Updates for improved reference count management over DO.

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@17983 72102866-910b-0410-8b05-ffd578937521

ChangeLog

@@ -1,3 +1,18 @@
+Mon Oct 27 13:37:00 2003  Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Source/NSConnection.m: Rewrite/simplify methods dealing with DO
+	retain/release and handling interaction with NSDistantObject.
+	Attempts to make retain/release simpler and more reliable by
+	(among other things) counting the nujmber of times an object is
+	vended by reference.  Much care taken to try to ensure that
+	backward compatibility is not broken ... hope it is ok.
+	* Source/NSDistantObject.m: Modified to use slightly simpler 
+	interaction with NSConnecxtion, to include count of times an
+	object is vended by reference and to ensure thread safety.
+	* Testing/nsconnection_client.m: Make the -d  option produce detailed
+	debug output.
+	* Testing/nsconnection_server.m: ditto.
+
 Mon Oct 27 13:24:00 2003  Richard Frith-Macdonald <rfm@gnu.org>
 
 	* Source/GNUmakefile: build new lock classes

Source/NSConnection.m

@@ -195,8 +195,7 @@ stringFromMsgType(int type)
 + (void) setDebug: (int)val;
 
 - (void) addLocalObject: (NSDistantObject*)anObj;
-- (NSDistantObject*) localForObject: (id)object;
+- (void) removeLocalObject: (NSDistantObject*)anObj;
-- (void) removeLocalObject: (id)anObj;
 
 - (void) _doneInReply: (NSPortCoder*)c;
 - (void) _doneInRmc: (NSPortCoder*)c;
@@ -1107,9 +1106,7 @@ static BOOL	multi_threaded = NO;
 	}
       while (i-- > 0)
 	{
-	  id	t = ((ProxyStruct*)[targets objectAtIndex: i])->_object;
+	  [self removeLocalObject: [targets objectAtIndex: i]];
-
-	  [self removeLocalObject: t];
 	}
       RELEASE(targets);
       GSIMapEmptyMap(_localTargets);
@@ -2533,9 +2530,17 @@ static void callEncoder (DOContext *ctxt)
       if (prox != nil)
 	{
 	  if (debug_connection > 3)
-	    NSLog(@"releasing object with target (0x%x) on (0x%x)",
+	    NSLog(@"releasing object with target (0x%x) on (0x%x) counter %d",
-		target, (gsaddr)self);
+		target, (gsaddr)self, ((ProxyStruct*)prox)->_counter);
-	  [self removeLocalObject: ((ProxyStruct*)prox)->_object];
+#if 1
+	  // FIXME thread safety
+	  if (--(((ProxyStruct*)prox)->_counter) == 0)
+	    {
+	      [self removeLocalObject: prox];
+	    }
+#else
+	  [self removeLocalObject: prox];
+#endif
 	}
       else if (debug_connection > 3)
 	NSLog(@"releasing object with target (0x%x) on (0x%x) - nothing to do",
@@ -2546,9 +2551,11 @@ static void callEncoder (DOContext *ctxt)
 
 - (void) _service_retain: (NSPortCoder*)rmc
 {
-  unsigned	target;
+  unsigned		target;
-  NSPortCoder	*op;
+  NSPortCoder		*op;
-  int		sequence;
+  int			sequence;
+  NSDistantObject	*local;
+  NSString		*response = nil;
 
   NSParameterAssert (_isValid);
 
@@ -2562,27 +2569,19 @@ static void callEncoder (DOContext *ctxt)
     NSLog(@"looking to retain local object with target (0x%x) on (0x%x)",
 		target, (gsaddr)self);
 
-  if ([self includesLocalTarget: target] == nil)
+  M_LOCK(_proxiesGate);
+  local = [self locateLocalTarget: target];
+  if (local == nil)
     {
-      NSDistantObject	*proxy = [self locateLocalTarget: target];
+      response = @"target not found anywhere";
-
-      if (proxy == nil)
-	{
-	  [op encodeObject: @"target not found anywhere"];
-	}
-      else
-	{
-	  [op encodeObject: nil];	// success
-	}
     }
-  else 
+  else
     {
-      [op encodeObject: nil];
+      ((ProxyStruct*)local)->_counter++;	// Vended on connection.
-      if (debug_connection > 3)
-	NSLog(@"target (0x%x) already retained on connection (0x%x)",
-		target, self);
     }
+  M_UNLOCK(_proxiesGate);
 
+  [op encodeObject: response];
   [self _sendOutRmc: op type: RETAIN_REPLY];
 }
 
@@ -3012,7 +3011,7 @@ static void callEncoder (DOContext *ctxt)
   M_LOCK(_refGate);
 
   /*
-   * We replace the code we have just used in the cache, and tell it not to
+   * We replace the coder we have just used in the cache, and tell it not to
    * retain this connection any more.
    */
   if (cacheCoders == YES && _cachedEncoders != nil)
@@ -3099,7 +3098,8 @@ static void callEncoder (DOContext *ctxt)
   M_UNLOCK(_proxiesGate);
 }
 
