[android_webview] Don't block the IO thread when reading from an InputStream.

android_webview/browser/net/android_stream_reader_url_request_job.cc

+// Copyright (c) 2012 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 "android_webview/browser/net/android_stream_reader_url_request_job.h"
+
+#include "android_webview/browser/input_stream.h"
+#include "android_webview/browser/net/input_stream_reader.h"
+#include "base/android/jni_android.h"
+#include "base/android/jni_string.h"
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/lazy_instance.h"
+#include "base/message_loop.h"
+#include "base/task_runner.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "base/threading/thread.h"
+#include "content/public/browser/browser_thread.h"
+#include "net/base/io_buffer.h"
+#include "net/base/mime_util.h"
+#include "net/base/net_errors.h"
+#include "net/base/net_util.h"
+#include "net/http/http_util.h"
+#include "net/url_request/url_request.h"
+#include "net/url_request/url_request_job_manager.h"
+
+using android_webview::InputStream;
+using android_webview::InputStreamReader;
+using base::android::AttachCurrentThread;
+using base::PostTaskAndReplyWithResult;
+using content::BrowserThread;
+
+AndroidStreamReaderURLRequestJob::AndroidStreamReaderURLRequestJob(
+    net::URLRequest* request,
+    net::NetworkDelegate* network_delegate,
+    scoped_ptr<Delegate> delegate)
+    : URLRequestJob(request, network_delegate),
+      delegate_(delegate.Pass()),
+      ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)) {
+  DCHECK(delegate_.get());
+}
+
+AndroidStreamReaderURLRequestJob::~AndroidStreamReaderURLRequestJob() {
+}
+
+void AndroidStreamReaderURLRequestJob::Start() {
+  // Start reading asynchronously so that all error reporting and data
+  // callbacks happen as they would for network requests.
+  SetStatus(net::URLRequestStatus(net::URLRequestStatus::IO_PENDING, 0));
+  MessageLoop::current()->PostTask(
+      FROM_HERE,
+      base::Bind(
+          &AndroidStreamReaderURLRequestJob::StartAsync,
+          weak_factory_.GetWeakPtr()));
+}
+
+void AndroidStreamReaderURLRequestJob::Kill() {
+  weak_factory_.InvalidateWeakPtrs();
+  URLRequestJob::Kill();
+}
+
+scoped_refptr<InputStreamReader>
+AndroidStreamReaderURLRequestJob::CreateStreamReader(InputStream* stream) {
+  return make_scoped_refptr(new InputStreamReader(stream));
+}
+
+void AndroidStreamReaderURLRequestJob::StartAsync() {
+  JNIEnv* env = AttachCurrentThread();
+  DCHECK(env);
+
+  // This could be done in the InputStreamReader but would force more
+  // complex synchronization in the delegate.
+  stream_ = delegate_->OpenInputStream(env, request());
+  if (!stream_) {
+    NotifyDone(
+        net::URLRequestStatus(net::URLRequestStatus::FAILED, net::ERR_FAILED));
+    return;
+  }
+
+  DCHECK(!input_stream_reader_);
+  input_stream_reader_ = CreateStreamReader(stream_.get());
+  CHECK(input_stream_reader_);
+
+  PostTaskAndReplyWithResult(
+      GetWorkerThreadRunner(),
+      FROM_HERE,
+      base::Bind(&InputStreamReader::Seek, input_stream_reader_, byte_range_),
+      base::Bind(&AndroidStreamReaderURLRequestJob::OnReaderSeekCompleted,
+                 weak_factory_.GetWeakPtr()));
+}
+
+void AndroidStreamReaderURLRequestJob::OnReaderSeekCompleted(
+    int result) {
+  // Clear the IO_PENDING status set in Start().
+  SetStatus(net::URLRequestStatus());
+  if (result >= 0) {
+    set_expected_content_size(result);
+    NotifyHeadersComplete();
+  } else {
+    NotifyDone(net::URLRequestStatus(net::URLRequestStatus::FAILED, result));
+  }
+}
+
+void AndroidStreamReaderURLRequestJob::OnReaderReadCompleted(
+    int result) {
+  // The URLRequest API contract requires that:
+  // * NotifyDone be called once, to set the status code, indicate the job is
+  //   finished (there will be no further IO),
+  // * NotifyReadComplete be called if false is returned from ReadRawData to
+  //   indicate that the IOBuffer will not be used by the job anymore.
+  // There might be multiple calls to ReadRawData (and thus multiple calls to
+  // NotifyReadComplete), which is why NotifyDone is called only on errors
+  // (result < 0) and end of data (result == 0).
+  if (result == 0) {
+    NotifyDone(net::URLRequestStatus());
+  } else if (result < 0) {
+    NotifyDone(net::URLRequestStatus(net::URLRequestStatus::FAILED, result));
+  } else {
+    // Clear the IO_PENDING status.
+    SetStatus(net::URLRequestStatus());
+  }
+  NotifyReadComplete(result);
+}
+
+base::TaskRunner* AndroidStreamReaderURLRequestJob::GetWorkerThreadRunner() {
+  return static_cast<base::TaskRunner*>(BrowserThread::GetBlockingPool());
+}
+
+bool AndroidStreamReaderURLRequestJob::ReadRawData(net::IOBuffer* dest,
+                                                   int dest_size,
+                                                   int* bytes_read) {
+  DCHECK(input_stream_reader_);
+
+  PostTaskAndReplyWithResult(
+      GetWorkerThreadRunner(),
+      FROM_HERE,
+      base::Bind(&InputStreamReader::ReadRawData,
+                 input_stream_reader_,
+                 base::Unretained(dest),
+                 dest_size),
+      base::Bind(&AndroidStreamReaderURLRequestJob::OnReaderReadCompleted,
+                 weak_factory_.GetWeakPtr()));
+
+  SetStatus(net::URLRequestStatus(net::URLRequestStatus::IO_PENDING, 0));
+  return false;
+}
+
+bool AndroidStreamReaderURLRequestJob::GetMimeType(
+    std::string* mime_type) const {
+  JNIEnv* env = AttachCurrentThread();
+  DCHECK(env);
+
+  if (!stream_)
+    return false;
+
+  return delegate_->GetMimeType(env, request(), *stream_, mime_type);
+}
+
+bool AndroidStreamReaderURLRequestJob::GetCharset(
+    std::string* charset) {
+  JNIEnv* env = AttachCurrentThread();
+  DCHECK(env);
+
+  if (!stream_)
+    return false;
+
+  return delegate_->GetCharset(env, request(), *stream_, charset);
+}
+
+void AndroidStreamReaderURLRequestJob::SetExtraRequestHeaders(
+    const net::HttpRequestHeaders& headers) {
+  std::string range_header;
+  if (headers.GetHeader(net::HttpRequestHeaders::kRange, &range_header)) {
+    // We only extract the "Range" header so that we know how many bytes in the
+    // stream to skip and how many to read after that.
+    std::vector<net::HttpByteRange> ranges;
+    if (net::HttpUtil::ParseRangeHeader(range_header, &ranges)) {
+      if (ranges.size() == 1) {
+        byte_range_ = ranges[0];
+      } else {
+        // We don't support multiple range requests in one single URL request,
+        // because we need to do multipart encoding here.
+        NotifyDone(net::URLRequestStatus(
+            net::URLRequestStatus::FAILED,
+            net::ERR_REQUEST_RANGE_NOT_SATISFIABLE));
+      }
+    }
+  }
+}