Implement BlobBytesConsumer

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

+// Copyright 2016 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/fetch/BlobBytesConsumer.h"
+
+#include "core/fetch/FetchInitiatorTypeNames.h"
+#include "core/loader/ThreadableLoader.h"
+#include "modules/fetch/BytesConsumerForDataConsumerHandle.h"
+#include "modules/fetch/DataConsumerHandleUtil.h"
+#include "platform/blob/BlobData.h"
+#include "platform/blob/BlobRegistry.h"
+#include "platform/blob/BlobURL.h"
+#include "platform/network/ResourceError.h"
+#include "platform/network/ResourceRequest.h"
+#include "platform/weborigin/KURL.h"
+#include "platform/weborigin/SecurityOrigin.h"
+
+namespace blink {
+
+BlobBytesConsumer::BlobBytesConsumer(ExecutionContext* executionContext, PassRefPtr<BlobDataHandle> blobDataHandle, ThreadableLoader* loader)
+    : ContextLifecycleObserver(executionContext)
+    , m_blobDataHandle(blobDataHandle)
+    , m_loader(loader)
+{
+    ThreadState::current()->registerPreFinalizer(this);
+}
+
+BlobBytesConsumer::BlobBytesConsumer(ExecutionContext* executionContext, PassRefPtr<BlobDataHandle> blobDataHandle)
+    : BlobBytesConsumer(executionContext, blobDataHandle, nullptr)
+{
+}
+
+BlobBytesConsumer::~BlobBytesConsumer()
+{
+}
+
+BytesConsumer::Result BlobBytesConsumer::beginRead(const char** buffer, size_t* available)
+{
+    *buffer = nullptr;
+    *available = 0;
+
+    if (m_state == PublicState::Closed) {
+        // It's possible that |cancel| has been called before the first
+        // |beginRead| call. That's why we need to check this condition
+        // before checking |isClean()|.
+        return Result::Done;
+    }
+
+    if (isClean()) {
+        KURL m_blobURL = BlobURL::createPublicURL(getExecutionContext()->getSecurityOrigin());
+        if (m_blobURL.isEmpty()) {
+            m_state = PublicState::Errored;
+        } else {
+            BlobRegistry::registerPublicBlobURL(getExecutionContext()->getSecurityOrigin(), m_blobURL, m_blobDataHandle);
+
+            // m_loader is non-null only in tests.
+            if (!m_loader)
+                m_loader = createLoader();
+
+            ResourceRequest request(m_blobURL);
+            request.setRequestContext(WebURLRequest::RequestContextInternal);
+            request.setUseStreamOnResponse(true);
+            // We intentionally skip
+            // 'setExternalRequestStateFromRequestorAddressSpace', as 'blob:'
+            // can never be external.
+            m_loader->start(request);
+        }
+        m_blobDataHandle = nullptr;
+    }
+
+    if (m_state == PublicState::Errored)
+        return Result::Error;
+
+    if (!m_body) {
+        // The response has not arrived.
+        return Result::ShouldWait;
+    }
+
+    auto result = m_body->beginRead(buffer, available);
+    switch (result) {
+    case Result::Ok:
+    case Result::ShouldWait:
+        break;
+    case Result::Done:
+        m_hasSeenEndOfData = true;
+        if (m_hasFinishedLoading)
+            m_state = PublicState::Closed;
+        clearIfNecessary();
+        return m_state == PublicState::Closed ? Result::Done : Result::ShouldWait;
+    case Result::Error:
+        m_state = PublicState::Errored;
+        clearIfNecessary();
+        break;
+    }
+    return result;
+}
+
+BytesConsumer::Result BlobBytesConsumer::endRead(size_t read)
+{
+    DCHECK(m_body);
+    auto result = m_body->endRead(read);
+    clearIfNecessary();
+    return result;
+}
+
+PassRefPtr<BlobDataHandle> BlobBytesConsumer::drainAsBlobDataHandle(BlobSizePolicy policy)
+{
+    if (!isClean())
+        return nullptr;
+    DCHECK(m_blobDataHandle);
+    if (policy == BlobSizePolicy::DisallowBlobWithInvalidSize && m_blobDataHandle->size() == UINT64_MAX)
+        return nullptr;
+    m_state = PublicState::Closed;
+    return m_blobDataHandle.release();
+}
+
+PassRefPtr<EncodedFormData> BlobBytesConsumer::drainAsFormData()
+{
+    RefPtr<BlobDataHandle> handle = drainAsBlobDataHandle(BlobSizePolicy::AllowBlobWithInvalidSize);
+    if (!handle)
+        return nullptr;
+    RefPtr<EncodedFormData> formData = EncodedFormData::create();
+    formData->appendBlob(handle->uuid(), handle);
+    return formData.release();
+}
+
+void BlobBytesConsumer::setClient(BytesConsumer::Client* client)
+{
+    DCHECK(!m_client);
+    DCHECK(client);
+    m_client = client;
+}
+
+void BlobBytesConsumer::clearClient()
+{
+    m_client = nullptr;
+}
+
+void BlobBytesConsumer::cancel()
+{
+    if (m_state == PublicState::Closed || m_state == PublicState::Errored)
+        return;
+    m_state = PublicState::Closed;
+    clearIfNecessary();
+    if (m_body) {
+        m_body->cancel();
+        m_body = nullptr;
+    }
+    if (!m_blobURL.isEmpty()) {
+        BlobRegistry::revokePublicBlobURL(m_blobURL);
+        m_blobURL = KURL();
+    }
+}
+
+BytesConsumer::Error BlobBytesConsumer::getError() const
+{
+    DCHECK_EQ(PublicState::Errored, m_state);
+    return Error("Failed to load a blob.");
+}
+
+BytesConsumer::PublicState BlobBytesConsumer::getPublicState() const
+{
+    return m_state;
+}
+
+void BlobBytesConsumer::contextDestroyed()
+{
+    if (m_loader) {

[hiroshige, 2016/09/15 05:54:51]

Do we need this block?
when |m_state| is set to Errored/Closed, |m_loader| seems cleared.

