Bug 1154990 - Better error messages when IPC send fails (r=bent)

ipc/glue/MessageChannel.cpp

@@ -522,7 +522,7 @@ MessageChannel::Echo(Message* aMsg)
     MonitorAutoLock lock(*mMonitor);
 
     if (!Connected()) {
-        ReportConnectionError("MessageChannel");
+        ReportConnectionError("MessageChannel", msg);
         return false;
     }
 
@@ -545,7 +545,7 @@ MessageChannel::Send(Message* aMsg)
 
     MonitorAutoLock lock(*mMonitor);
     if (!Connected()) {
-        ReportConnectionError("MessageChannel");
+        ReportConnectionError("MessageChannel", msg);
         return false;
     }
     mLink->SendMessage(msg.forget());
@@ -778,7 +778,7 @@ MessageChannel::Send(Message* aMsg, Message* aReply)
     nsAutoPtr<Message> msg(aMsg);
 
     if (!Connected()) {
-        ReportConnectionError("MessageChannel::SendAndWait");
+        ReportConnectionError("MessageChannel::SendAndWait", msg);
         return false;
     }
 
@@ -871,7 +871,7 @@ MessageChannel::Call(Message* aMsg, Message* aReply)
 
     MonitorAutoLock lock(*mMonitor);
     if (!Connected()) {
-        ReportConnectionError("MessageChannel::Call");
+        ReportConnectionError("MessageChannel::Call", aMsg);
         return false;
     }
 
@@ -1527,7 +1527,7 @@ MessageChannel::ReportMessageRouteError(const char* channelName) const
 }
 
 void
-MessageChannel::ReportConnectionError(const char* aChannelName) const
+MessageChannel::ReportConnectionError(const char* aChannelName, Message* aMsg) const
 {
     AssertWorkerThread();
     mMonitor->AssertCurrentThreadOwns();
@@ -1554,7 +1554,16 @@ MessageChannel::ReportConnectionError(const char* aChannelName) const
         NS_RUNTIMEABORT("unreached");
     }
 
-    PrintErrorMessage(mSide, aChannelName, errorMsg);
+    if (aMsg) {
+        char reason[512];
+        PR_snprintf(reason, sizeof(reason),
+                    "(msgtype=0x%lX,name=%s) %s",
+                    aMsg->type(), aMsg->name(), errorMsg);
+
+        PrintErrorMessage(mSide, aChannelName, reason);
+    } else {
+        PrintErrorMessage(mSide, aChannelName, errorMsg);
+    }
 
     MonitorAutoUnlock unlock(*mMonitor);
     mListener->OnProcessingError(MsgDropped, errorMsg);

ipc/glue/MessageChannel.h

@@ -215,7 +215,7 @@ class MessageChannel : HasResultCodes
 
     void PostErrorNotifyTask();
     void OnNotifyMaybeChannelError();
-    void ReportConnectionError(const char* aChannelName) const;
+    void ReportConnectionError(const char* aChannelName, Message* aMsg = nullptr) const;
     void ReportMessageRouteError(const char* channelName) const;
     bool MaybeHandleError(Result code, const Message& aMsg, const char* channelName);