Relanding #2: Fixing crash that can occur if signal is modified while firing.

webrtc/base/sigslot_unittest.cc

 /*
  *  Copyright 2012 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 254 matching lines @@
   sigslot::signal<> signal;
   SigslotReceiver<> receiver;
   receiver.Connect(&signal);
 
   // Fire the signal after copying the receiver, expecting the copied receiver
   // to be notified.
   SigslotReceiver<> copied_receiver(receiver);
   signal();
   EXPECT_EQ(1, copied_receiver.signal_count());
 }
+
+// Just used for the test below.
+class Disconnector : public sigslot::has_slots<> {
+ public:
+  Disconnector(SigslotReceiver<>* receiver1, SigslotReceiver<>* receiver2)
+      : receiver1_(receiver1), receiver2_(receiver2) {}
+
+  void Connect(sigslot::signal<>* signal) {
+    signal_ = signal;
+    signal->connect(this, &Disconnector::Disconnect);
+  }
+
+ private:
+  void Disconnect() {
+    receiver1_->Disconnect();
+    receiver2_->Disconnect();
+    signal_->disconnect(this);
+  }
+
+  sigslot::signal<>* signal_;
+  SigslotReceiver<>* receiver1_;
+  SigslotReceiver<>* receiver2_;
+};
+
+// Test that things work as expected if a signal is disconnected from a slot
+// while it's firing.
+TEST(SigslotTest, DisconnectFromSignalWhileFiring) {
+  sigslot::signal<> signal;
+  SigslotReceiver<> receiver1;
+  SigslotReceiver<> receiver2;
+  SigslotReceiver<> receiver3;
+  Disconnector disconnector(&receiver1, &receiver2);
+
+  // From this ordering, receiver1 should receive the signal, then the
+  // disconnector will be invoked, causing receiver2 to be disconnected before
+  // it receives the signal. And receiver3 should also receive the signal,
+  // since it was never disconnected.
+  receiver1.Connect(&signal);
+  disconnector.Connect(&signal);
+  receiver2.Connect(&signal);
+  receiver3.Connect(&signal);
+  signal();
+
+  EXPECT_EQ(1, receiver1.signal_count());
+  EXPECT_EQ(0, receiver2.signal_count());
+  EXPECT_EQ(1, receiver3.signal_count());
+}
+
+// Uses disconnect_all instead of disconnect.
+class Disconnector2 : public sigslot::has_slots<> {
+ public:
+  void Connect(sigslot::signal<>* signal) {
+    signal_ = signal;
+    signal->connect(this, &Disconnector2::Disconnect);
+  }
+
+ private:
+  void Disconnect() {
+    signal_->disconnect_all();
+  }
+
+  sigslot::signal<>* signal_;
+};
+
+// Test that things work as expected if a signal is disconnected from a slot
+// while it's firing using disconnect_all.
+TEST(SigslotTest, CallDisconnectAllWhileSignalFiring) {
+  sigslot::signal<> signal;
+  SigslotReceiver<> receiver1;
+  SigslotReceiver<> receiver2;
+  Disconnector2 disconnector;
+
+  // From this ordering, receiver1 should receive the signal, then the
+  // disconnector will be invoked, causing receiver2 to be disconnected before
+  // it receives the signal.
+  receiver1.Connect(&signal);
+  disconnector.Connect(&signal);
+  receiver2.Connect(&signal);
+  signal();
+
+  EXPECT_EQ(1, receiver1.signal_count());
+  EXPECT_EQ(0, receiver2.signal_count());
+}