChain is used in existing signaling operations
> with little intended side-effects. An operation that is chained onto an
> empty OperationsChain will for instance execute immediately, and
> SetLocalDescription() and SetRemoteDescription() are implemented as
> "synchronous operations".
>
> The lifetime of the PeerConnection is not indended to change as a result
> of this CL: All chained operations use a WeakPtr to the PC to ensure
> use-after-free does not happen.
>
> There is one notable change though: CreateOffer() and CreateAnswer() will
> asynchronously delay other signaling methods from executing until they
> have completed.
>
> Drive-by fix: This CL also ensures that early failing
> CreateOffer/CreateAnswer operation's observers are invoked if the
> PeerConnection is destroyed while a PostCreateSessionDescriptionFailure
> is pending.
>
> Bug: webrtc:11019
> Change-Id: I521333e41d20d9bbfb1e721609f2c9db2a5f93a9
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/157305
> Reviewed-by: Steve Anton <steveanton@webrtc.org>
> Commit-Queue: Henrik Boström <hbos@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#29605}
TBR=steveanton@webrtc.org
Bug: webrtc:11019
Change-Id: I57b4496e63378c91c24679ee496e21f5cb6a0e59
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/158524
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29630}
diff --git a/pc/BUILD.gn b/pc/BUILD.gn
index 0da5150..2dcbd91 100644
--- a/pc/BUILD.gn
+++ b/pc/BUILD.gn
@@ -255,7 +255,9 @@
"../rtc_base",
"../rtc_base:checks",
"../rtc_base:rtc_base_approved",
+ "../rtc_base:rtc_operations_chain",
"../rtc_base:safe_minmax",
+ "../rtc_base:weak_ptr",
"../rtc_base/experiments:field_trial_parser",
"../rtc_base/system:fallthrough",
"../rtc_base/system:file_wrapper",
diff --git a/pc/peer_connection.cc b/pc/peer_connection.cc
index 08fbe41..7dc2e35 100644
--- a/pc/peer_connection.cc
+++ b/pc/peer_connection.cc
@@ -647,6 +647,51 @@
: nullptr;
}
+// Wraps a CreateSessionDescriptionObserver and an OperationsChain operation
+// complete callback. When the observer is invoked, the wrapped observer is
+// invoked followed by invoking the completion callback.
+class CreateSessionDescriptionObserverOperationWrapper
+ : public CreateSessionDescriptionObserver {
+ public:
+ CreateSessionDescriptionObserverOperationWrapper(
+ rtc::scoped_refptr<CreateSessionDescriptionObserver> observer,
+ std::function<void()> operation_complete_callback)
+ : observer_(std::move(observer)),
+ operation_complete_callback_(std::move(operation_complete_callback)) {
+ RTC_DCHECK(observer_);
+ }
+ ~CreateSessionDescriptionObserverOperationWrapper() override {
+ RTC_DCHECK(was_called_);
+ }
+
+ void OnSuccess(SessionDescriptionInterface* desc) override {
+ RTC_DCHECK(!was_called_);
+#ifdef RTC_DCHECK_IS_ON
+ was_called_ = true;
+#endif // RTC_DCHECK_IS_ON
+ // Completing the operation before invoking the observer allows the observer
+ // to execute SetLocalDescription() without delay.
