Fix wasm loading in workers, and refactor async promise code

emcc.py

@@ -1298,7 +1298,8 @@ def check(input_file):
         if shared.Building.is_wasm_only() and shared.Settings.EVAL_CTORS:
           logging.debug('disabling EVAL_CTORS, as in wasm-only mode it hurts more than it helps. TODO: a wasm version of it')
           shared.Settings.EVAL_CTORS = 0
-        if shared.Settings.BINARYEN_ASYNC_COMPILATION == 1 and shared.Building.is_wasm_only():
+        # async compilation requires wasm-only mode, and also not interpreting (the interpreter needs sync input)
+        if shared.Settings.BINARYEN_ASYNC_COMPILATION == 1 and shared.Building.is_wasm_only() and 'interpret' not in shared.Settings.BINARYEN_METHOD:
           # async compilation requires a swappable module - we swap it in when it's ready
           shared.Settings.SWAPPABLE_ASM_MODULE = 1
         else:
@@ -2339,7 +2340,7 @@ def un_src(): # use this if you want to modify the script and need it to be inli
         else:
           assert len(asm_mods) == 0, 'no --separate-asm means no client code mods are possible'
 
-        if shared.Settings.BINARYEN:
+        if shared.Settings.BINARYEN and not shared.Settings.BINARYEN_ASYNC_COMPILATION:
           # We need to load the wasm file before anything else, it has to be synchronously ready TODO: optimize
           un_src()
           script_inline = '''

src/preamble.js

@@ -2153,16 +2153,28 @@ function integrateWasmJS(Module) {
 
   function getBinary() {
     var binary;
-    if (ENVIRONMENT_IS_WEB || ENVIRONMENT_IS_WORKER) {
+    if (Module['wasmBinary']) {
       binary = Module['wasmBinary'];
-      assert(binary, "on the web, we need the wasm binary to be preloaded and set on Module['wasmBinary']. emcc.py will do that for you when generating HTML (but not JS)");
       binary = new Uint8Array(binary);
-    } else {
+    } else if (Module['readBinary']) {
       binary = Module['readBinary'](wasmBinaryFile);
+    } else {
+      throw "on the web, we need the wasm binary to be preloaded and set on Module['wasmBinary']. emcc.py will do that for you when generating HTML (but not JS)";
     }
     return binary;
   }
 
+  function getBinaryPromise() {
+    // if we don't have the binary yet, and have the Fetch api, use that
+    if (!Module['wasmBinary'] && typeof fetch === 'function') {
+      return fetch(wasmBinaryFile).then(function(response) { return response.arrayBuffer() });
+    }
+    // Otherwise, getBinary should be able to get it synchronously
+    return new Promise(function(resolve, reject) {
+      resolve(getBinary());
+    });
+  }
+
   // do-method functions
 
   function doJustAsm(global, env, providedBuffer) {
@@ -2212,7 +2224,9 @@ function integrateWasmJS(Module) {
 #if BINARYEN_ASYNC_COMPILATION
     Module['printErr']('asynchronously preparing wasm');
     addRunDependency('wasm-instantiate'); // we can't run yet
-    WebAssembly.instantiate(getBinary(), info).then(function(output) {
+    getBinaryPromise().then(function(binary) {
+      return WebAssembly.instantiate(binary, info)
+    }).then(function(output) {
       // receiveInstance() will swap in the exports (to Module.asm) so they can be called
       receiveInstance(output.instance);
       removeRunDependency('wasm-instantiate');
@@ -2221,7 +2235,7 @@ function integrateWasmJS(Module) {
       Module['quit'](1, reason);
     });
     return {}; // no exports yet; we'll fill them in later
-#endif
+#else
     var instance;
     try {
       instance = new WebAssembly.Instance(new WebAssembly.Module(getBinary()), info)
@@ -2234,6 +2248,7 @@ function integrateWasmJS(Module) {
     }
     receiveInstance(instance);
     return exports;
+#endif
   }
 
   function doWasmPolyfill(global, env, providedBuffer, method) {

src/shell.js

@@ -169,6 +169,16 @@ else if (ENVIRONMENT_IS_WEB || ENVIRONMENT_IS_WORKER) {
     return xhr.responseText;
   };
 
+  if (ENVIRONMENT_IS_WORKER) {
+    Module['readBinary'] = function read(url) {
+      var xhr = new XMLHttpRequest();
+      xhr.open('GET', url, false);
+      xhr.responseType = 'arraybuffer';
+      xhr.send(null);
+      return xhr.response;
+    };
+  }
+
   Module['readAsync'] = function readAsync(url, onload, onerror) {
     var xhr = new XMLHttpRequest();
     xhr.open('GET', url, true);

tests/test_browser.py

@@ -1352,7 +1352,7 @@ def test_egl_width_height(self):
     Popen([PYTHON, EMCC, '-O2', os.path.join(self.get_dir(), 'test_egl_width_height.c'), '-o', 'page.html', '-lEGL', '-lGL']).communicate()
     self.run_browser('page.html', 'Should print "(300, 150)" -- the size of the canvas in pixels', '/report_result?1')
 
-  def test_worker(self):
+  def do_test_worker(self, args=[]):
     # Test running in a web worker
     open('file.dat', 'w').write('data for worker')
     html_file = open('main.html', 'w')
@@ -1374,15 +1374,17 @@ def test_worker(self):
     ''')
     html_file.close()
 
-    # no file data
-    for file_data in [0, 1]:
-      print 'file data', file_data
-      output = Popen([PYTHON, EMCC, path_from_root('tests', 'hello_world_worker.cpp'), '-o', 'worker.js'] + (['--preload-file', 'file.dat'] if file_data else []) , stdout=PIPE, stderr=PIPE).communicate()
-      assert len(output[0]) == 0, output[0]
-      assert os.path.exists('worker.js'), output
-      if not file_data: self.assertContained('you should not see this text when in a worker!', run_js('worker.js')) # code should run standalone
+    for file_data in [1, 0]:
+      cmd = [PYTHON, EMCC, path_from_root('tests', 'hello_world_worker.cpp'), '-o', 'worker.js'] + (['--preload-file', 'file.dat'] if file_data else []) + args
+      print cmd
+      subprocess.check_call(cmd)
+      assert os.path.exists('worker.js')
       self.run_browser('main.html', '', '/report_result?hello%20from%20worker,%20and%20|' + ('data%20for%20w' if file_data else '') + '|')
 
+  def test_worker(self):
+    self.do_test_worker()
+    self.assertContained('you should not see this text when in a worker!', run_js('worker.js')) # code should run standalone too
+
   def test_chunked_synchronous_xhr(self):
     main = 'chunked_sync_xhr.html'
     worker_filename = "download_and_checksum_worker.js"
@@ -3337,6 +3339,9 @@ def test_binaryen_async(self):
       print opts, expect
       self.btest('binaryen_async.c', expected=str(expect), args=['-s', 'BINARYEN=1', '--shell-file', 'shell.html'] + opts)
 
+  def test_binaryen_worker(self):
+    self.do_test_worker(['-s', 'WASM=1'])
+
   def test_utf8_textdecoder(self):
     self.btest('benchmark_utf8.cpp', expected='0', args=['--embed-file', path_from_root('tests/utf8_corpus.txt') + '@/utf8_corpus.txt'])