net: Make UploadDataStream::Read() asynchronous

net/base/upload_data_stream.h

Index: net/base/upload_data_stream.h
diff --git a/net/base/upload_data_stream.h b/net/base/upload_data_stream.h
index 8679b2c9347a91bb945b3d5242234986e2f7144c..45830b3aea3683e0137239046dd8a34b752f4525 100644
--- a/net/base/upload_data_stream.h
+++ b/net/base/upload_data_stream.h
@@ -39,10 +39,11 @@ class NET_EXPORT UploadDataStream {
   // Use this method only in tests and Chrome Frame.

[mmenke, 2012/10/11 18:05:40]

While you're here, mentioning Chrome frame in net/ is a layering violation. 
Suggest you mention this can cause jank instead.

[hashimoto, 2012/10/12 07:36:56]

Stopped mentioning Chrome Frame.

   int InitSync();
 
-  // Reads up to |buf_len| bytes from the upload data stream to |buf|. The
-  // number of bytes read is returned. Partial reads are allowed.  Zero is
-  // returned on a call to Read when there are no remaining bytes in the
-  // stream, and IsEof() will return true hereafter.
+  // Reads up to |buf_len| bytes synchronously from the upload data stream to
+  // |buf| and returns the number of bytes read when possible, otherwise,
+  // returns ERR_IO_PENDING and calls |callback| with the result. Partial reads
+  // are allowed.  Zero is returned on a call to Read when there are no
+  // remaining bytes in the stream, and IsEof() will return true hereafter.
   //
   // If there's less data to read than we initially observed (i.e. the actual
   // upload data is smaller than size()), zeros are padded to ensure that
@@ -50,9 +51,12 @@ class NET_EXPORT UploadDataStream {
   //
   // If the upload data stream is chunked (i.e. is_chunked() is true),
   // ERR_IO_PENDING is returned to indicate there is nothing to read at the
-  // moment, but more data to come at a later time. If not chunked, reads
-  // won't fail.
-  int Read(IOBuffer* buf, int buf_len);
+  // moment, but more data to come at a later time.

[mmenke, 2012/10/11 18:05:40]

This comment isn't accurate:  HttpStreamParser allows chunked streams to be read
synchronously, and as of the CL after this one, it will also allow non-chunked
streams to be read asynchronously.  You should also say what |callback| is
called with (Bytes read or error code, presumably).

[hashimoto, 2012/10/12 07:36:56]

Revised the comment.

+  int Read(IOBuffer* buf, int buf_len, const CompletionCallback& callback);
+
+  // Reads data always synchronously.
+  // Use this method only in tests and Chrome Frame.

[mmenke, 2012/10/11 18:05:40]

Mentioning Chrome Frame here is a layering violation.

[hashimoto, 2012/10/12 07:36:56]

Done.

+  int ReadSync(IOBuffer* buf, int buf_len);
 
   // Sets the callback to be invoked when new chunks are available to upload.
   void set_chunk_callback(ChunkCallback* callback) {
@@ -86,6 +90,7 @@ class NET_EXPORT UploadDataStream {
   FRIEND_TEST_ALL_PREFIXES(UploadDataStreamTest, InitAsync);
   FRIEND_TEST_ALL_PREFIXES(UploadDataStreamTest, InitAsyncFailureAsync);
   FRIEND_TEST_ALL_PREFIXES(UploadDataStreamTest, InitAsyncFailureSync);
+  FRIEND_TEST_ALL_PREFIXES(UploadDataStreamTest, ReadAsync);
 
   // Runs Init() for all element readers.
   // This method is used to implement Init().
@@ -97,6 +102,15 @@ class NET_EXPORT UploadDataStream {
   // This method is used to implement Init().
   void FinalizeInitialization();
 
+  // Reads data from the element readers.
+  // This method is used to implement Read().
+  int ReadInternal(scoped_refptr<IOBuffer> buf,
+                   int buf_len,
+                   int bytes_copied,
+                   bool invoked_asynchronously,
+                   const CompletionCallback& callback,
+                   int previous_result);
+
   // These methods are provided only to be used by unit tests.
   static void ResetMergeChunks();
   static void set_merge_chunks(bool merge) { merge_chunks_ = merge; }