-- (NSDistantObject*) localForObject: (id)object
+- (NSDistantObject*) retainOrAddLocal: (NSDistantObject*)proxy
+			    forObject: (id)object
 {
   GSIMapNode		node;
   NSDistantObject	*p;
@@ -3114,78 +3114,87 @@ static void callEncoder (DOContext *ctxt)
   else
     {
       p = node->value.obj;
+      RETAIN(p);
+      DESTROY(proxy);
+    }
+  if (p == nil && proxy != nil)
+    {
+      p = proxy;
+      [self addLocalObject: p];
     }
   M_UNLOCK(_proxiesGate);
-  NSParameterAssert(p == nil || [p connectionForProxy] == self);
   return p;
 }
 
-- (void) removeLocalObject: (id)anObj
+- (void) removeLocalObject: (NSDistantObject*)prox
 {
-  NSDistantObject	*prox;
+  id		anObj;
-  unsigned		target;
+  unsigned	target;
-  unsigned		val = 0;
+  unsigned	val = 0;
-  GSIMapNode		node;
+  GSIMapNode	node;
 
   M_LOCK(_proxiesGate);
-
+  anObj = ((ProxyStruct*)prox)->_object;
   node = GSIMapNodeForKey(_localObjects, (GSIMapKey)anObj);
-  if (node == 0)
-    {
-      M_UNLOCK(_proxiesGate);
-      [NSException raise: NSInternalInconsistencyException
-      		  format: @"Attempt to remove non-existent local %@", anObj];
-    }
-  prox = node->value.obj;
-  target = ((ProxyStruct*)prox)->_handle;
 
-  if (1)
+  /*
+   * The NSDistantObject concerned may not belong to this connection,
+   * so we need to check that any matching proxy is identical to the
+   * argument we were given.
+   */
+  if (node != 0 && node->value.obj == prox)
     {
-      id	item;
+      target = ((ProxyStruct*)prox)->_handle;
 
-      M_LOCK(cached_proxies_gate);
       /*
-       * If this proxy has been vended onwards by another process, we
+       * If this proxy has been vended onwards to another process
-       * need to keep a reference to the local object around for a
+       * which has not myet released it, we need to keep a reference
-       * while in case that other process needs it.
+       * to the local object around for a while in case that other
+       * process needs it.
        */
-      if (timer == nil)
+      if ((((ProxyStruct*)prox)->_counter) != 0)
 	{
-	  timer = [NSTimer scheduledTimerWithTimeInterval: 1.0
+	  CachedLocalObject	*item;
-				 target: connectionClass
+
-				 selector: @selector(_timeout:)
+	  (((ProxyStruct*)prox)->_counter) = 0;
-				 userInfo: nil
+	  M_LOCK(cached_proxies_gate);
-				  repeats: YES];
+	  if (timer == nil)
+	    {
+	      timer = [NSTimer scheduledTimerWithTimeInterval: 1.0
+		target: connectionClass
+		selector: @selector(_timeout:)
+		userInfo: nil
+		repeats: YES];
+	    }
+	  item = [CachedLocalObject newWithObject: prox time: 5];
+	  NSMapInsert(targetToCached, (void*)target, item);
+	  M_UNLOCK(cached_proxies_gate);
+	  RELEASE(item);
+	  if (debug_connection > 3)
+	    NSLog(@"placed local object (0x%x) target (0x%x) in cache",
+			(gsaddr)anObj, target);
 	}
-      item = [CachedLocalObject newWithObject: prox time: 5];
+
-      NSMapInsert(targetToCached, (void*)target, item);
+      /*
-      M_UNLOCK(cached_proxies_gate);
+       * Remove the proxy from _localObjects and release it.
-      RELEASE(item);
+       */
-      if (debug_connection > 3)
+      GSIMapRemoveKey(_localObjects, (GSIMapKey)anObj);
-	NSLog(@"placed local object (0x%x) target (0x%x) in cache",
+      RELEASE(prox);
-		    (gsaddr)anObj, target);
+
+      /*
+       * Remove the target info too - no release required.
+       */
+      GSIMapRemoveKey(_localTargets, (GSIMapKey)target);
+
+      if (debug_connection > 2)
+	NSLog(@"removed local object (0x%x) target (0x%x) "
+	    @"from connection (0x%x) (ref %d)",
+		    (gsaddr)anObj, target, (gsaddr)self, val);
     }
-
-  /*
-   * Remove the proxy from _localObjects and release it.
-   */
-  GSIMapRemoveKey(_localObjects, (GSIMapKey)anObj);
-  RELEASE(prox);
-
-  /*
-   * Remove the target info too - no release required.
-   */
-  GSIMapRemoveKey(_localTargets, (GSIMapKey)target);
-
-  if (debug_connection > 2)
-    NSLog(@"remove local object (0x%x) target (0x%x) "
-	@"from connection (0x%x) (ref %d)",
-		(gsaddr)anObj, target, (gsaddr)self, val);
-
   M_UNLOCK(_proxiesGate);
 }
 