+ operation_complete_callback_();
+ observer_->OnSuccess(desc);
+ }
+
+ void OnFailure(RTCError error) override {
+ RTC_DCHECK(!was_called_);
+#ifdef RTC_DCHECK_IS_ON
+ was_called_ = true;
+#endif // RTC_DCHECK_IS_ON
+ operation_complete_callback_();
+ observer_->OnFailure(std::move(error));
+ }
+
+ private:
+#ifdef RTC_DCHECK_IS_ON
+ bool was_called_ = false;
+#endif // RTC_DCHECK_IS_ON
+ rtc::scoped_refptr<CreateSessionDescriptionObserver> observer_;
+ std::function<void()> operation_complete_callback_;
+};
+
} // namespace
class PeerConnection::LocalIceCredentialsToReplace {
@@ -894,6 +939,7 @@
: factory_(factory),
event_log_(std::move(event_log)),
event_log_ptr_(event_log_.get()),
+ operations_chain_(rtc::OperationsChain::Create()),
datagram_transport_config_(
field_trial::FindFullName(kDatagramTransportFieldTrial)),
datagram_transport_data_channel_config_(
@@ -904,12 +950,15 @@
call_(std::move(call)),
call_ptr_(call_.get()),
data_channel_transport_(nullptr),
- local_ice_credentials_to_replace_(new LocalIceCredentialsToReplace()) {}
+ local_ice_credentials_to_replace_(new LocalIceCredentialsToReplace()),
+ weak_ptr_factory_(this) {}
PeerConnection::~PeerConnection() {
TRACE_EVENT0("webrtc", "PeerConnection::~PeerConnection");
RTC_DCHECK_RUN_ON(signaling_thread());
+ weak_ptr_factory_.InvalidateWeakPtrs();
+
// Need to stop transceivers before destroying the stats collector because
// AudioRtpSender has a reference to the StatsCollector it will update when
// stopping.
@@ -946,6 +995,23 @@
// The event log must outlive call (and any other object that uses it).
event_log_.reset();
});
+
+ // Process all pending notifications in the message queue. If we don't do
+ // this, requests will linger and not know they succeeded or failed.
+ rtc::MessageList list;
+ signaling_thread()->Clear(this, rtc::MQID_ANY, &list);
+ for (auto& msg : list) {
+ if (msg.message_id == MSG_CREATE_SESSIONDESCRIPTION_FAILED) {
+ // Processing CreateOffer() and CreateAnswer() messages ensures their
+ // observers are invoked even if the PeerConnection is destroyed early.
+ OnMessage(&msg);
+ } else {
+ // TODO(hbos): Consider processing all pending messages. This would mean
+ // that SetLocalDescription() and SetRemoteDescription() observers are
+ // informed of successes and failures; this is currently NOT the case.
+ delete msg.pdata;
+ }
+ }
}
void PeerConnection::DestroyAllChannels() {
@@ -2052,7 +2118,37 @@
void PeerConnection::CreateOffer(CreateSessionDescriptionObserver* observer,
const RTCOfferAnswerOptions& options) {
RTC_DCHECK_RUN_ON(signaling_thread());
- TRACE_EVENT0("webrtc", "PeerConnection::CreateOffer");
+ // Chain this operation. If asynchronous operations are pending on the chain,
+ // this operation will be queued to be invoked, otherwise the contents of the
+ // lambda will execute immediately.
+ operations_chain_->ChainOperation(
+ [this_weak_ptr = weak_ptr_factory_.GetWeakPtr(),
+ observer_refptr =
+ rtc::scoped_refptr<CreateSessionDescriptionObserver>(observer),
+ options](std::function<void()> operations_chain_callback) {
+ // Abort early if |this_weak_ptr| is no longer valid.
+ if (!this_weak_ptr) {
+ observer_refptr->OnFailure(
+ RTCError(RTCErrorType::INTERNAL_ERROR,
+ "CreateOffer failed because the session was shut down"));
+ operations_chain_callback();
+ return;
+ }
+ // The operation completes asynchronously when the wrapper is invoked.
+ rtc::scoped_refptr<CreateSessionDescriptionObserverOperationWrapper>
+ observer_wrapper(new rtc::RefCountedObject<
+ CreateSessionDescriptionObserverOperationWrapper>(
+ std::move(observer_refptr),
+ std::move(operations_chain_callback)));
+ this_weak_ptr->DoCreateOffer(options, observer_wrapper);
+ });
+}
+
+void PeerConnection::DoCreateOffer(
+ const RTCOfferAnswerOptions& options,
+ rtc::scoped_refptr<CreateSessionDescriptionObserver> observer) {
+ RTC_DCHECK_RUN_ON(signaling_thread());
+ TRACE_EVENT0("webrtc", "PeerConnection::DoCreateOffer");
if (!observer) {
RTC_LOG(LS_ERROR) << "CreateOffer - observer is NULL.";
@@ -2178,7 +2274,37 @@
void PeerConnection::CreateAnswer(CreateSessionDescriptionObserver* observer,
const RTCOfferAnswerOptions& options) {
RTC_DCHECK_RUN_ON(signaling_thread());
- TRACE_EVENT0("webrtc", "PeerConnection::CreateAnswer");
+ // Chain this operation. If asynchronous operations are pending on the chain,
+ // this operation will be queued to be invoked, otherwise the contents of the
+ // lambda will execute immediately.
