fixed proper shutdown of local CA subscriptions

src/db/dbCAC.h

@@ -72,7 +72,8 @@ public:
     dbSubscriptionIO ( dbServiceIO &, dbChannelIO &, struct dbAddr &, cacStateNotify &, 
         unsigned type, unsigned long count, unsigned mask, cacChannel::ioid * );
     void destroy ();
-    void channelDestroyException ();
+    void unsubscribe ();
+    void channelDeleteException ();
     void show ( unsigned level ) const;
     void * operator new ( size_t size );
     void operator delete ( void *pCadaver, size_t size );

src/db/dbServiceIO.cpp

@@ -257,6 +257,9 @@ void dbServiceIO::destroyAllIO ( dbChannelIO & chan )
         while ( ( pIO = chan.dbServicePrivateListOfIO::eventq.get() ) ) {
             this->ioTable.remove ( *pIO );
             tmp.add ( *pIO );
+            // this prevents a db event callback from coming 
+            // through after the IO is deleted
+            pIO->unsubscribe ();
         }
         if ( chan.dbServicePrivateListOfIO::pBlocker ) {
             this->ioTable.remove ( *chan.dbServicePrivateListOfIO::pBlocker );
@@ -265,7 +268,7 @@ void dbServiceIO::destroyAllIO ( dbChannelIO & chan )
     while ( ( pIO = tmp.get() ) ) {
         // If they call ioCancel() here it will be ignored
         // because the IO has been unregistered above
-        pIO->channelDestroyException ();
+        pIO->channelDeleteException ();
         pIO->destroy ();
     }
     if ( chan.dbServicePrivateListOfIO::pBlocker ) {

src/db/dbSubscriptionIO.cpp

@@ -64,7 +64,16 @@ void dbSubscriptionIO::destroy ()
     delete this;
 }
 
-void dbSubscriptionIO::channelDestroyException ()
+// lock should be applied
+void dbSubscriptionIO::unsubscribe ()
+{
+    if ( this->es ) {
+        db_cancel_event ( this->es );
+        this->es = 0;
+    }
+}
+
+void dbSubscriptionIO::channelDeleteException ()
 {
     this->notify.exception ( ECA_CHANDESTROY, 
         this->chan.pName(), this->type, this->count );