-- (void) _release_targets: (unsigned*)list count: (unsigned)number
+- (void) _release_target: (unsigned)target count: (unsigned)number
 {
   NS_DURING
     {
@@ -3206,10 +3215,10 @@ static void callEncoder (DOContext *ctxt)
 
 	  for (i = 0; i < number; i++)
 	    {
-	      [op encodeValueOfObjCType: @encode(unsigned) at: &list[i]];
+	      [op encodeValueOfObjCType: @encode(unsigned) at: &target];
 	      if (debug_connection > 3)
 		NSLog(@"sending release for target (0x%x) on (0x%x)",
-		      list[i], (gsaddr)self);
+		      target, (gsaddr)self);
 	    }
 
 	  [self _sendOutRmc: op type: PROXY_RELEASE];
@@ -3229,6 +3238,11 @@ static void callEncoder (DOContext *ctxt)
   GSIMapNode		node;
 
   M_LOCK(_proxiesGate);
+
+  /*
+   * Try a quick lookup to see if the target references a local object
+   * belonging to the receiver ... usually it should.
+   */
   node = GSIMapNodeForKey(_localTargets, (GSIMapKey)target);
   if (node != 0)
     {
@@ -3236,8 +3250,35 @@ static void callEncoder (DOContext *ctxt)
     }
 
   /*
-   * If not found in the current connection, try all other existing
+   * If the target doesn't exist in the receiver, but still
-   * connections.
+   * persists in the cache (ie it was recently released) then
+   * we move it back from the cache to the receiver.
+   */
+  if (proxy == nil)
+    {
+      CachedLocalObject	*cached;
+
+      M_LOCK(cached_proxies_gate);
+      cached = NSMapGet (targetToCached, (void*)target);
+      if (cached != nil)
+	{
+	  proxy = [cached obj];
+	  /*
+	   * Found in cache ... add to this connection as the object
+	   * is no longer in use by any connection.
+	   */
+	  ASSIGN(((ProxyStruct*)proxy)->_connection, self);
+	  [self addLocalObject: proxy];
+	  NSMapRemove(targetToCached, (void*)target);
+	  if (debug_connection > 3)
+	    NSLog(@"target (0x%x) moved from cache", target);
+	}
+      M_UNLOCK(cached_proxies_gate);
+    }
+
+  /*
+   * If not found in the current connection or the cache of local references
+   * of recently invalidated connections, try all other existing connections.
    */
   if (proxy == nil)
     {
@@ -3255,11 +3296,29 @@ static void callEncoder (DOContext *ctxt)
 	      node = GSIMapNodeForKey(c->_localTargets, (GSIMapKey)target);
 	      if (node != 0)
 		{
-		  proxy = node->value.obj;
+		  id		local;
+		  unsigned	nTarget;
+
 		  /*
-		   * Found in another connection ... add to this one.
+		   * We found the local object in use in another connection
+		   * so we create a new reference to the same object and
+		   * add it to our connection, adjusting the target of the
+		   * new reference to be the value we need.
+		   *
+		   * We don't want to just share the NSDistantObject with
+		   * the other connection, since we might want to keep
+		   * track of information on a per-connection basis in
+		   * order to handle connection shutdown cleanly.
 		   */
-		  [self addLocalObject: proxy];
+		  proxy = node->value.obj;
+		  local = RETAIN(((ProxyStruct*)proxy)->_object);
+		  proxy = [NSDistantObject proxyWithLocal: local
+					       connection: self];
+		  nTarget = ((ProxyStruct*)proxy)->_handle;
+		  GSIMapRemoveKey(_localTargets, (GSIMapKey)nTarget);
+		  ((ProxyStruct*)proxy)->_handle = target;
+		  GSIMapAddPair(_localTargets, (GSIMapKey)target,
+		    (GSIMapVal)proxy);
 		}
 	      M_UNLOCK(c->_proxiesGate);
 	    }
@@ -3268,33 +3327,6 @@ static void callEncoder (DOContext *ctxt)
       M_UNLOCK(connection_table_gate);
     }
 
-  if (proxy == nil)
-    {
-      CachedLocalObject	*cached;
-
-      /*
-       * If the target doesn't exist for any connection, but still
-       * persists in the cache (ie it was recently released) then
-       * we move it back from the cache to the connection so we can
-       * retain it on this connection.
-       */
-      M_LOCK(cached_proxies_gate);
-      cached = NSMapGet (targetToCached, (void*)target);
-      if (cached != nil)
-	{
-	  proxy = [cached obj];
-	  /*
-	   * Found in cache ... add to this connection.
-	   */
-	  ASSIGN(((ProxyStruct*)proxy)->_connection, self);
-	  [self addLocalObject: proxy];
-	  NSMapRemove(targetToCached, (void*)target);
-	  if (debug_connection > 3)
-	    NSLog(@"target (0x%x) moved from cache", target);
-	}
-      M_UNLOCK(cached_proxies_gate);
-    }
-
   M_UNLOCK(_proxiesGate);
 
   if (proxy == nil)
@@ -3305,39 +3337,69 @@ static void callEncoder (DOContext *ctxt)
   return proxy;
 }
 
