Initialize WebWorker earlier.

 - Moved ChannelLib to be pre-js so worker init can happen earlier.
Add function for WebWorker shutdown. This is needed to not deadlock test
harness.
Document where SubtleCrypto API was looked for in the v8 test harness. It
was not found.

src/libraries/Native/AnyOS/System.Security.Cryptography.Native.Browser/pal_crypto_webworker.js

@@ -12,7 +12,7 @@ var CryptoWebWorkerLib = {
             var response = MONO.mono_wasm_crypto.channel.send_msg(JSON.stringify(msg));
             var digest = JSON.parse(response);
             if (digest.length !== output_len) {
-                throw "SHA HASH: Unexpected output length";
+                throw "SHA HASH: Unexpected output length: " + digest.length + ", expected: " + output_len;
             }
 
             Module.HEAPU8.set(digest, output_buffer);

src/mono/wasm/Makefile

@@ -104,7 +104,7 @@ $(BUILDS_OBJ_DIR):
 	mkdir -p $$@
 
 $(NATIVE_BIN_DIR)/dotnet.js: $(BUILDS_OBJ_DIR)/driver.o $(BUILDS_OBJ_DIR)/pinvoke.o $(BUILDS_OBJ_DIR)/corebindings.o runtime/library_mono.js runtime/binding_support.js runtime/dotnet_support.js runtime/library_channel.js $(SYSTEM_NATIVE_LIBDIR)/pal_random.js $(SYSTEM_CRYPTO_NATIVE_LIBDIR)/pal_crypto_webworker.js $(2) | $(NATIVE_BIN_DIR)
-	$(EMCC) $(EMCC_FLAGS) $(1) --js-library runtime/library_mono.js --js-library runtime/binding_support.js --js-library runtime/dotnet_support.js --post-js runtime/library_channel.js --js-library $(SYSTEM_NATIVE_LIBDIR)/pal_random.js --js-library $(SYSTEM_CRYPTO_NATIVE_LIBDIR)/pal_crypto_webworker.js $(BUILDS_OBJ_DIR)/driver.o $(BUILDS_OBJ_DIR)/pinvoke.o $(BUILDS_OBJ_DIR)/corebindings.o $(2) -o $(NATIVE_BIN_DIR)/dotnet.js $(3)
+	$(EMCC) $(EMCC_FLAGS) $(1) --js-library runtime/library_mono.js --js-library runtime/binding_support.js --js-library runtime/dotnet_support.js --pre-js runtime/library_channel.js --js-library $(SYSTEM_NATIVE_LIBDIR)/pal_random.js --js-library $(SYSTEM_CRYPTO_NATIVE_LIBDIR)/pal_crypto_webworker.js $(BUILDS_OBJ_DIR)/driver.o $(BUILDS_OBJ_DIR)/pinvoke.o $(BUILDS_OBJ_DIR)/corebindings.o $(2) -o $(NATIVE_BIN_DIR)/dotnet.js $(3)
 
 $(BUILDS_OBJ_DIR)/pinvoke-table.h: $(PINVOKE_TABLE) | $(BUILDS_OBJ_DIR)
 	if cmp -s $(PINVOKE_TABLE) $$@ ; then : ; else cp $(PINVOKE_TABLE) $$@ ; fi

src/mono/wasm/runtime/crypto_worker.js

@@ -8,6 +8,7 @@ var ChannelWorker = {
         get MSG_SIZE_IDX() { return 1; }
 
         // Communication states.
+        get STATE_SHUTDOWN() { return -1; } // Shutdown
         get STATE_IDLE() { return 0; }
         get STATE_REQ() { return 1; }
         get STATE_RESP() { return 2; }
@@ -32,13 +33,16 @@ var ChannelWorker = {
                 // Read in request
                 var req = this._read_request();
                 // console.log("Request: " + req);
+                if (req === this.STATE_SHUTDOWN)
+                    break;
 
                 var resp = null;
                 try {
                     // Perform async action based on request
                     resp = await async_call(req);
                 }
                 catch (err) {
+                    console.log("Request error: " + err);
                     resp = JSON.stringify(err);
                 }
 
@@ -61,6 +65,10 @@ var ChannelWorker = {
                 if (state === this.STATE_REQ)
                     break;
 
