Fix some cluster sync state issues

Namely, the sync threads weren't always reporting that they were done,
so the master node would just wait on them forever instead of moving on.

src/utils/protocol/server.c

@@ -281,27 +281,29 @@ struct syncThreadParams {
 	bool done;
 };
 
-//TODO: Rename to clientSyncThread
-static void *handleClientSync(void *arg) {
+static void *client_sync_thread(void *arg) {
 	block_signals();
 	struct syncThreadParams *params = (struct syncThreadParams *)thread_user_data(arg);
 	struct renderClient *client = params->client;
 	if (client->status != Connected) {
 		logr(warning, "Won't sync with client %i, no connection.\n", client->id);
+		params->done = true;
 		return NULL;
 	}
 	client->status = Syncing;
 
 	// Handshake with the client
 	if (!sendJSON(client->socket, makeHandshake(), NULL)) {
 		client->status = SyncFailed;
+		params->done = true;
 		return NULL;
 	}
 	cJSON *response = readJSON(client->socket);
 	if (cJSON_HasObjectItem(response, "error")) {
 		cJSON *error = cJSON_GetObjectItem(response, "error");
 		logr(warning, "Client handshake error: %s\n", error->valuestring);
 		client->status = SyncFailed;
+		params->done = true;
 		cJSON_Delete(response);
 		return NULL;
 	}
@@ -321,12 +323,14 @@ static void *handleClientSync(void *arg) {
 	if (!response) {
 		logr(debug, "no response\n");
 		client->status = SyncFailed;
+		params->done = true;
 		return NULL;
 	}
 	if (cJSON_HasObjectItem(response, "error")) {
 		cJSON *error = cJSON_GetObjectItem(response, "error");
 		logr(warning, "Client scene sync error: %s\n", error->valuestring);
 		client->status = SyncFailed;
+		params->done = true;
 		cJSON_Delete(error);
 		cJSON_Delete(response);
 		disconnectFromClient(client);
@@ -418,7 +422,7 @@ struct renderClient *syncWithClients(const struct renderer *r, size_t *count) {
 	struct cr_thread *sync_threads = calloc(clientCount, sizeof(*sync_threads));
 	for (size_t i = 0; i < clientCount; ++i) {
 		sync_threads[i] = (struct cr_thread){
-			.thread_fn = handleClientSync,
+			.thread_fn = client_sync_thread,
 			.user_data = &params[i]
 		};
 	}
@@ -452,8 +456,26 @@ struct renderClient *syncWithClients(const struct renderer *r, size_t *count) {
 	free(assetCache);
 	for (size_t i = 0; i < clientCount; ++i) printf("\n");
 	logr(info, "Client sync finished.\n");
-	//FIXME: We should prune clients that dropped out during sync here
-	if (count) *count = clientCount;
+
+	size_t validClients = 0;
+	for (size_t i = 0; i < clientCount; ++i) {
+		validClients += clients[i].status == ConnectionFailed ? 0 : 1;
+	}
+	if (validClients < clientCount) {
+		// Prune unavailable clients
+		struct renderClient *confirmedClients = calloc(validClients, sizeof(*confirmedClients));
+		size_t j = 0;
+		for (size_t i = 0; i < clientCount; ++i) {
+			if (clients[i].status == Synced) {
+				confirmedClients[j++] = clients[i];
+			}
+		}
+		free(clients);
+		clients = confirmedClients;
+		logr(debug, "Pruned %zu clients that failed to sync\n", clientCount - validClients);
+	}
+
+	if (count) *count = validClients;
 	free(sync_threads);
 	return clients;
 }