[Cronet] When connection is disconnected, InputStream#read should give an exception

components/cronet/android/java/src/org/chromium/net/urlconnection/CronetInputStream.java

 // Copyright 2014 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.
 
 package org.chromium.net.urlconnection;
 
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.ByteBuffer;
 
 /**
  * An InputStream that is used by {@link CronetHttpURLConnection} to request
  * data from the network stack as needed.
  */
 class CronetInputStream extends InputStream {
     private final CronetHttpURLConnection mHttpURLConnection;
     // Indicates whether listener's onSucceeded or onFailed callback is invoked.
     private boolean mResponseDataCompleted;
     private ByteBuffer mBuffer;
+    private IOException mException;
 
     private static final int READ_BUFFER_SIZE = 32 * 1024;
 
     /**
      * Constructs a CronetInputStream.
      * @param httpURLConnection the CronetHttpURLConnection that is associated
      *            with this InputStream.
      */
     public CronetInputStream(CronetHttpURLConnection httpURLConnection) {
         mHttpURLConnection = httpURLConnection;
@@ skipping 21 matching lines @@
             int bytesRead = Math.min(mBuffer.limit() - mBuffer.position(), byteCount);
             mBuffer.get(buffer, byteOffset, bytesRead);
             return bytesRead;
         }
         return -1;
     }
 
     /**
      * Called by {@link CronetHttpURLConnection} to notify that the entire
      * response body has been read.
+     * @param exception if not {@code null}, it is the exception to throw when caller
+     *            tries to read more data than what is buffered.

[pauljensen, 2015/12/07 15:20:07]

nit: I'm a little confused by the "more data than what is buffered" comment. 
This function clears the buffer, so any further request will be for more data
than is buffered, correct?  Can we just leave it as "...tries to read more
data."

[xunjieli, 2015/12/07 15:53:12]

Done.

      */
-    void setResponseDataCompleted() {
+    void setResponseDataCompleted(IOException exception) {
+        mException = exception;
         mResponseDataCompleted = true;
         // Nothing else to read, so can free the buffer.
         mBuffer = null;
     }
 
     private void getMoreDataIfNeeded() throws IOException {
-        if (!mResponseDataCompleted && !hasUnreadData()) {
+        if (mResponseDataCompleted) {
+            if (mException != null) {
+                throw mException;
+            }
+            return;
+        }
+        if (!hasUnreadData()) {
             // Allocate read buffer if needed.
             if (mBuffer == null) {
                 mBuffer = ByteBuffer.allocateDirect(READ_BUFFER_SIZE);
             }
             mBuffer.clear();
 
             // Requests more data from CronetHttpURLConnection.
             mHttpURLConnection.getMoreData(mBuffer);
+            if (mException != null) {
+                throw mException;
+            }
             if (mBuffer != null) {
                 mBuffer.flip();
             }
         }
     }
 
     /**
      * Returns whether {@link #mBuffer} has unread data.
      */
     private boolean hasUnreadData() {
         return mBuffer != null && mBuffer.hasRemaining();
     }
 }