+ operations_chain_->ChainOperation(
+ [this_weak_ptr = weak_ptr_factory_.GetWeakPtr(),
+ observer_refptr =
+ rtc::scoped_refptr<CreateSessionDescriptionObserver>(observer),
+ options](std::function<void()> operations_chain_callback) {
+ // Abort early if |this_weak_ptr| is no longer valid.
+ if (!this_weak_ptr) {
+ observer_refptr->OnFailure(RTCError(
+ RTCErrorType::INTERNAL_ERROR,
+ "CreateAnswer failed because the session was shut down"));
+ operations_chain_callback();
+ return;
+ }
+ // The operation completes asynchronously when the wrapper is invoked.
+ rtc::scoped_refptr<CreateSessionDescriptionObserverOperationWrapper>
+ observer_wrapper(new rtc::RefCountedObject<
+ CreateSessionDescriptionObserverOperationWrapper>(
+ std::move(observer_refptr),
+ std::move(operations_chain_callback)));
+ this_weak_ptr->DoCreateAnswer(options, observer_wrapper);
+ });
+}
+
+void PeerConnection::DoCreateAnswer(
+ const RTCOfferAnswerOptions& options,
+ rtc::scoped_refptr<CreateSessionDescriptionObserver> observer) {
+ RTC_DCHECK_RUN_ON(signaling_thread());
+ TRACE_EVENT0("webrtc", "PeerConnection::DoCreateAnswer");
if (!observer) {
RTC_LOG(LS_ERROR) << "CreateAnswer - observer is NULL.";
return;
@@ -2232,13 +2358,44 @@
SetSessionDescriptionObserver* observer,
SessionDescriptionInterface* desc_ptr) {
RTC_DCHECK_RUN_ON(signaling_thread());
- TRACE_EVENT0("webrtc", "PeerConnection::SetLocalDescription");
+ // Chain this operation. If asynchronous operations are pending on the chain,
+ // this operation will be queued to be invoked, otherwise the contents of the
+ // lambda will execute immediately.
+ operations_chain_->ChainOperation(
+ [this_weak_ptr = weak_ptr_factory_.GetWeakPtr(),
+ observer_refptr =
+ rtc::scoped_refptr<SetSessionDescriptionObserver>(observer),
+ desc = std::unique_ptr<SessionDescriptionInterface>(desc_ptr)](
+ std::function<void()> operations_chain_callback) mutable {
+ // Abort early if |this_weak_ptr| is no longer valid.
+ if (!this_weak_ptr) {
+ // For consistency with DoSetLocalDescription(), we DO NOT inform the
+ // |observer_refptr| that the operation failed in this case.
+ // TODO(hbos): If/when we process SLD messages in ~PeerConnection,
+ // the consistent thing would be to inform the observer here.
+ operations_chain_callback();
+ return;
+ }
+ this_weak_ptr->DoSetLocalDescription(std::move(desc),
+ std::move(observer_refptr));
+ // DoSetLocalDescription() is currently implemented as a synchronous
+ // operation but where the |observer|'s callbacks are invoked
+ // asynchronously in a post to OnMessage().
+ // For backwards-compatability reasons, we declare the operation as
+ // completed here (rather than in OnMessage()). This ensures that:
+ // - This operation is not keeping the PeerConnection alive past this
+ // point.
+ // - Subsequent offer/answer operations can start immediately (without
+ // waiting for OnMessage()).
+ operations_chain_callback();
+ });
+}
- // The SetLocalDescription contract is that we take ownership of the session
- // description regardless of the outcome, so wrap it in a unique_ptr right
- // away. Ideally, SetLocalDescription's signature will be changed to take the
- // description as a unique_ptr argument to formalize this agreement.
