Multithreaded. Is this gonna help?

Only tested with single-thread mode still on so far.

extension/background.js

@@ -160,6 +160,7 @@ ws.onmessage = async function(event) {
   const req = JSON.parse(event.data);
 
   let response = { op: req.op, error: unix.EIO };
+  console.time(req.op + ':' + req.path);
   try {
     if (req.op === 'getattr') {
       response = {
@@ -195,13 +196,14 @@ ws.onmessage = async function(event) {
         op: 'release'
       };
     }
-
   } catch (e) {
     response = {
       op: req.op,
       error: e instanceof UnixError ? e.error : unix.EIO
     }
   }
+  console.timeEnd(req.op + ':' + req.path);
 
+  response.id = req.id;
   ws.send(JSON.stringify(response));
 };

fs/hello.c

@@ -17,52 +17,86 @@
 struct wby_server server;
 struct wby_con *con = NULL;
 
-pthread_mutex_t request_data_mutex = PTHREAD_MUTEX_INITIALIZER;
-char *request_data = NULL;
+pthread_cond_t queue_cv = PTHREAD_COND_INITIALIZER;
+pthread_mutex_t queue_mutex = PTHREAD_MUTEX_INITIALIZER;
 
-pthread_cond_t response_cv = PTHREAD_COND_INITIALIZER;
-pthread_mutex_t response_mutex = PTHREAD_MUTEX_INITIALIZER;
-cJSON *response = NULL;
+enum request_response_state {
+  EMPTY = 0,
+  SEND_REQUEST,
+  RECEIVE_RESPONSE,
+  HANDLE_RESPONSE
+};
 
-static const char  *file_path      = "/hello.txt";
-static const char   file_content[] = "Hello World!\n";
-static const size_t file_size      = sizeof(file_content)/sizeof(char) - 1;
+struct request_response {
+  enum request_response_state state;
+  char *request;
+  cJSON *response;
+};
 
-static void dispatch_send_req(cJSON *req) {
-  pthread_mutex_lock(&request_data_mutex);
+#define REQUEST_RESPONSE_QUEUE_SIZE 128
+typedef int request_id;
+struct request_response queue[REQUEST_RESPONSE_QUEUE_SIZE];
 
-  request_data = cJSON_Print(req);
-  printf("%s\n", request_data);
+static request_id enqueue_request(cJSON *req) {
+  pthread_mutex_lock(&queue_mutex);
 
-  pthread_mutex_unlock(&request_data_mutex);
+  // Look for the first free slot.
+  request_id id;
+  for (id = 0; id < REQUEST_RESPONSE_QUEUE_SIZE; id++) {
+    if (queue[id].state == EMPTY) break;
+  }
+  if (id >= REQUEST_RESPONSE_QUEUE_SIZE) {
+    printf("Request-response queue is full!\n");
+    exit(1);
+  }
+  cJSON_AddNumberToObject(req, "id", id);
+
+  queue[id].state = SEND_REQUEST;
+  queue[id].request = cJSON_Print(req);
+  queue[id].response = NULL;
+
+  printf("%s\n", queue[id].request);
+
+  pthread_mutex_unlock(&queue_mutex);
+
+  return id;
 }
 
-void send_req_if_any() {
-  pthread_mutex_lock(&request_data_mutex);
+void send_any_enqueued_requests() {
+  pthread_mutex_lock(&queue_mutex);
 
-  if (con == NULL || request_data == NULL) goto done;
+  if (con == NULL) goto done;
 
-  wby_frame_begin(con, WBY_WSOP_TEXT_FRAME);
-  wby_write(con, request_data, strlen(request_data));
-  wby_frame_end(con);
+  for (request_id id = 0; id < REQUEST_RESPONSE_QUEUE_SIZE; id++) {
+    if (queue[id].state == SEND_REQUEST) {
+      char *request = queue[id].request;
 
-  free(request_data);
-  request_data = NULL;
+      wby_frame_begin(con, WBY_WSOP_TEXT_FRAME);
+      wby_write(con, request, strlen(request));
+      wby_frame_end(con);
 
- done:
-  pthread_mutex_unlock(&request_data_mutex);
-}
-
-static cJSON *await_response() {
-  pthread_mutex_lock(&response_mutex);
-
-  response = NULL;
-  while (response == NULL) {
-    pthread_cond_wait(&response_cv, &response_mutex);
+      queue[id].state = RECEIVE_RESPONSE;
+      free(request);
+      queue[id].request = NULL;
+    }
   }
 
-  cJSON *resp = response;
-  pthread_mutex_unlock(&response_mutex);
+ done:
+  pthread_mutex_unlock(&queue_mutex);
+}
+
+static cJSON *await_response(request_id id) {
+  pthread_mutex_lock(&queue_mutex);
+
+  while (queue[id].state != HANDLE_RESPONSE) {
+    pthread_cond_wait(&queue_cv, &queue_mutex);
+  }
+
+  cJSON *resp = queue[id].response;
+  queue[id].state = EMPTY;
+  queue[id].response = NULL;
+
+  pthread_mutex_unlock(&queue_mutex);
 
   return resp;
 }
@@ -73,18 +107,17 @@ static cJSON *await_response() {
     cJSON *req = NULL;                              \
     cJSON *resp = NULL;                           \
                                                   \
-    pthread_mutex_lock(&request_data_mutex); \
+    pthread_mutex_lock(&queue_mutex); \
     int disconnected = (con == NULL); \
-    pthread_mutex_unlock(&request_data_mutex); \
+    pthread_mutex_unlock(&queue_mutex); \
     if (disconnected) { ret = -EIO; goto done; }        \
     \
     req = cJSON_CreateObject(); \
     cJSON_AddStringToObject(req, "op", op);        \
     req_body \
     \
-    dispatch_send_req(req); \
-    \
-    resp = await_response();\
+    request_id id = enqueue_request(req); \
+    resp = await_response(id);        \
     \
     cJSON *error_item = cJSON_GetObjectItemCaseSensitive(resp, "error"); \
     if (error_item) { \
@@ -269,10 +302,27 @@ websocket_frame(struct wby_con *connection, const struct wby_frame *frame, void
       printf("Null in data! [%s]\n", data);
     }
 
-    pthread_mutex_lock(&response_mutex);
-    response = cJSON_Parse((const char *) data);
-    pthread_cond_signal(&response_cv);
-    pthread_mutex_unlock(&response_mutex);
+    // Will be freed at the receiver end.
+    cJSON *resp = cJSON_Parse((const char *) data);
+
+    cJSON *id_item = cJSON_GetObjectItemCaseSensitive(resp, "id");
+    if (id_item == NULL) {
+      printf("No id in response!\n");
+      exit(1);
+    }
+    request_id id = id_item->valueint;
+
+    pthread_mutex_lock(&queue_mutex);
+    printf("got resp");
+    if (queue[id].state != RECEIVE_RESPONSE) {
+      printf("Got response to request in wrong state!\n");
+      exit(1);
+    }
+    queue[id].state = HANDLE_RESPONSE;
+    queue[id].response = resp;
+
+    pthread_cond_signal(&queue_cv);
+    pthread_mutex_unlock(&queue_mutex);
 
     return 0;
 }
@@ -316,7 +366,7 @@ void *websocket_main(void *threadid)
 
     printf("Awaiting WebSocket connection from Chrome extension.\n");
     for (;;) {
-        send_req_if_any();
+        send_any_enqueued_requests();
 
         wby_update(&server);
     }