Only register XPC interest when a delegate exists

src/darwin/Framework/CHIP/MTRDevice.mm

@@ -201,10 +201,10 @@ - (void)_addDelegate:(id<MTRDeviceDelegate>)delegate queue:(dispatch_queue_t)que
     MTR_LOG("%@ added delegate info %@", self, newDelegateInfo);
 
     // Call hook to allow subclasses to act on delegate addition.
-    [self _delegateAdded];
+    [self _delegateAdded:delegate];
 }
 
-- (void)_delegateAdded
+- (void)_delegateAdded:(id<MTRDeviceDelegate>)delegate
 {
     os_unfair_lock_assert_owner(&self->_lock);
 
@@ -233,6 +233,16 @@ - (void)removeDelegate:(id<MTRDeviceDelegate>)delegate
         [_delegates minusSet:delegatesToRemove];
         MTR_LOG("%@ removeDelegate: removed %lu", self, static_cast<unsigned long>(_delegates.count - oldDelegatesCount));
     }
+
+    // Call hook to allow subclasses to act on delegate addition.
+    [self _delegateRemoved:delegate];
+}
+
+- (void)_delegateRemoved:(id<MTRDeviceDelegate>)delegate
+{
+    os_unfair_lock_assert_owner(&self->_lock);
+
+    // Nothing to do for now. At the moment this is a hook for subclasses.
 }
 
 - (void)invalidate

src/darwin/Framework/CHIP/MTRDeviceController_XPC.mm

@@ -18,6 +18,7 @@
 
 #import "MTRDefines_Internal.h"
 #import "MTRDeviceController_Internal.h"
+#import "MTRDevice_Internal.h"
 #import "MTRDevice_XPC.h"
 #import "MTRDevice_XPC_Internal.h"
 #import "MTRError_Internal.h"
@@ -77,10 +78,13 @@ - (void)_updateRegistrationInfo
     NSMutableArray * nodeIDs = [NSMutableArray array];
 
     for (NSNumber * nodeID in [self.nodeIDToDeviceMap keyEnumerator]) {
-        NSMutableDictionary * nodeDictionary = [NSMutableDictionary dictionary];
-        MTR_REQUIRED_ATTRIBUTE(MTRDeviceControllerRegistrationNodeIDKey, nodeID, nodeDictionary)
+        MTRDevice * device = [self _deviceForNodeID:nodeID createIfNeeded:NO];
+        if ([device _delegateExists]) {
+            NSMutableDictionary * nodeDictionary = [NSMutableDictionary dictionary];
+            MTR_REQUIRED_ATTRIBUTE(MTRDeviceControllerRegistrationNodeIDKey, nodeID, nodeDictionary)
 
-        [nodeIDs addObject:nodeDictionary];
+            [nodeIDs addObject:nodeDictionary];
+        }
     }
     MTR_REQUIRED_ATTRIBUTE(MTRDeviceControllerRegistrationNodeIDsKey, nodeIDs, registrationInfo)
     MTR_REQUIRED_ATTRIBUTE(MTRDeviceControllerRegistrationControllerContextKey, controllerContext, registrationInfo)
@@ -386,8 +390,6 @@ - (MTRDevice *)_setupDeviceForNodeID:(NSNumber *)nodeID prefetchedClusterData:(N
     [self.nodeIDToDeviceMap setObject:deviceToReturn forKey:nodeID];
     MTR_LOG("%s: returning XPC device for node id %@", __PRETTY_FUNCTION__, nodeID);
 
-    [self _updateRegistrationInfo];
-
     return deviceToReturn;
 }
 

src/darwin/Framework/CHIP/MTRDeviceController_XPC_Internal.h

@@ -19,5 +19,6 @@
 @interface MTRDeviceController_XPC (Internal)
 
 - (id)initWithMachServiceName:(NSString *)machServiceName options:(NSXPCConnectionOptions)options;
+- (void)_updateRegistrationInfo;
 
 @end

src/darwin/Framework/CHIP/MTRDevice_Concrete.mm

@@ -884,11 +884,11 @@ - (BOOL)_subscriptionsAllowed
     return self.suspended == NO && ![_deviceController isKindOfClass:MTRDeviceControllerOverXPC.class];
 }
 
-- (void)_delegateAdded
+- (void)_delegateAdded:(id<MTRDeviceDelegate>)delegate
 {
     os_unfair_lock_assert_owner(&self->_lock);
 
-    [super _delegateAdded];
+    [super _delegateAdded:delegate];
 
     [self _ensureSubscriptionForExistingDelegates:@"delegate is set"];
 }

src/darwin/Framework/CHIP/MTRDevice_Internal.h

@@ -149,7 +149,8 @@ MTR_DIRECT_MEMBERS
 - (BOOL)_delegateExists;
 
 // Must be called by subclasses or MTRDevice implementation only.
-- (void)_delegateAdded;
+- (void)_delegateAdded:(id<MTRDeviceDelegate>)delegate;
+- (void)_delegateRemoved:(id<MTRDeviceDelegate>)delegate;
 
 #ifdef DEBUG
 // Only used for unit test purposes - normal delegate should not expect or handle being called back synchronously

src/darwin/Framework/CHIP/MTRDevice_XPC.mm

@@ -22,6 +22,7 @@
 #import <Matter/MTRDeviceControllerParameters.h>
 
 #import "MTRDeviceController_Internal.h"
+#import "MTRDeviceController_XPC_Internal.h"
 
 #import "MTRAsyncWorkQueue.h"
 #import "MTRAttestationTrustStoreBridge.h"
@@ -146,6 +147,22 @@ - (MTRNetworkCommissioningFeature)networkCommissioningFeatures
     return [[self._internalState objectForKey:kMTRDeviceInternalPropertyNetworkFeatures] unsignedIntValue];
 }
 
+#pragma mark - Delegate added/removed callbacks
+
+- (void)_delegateAdded:(id<MTRDeviceDelegate>)delegate
+{
+    [super _delegateAdded:delegate];
+    MTR_LOG("%@ delegate added: %@", self, delegate);
+    [(MTRDeviceController_XPC *) [self deviceController] _updateRegistrationInfo];
+}
+
+- (void)_delegateRemoved:(id<MTRDeviceDelegate>)delegate
+{
+    [super _delegateRemoved:delegate];
+    MTR_LOG("%@ delegate removed: %@", self, delegate);
+    [(MTRDeviceController_XPC *) [self deviceController] _updateRegistrationInfo];
+}
+
 #pragma mark - Client Callbacks (MTRDeviceDelegate)
 
 // required methods for MTRDeviceDelegates