- std::unique_ptr<SessionDescriptionInterface> desc(desc_ptr);
+void PeerConnection::DoSetLocalDescription(
+ std::unique_ptr<SessionDescriptionInterface> desc,
+ rtc::scoped_refptr<SetSessionDescriptionObserver> observer) {
+ RTC_DCHECK_RUN_ON(signaling_thread());
+ TRACE_EVENT0("webrtc", "PeerConnection::DoSetLocalDescription");
if (!observer) {
RTC_LOG(LS_ERROR) << "SetLocalDescription - observer is NULL.";
@@ -2619,18 +2776,83 @@
void PeerConnection::SetRemoteDescription(
SetSessionDescriptionObserver* observer,
- SessionDescriptionInterface* desc) {
- SetRemoteDescription(
- std::unique_ptr<SessionDescriptionInterface>(desc),
- rtc::scoped_refptr<SetRemoteDescriptionObserverInterface>(
- new SetRemoteDescriptionObserverAdapter(this, observer)));
+ SessionDescriptionInterface* desc_ptr) {
+ RTC_DCHECK_RUN_ON(signaling_thread());
+ // Chain this operation. If asynchronous operations are pending on the chain,
+ // this operation will be queued to be invoked, otherwise the contents of the
+ // lambda will execute immediately.
+ operations_chain_->ChainOperation(
+ [this_weak_ptr = weak_ptr_factory_.GetWeakPtr(),
+ observer_refptr =
+ rtc::scoped_refptr<SetSessionDescriptionObserver>(observer),
+ desc = std::unique_ptr<SessionDescriptionInterface>(desc_ptr)](
+ std::function<void()> operations_chain_callback) mutable {
+ // Abort early if |this_weak_ptr| is no longer valid.
+ if (!this_weak_ptr) {
+ // For consistency with SetRemoteDescriptionObserverAdapter, we DO NOT
+ // inform the |observer_refptr| that the operation failed in this
+ // case.
+ // TODO(hbos): If/when we process SRD messages in ~PeerConnection,
+ // the consistent thing would be to inform the observer here.
+ operations_chain_callback();
+ return;
+ }
+ this_weak_ptr->DoSetRemoteDescription(
+ std::move(desc),
+ rtc::scoped_refptr<SetRemoteDescriptionObserverInterface>(
+ new SetRemoteDescriptionObserverAdapter(
+ this_weak_ptr.get(), std::move(observer_refptr))));
+ // DoSetRemoteDescription() is currently implemented as a synchronous
+ // operation but where SetRemoteDescriptionObserverAdapter ensures that
+ // the |observer|'s callbacks are invoked asynchronously in a post to
+ // OnMessage().
+ // For backwards-compatability reasons, we declare the operation as
+ // completed here (rather than in OnMessage()). This ensures that:
+ // - This operation is not keeping the PeerConnection alive past this
+ // point.
+ // - Subsequent offer/answer operations can start immediately (without
+ // waiting for OnMessage()).
+ operations_chain_callback();
+ });
}
void PeerConnection::SetRemoteDescription(
std::unique_ptr<SessionDescriptionInterface> desc,
rtc::scoped_refptr<SetRemoteDescriptionObserverInterface> observer) {
RTC_DCHECK_RUN_ON(signaling_thread());
- TRACE_EVENT0("webrtc", "PeerConnection::SetRemoteDescription");
+ // Chain this operation. If asynchronous operations are pending on the chain,
+ // this operation will be queued to be invoked, otherwise the contents of the
+ // lambda will execute immediately.
+ operations_chain_->ChainOperation(
+ [this_weak_ptr = weak_ptr_factory_.GetWeakPtr(), observer,
+ desc = std::move(desc)](
+ std::function<void()> operations_chain_callback) mutable {
+ // Abort early if |this_weak_ptr| is no longer valid.
+ if (!this_weak_ptr) {
+ // For consistency with DoSetRemoteDescription(), we DO inform the
+ // |observer| that the operation failed in this case.
