[wasm] response-based compile APIs

third_party/WebKit/Source/modules/wasm/WasmResponseExtensions.cpp

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "modules/wasm/WasmResponseExtensions.h"
+
+#include "bindings/core/v8/ExceptionState.h"
+#include "bindings/core/v8/ScriptPromise.h"
+#include "bindings/core/v8/ScriptPromiseResolver.h"
+#include "bindings/core/v8/ScriptState.h"
+#include "bindings/modules/v8/V8Response.h"
+#include "modules/fetch/BodyStreamBuffer.h"
+#include "modules/fetch/FetchDataLoader.h"
+#include "platform/heap/Handle.h"
+#include "wtf/RefPtr.h"
+
+namespace blink {
+
+namespace {
+
+class FetchDataLoaderAsWasmModule final : public FetchDataLoader,
+                                          public BytesConsumer::Client {
+  USING_GARBAGE_COLLECTED_MIXIN(FetchDataLoaderAsWasmModule);
+
+ public:
+  FetchDataLoaderAsWasmModule(ScriptPromiseResolver* resolver,
+                              ScriptState* scriptState)
+      : m_resolver(resolver),
+        m_builder(scriptState->isolate()),
+        m_scriptState(scriptState) {}
+
+  void start(BytesConsumer* consumer,
+             FetchDataLoader::Client* client) override {
+    DCHECK(!m_consumer);
+    DCHECK(!m_client);
+    m_client = client;
+    m_consumer = consumer;
+    m_consumer->setClient(this);
+    onStateChange();
+  }
+
+  void onStateChange() override {
+    while (true) {
+      // buffer is allocated by beginRead and de-allocated by endRead.

[haraken, 2017/04/07 10:22:40]

allocated / deallocated sounds misleading to me. beginRead / endRead never
allocates / deallocates.

[Mircea Trofin, 2017/04/07 15:33:08]

True - rephrased.

+      const char* buffer = nullptr;
+      size_t available = 0;
+      BytesConsumer::Result result = m_consumer->beginRead(&buffer, &available);
+
+      if (result == BytesConsumer::Result::ShouldWait)
+        return;
+      if (result == BytesConsumer::Result::Ok) {
+        if (available > 0) {
+          DCHECK_NE(buffer, nullptr);
+          m_builder.OnBytesReceived(reinterpret_cast<const uint8_t*>(buffer),
+                                    available);
+        }
+        result = m_consumer->endRead(available);
+      }
+      switch (result) {
+        case BytesConsumer::Result::ShouldWait:
+          NOTREACHED();
+          return;
+        case BytesConsumer::Result::Ok: {
+          break;
+        }
+        case BytesConsumer::Result::Done: {
+          v8::Isolate* isolate = m_scriptState->isolate();
+          ScriptState::Scope scope(m_scriptState.get());
+          v8::TryCatch trycatch(isolate);
+          v8::Local<v8::WasmCompiledModule> module;
+          if (m_builder.Finish().ToLocal(&module)) {
+            DCHECK(!trycatch.HasCaught());
+            ScriptValue scriptValue(m_scriptState.get(), module);
+            m_resolver->resolve(scriptValue);
+          } else {
+            DCHECK(trycatch.HasCaught());
+            m_resolver->reject(trycatch.Exception());
+            trycatch.Reset();

[haraken, 2017/04/07 10:22:40]

I don't fully understand why you need to reset it. You're not using trycatch
after this line, right?

[Mircea Trofin, 2017/04/07 15:33:09]

Granted, the destructor of TryCatch clears the exception
(https://cs.chromium.org/chromium/src/v8/include/v8.h?l=7997), but perhaps my
paranoia is to blame :)

I refactored a bit and commented.

