Add another body function returning a V8 Extra ReadableStream to Response

third_party/WebKit/Source/modules/fetch/Body.cpp

Index: third_party/WebKit/Source/modules/fetch/Body.cpp
diff --git a/third_party/WebKit/Source/modules/fetch/Body.cpp b/third_party/WebKit/Source/modules/fetch/Body.cpp
index 1e64fe123a83319bc00f9ea7a453c3a6c61a3caa..6e0d6c8e23c9c6374e1cb0a0ab438e206f8445a9 100644
--- a/third_party/WebKit/Source/modules/fetch/Body.cpp
+++ b/third_party/WebKit/Source/modules/fetch/Body.cpp
@@ -14,8 +14,13 @@
 #include "core/dom/ExceptionCode.h"
 #include "core/fileapi/Blob.h"
 #include "core/frame/UseCounter.h"
+#include "core/streams/ReadableStreamController.h"
+#include "core/streams/ReadableStreamOperations.h"
+#include "core/streams/UnderlyingSourceBase.h"
 #include "modules/fetch/BodyStreamBuffer.h"
 #include "modules/fetch/FetchDataLoader.h"
+#include "public/platform/WebDataConsumerHandle.h"
+#include "wtf/OwnPtr.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefPtr.h"
 
@@ -99,6 +104,59 @@ public:
     }
 };
 
+class UnderlyingSourceFromDataConsumerHandle final : public UnderlyingSourceBase, public WebDataConsumerHandle::Client {
+    EAGERLY_FINALIZE();
+    DECLARE_EAGER_FINALIZATION_OPERATOR_NEW();

[sof, 2016/04/04 11:26:32]

this derived class looks fine & macro is needed as the GC mixin instance it
derives from declares its own override of new(), but as non-eagerly finalized.

+public:
+    UnderlyingSourceFromDataConsumerHandle(ScriptState* scriptState, PassOwnPtr<WebDataConsumerHandle> handle)
+        : UnderlyingSourceBase(scriptState)
+        , m_scriptState(scriptState)
+        , m_reader(handle->obtainReader(this))
+    {
+    }
+
+    ScriptPromise pull(ScriptState* scriptState) override
+    {
+        didGetReadable();
+        return ScriptPromise::castUndefined(scriptState);
+    }
+
+    ScriptPromise cancel(ScriptState* scriptState, ScriptValue reason) override
+    {
+        m_reader = nullptr;
+        return ScriptPromise::castUndefined(scriptState);
+    }
+
+    void didGetReadable() override
+    {
+        while (controller()->desiredSize() > 0) {
+            size_t available;

[sof, 2016/04/04 11:26:32]

Don't you risk running into "potentially uninitialized" warnings by leaving this
as uninitialized?

[yhirano, 2016/04/04 11:42:32]

Done.

+            const void* buffer = nullptr;
+            WebDataConsumerHandle::Result result = m_reader->beginRead(&buffer, WebDataConsumerHandle::FlagNone, &available);
+            if (result == WebDataConsumerHandle::Ok) {
+                RefPtr<ArrayBuffer> arrayBuffer = ArrayBuffer::create(available, 1);
+                memcpy(arrayBuffer->data(), buffer, available);
+                m_reader->endRead(available);
+                controller()->enqueue(DOMUint8Array::create(arrayBuffer.release(), 0, available));
+            } else if (result == WebDataConsumerHandle::ShouldWait) {
+                break;
+            } else if (result == WebDataConsumerHandle::Done) {
+                m_reader = nullptr;
+                controller()->close();
+                break;
+            } else {
+                m_reader = nullptr;
+                controller()->error(V8ThrowException::createTypeError(m_scriptState->isolate(), "Network error"));
+                break;
+            }
+        }
+    }
+
+private:
+    RefPtr<ScriptState> m_scriptState;
+    OwnPtr<WebDataConsumerHandle::Reader> m_reader;
+};
+
 } // namespace
 
 ScriptPromise Body::arrayBuffer(ScriptState* scriptState)
@@ -200,6 +258,16 @@ ReadableByteStream* Body::bodyWithUseCounter()
     return body();
 }
 
+ScriptValue Body::v8ExtraStreamBody(ScriptState* scriptState)
+{
+    if (bodyUsed() || isBodyLocked() || !bodyBuffer())
+        return ScriptValue(scriptState, v8::Undefined(scriptState->isolate()));
+    OwnPtr<FetchDataConsumerHandle> handle = bodyBuffer()->releaseHandle(scriptState->getExecutionContext());
+    return ReadableStreamOperations::createReadableStream(scriptState,
+        new UnderlyingSourceFromDataConsumerHandle(scriptState, handle.release()),
+        ScriptValue(scriptState, v8::Undefined(scriptState->isolate())));
+}
+
 bool Body::bodyUsed()
 {
     return body() && body()->isDisturbed();