-added write io cancellation

1 files changed, 19 insertions, 3 deletions

diff --git a/src/include/gnunet_stream_lib.h b/src/include/gnunet_stream_lib.h
index 78b11d1c5..5a2f9b2e4 100644
--- a/src/include/gnunet_stream_lib.h
+++ b/src/include/gnunet_stream_lib.h
@@ -217,13 +217,17 @@ struct GNUNET_STREAM_IOWriteHandle;
 struct GNUNET_STREAM_IOReadHandle;
 
 /**
- * Tries to write the given data to the stream
+ * Tries to write the given data to the stream. The maximum size of data that
+ * can be written as part of a write operation is (64 * (64000 - sizeof (struct
+ * GNUNET_STREAM_DataMessage))). If size is greater than this it is not an API
+ * violation, however only the said number of maximum bytes will be written.
  *
  * @param socket the socket representing a stream
  * @param data the data buffer from where the data is written into the stream
  * @param size the number of bytes to be written from the data buffer
  * @param timeout the timeout period
- * @param write_cont the function to call upon writing some bytes into the stream
+ * @param write_cont the function to call upon writing some bytes into the
+ *          stream 
  * @param write_cont_cls the closure
  * @return handle to cancel the operation; NULL if a previous write is pending
  */
@@ -270,7 +274,19 @@ GNUNET_STREAM_read (struct GNUNET_STREAM_Socket *socket,
 
 
 /**
- * Cancel pending write operation.
+ * Cancels pending write operation. Also cancels packet retransmissions which
+ * may have resulted otherwise.
+ *
+ * CAUTION: Normally a write operation is considered successful if the data
+ * given to it is sent and acknowledged by the receiver. As data is divided
+ * into packets, it is possible that not all packets are received by the
+ * receiver. Any missing packets are then retransmitted till the receiver
+ * acknowledges all packets or until a timeout . During this scenario if the
+ * write operation is cancelled all such retransmissions are also
+ * cancelled. This may leave the receiver's receive buffer incompletely filled
+ * as some missing packets are never retransmitted. So this operation should be
+ * used before shutting down transmission from our side or before closing the
+ * socket.
  *
  * @param ioh handle to operation to cancel
  */