-- (void) retainTarget: (unsigned)target
+- (void) vendLocal: (NSDistantObject*)aProxy
 {
-  NS_DURING
+  M_LOCK(_proxiesGate);
+  ((ProxyStruct*)aProxy)->_counter++;
+  M_UNLOCK(_proxiesGate);
+}
+
+- (void) aquireProxyForTarget: (unsigned)target
+{
+  NSDistantObject	*found;
+  GSIMapNode		node;
+
+  /* Don't assert (_isValid); */
+  M_LOCK(_proxiesGate);
+  node = GSIMapNodeForKey(_remoteProxies, (GSIMapKey)target);
+  if (node == 0)
     {
-      /*
+      found = nil;
-       * Tell the remote app that it must retain the local object
+    }
-       * for the target on this connection.
+  else
-       */
+    {
-      if (_receivePort && _isValid)
+      found = node->value.obj;
+    }
+  M_UNLOCK(_proxiesGate);
+  if (found == nil)
+    {
+      NS_DURING
 	{
-	  NSPortCoder	*op;
+	  /*
-	  id	ip;
+	   * Tell the remote app that it must retain the local object
-	  id	result;
+	   * for the target on this connection.
-	  int	seq_num;
+	   */
+	  if (_receivePort && _isValid)
+	    {
+	      NSPortCoder	*op;
+	      id	ip;
+	      id	result;
+	      int	seq_num;
 
-	  op = [self _makeOutRmc: 0 generate: &seq_num reply: YES];
+	      op = [self _makeOutRmc: 0 generate: &seq_num reply: YES];
-	  [op encodeValueOfObjCType: @encode(typeof(target)) at: &target];
+	      [op encodeValueOfObjCType: @encode(typeof(target)) at: &target];
-	  [self _sendOutRmc: op type: PROXY_RETAIN];
+	      [self _sendOutRmc: op type: PROXY_RETAIN];
 
-	  ip = [self _getReplyRmc: seq_num];
+	      ip = [self _getReplyRmc: seq_num];
-	  [ip decodeValueOfObjCType: @encode(id) at: &result];
+	      [ip decodeValueOfObjCType: @encode(id) at: &result];
-	  [self _doneInRmc: ip];
+	      [self _doneInRmc: ip];
-	  if (result != nil)
+	      if (result != nil)
-	    NSLog(@"failed to retain target - %@", result);
+		NSLog(@"failed to retain target - %@", result);
-	  else if (debug_connection > 3)
+	      else if (debug_connection > 3)
-	    NSLog(@"sending retain for target - %u", target);
+		NSLog(@"sending retain for target - %u", target);
+	    }
 	}
+      NS_HANDLER
+	{
+	  NSLog(@"failed to retain target - %@", localException);
+	}
+      NS_ENDHANDLER
     }
-  NS_HANDLER
+}
-    {
+
-      NSLog(@"failed to retain target - %@", localException);
+- (id) retain
-    }
+{
-  NS_ENDHANDLER
+  return [super retain];
 }
 
 - (void) removeProxy: (NSDistantObject*)aProxy
@@ -3346,31 +3408,60 @@ static void callEncoder (DOContext *ctxt)
   if (_isValid == YES)
     {
       unsigned		target;
+      unsigned		count = 1;
       GSIMapNode	node;
 
       target = ((ProxyStruct*)aProxy)->_handle;
       node = GSIMapNodeForKey(_remoteProxies, (GSIMapKey)target);
-      if (node != 0)
+
-	{
-	  GSIMapRemoveKey(_remoteProxies, (GSIMapKey)target);
-	}
       /*
-       * Tell the remote application that we have removed our proxy and
+       * Only remove if the proxy for the target is the same as the
-       * it can release it's local object.
+       * supplied argument.
        */
-      [self _release_targets: &target count: 1];
+      if (node != 0 && node->value.obj == aProxy)
+	{
+	  count = ((ProxyStruct*)aProxy)->_counter;
+	  GSIMapRemoveKey(_remoteProxies, (GSIMapKey)target);
+	  /*
+	   * Tell the remote application that we have removed our proxy and
+	   * it can release it's local object.
+	   */
+	  [self _release_target: target count: count];
+	}
     }
   M_UNLOCK(_proxiesGate);
 }
 
-- (NSDistantObject*) proxyForTarget: (unsigned)target
+
+/**
+ * Private method used only when a remote process/thread has sent us a
+ * target which we are decoding into a proxy in this process/thread.
+ * <p>The argument aProxy may be nil, in which case an existing proxy
+ * matching aTarget is retrieved retained, and returned (this is done
+ * when a proxy target is sent to us by a remote process).
+ * </p>
+ * <p>If aProxy is not nil, but a proxy with the same target already
+ * exists, then aProxy is released and the existing proxy is returned
+ * as in the case where aProxy was nil.
+ * </p>
+ * <p>If aProxy is not nil and there was no prior proxy with the same
+ * target, aProxy is added to the receiver and returned.
+ * </p>
+ */
+- (NSDistantObject*) retainOrAddProxy: (NSDistantObject*)aProxy
+			    forTarget: (unsigned)aTarget
 {
   NSDistantObject	*p;
   GSIMapNode		node;
 
