Coalesce operational instance adds in MTROperationalBrowser. (#37906)

This way we will only notify once if we get Add notifications all together
on multiple interfaces.

Author: bzbarsky-apple

src/darwin/Framework/CHIP/MTROperationalBrowser.h

@@ -20,8 +20,7 @@
 #import <Matter/MTRDeviceControllerFactory.h>
 #import <dns_sd.h>
 
-class MTROperationalBrowser
-{
+class MTROperationalBrowser {
 public:
     // Should be created at a point when the dispatch queue is available.
     MTROperationalBrowser(MTRDeviceControllerFactory * aFactory, dispatch_queue_t aQueue);
@@ -40,7 +39,7 @@ class MTROperationalBrowser
 
 private:
     static void OnBrowse(DNSServiceRef aServiceRef, DNSServiceFlags aFlags, uint32_t aInterfaceId, DNSServiceErrorType aError,
-                         const char * aName, const char * aType, const char * aDomain, void * aContext);
+        const char * aName, const char * aType, const char * aDomain, void * aContext);
 
     void EnsureBrowse();
     void StopBrowse();
@@ -58,4 +57,7 @@ class MTROperationalBrowser
     // Count of controllers that are currently active; we aim to have a browse
     // going while this is nonzero;
     size_t mActiveControllerCount = 0;
+
+    // Queued-up instance names to notify about.
+    NSMutableSet<NSString *> * mAddedInstanceNames = nil;
 };

src/darwin/Framework/CHIP/MTROperationalBrowser.mm

@@ -85,6 +85,8 @@
         return;
     }
 
+    mAddedInstanceNames = [[NSMutableSet alloc] init];
+
     mInitialized = true;
 
     for (auto domain : kBrowseDomains) {
@@ -100,6 +102,7 @@
 {
     ChipLogProgress(Controller, "%p stopping persistent operational browse", this);
     if (mInitialized) {
+        mAddedInstanceNames = nil;
         DNSServiceRefDeallocate(mBrowseRef);
         mInitialized = false;
     }
@@ -126,22 +129,33 @@
         return;
     }
 
-    chip::PeerId peerId;
-    CHIP_ERROR err = chip::Dnssd::ExtractIdFromInstanceName(aName, &peerId);
-    if (err != CHIP_NO_ERROR) {
-        ChipLogError(Controller, "Invalid instance name: '%s'\n", aName);
+    auto * newInstanceName = [NSString stringWithUTF8String:aName];
+    if (!(aFlags & kDNSServiceFlagsAdd)) {
+        MTR_LOG("Matter operational instance advertisement removed: '%@'\n", newInstanceName);
+        // Make sure that we don't notify about things that appear and then disappear.
+        [self->mAddedInstanceNames removeObject:newInstanceName];
         return;
     }
 
-    if (!(aFlags & kDNSServiceFlagsAdd)) {
-        // We mostly only care about new things appearing, but log it when things
-        // disappear.
-        MTR_LOG("Matter operational instance advertisement removed: '%s'\n", aName);
+    [self->mAddedInstanceNames addObject:newInstanceName];
+
+    if (aFlags & kDNSServiceFlagsMoreComing) {
+        // Just wait for those other notifications, so we coalesce everything.
         return;
     }
 
-    ChipLogProgress(Controller, "Notifying controller factory about new operational instance: '%s'", aName);
-    [self->mDeviceControllerFactory operationalInstanceAdded:peerId];
+    for (NSString * instanceName in self->mAddedInstanceNames) {
+        chip::PeerId peerId;
+        CHIP_ERROR err = chip::Dnssd::ExtractIdFromInstanceName(instanceName.UTF8String, &peerId);
+        if (err != CHIP_NO_ERROR) {
+            ChipLogError(Controller, "Invalid instance name: '%@'\n", instanceName);
+            continue;
+        }
+
+        ChipLogProgress(Controller, "Notifying controller factory about new operational instance: '%@'", instanceName);
+        [self->mDeviceControllerFactory operationalInstanceAdded:peerId];
+    }
+    [self->mAddedInstanceNames removeAllObjects];
 }
 
 MTROperationalBrowser::~MTROperationalBrowser()