[Cronet] Upload support for async APIs

components/cronet/android/cronet_upload_data_stream_adapter.h

+// Copyright 2015 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.
+
+#ifndef COMPONENTS_CRONET_ANDROID_CRONET_UPLOAD_DATA_STREAM_ADAPTER_H_
+#define COMPONENTS_CRONET_ANDROID_CRONET_UPLOAD_DATA_STREAM_ADAPTER_H_
+
+#include "base/basictypes.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "net/base/upload_data_stream.h"
+
+namespace net {
+class IOBuffer;
+}  // namespace net
+
+namespace cronet {
+
+// The CronetUploadDataStreamAdapter is created on a Java thread, but
+// afterwards, lives on the network thread. It's responsible for invoking
+// UploadDataStream's callbacks, and ensuring only only one read/rewind request
+// send to Java is outstanding at a time. The main complexity is around
+// Reset/Initialize calls while there's a pending read or rewind.
+class CronetUploadDataStreamAdapter : public net::UploadDataStream {
+ public:
+  class Delegate {
+   public:
+    // Called once during initial setup on the network thread, called before
+    // all other methods.
+    virtual void InitializeOnNetworkThread(
+        base::WeakPtr<CronetUploadDataStreamAdapter> adapter) = 0;
+
+    // Called for each read request. Delegate must respond by calling
+    // OnReadSuccess on the network thread asynchronous, or failing the request.
+    // Only called when there's no other pending read or rewind operation.
+    virtual void Read(net::IOBuffer* buffer, int buf_len) = 0;
+
+    // Called to rewind the stream. Not called when already at the start of the
+    // stream. The delegate must respond by calling OnRewindSuccess
+    // asynchronously on the network thread, or failing the request. Only called
+    // when there's no other pending read or rewind operation.
+    virtual void Rewind() = 0;
+
+    // Called when the adapter is destroyed. May be called when there's a
+    // pending read or rewind operation. The Delegate is then responsible for
+    // destroying itself.
+    virtual void OnAdapterDestroyed() = 0;
+
+   protected:
+    Delegate() {}
+    virtual ~Delegate() {}
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(Delegate);
+  };
+
+  CronetUploadDataStreamAdapter(Delegate* delegate, int64 size);
+  ~CronetUploadDataStreamAdapter() override;
+
+  // Failure is handled at the Java layer.

[mef, 2015/02/06 19:46:09]

I would elaborate that these 2 are called from Java layer upon completion of
operation, maybe even mention the Sink.

[xunjieli, 2015/02/06 20:48:29]

Done.

+  void OnReadSuccess(int bytes_read, bool final_chunk);
+  void OnRewindSuccess();
+
+  // net::UploadDataStream implementation:

[mef, 2015/02/06 19:46:09]

Does it have to be public?

[xunjieli, 2015/02/06 20:48:29]

Done.

+  int InitInternal() override;
+  int ReadInternal(net::IOBuffer* buf, int buf_len) override;
+  void ResetInternal() override;
+
+ private:
+  // Starts rewinding the stream. Only called when not already at the front of
+  // the stream, and no operation is pending. Completes asynchronously.
+  void StartRewind();
+
+  // Size of the upload.  -1 if chunked.
+  const int64 size_;
+
+  // True if ReadInternal has been called, the read hasn't completed, and there
+  // hasn't been a ResetInternal call yet.
+  bool waiting_on_read_;
+  // True if there's a read operation in progress. This will always be true
+  // when |waiting_on_read_| is true. This will only be set to false once it
+  // completes, even though ResetInternal may have been called since the read
+  // started.
+  bool read_in_progress_;
+
+  // True if ReadInternal has been called, the rewind hasn't completed, and
+  // there hasn't been a ResetInternal call yet. Note that this may be true
+  // even when the rewind hasn't yet started, if there's a read in progress.
+  bool waiting_on_rewind_;
+  // True if there's a rewind operation in progress. Rewinding will only start
+  // when |waiting_on_rewind_| is true, and |read_in_progress_| is false. This
+  // will only be set to false once it completes, even though ResetInternal may
+  // have been called since the rewind started.
+  bool rewind_in_progress_;
+
+  // Set to false when a read starts, true when a rewind completes.
+  bool at_front_of_stream_;
+
+  Delegate* delegate_;
+
+  // Vends pointers on the network thread, though created on a Java thread.
+  base::WeakPtrFactory<CronetUploadDataStreamAdapter> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(CronetUploadDataStreamAdapter);
+};
+
+}  // namespace cronet
+
+#endif  // COMPONENTS_CRONET_ANDROID_CRONET_UPLOAD_DATA_STREAM_ADAPTER_H_