emscripten_get_worker_queue_size

3 files changed, 33 insertions, 1 deletions

diff --git a/src/library_browser.js b/src/library_browser.js
index 7c1d4320..d7aba76f 100644
--- a/src/library_browser.js
+++ b/src/library_browser.js
@@ -574,6 +574,7 @@ mergeInto(LibraryManager.library, {
     var info = {
       worker: new Worker(url),
       callbacks: [],
+      awaited: 0,
       buffer: 0,
       bufferSize: 0
     };
@@ -583,6 +584,7 @@ mergeInto(LibraryManager.library, {
       var callbackId = msg.data['callbackId'];
       var callbackInfo = info.callbacks[callbackId];
       if (!callbackInfo) return; // no callback or callback removed meanwhile
+      info.awaited--;
       info.callbacks[callbackId] = null; // TODO: reuse callbackIds, compress this
       var data = msg.data['data'];
       if (data) {
@@ -619,6 +621,7 @@ mergeInto(LibraryManager.library, {
         func: Runtime.getFuncWrapper(callback),
         arg: arg
       });
+      info.awaited++;
     }
     info.worker.postMessage({
       'funcName': funcName,
@@ -635,6 +638,12 @@ mergeInto(LibraryManager.library, {
       'callbackId': workerCallbackId,
       'data': data ? {{{ makeHEAPView('U8', 'data', 'data + size') }}} : 0
     });
+  },
+
+  emscripten_get_worker_queue_size: function(id) {
+    var info = Browser.workers[id];
+    if (!info) return -1;
+    return info.awaited;
   }
 });
 
diff --git a/system/include/emscripten/emscripten.h b/system/include/emscripten/emscripten.h
index 0a136f66..6c421eb5 100644
--- a/system/include/emscripten/emscripten.h
+++ b/system/include/emscripten/emscripten.h
@@ -268,6 +268,16 @@ void emscripten_call_worker(worker_t worker, const char *funcname, char *data, i
 void emscripten_worker_respond(char *data, int size);
 
 /*
+ * Checks how many responses are being waited for from a worker. This
+ * only counts calls to emscripten_call_worker that had a non-null
+ * callback (if it's null, we do not have any tracking of a response),
+ * and that the response was not yet received. It is a simple way to
+ * check on the status of the worker to see how busy it is, and do
+ * basic decisions about throttling.
+ */
+int emscripten_get_worker_queue_size(worker_t worker);
+
+/*
  * Profiling tools.
  * INIT must be called first, with the maximum identifier that
  * will be used. BEGIN will add some code that marks
diff --git a/tests/worker_api_2_main.cpp b/tests/worker_api_2_main.cpp
index da24a43b..ec8a6d4b 100644
--- a/tests/worker_api_2_main.cpp
+++ b/tests/worker_api_2_main.cpp
@@ -15,7 +15,7 @@ Info x[3] = { {    22,      3.159,  97, 2.1828 },
               { 55123, 987612.563, 190, 0.0009 },
               {  -102,    -12.532, -21, -51252 } };
 
-int stage = 1;
+int stage = -1;
 
 int c3_7 = 0, c3_8 = 0;
 
@@ -64,6 +64,10 @@ void c2(char *data, int size, void *arg) { // tests queuing up several messages,
 
 void c1(char *data, int size, void *arg) { // tests copying + buffer enlargement
   assert((int)arg == stage);
+  if (stage == 1) {
+    printf("wait 0? %d\n", emscripten_get_worker_queue_size(w1));
+    assert(emscripten_get_worker_queue_size(w1) == 0);
+  }
   Info *x2 = (Info*)data;
   assert(x2 != x && x2 != x+1 && x2 != x+2);
   for (int i = 0; i < size/sizeof(Info); i++) {
@@ -78,9 +82,13 @@ void c1(char *data, int size, void *arg) { // tests copying + buffer enlargement
   if (stage < 2) {
     emscripten_call_worker(w1, "one", (char*)x, sizeof(Info)*3, c1, (void*)2);
   } else {
+    printf("wait 1? %d\n", emscripten_get_worker_queue_size(w1));
+    assert(emscripten_get_worker_queue_size(w1) == 0);
     emscripten_call_worker(w1, "two", (char*)&x[0], sizeof(Info), c2, (void*)3);
     emscripten_call_worker(w1, "two", (char*)&x[1], sizeof(Info), c2, (void*)4);
     emscripten_call_worker(w1, "two", (char*)&x[2], sizeof(Info), c2, (void*)5);
+    printf("wait 2? %d\n", emscripten_get_worker_queue_size(w1));
+    assert(emscripten_get_worker_queue_size(w1) == 3);
   }
   stage++;
 }
@@ -88,7 +96,12 @@ void c1(char *data, int size, void *arg) { // tests copying + buffer enlargement
 int main() {
   w1 = emscripten_create_worker("worker.js");
 
+  printf("wait -1? %d\n", emscripten_get_worker_queue_size(w1));
+  assert(emscripten_get_worker_queue_size(w1) == 0);
   emscripten_call_worker(w1, "one", (char*)x, sizeof(Info)*2, c1, (void*)1);
+  printf("wait -1? %d\n", emscripten_get_worker_queue_size(w1));
+  assert(emscripten_get_worker_queue_size(w1) == 1);
+  stage = 1; // make sure we get here
 
   return 0;
 }