   /* Don't assert (_isValid); */
+  NSParameterAssert(aTarget > 0);
+  NSParameterAssert(aProxy==nil || aProxy->isa == distantObjectClass);
+  NSParameterAssert(aProxy==nil || [aProxy connectionForProxy] == self);
+  NSParameterAssert(aProxy==nil || aTarget == ((ProxyStruct*)aProxy)->_handle);
+
   M_LOCK(_proxiesGate);
-  node = GSIMapNodeForKey(_remoteProxies, (GSIMapKey)target);
+  node = GSIMapNodeForKey(_remoteProxies, (GSIMapKey)aTarget);
   if (node == 0)
     {
       p = nil;
@@ -3378,52 +3469,28 @@ static void callEncoder (DOContext *ctxt)
   else
     {
       p = node->value.obj;
+      RETAIN(p);
+      DESTROY(aProxy);
+    }
+  if (p == nil && aProxy != nil)
+    {
+      p = aProxy;
+      GSIMapAddPair(_remoteProxies, (GSIMapKey)aTarget, (GSIMapVal)p);
+    }
+  /*
+   * Whether this is a new proxy or an existing proxy, this method is
+   * only called for an object being vended by a remote process/thread.
+   * We therefore need to increment the count of the number of times
+   * the proxy has been vended.
+   */
+  if (p != nil)
+    {
+      ((ProxyStruct*)p)->_counter++;
     }
   M_UNLOCK(_proxiesGate);
   return p;
 }
 
-- (void) addProxy: (NSDistantObject*)aProxy
-{
-  unsigned	target;
-  GSIMapNode	node;
-
-  M_LOCK(_proxiesGate);
-  NSParameterAssert(_isValid);
-  NSParameterAssert(aProxy->isa == distantObjectClass);
-  NSParameterAssert([aProxy connectionForProxy] == self);
-  target = ((ProxyStruct*)aProxy)->_handle;
-  node = GSIMapNodeForKey(_remoteProxies, (GSIMapKey)target);
-  if (node != 0)
-    {
-      M_UNLOCK(_proxiesGate);
-      [NSException raise: NSGenericException
-		  format: @"Trying to add the same proxy twice"];
-    }
-  GSIMapAddPair(_remoteProxies, (GSIMapKey)target, (GSIMapVal)aProxy);
-  M_UNLOCK(_proxiesGate);
-}
-
-- (id) includesProxyForTarget: (unsigned)target
-{
-  NSDistantObject	*ret;
-  GSIMapNode		node;
-
-  /* Don't assert (_isValid); */
-  M_LOCK(_proxiesGate);
-  node = GSIMapNodeForKey(_remoteProxies, (GSIMapKey)target);
-  if (node == 0)
-    {
-      ret = nil;
-    }
-  else
-    {
-      ret = node->value.obj;
-    }
-  M_UNLOCK(_proxiesGate);
-  return ret;
-}
-
 - (id) includesLocalObject: (id)anObj
 {
   NSDistantObject	*ret;

Source/NSDistantObject.m

@@ -55,10 +55,13 @@ typedef struct {
 } NSDO;
 
 @interface NSConnection (DistantObjectHacks)
-- (BOOL) includesProxyForTarget: (unsigned)target;
+- (void) aquireProxyForTarget: (unsigned)target;
-- (void) addLocalObject: (id)obj;
+- (NSDistantObject*) retainOrAddLocal: (NSDistantObject*)aProxy
-- (void) addProxy: (id)obj;
+			    forObject: (id)anObject;
+- (NSDistantObject*) retainOrAddProxy: (NSDistantObject*)aProxy
+			    forTarget: (unsigned)aTarget;
 - (void) removeProxy: (id)obj;
+- (void) vendLocal: (NSDistantObject*)aProxy;
 @end
 
 /* This is the proxy tag; it indicates where the local object is,
@@ -171,7 +174,7 @@ enum
 		NSLog(@"Local object is 0x%x (0x%x)\n",
 		  (gsaddr)o, (gsaddr)o ? ((NSDO*)o)->_object : 0);
 	      }
-	    return o ? RETAIN(((NSDO*)o)->_object) : nil;
+	    return RETAIN(((NSDO*)o)->_object);
 	  }
 
       case PROXY_LOCAL_FOR_SENDER:
@@ -187,8 +190,9 @@ enum
 	if (debug_proxy)
 	  NSLog(@"Receiving a proxy, was local 0x%x connection 0x%x\n",
 		  target, (gsaddr)decoder_connection);
-	return [self initWithTarget: target
+	o = [self initWithTarget: target
-			 connection: decoder_connection];
+		      connection: decoder_connection];
+	return o;
 
       case PROXY_REMOTE_FOR_BOTH:
         /*
@@ -260,12 +264,11 @@ enum
 	    NSInternalInconsistencyException);
 