+          }
+          m_client->didFetchDataLoadedCustomFormat();
+          return;
+        }
+        case BytesConsumer::Result::Error: {
+          // TODO(mtrofin): do we need an abort on the wasm side?
+          // Something like "m_outStream->abort()" maybe?
+          return rejectPromise();
+        }
+      }
+    }
+  }
+
+  void cancel() override {
+    m_consumer->cancel();
+    return rejectPromise();
+  }
+
+  DEFINE_INLINE_TRACE() {
+    visitor->trace(m_consumer);
+    visitor->trace(m_resolver);
+    visitor->trace(m_client);
+    FetchDataLoader::trace(visitor);
+    BytesConsumer::Client::trace(visitor);
+  }
+
+ private:
+  // TODO(mtrofin): replace with spec-ed error types, once spec clarifies
+  // what they are.
+  void rejectPromise() {
+    m_resolver->reject(V8ThrowException::createTypeError(
+        m_scriptState->isolate(), "Could not download wasm module"));
+  }
+  Member<BytesConsumer> m_consumer;
+  Member<ScriptPromiseResolver> m_resolver;
+  Member<FetchDataLoader::Client> m_client;
+  v8::WasmModuleObjectBuilder m_builder;
+  const RefPtr<ScriptState> m_scriptState;
+};
+
+// TODO(mtrofin): WasmDataLoaderClient is necessary so we may provide an
+// argument to BodyStreamBuffer::startLoading, however, it fulfills
+// a very small role. Consider refactoring to avoid it.
+class WasmDataLoaderClient final
+    : public GarbageCollectedFinalized<WasmDataLoaderClient>,
+      public FetchDataLoader::Client {
+  WTF_MAKE_NONCOPYABLE(WasmDataLoaderClient);
+  USING_GARBAGE_COLLECTED_MIXIN(WasmDataLoaderClient);
+
+ public:
+  explicit WasmDataLoaderClient() {}
+  void didFetchDataLoadedCustomFormat() override {}
+  void didFetchDataLoadFailed() override { NOTREACHED(); }
+};
+
+// This callback may be entered as a promise is resolved, or directly
+// from the overload callback.
+// See
+// https://github.com/WebAssembly/design/blob/master/Web.md#webassemblycompile
+void compileFromResponseCallback(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  ExceptionState exceptionState(args.GetIsolate(),
+                                ExceptionState::ExecutionContext, "WebAssembly",
+                                "compile");
+  ExceptionToRejectPromiseScope rejectPromiseScope(args, exceptionState);
+
+  ScriptState* scriptState = ScriptState::forReceiverObject(args);
+  if (!scriptState->getExecutionContext()) {
+    v8SetReturnValue(args, ScriptPromise().v8Value());
+    return;
+  }
+
+  if (args.Length() < 1 || !args[0]->IsObject() ||
+      !V8Response::hasInstance(args[0], args.GetIsolate())) {
+    v8SetReturnValue(
+        args, ScriptPromise::reject(
+                  scriptState, V8ThrowException::createTypeError(
+                                   scriptState->isolate(),
+                                   "Promise argument must be called with a "
+                                   "Promise<Response> object"))
+                  .v8Value());
+    return;
+  }
+
+  Response* response = V8Response::toImpl(v8::Local<v8::Object>::Cast(args[0]));
+  ScriptPromise promise;
+  if (response->isBodyLocked() || response->bodyUsed()) {
+    promise = ScriptPromise::reject(
+        scriptState,
+        V8ThrowException::createTypeError(
+            scriptState->isolate(),
+            "Cannot compile WebAssembly.Module from an already read Response"));
+  } else {
+    ScriptPromiseResolver* resolver =
+        ScriptPromiseResolver::create(scriptState);
+    if (response->bodyBuffer()) {
+      promise = resolver->promise();
+      response->bodyBuffer()->startLoading(
+          new FetchDataLoaderAsWasmModule(resolver, scriptState),
+          new WasmDataLoaderClient());
+    } else {
+      promise = ScriptPromise::reject(
+          scriptState,
+          V8ThrowException::createTypeError(
+              scriptState->isolate(), "Response object has a null body."));
+    }
+  }
+  v8SetReturnValue(args, promise.v8Value());
+}
+
+// See https://crbug.com/708238 for tracking avoiding the hand-generated code.
+bool wasmCompileOverload(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  if (args.Length() < 1 || !args[0]->IsObject())
+    return false;
+
+  if (!args[0]->IsPromise() &&
+      !V8Response::hasInstance(args[0], args.GetIsolate()))
+    return false;
+
+  v8::Isolate* isolate = args.GetIsolate();
+  ScriptState* scriptState = ScriptState::forReceiverObject(args);
+
+  v8::Local<v8::Function> compileCallback =
+      v8::Function::New(isolate, compileFromResponseCallback);
+

[yhirano, 2017/04/07 07:39:47]

V8SetReturnValue(args, ScriptPromise::cast(scriptState,
args[0]).then(compileCallback).v8Value());
return;

[Mircea Trofin, 2017/04/07 15:33:08]

Nice! Thanks!

+  ScriptPromiseResolver* scriptPromiseResolver =
+      ScriptPromiseResolver::create(scriptState);
+  // treat either case of parameter as
+  // Promise.resolve(parameter)
+  // as per https://www.w3.org/2001/tag/doc/promises-guide#resolve-arguments
+
+  // Ending with:
+  //    return Promise.resolve(parameter).then(compileCallback);
+  ScriptPromise parameterAsPromise = scriptPromiseResolver->promise();
+  v8SetReturnValue(args, parameterAsPromise.then(compileCallback).v8Value());
+
+  // resolve the first parameter promise.
+  scriptPromiseResolver->resolve(ScriptValue::from(scriptState, args[0]));
+  return true;
+}
+
+}  // namespace
+
+void WasmResponseExtensions::initialize(v8::Isolate* isolate) {
+  isolate->SetWasmCompileCallback(wasmCompileOverload);
+}
+
+}  // namespace blink