Mark CQN subscription as invalid before connection.unsubscribe() completes

Author: cjbj

CHANGELOG.md

@@ -6,6 +6,9 @@ This release is under development.
 
 - Fixed a bug that caused random CQN crashes ([ODPI-C change](https://github.com/oracle/odpi/issues/96)).
 
+- Fixed a CQN race condition to prevent a crash when a multiple
+  `conn.unsubscribe()` calls are made on the same subscription.
+
 - Improve validation of `executeMany()` arguments to prevent a crash.
 
 - Use a relative URL for the ODPI-C submodule to make cloning from

src/njsConnection.cpp

@@ -2752,7 +2752,8 @@ NAN_METHOD(njsConnection::Unsubscribe)
     } else {
         baton->error = njsMessages::Get(errInvalidSubscription);
     }
-    baton->QueueWork("Unsubscribe", Async_Unsubscribe, NULL, 1);
+    baton->QueueWork("Unsubscribe", Async_Unsubscribe, Async_AfterUnsubscribe,
+            1);
 }
 
 
@@ -2773,6 +2774,17 @@ void njsConnection::Async_Unsubscribe(njsBaton *baton)
 }
 
 
+//-----------------------------------------------------------------------------
+// njsConnection::Async_AfterUnsubscribe()
+//   Returns result to JS by invoking JS callback.
+//-----------------------------------------------------------------------------
+void njsConnection::Async_AfterUnsubscribe(njsBaton *baton,
+        Local<Value> argv[])
+{
+    njsOracledb::ClearSubscription(baton->name);
+}
+
+
 //-----------------------------------------------------------------------------
 // njsConnection::GetSodaDatabase()
 //   Creates a top-level soda obect (pseudo) associated with the connection.

src/njsConnection.h

@@ -143,6 +143,7 @@ class njsConnection: public njsCommon {
     // Unsubscribe Method on Connection class
     static NAN_METHOD(Unsubscribe);
     static void Async_Unsubscribe(njsBaton *baton);
+    static void Async_AfterUnsubscribe(njsBaton *baton, Local<Value> argv[]);
 
     // GetSodaDatabase Method on Connection class
     static NAN_METHOD(GetSodaDatabase);