+ observer->OnSetRemoteDescriptionComplete(RTCError(
+ RTCErrorType::INVALID_STATE,
+ "Failed to set remote offer sdp: failed because the session was "
+ "shut down"));
+ operations_chain_callback();
+ return;
+ }
+ this_weak_ptr->DoSetRemoteDescription(std::move(desc),
+ std::move(observer));
+ // DoSetRemoteDescription() is currently implemented as a synchronous
+ // operation. The |observer| will already have been informed that it
+ // completed, and we can mark this operation as complete without any
+ // loose ends.
+ operations_chain_callback();
+ });
+}
+
+void PeerConnection::DoSetRemoteDescription(
+ std::unique_ptr<SessionDescriptionInterface> desc,
+ rtc::scoped_refptr<SetRemoteDescriptionObserverInterface> observer) {
+ RTC_DCHECK_RUN_ON(signaling_thread());
+ TRACE_EVENT0("webrtc", "PeerConnection::DoSetRemoteDescription");
if (!observer) {
RTC_LOG(LS_ERROR) << "SetRemoteDescription - observer is NULL.";
diff --git a/pc/peer_connection.h b/pc/peer_connection.h
index baaa14d..7a576f3 100644
--- a/pc/peer_connection.h
+++ b/pc/peer_connection.h
@@ -34,8 +34,10 @@
#include "pc/stream_collection.h"
#include "pc/webrtc_session_description_factory.h"
#include "rtc_base/experiments/field_trial_parser.h"
+#include "rtc_base/operations_chain.h"
#include "rtc_base/race_checker.h"
#include "rtc_base/unique_id_generator.h"
+#include "rtc_base/weak_ptr.h"
namespace webrtc {
@@ -443,6 +445,22 @@
rtc::scoped_refptr<RtpTransceiverProxyWithInternal<RtpTransceiver>>
GetFirstAudioTransceiver() const RTC_RUN_ON(signaling_thread());
+ // Implementation of the offer/answer exchange operations. These are chained
+ // onto the |operations_chain_| when the public CreateOffer(), CreateAnswer(),
+ // SetLocalDescription() and SetRemoteDescription() methods are invoked.
+ void DoCreateOffer(
+ const RTCOfferAnswerOptions& options,
+ rtc::scoped_refptr<CreateSessionDescriptionObserver> observer);
+ void DoCreateAnswer(
+ const RTCOfferAnswerOptions& options,
+ rtc::scoped_refptr<CreateSessionDescriptionObserver> observer);
+ void DoSetLocalDescription(
+ std::unique_ptr<SessionDescriptionInterface> desc,
+ rtc::scoped_refptr<SetSessionDescriptionObserver> observer);
+ void DoSetRemoteDescription(
+ std::unique_ptr<SessionDescriptionInterface> desc,
+ rtc::scoped_refptr<SetRemoteDescriptionObserverInterface> observer);
+
void CreateAudioReceiver(MediaStreamInterface* stream,
const RtpSenderInfo& remote_sender_info)
RTC_RUN_ON(signaling_thread());
@@ -1217,6 +1235,14 @@
// pointer (but not touch the object) from any thread.
RtcEventLog* const event_log_ptr_ RTC_PT_GUARDED_BY(worker_thread());
+ // The operations chain is used by the offer/answer exchange methods to ensure
+ // they are executed in the right order. For example, if
+ // SetRemoteDescription() is invoked while CreateOffer() is still pending, the
+ // SRD operation will not start until CreateOffer() has completed. See
+ // https://w3c.github.io/webrtc-pc/#dfn-operations-chain.