 	  /*
-	   *	If we don't already have a proxy for the object on the
+	   * We may not already have a proxy for the object on the
-	   *	remote system, we must tell the other end to retain its
+	   * remote system, we must tell the connection to make sure
-	   *	local object for our use.
+	   * the other end knows we are creating one.
 	   */
-	  if ([proxy_connection includesProxyForTarget: target] == NO)
+	  [proxy_connection aquireProxyForTarget: target];
-	    [proxy_connection retainTarget: target];
 
 	  /*
 	   *	Finally - we get a proxy via a direct connection to the
@@ -274,8 +277,9 @@ enum
 	   *	and will therefore go away when the current autorelease
 	   *	pool is destroyed.
 	   */
-	  return [self initWithTarget: target
+	  o = [self initWithTarget: target
-			   connection: proxy_connection];
+			connection: proxy_connection];
+	  return o;
         }
 
     default:
@@ -297,14 +301,14 @@ enum
    *	If there already is a local proxy for this target/connection
    *	combination, don't create a new one, just return the old one.
    */
-  if ((proxy = [aConnection localForObject: anObject]))
+  proxy = [aConnection retainOrAddLocal: nil forObject: anObject];
+  if (proxy == nil)
     {
-      return RETAIN(proxy);
+      proxy = (NSDistantObject*)NSAllocateObject(distantObjectClass,
-    }
-
-  proxy = (NSDistantObject*)NSAllocateObject(distantObjectClass,
 	0, NSDefaultMallocZone());
-  return [proxy initWithLocal: anObject connection: aConnection];
+      proxy = [proxy initWithLocal: anObject connection: aConnection];
+    }
+  return proxy;
 }
 
 + (id) initWithTarget: (unsigned)target connection: (NSConnection*)aConnection
@@ -314,17 +318,17 @@ enum
   NSAssert([aConnection isValid], NSInternalInconsistencyException);
 
   /*
-   *	If there already is a local proxy for this target/connection
+   * If there already is a local proxy for this target/connection
-   *	combination, don't create a new one, just return the old one.
+   * combination, don't create a new one, just return the old one.
    */
-  if ((proxy = [aConnection proxyForTarget: target]))
+  proxy = [aConnection retainOrAddProxy: nil forTarget: target];
+  if (proxy == nil)
     {
-      return RETAIN(proxy);
+      proxy = (NSDistantObject*)NSAllocateObject(distantObjectClass,
-    }
-
-  proxy = (NSDistantObject*)NSAllocateObject(distantObjectClass,
 	0, NSDefaultMallocZone());
-  return [proxy initWithTarget: target connection: aConnection];
+      proxy = [proxy initWithTarget: target connection: aConnection];
+    }
+  return proxy;
 }
 @end
 
@@ -441,6 +445,10 @@ enum
 
 	  [aRmc encodeValueOfObjCType: @encode(typeof(proxy_target))
 				   at: &proxy_target];
+	  /*
+	   * Tell connection this object is being vended.
+	   */
+	  [_connection vendLocal: self];
 	}
       else
 	{
@@ -478,10 +486,10 @@ enum
       proxy_tag = PROXY_REMOTE_FOR_BOTH;
 
       /*
-       *	Get a proxy to refer to self - we send this to the other
+       * Get a proxy to refer to self - we send this to the other
-       *	side so we will be retained until the other side has
+       * side so we will be retained until the other side has
-       *	obtained a proxy to the original object via a connection
+       * obtained a proxy to the original object via a connection
-       *	to the original vendor.
+       * to the original vendor.
        */
       localProxy = [NSDistantObject proxyWithLocal: self
 					connection: encoder_connection];
@@ -493,8 +501,8 @@ enum
 		proxy_target, (gsaddr)_connection);
 
       /*
-       *	It's remote here, so we need to tell other side where to form
+       * It's remote here, so we need to tell other side where to form
-       *	triangle connection to
+       * triangle connection to
        */
       [aRmc encodeValueOfObjCType: @encode(typeof(proxy_tag))
 			       at: &proxy_tag];
@@ -506,6 +514,11 @@ enum
 			       at: &proxy_target];
 
       [aRmc encodeBycopyObject: proxy_connection_out_port];
+
+      /*
+       * Tell connection that localProxy is being vended.
+       */
+      [encoder_connection vendLocal: localProxy];
     }
 }
 