[yhirano, 2016/09/15 08:13:32]

Done.

+        m_loader->cancel();
+        m_loader = nullptr;
+    }
+
+    if (m_state != PublicState::ReadableOrWaiting)
+        return;
+
+    m_state = PublicState::Errored;

[hiroshige, 2016/09/15 05:54:51]

Can we make a method like

void BlobBytesConsumer::setState(PublicState newState, bool shouldNotifyClient)
{
    m_state = newState;
    BytesConsumer::Client* client = m_client;
    clearIfNecessary();
    if (client && shouldNotifyClient)
        client->onStateChange();
}

and use it when changing state?

- By calling clearIfNecessary() before onStateChange(), we can make the
invariant that |m_loader| is null when m_state is Done/Errored stronger, and
- There are multiple occurrences of "set m_state, onStateChange(), and
clearIfNecessary()". Merging them into a single method is helpful to make code
clearer.

[yhirano, 2016/09/15 08:13:32]

I'm more comfortable with saving m_client manually. Is this acceptable to you?

+    if (m_client)
+        m_client->onStateChange();
+    clearIfNecessary();
+}
+
+void BlobBytesConsumer::onStateChange()
+{
+    if (m_state != PublicState::ReadableOrWaiting)
+        return;
+    DCHECK(m_body);
+
+    switch (m_body->getPublicState()) {
+    case PublicState::ReadableOrWaiting:
+        break;
+    case PublicState::Closed:
+        m_hasSeenEndOfData = true;
+        if (m_hasFinishedLoading)
+            m_state = PublicState::Closed;
+        break;
+    case PublicState::Errored:
+        m_state = PublicState::Errored;
+        break;
+    }
+
+    if (m_client)
+        m_client->onStateChange();
+    clearIfNecessary();
+}
+
+void BlobBytesConsumer::didReceiveResponse(unsigned long identifier, const ResourceResponse&, std::unique_ptr<WebDataConsumerHandle> handle)
+{
+    DCHECK(handle);
+    DCHECK(!m_body);
+    DCHECK_EQ(PublicState::ReadableOrWaiting, m_state);
+
+    m_body = new BytesConsumerForDataConsumerHandle(getExecutionContext(), createFetchDataConsumerHandleFromWebHandle(std::move(handle)));
+    m_body->setClient(this);
+
+    if (isClean()) {
+        // This function is called synchronously in ThreadableLoader::start.
+        return;
+    }
+    onStateChange();
+}
+
+void BlobBytesConsumer::didFinishLoading(unsigned long identifier, double finishTime)
+{
+    DCHECK_EQ(PublicState::ReadableOrWaiting, m_state);
+    m_hasFinishedLoading = true;
+    m_loader = nullptr;
+    if (!m_hasSeenEndOfData)
+        return;
+    DCHECK(!isClean());
+    m_state = PublicState::Closed;
+    if (m_client) {
+        m_client->onStateChange();
+        m_client = nullptr;
+    }
+}
+
+void BlobBytesConsumer::didFail(const ResourceError& error)
+{
+    if (error.isCancellation()) {
+        DCHECK_EQ(PublicState::Closed, m_state);
+        return;
+    }
+    DCHECK_EQ(PublicState::ReadableOrWaiting, m_state);
+    m_state = PublicState::Errored;
+    m_loader = nullptr;
+    if (isClean()) {
+        // This function is called synchronously in ThreadableLoader::start.
+        return;
+    }
+    if (m_client) {
+        m_client->onStateChange();
+        m_client = nullptr;
+    }
+}
+
+void BlobBytesConsumer::didFailRedirectCheck()
+{
+    NOTREACHED();
+}
+
+DEFINE_TRACE(BlobBytesConsumer)
+{
+    visitor->trace(m_body);
+    visitor->trace(m_client);
+    visitor->trace(m_loader);
+    BytesConsumer::trace(visitor);
+    BytesConsumer::Client::trace(visitor);
+    ContextLifecycleObserver::trace(visitor);
+}
+
+BlobBytesConsumer* BlobBytesConsumer::createForTesting(ExecutionContext* executionContext, PassRefPtr<BlobDataHandle> blobDataHandle, ThreadableLoader* loader)
+{
+    return new BlobBytesConsumer(executionContext, blobDataHandle, loader);
+}
+
+ThreadableLoader* BlobBytesConsumer::createLoader()
+{
+    ThreadableLoaderOptions options;
+    options.preflightPolicy = ConsiderPreflight;
+    options.crossOriginRequestPolicy = DenyCrossOriginRequests;
+    options.contentSecurityPolicyEnforcement = DoNotEnforceContentSecurityPolicy;
+    options.initiator = FetchInitiatorTypeNames::internal;
+
+    ResourceLoaderOptions resourceLoaderOptions;
+    resourceLoaderOptions.dataBufferingPolicy = DoNotBufferData;
+
+    return ThreadableLoader::create(*getExecutionContext(), this, options, resourceLoaderOptions);
+}
+
+void BlobBytesConsumer::clearIfNecessary()
+{
+    if (m_state == PublicState::ReadableOrWaiting)
+        return;
+
+    if (m_loader) {
+        m_loader->cancel();
+        m_loader = nullptr;
+    }
+    m_client = nullptr;
+}
+
+} // namespace blink