+ rtc::scoped_refptr<rtc::OperationsChain> operations_chain_
+ RTC_GUARDED_BY(signaling_thread());
+
SignalingState signaling_state_ RTC_GUARDED_BY(signaling_thread()) = kStable;
IceConnectionState ice_connection_state_ RTC_GUARDED_BY(signaling_thread()) =
kIceConnectionNew;
@@ -1446,6 +1472,9 @@
std::unique_ptr<LocalIceCredentialsToReplace>
local_ice_credentials_to_replace_ RTC_GUARDED_BY(signaling_thread());
bool is_negotiation_needed_ RTC_GUARDED_BY(signaling_thread()) = false;
+
+ rtc::WeakPtrFactory<PeerConnection> weak_ptr_factory_
+ RTC_GUARDED_BY(signaling_thread());
};
} // namespace webrtc
diff --git a/pc/peer_connection_signaling_unittest.cc b/pc/peer_connection_signaling_unittest.cc
index 9916539..e79ee3d 100644
--- a/pc/peer_connection_signaling_unittest.cc
+++ b/pc/peer_connection_signaling_unittest.cc
@@ -41,6 +41,10 @@
using ::testing::Combine;
using ::testing::Values;
+namespace {
+const int64_t kWaitTimeout = 10000;
+} // namespace
+
class PeerConnectionWrapperForSignalingTest : public PeerConnectionWrapper {
public:
using PeerConnectionWrapper::PeerConnectionWrapper;
@@ -57,6 +61,31 @@
}
};
+class ExecuteFunctionOnCreateSessionDescriptionObserver
+ : public CreateSessionDescriptionObserver {
+ public:
+ ExecuteFunctionOnCreateSessionDescriptionObserver(
+ std::function<void(SessionDescriptionInterface*)> function)
+ : function_(std::move(function)) {}
+ ~ExecuteFunctionOnCreateSessionDescriptionObserver() override {
+ RTC_DCHECK(was_called_);
+ }
+
+ bool was_called() const { return was_called_; }
+
+ void OnSuccess(SessionDescriptionInterface* desc) override {
+ RTC_DCHECK(!was_called_);
+ was_called_ = true;
+ function_(desc);
+ }
+
+ void OnFailure(RTCError error) override { RTC_NOTREACHED(); }
+
+ private:
+ bool was_called_ = false;
+ std::function<void(SessionDescriptionInterface*)> function_;
+};
+
class PeerConnectionSignalingBaseTest : public ::testing::Test {
protected:
typedef std::unique_ptr<PeerConnectionWrapperForSignalingTest> WrapperPtr;
@@ -522,6 +551,63 @@
}
}
+// Similar to the above test, but by closing the PC first the CreateOffer() will
+// fail "early", which triggers a codepath where the PeerConnection is
+// reponsible for invoking the observer, instead of the normal codepath where
+// the WebRtcSessionDescriptionFactory is responsible for it.
+TEST_P(PeerConnectionSignalingTest, CloseCreateOfferAndShutdown) {
+ auto caller = CreatePeerConnection();
+ rtc::scoped_refptr<MockCreateSessionDescriptionObserver> observer =
+ new rtc::RefCountedObject<MockCreateSessionDescriptionObserver>();
+ caller->pc()->Close();
+ caller->pc()->CreateOffer(observer, RTCOfferAnswerOptions());
+ caller.reset(nullptr);
+ EXPECT_TRUE(observer->called());
+}
+
+TEST_P(PeerConnectionSignalingTest, SetRemoteDescriptionExecutesImmediately) {
+ auto caller = CreatePeerConnectionWithAudioVideo();
+ auto callee = CreatePeerConnection();
+
+ // This offer will cause receivers to be created.
+ auto offer = caller->CreateOffer(RTCOfferAnswerOptions());
+
+ // By not waiting for the observer's callback we can verify that the operation
+ // executed immediately.
+ callee->pc()->SetRemoteDescription(std::move(offer),
+ new MockSetRemoteDescriptionObserver());
+ EXPECT_EQ(2u, callee->pc()->GetReceivers().size());
+}
+
+TEST_P(PeerConnectionSignalingTest, CreateOfferBlocksSetRemoteDescription) {
+ auto caller = CreatePeerConnectionWithAudioVideo();
+ auto callee = CreatePeerConnection();
+
+ // This offer will cause receivers to be created.
