Remove unnecessary array allocation in cronet_bidirectional_stream_adapter.cc

components/cronet/android/cronet_bidirectional_stream_adapter.h

Index: components/cronet/android/cronet_bidirectional_stream_adapter.h
diff --git a/components/cronet/android/cronet_bidirectional_stream_adapter.h b/components/cronet/android/cronet_bidirectional_stream_adapter.h
index 4ed2dea985f4ec8e7787da535d563387fea15b25..a807960c3de48ee951348865a63f29b4c499180a 100644
--- a/components/cronet/android/cronet_bidirectional_stream_adapter.h
+++ b/components/cronet/android/cronet_bidirectional_stream_adapter.h
@@ -28,6 +28,26 @@ namespace cronet {
 class CronetURLRequestContextAdapter;
 class IOBufferWithByteBuffer;
 
+// Convenient wrapper to hold Java references and data to represent the pending
+// data to be written.
+struct PendingWriteData {
+  PendingWriteData(JNIEnv* env,
+                   jobjectArray jwrite_buffer_list,
+                   jintArray jwrite_buffer_pos_list,
+                   jintArray jwrite_buffer_limit_list,
+                   jboolean jwrite_end_of_stream);
+  ~PendingWriteData();
+
+  base::android::ScopedJavaGlobalRef<jobjectArray> jwrite_buffer_list;
+  base::android::ScopedJavaGlobalRef<jintArray> jwrite_buffer_pos_list;
+  base::android::ScopedJavaGlobalRef<jintArray> jwrite_buffer_limit_list;
+  jboolean jwrite_end_of_stream;
+  std::vector<scoped_refptr<net::IOBuffer>> write_buffer_list;

[mef, 2016/05/13 15:12:58]

My concern about using net::IOBuffer insted of IOBufferWithByteBuffer is that it
is theoretically possible to destroy ByteBuffer making memory backing IOBuffer
invalid.

[xunjieli, 2016/05/13 15:35:22]

But the Java ByteBuffer is not going to be destroyed/GC-ed since we retain a
global reference to it as |jwrite_buffer_list|, right?

[mef, 2016/05/16 13:54:18]

Yeah, that's fine.

+  std::vector<int> write_buffer_len_list;
+
+  DISALLOW_COPY_AND_ASSIGN(PendingWriteData);
+};
+
 // An adapter from Java BidirectionalStream object to net::BidirectionalStream.
 // Created and configured from a Java thread. Start, ReadData, WritevData and
 // Destroy can be called on any thread (including network thread), and post
@@ -94,8 +114,6 @@ class CronetBidirectionalStreamAdapter
                jboolean jsend_on_canceled);
 
  private:
-  typedef std::vector<scoped_refptr<IOBufferWithByteBuffer>>
-      IOBufferWithByteBufferList;
   // net::BidirectionalStream::Delegate implementations:
   void OnStreamReady() override;
   void OnHeadersReceived(const net::SpdyHeaderBlock& response_headers) override;
@@ -109,8 +127,8 @@ class CronetBidirectionalStreamAdapter
   void ReadDataOnNetworkThread(
       scoped_refptr<IOBufferWithByteBuffer> read_buffer,
       int buffer_size);
-  void WritevDataOnNetworkThread(const IOBufferWithByteBufferList& buffers,
-                                 bool end_of_stream);
+  void WritevDataOnNetworkThread(
+      std::unique_ptr<PendingWriteData> pending_write_data);
   void DestroyOnNetworkThread(bool send_on_canceled);
   // Gets headers as a Java array.
   base::android::ScopedJavaLocalRef<jobjectArray> GetHeadersArray(
@@ -127,7 +145,7 @@ class CronetBidirectionalStreamAdapter
   bool write_end_of_stream_;
 
   scoped_refptr<IOBufferWithByteBuffer> read_buffer_;
-  IOBufferWithByteBufferList write_buffer_list_;
+  std::unique_ptr<PendingWriteData> pending_write_data_;
   std::unique_ptr<net::BidirectionalStream> bidi_stream_;
 
   // Whether BidirectionalStream::Delegate::OnFailed callback is invoked.