@@ -529,179 +542,9 @@ enum
 
 - (id) initWithCoder: (NSCoder*)aCoder
 {
-  gsu8			proxy_tag;
+  DESTROY(self);
-  unsigned		target;
+  [NSException raise: NSGenericException
-  id			decoder_connection;
+	      format: @"NSDistantObject decodes from placeholder"];
-  NSDistantObject	*o;
-
-/*
-  if ([aCoder isKindOfClass: [NSPortCoder class]] == NO)
-    {
-      RELEASE(self);
-      [NSException raise: NSGenericException
-		  format: @"NSDistantObject objects only decode with "
-			  @"NSPortCoder class"];
-    }
-*/
-
-  decoder_connection = [(NSPortCoder*)aCoder connection];
-  NSAssert(decoder_connection, NSInternalInconsistencyException);
-
-  /* First get the tag, so we know what values need to be decoded. */
-  [aCoder decodeValueOfObjCType: @encode(typeof(proxy_tag))
-			     at: &proxy_tag];
-
-  switch (proxy_tag)
-    {
-      case PROXY_LOCAL_FOR_RECEIVER:
-	/*
-	 *	This was a proxy on the other side of the connection, but
-	 *	here it's local.
-	 *	Lookup the target handle to ensure that it exists here.
-	 *	Return a retained copy of the local target object.
-	 */
-	[aCoder decodeValueOfObjCType: @encode(typeof(target))
-				   at: &target];
-
-        if (debug_proxy)
-	  NSLog(@"Receiving a proxy for local object 0x%x "
-		@"connection 0x%x\n", target, (gsaddr)decoder_connection);
-
-	o = [decoder_connection locateLocalTarget: target];
-        if (o == nil)
-	  {
-	    RELEASE(self);
-	    [NSException raise: @"ProxyDecodedBadTarget"
-			format: @"No local object with given target (0x%x)",
-				target];
-	  }
-	else
-	  {
-	    if (debug_proxy)
-	      {
-		NSLog(@"Local object is 0x%x (0x%x)\n",
-		  (gsaddr)o, (gsaddr)o ? o->_object : 0);
-	      }
-	    RELEASE(self);
-	    return o ? RETAIN(o->_object) : nil;
-	  }
-
-      case PROXY_LOCAL_FOR_SENDER:
-        /*
-	 *	This was a local object on the other side of the connection,
-	 *	but here it's a proxy object.  Get the target address, and
-	 *	send [NSDistantObject +proxyWithTarget:connection:]; this will
-	 *	return the proxy object we already created for this target, or
-	 *	create a new proxy object if necessary.
-	 */
-	[aCoder decodeValueOfObjCType: @encode(typeof(target))
-				   at: &target];
-	if (debug_proxy)
-	  NSLog(@"Receiving a proxy, was local 0x%x connection 0x%x\n",
-		  target, (gsaddr)decoder_connection);
-        RELEASE(self);
-	return RETAIN([NSDistantObject proxyWithTarget: target
-					    connection: decoder_connection]);
-
-      case PROXY_REMOTE_FOR_BOTH:
-        /*
-	 *	This was a proxy on the other side of the connection, and it
-	 *	will be a proxy on this side too; that is, the local version
-	 *	of this object is not on this host, not on the host the
-	 *	NSPortCoder is connected to, but on a *third* host.
-	 *	This is why I call this a "triangle connection".  In addition
-	 *	to decoding the target, we decode the OutPort object that we
-	 *	will use to talk directly to this third host.  We send
-	 *	[NSConnection +newForInPort:outPort:ancestorConnection:]; this
-	 *	will either return the connection already created for this
-	 *	inPort/outPort pair, or create a new connection if necessary.
-	 */
-	{
-	  NSDistantObject	*result;
-	  NSConnection		*proxy_connection;
-	  NSPort		*proxy_connection_out_port = nil;
-	  unsigned		intermediary;
-
-	  /*
-	   *	There is an object on the intermediary host that is keeping
-	   *	that hosts proxy for the original object retained, thus
-	   *	ensuring that the original is not released.  We create a
-	   *	proxy for that intermediate proxy.  When we release this
-	   *	proxy, the intermediary will be free to release it's proxy
-	   *	and the original can then be released.  Of course, by that
-	   *	time we will have obtained our own proxy for the original
-	   *	object ...
-	   */
-	  [aCoder decodeValueOfObjCType: @encode(typeof(intermediary))
-				     at: &intermediary];
-	  [NSDistantObject proxyWithTarget: intermediary
-				connection: decoder_connection];
-
-	  /*
-	   *	Now we get the target number and port for the orignal object
-	   *	and (if necessary) get the originating process to retain the
-	   *	object for us.
-	   */
-	  [aCoder decodeValueOfObjCType: @encode(typeof(target))
-				     at: &target];
-
-	  [aCoder decodeValueOfObjCType: @encode(id)
-				     at: &proxy_connection_out_port];
-
-	  NSAssert(proxy_connection_out_port, NSInternalInconsistencyException);
-	  /*
-	   #	If there already exists a connection for talking to the
-	   *	out port, we use that one rather than creating a new one from
-	   *	our listening port. 
-	   *
-	   *	First we try for a connection from our receive port,
-	   *	Then we try any connection to the send port
-	   *	Finally we resort to creating a new connection - we don't
-	   *	release the newly created connection - it will get released
-	   *	automatically when no proxies are left on it.
-	   */
-	  proxy_connection = [[decoder_connection class]
-	    connectionWithReceivePort: [decoder_connection receivePort]
-			     sendPort: proxy_connection_out_port];
-
-	  if (debug_proxy)
-	    NSLog(@"Receiving a triangle-connection proxy 0x%x "
-		  @"connection 0x%x\n", target, (gsaddr)proxy_connection);
-
-	  NSAssert(proxy_connection != decoder_connection,
-	    NSInternalInconsistencyException);
-	  NSAssert([proxy_connection isValid],
-	    NSInternalInconsistencyException);
-
-	  /*
-	   *	If we don't already have a proxy for the object on the
-	   *	remote system, we must tell the other end to retain its
-	   *	local object for our use.
-	   */
-	  if ([proxy_connection includesProxyForTarget: target] == NO)
-	    [proxy_connection retainTarget: target];
-
-	  result = RETAIN([NSDistantObject proxyWithTarget: target
-						connection: proxy_connection]);
-	  RELEASE(self);
-
-	  /*
-	   *	Finally - we have a proxy via a direct connection to the
-	   *	originating server.  We have also created a proxy to an
-	   *	intermediate object - but this proxy has not been retained
-	   *	and will therefore go away when the current autorelease
-	   *	pool is destroyed.
-	   */
-	  return result;
-        }
-
-    default:
-      /* xxx This should be something different than NSGenericException. */
-      RELEASE(self);
-      [NSException raise: NSGenericException
-		  format: @"Bad proxy tag"];
-    }
-  /* Not reached. */
   return nil;
 }
 