+ auto offer = caller->CreateOffer(RTCOfferAnswerOptions());
+
+ EXPECT_EQ(0u, callee->pc()->GetReceivers().size());
+ rtc::scoped_refptr<MockCreateSessionDescriptionObserver> offer_observer(
+ new rtc::RefCountedObject<MockCreateSessionDescriptionObserver>());
+ // Synchronously invoke CreateOffer() and SetRemoteDescription(). The
+ // SetRemoteDescription() operation should be chained to be executed
+ // asynchronously, when CreateOffer() completes.
+ callee->pc()->CreateOffer(offer_observer, RTCOfferAnswerOptions());
+ callee->pc()->SetRemoteDescription(std::move(offer),
+ new MockSetRemoteDescriptionObserver());
+ // CreateOffer() is asynchronous; without message processing this operation
+ // should not have completed.
+ EXPECT_FALSE(offer_observer->called());
+ // Due to chaining, the receivers should not have been created by the offer
+ // yet.
+ EXPECT_EQ(0u, callee->pc()->GetReceivers().size());
+ // EXPECT_TRUE_WAIT causes messages to be processed...
+ EXPECT_TRUE_WAIT(offer_observer->called(), kWaitTimeout);
+ // Now that the offer has been completed, SetRemoteDescription() will have
+ // been executed next in the chain.
+ EXPECT_EQ(2u, callee->pc()->GetReceivers().size());
+}
+
INSTANTIATE_TEST_SUITE_P(PeerConnectionSignalingTest,
PeerConnectionSignalingTest,
Values(SdpSemantics::kPlanB,
@@ -534,6 +620,49 @@
: PeerConnectionSignalingBaseTest(SdpSemantics::kUnifiedPlan) {}
};
+// We verify that SetLocalDescription() executed immediately by verifying that
+// the transceiver mid values got assigned. SLD executing immeditately is not
+// unique to Unified Plan, but the transceivers used to verify this are only
+// available in Unified Plan.
+TEST_F(PeerConnectionSignalingUnifiedPlanTest,
+ SetLocalDescriptionExecutesImmediately) {
+ auto caller = CreatePeerConnectionWithAudioVideo();
+
+ // This offer will cause transceiver mids to get assigned.
+ auto offer = caller->CreateOffer(RTCOfferAnswerOptions());
+
+ // By not waiting for the observer's callback we can verify that the operation
+ // executed immediately.
+ RTC_DCHECK(!caller->pc()->GetTransceivers()[0]->mid().has_value());
+ caller->pc()->SetLocalDescription(
+ new rtc::RefCountedObject<MockSetSessionDescriptionObserver>(),
+ offer.release());
+ EXPECT_TRUE(caller->pc()->GetTransceivers()[0]->mid().has_value());
+}
+
+TEST_F(PeerConnectionSignalingUnifiedPlanTest,
+ SetLocalDescriptionExecutesImmediatelyInsideCreateOfferCallback) {
+ auto caller = CreatePeerConnectionWithAudioVideo();
+
+ // This offer will cause transceiver mids to get assigned.
+ auto offer = caller->CreateOffer(RTCOfferAnswerOptions());
+
+ rtc::scoped_refptr<ExecuteFunctionOnCreateSessionDescriptionObserver>
+ offer_observer(new rtc::RefCountedObject<
+ ExecuteFunctionOnCreateSessionDescriptionObserver>(
+ [pc = caller->pc()](SessionDescriptionInterface* desc) {
+ // By not waiting for the observer's callback we can verify that the
+ // operation executed immediately.
+ RTC_DCHECK(!pc->GetTransceivers()[0]->mid().has_value());
+ pc->SetLocalDescription(
+ new rtc::RefCountedObject<MockSetSessionDescriptionObserver>(),
+ desc);
+ EXPECT_TRUE(pc->GetTransceivers()[0]->mid().has_value());
+ }));
+ caller->pc()->CreateOffer(offer_observer, RTCOfferAnswerOptions());
+ EXPECT_TRUE_WAIT(offer_observer->was_called(), kWaitTimeout);
+}
+
// Test that transports are shown in the sender/receiver API after offer/answer.
// This only works in Unified Plan.
TEST_F(PeerConnectionSignalingUnifiedPlanTest,