Cancel avatar transfers after their last Android viewer closes

tools/chatgui-android/app/src/main/java/com/utun/chat/data/AvatarRepository.kt

@@ -45,6 +45,7 @@ class AvatarRepository(context: Context) {
     val edits: StateFlow<Map<String, AvatarEditState>> = _edits
     private val loads = mutableSetOf<String>()
     private val objectLoads = mutableMapOf<String, Deferred<Unit>>()
+    private val objectWaiters = mutableMapOf<String,Int>()
     private val memberRequests = mutableMapOf<String, Long>()
     private val editTokens = mutableMapOf<String, Long>()
     private val replications = mutableSetOf<String>()
@@ -163,7 +164,8 @@ class AvatarRepository(context: Context) {
             if (p.type in 49..50 && NativeLib.isReady()) { p.cancelled = true; NativeLib.cancelAvatar(id) }
         }
         scope.coroutineContext.cancelChildren()
-        pending.clear(); loads.clear(); objectLoads.clear(); replications.clear(); dirtyGroups.clear(); memberRequests.clear(); editTokens.clear()
+        pending.clear(); loads.clear(); objectLoads.clear(); objectWaiters.clear()
+        replications.clear(); dirtyGroups.clear(); memberRequests.clear(); editTokens.clear()
         account = 0; defaultAvatar = null; cache.evictAll()
         _members.value = emptyMap(); _groups.value = emptyMap(); _edits.value = emptyMap(); changed()
     }
@@ -325,8 +327,18 @@ class AvatarRepository(context: Context) {
                 alive(epoch); log("DEBUG", "Object ready file=$file cache=$hit group=$group")
             }
         }.also { objectLoads[file]=it }
+        objectWaiters[file]=(objectWaiters[file] ?: 0)+1
         try { operation.await(); alive(epoch) }
-        finally { if (generation==epoch && operation.isCompleted && objectLoads[file]===operation) objectLoads.remove(file) }
+        finally {
+            if (generation==epoch) {
+                val remaining=(objectWaiters[file] ?: 1)-1
+                if (remaining==0) {
+                    objectWaiters.remove(file)
+                    if (objectLoads[file]===operation) objectLoads.remove(file)
+                    if (!operation.isCompleted) { log("DEBUG", "Cancel unused object=$file"); operation.cancel() }
+                } else objectWaiters[file]=remaining
+            }
+        }
     }
 
     suspend fun loadAvatar(group: String, m: ChatMember, original: Boolean): Bitmap {