@@ -711,28 +554,12 @@ enum
  */
 - (id) initWithLocal: (id)anObject connection: (NSConnection*)aConnection
 {
-  NSDistantObject	*new_proxy;
-
   NSAssert([aConnection isValid], NSInternalInconsistencyException);
 
-  /*
-   *	If there already is a local proxy for this target/connection
-   *	combination, don't create a new one, just return the old one.
-   */
-  if ((new_proxy = [aConnection localForObject: anObject]))
-    {
-      RETAIN(new_proxy);
-      RELEASE(self);
-      return new_proxy;
-    }
-
   _object = RETAIN(anObject);
-
+  _handle = 0;
-  /*
-   * We register this proxy with the connection using it.
-   */
   _connection = RETAIN(aConnection);
-  [_connection addLocalObject: self];
+  self = [_connection retainOrAddLocal: self forObject: anObject];
 
   if (debug_proxy)
     NSLog(@"Created new local=0x%x object 0x%x target 0x%x connection 0x%x\n",
@@ -748,34 +575,17 @@ enum
  */
 - (id) initWithTarget: (unsigned)target connection: (NSConnection*)aConnection
 {
-  NSDistantObject	*new_proxy;
-
   NSAssert([aConnection isValid], NSInternalInconsistencyException);
 
-  /*
-   *	If there already is a proxy for this target/connection combination,
-   *	don't create a new one, just return the old one.
-   */
-  if ((new_proxy = [aConnection proxyForTarget: target]))
-    {
-      RETAIN(new_proxy);
-      RELEASE(self);
-      return new_proxy;
-    }
-
   _object = nil;
   _handle = target;
-
-  /*
-   *	We retain our connection so it can't disappear while the app
-   *	may want to use it.
-   */
   _connection = RETAIN(aConnection);
 
   /*
-   *	We register this object with the connection using it.
+   * We register this object with the connection using it.
+   * Conceivably this could result in self being changed.
    */
-  [_connection addProxy: self];
+  self = [_connection retainOrAddProxy: self forTarget: target];
 
   if (debug_proxy)
       NSLog(@"Created new proxy=0x%x target 0x%x connection 0x%x\n",

Testing/nsconnection_client.m

@@ -433,15 +433,16 @@ con_callback (id prx)
 
   localObj = [CallbackClient new];
   [prx registerClient: localObj];
-  k = 10000;
+  k = 1000;
   for (j = 0; j < k; j++)
     {
+      CREATE_AUTORELEASE_POOL(arp);
       [prx unregisterClient: localObj];
       [prx registerClient: localObj];
       [prx tryClientCallback];
       if (j < 10 || j %10 == 0)
 	printf("repeated client registration and callback %d\n", j);
-
+      RELEASE(arp);
     }
   printf("repeated client registration and callback %d\n", j);
   RELEASE(localObj);
@@ -493,7 +494,7 @@ int main (int argc, char *argv[], char **env)
     switch (c) 
       {
       case 'd':
-	debug = 1;
+	debug++;
 	break;
       case 't':
 	type_test = TYPE_TEST;
@@ -538,6 +539,13 @@ int main (int argc, char *argv[], char **env)
   else
     connect_attempts = 1;
 
+  if (debug > 0)
+    {
+      [NSConnection setDebug: debug];
+      [NSDistantObject setDebug: debug];
+      [NSObject enableDoubleReleaseCheck: YES];
+    }
+
   while (connect_attempts-- > 0)
     {
       if (optind < argc)

Testing/nsconnection_server.m

@@ -476,7 +476,7 @@ int main(int argc, char *argv[], char **env)
     switch (i) 
       {
       case 'd':
-	debug = 1;
+	debug++;
 	break;
       case 't':
 	timeout = atoi(optarg);;
@@ -497,6 +497,12 @@ int main(int argc, char *argv[], char **env)
   [NSDistantObject setProtocolForProxies:@protocol(AllProxies)];
 #endif
 
+  if (debug > 0)
+    {
+      [NSDistantObject setDebug: debug];
+      [NSConnection setDebug: debug];
+      [NSObject enableDoubleReleaseCheck: YES];
+    }
   c = [NSConnection defaultConnection];
   [c setRootObject: l];