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

webrtc/base/sigslot_unittest.cc

Index: webrtc/base/sigslot_unittest.cc
diff --git a/webrtc/base/sigslot_unittest.cc b/webrtc/base/sigslot_unittest.cc
index e860fe33736da248646b40e475d92ccdf9b7d351..6d21d84fab4c1fe91011e2afcbdcbb0f5623615c 100644
--- a/webrtc/base/sigslot_unittest.cc
+++ b/webrtc/base/sigslot_unittest.cc
@@ -272,3 +272,86 @@ TEST(SigslotTest, CopyConnectedSlot) {
   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());
+}