+                // Shutdown the worker.
+                if (state === this.STATE_SHUTDOWN)
+                    return this.STATE_SHUTDOWN;
+
                 // Reset the size and transition to await state.
                 Atomics.store(this.comm, this.MSG_SIZE_IDX, 0);
                 Atomics.store(this.comm, this.STATE_IDX, this.STATE_AWAIT);
@@ -134,6 +142,14 @@ async function sha_hash(type, data) {
             throw "CRYPTO: Unknown SHA: " + type;
     }
 
+    // [TODO] The 'crypto' API is not available within the current
+    // v8 test harness. The following were tried:
+    //      self
+    //      document
+    //      this
+    //      globalThis
+    //
+    // The below works in the browser scenario.
     var digest = await crypto.subtle.digest(sha_type, data);
     return Array.from(new Uint8Array(digest));
 }
@@ -154,6 +170,10 @@ var s_channel;
 
 // Initialize WebWorker
 onmessage = function (p) {
-    s_channel = ChannelWorker.create(p.data.comm_buf, p.data.msg_buf, p.data.msg_char_len);
+    var data = p;
+    if (p.data !== undefined) {
+        data = p.data;
+    }
+    s_channel = ChannelWorker.create(data.comm_buf, data.msg_buf, data.msg_char_len);
     s_channel.await_request(async_call);
 }

src/mono/wasm/runtime/library_channel.js

@@ -9,6 +9,7 @@ Module [ 'channel' ] = {
         get COMM_LAST_IDX() { return this.MSG_SIZE_IDX; }
 
         // Communication states.
+        get STATE_SHUTDOWN() { return -1; } // Shutdown
         get STATE_IDLE() { return 0; }
         get STATE_REQ() { return 1; }
         get STATE_RESP() { return 2; }
@@ -45,6 +46,17 @@ Module [ 'channel' ] = {
             return this._read_response();
         }
 
+        shutdown() {
+            if (Atomics.load(this.comm, this.STATE_IDX) !== this.STATE_IDLE) {
+                throw "OWNER: Invalid sync communication channel state.";
+            }
+
+            // Notify webworker
+            Atomics.store(this.comm, this.MSG_SIZE_IDX, 0);
+            Atomics.store(this.comm, this.STATE_IDX, this.STATE_SHUTDOWN);
+            Atomics.notify(this.comm, this.STATE_IDX);
+        }
+
         _send_request(msg) {
             var state;
             const msg_len = msg.length;

src/mono/wasm/runtime/library_mono.js

@@ -48,7 +48,7 @@
  */
 
 var MonoSupportLib = {
-	$MONO__postset: 'MONO.export_functions (Module);',
+	$MONO__postset: 'MONO.export_functions (Module); MONO._initialize_workers ();',
 	$MONO: {
 		pump_count: 0,
 		timeout_queue: [],
@@ -1707,7 +1707,6 @@ var MonoSupportLib = {
 			var chan = Module.channel.create();
 			var worker = new Worker ("crypto_worker.js");
 			worker.postMessage ({
-				salutation:"Message from main",
 				comm_buf: chan.get_comm_buffer(),
 				msg_buf: chan.get_msg_buffer(),
 				msg_char_len: chan.get_msg_len()
@@ -1716,6 +1715,14 @@ var MonoSupportLib = {
 			MONO.mono_wasm_crypto.worker = worker;
 		},
 
+		_shutdown_workers: function () {
+			console.debug ("MONO_WASM: WebWorkers shutdown");
+			var chan = MONO.mono_wasm_crypto.channel;
+			if (chan !== null) {
+				chan.shutdown ();
+			}
+		},
+
 		_finalize_startup: function (args, ctx) {
 			var loaded_files_with_debug_info = [];
 
@@ -1753,12 +1760,11 @@ var MonoSupportLib = {
 				tz = Intl.DateTimeFormat().resolvedOptions().timeZone;
 			} catch {}
 			MONO.mono_wasm_setenv ("TZ", tz || "UTC");
-
-			// Now that the runtime has been loaded, spin off any web workers needed
-			// for ancillary operations.
-			MONO._initialize_workers ();
 			MONO.mono_wasm_runtime_ready ();
 			args.loaded_cb ();
+
+			// [TODO] Shutdown workers when run under test environment
+			// MONO._shutdown_workers();
 		},
 
 		_load_assets_and_runtime: function (args) {