add shutdownWrite to wangle for closing socket write only

Summary: current wangle has no way to close socket write side. writeFlags is extended so that wangle/AsyncSocketHandler can distinguish closeNow(), closeWithReset() and shutdownWrite()

Reviewed By: @viswanathgs

Differential Revision: D2522056

fb-gh-sync-id: 60616176d78311a4a09f9761a6ccda01dd502a88

diff --git a/folly/io/async/AsyncTransport.h b/folly/io/async/AsyncTransport.h
index 3086958b7ab9178e75924c0b521ee32475591cc0..ee8e8ea646e5d8d5fda2f97ebefb007e517dfcf1 100644 (file)
--- a/folly/io/async/AsyncTransport.h
+++ b/folly/io/async/AsyncTransport.h
@@ -56,6 +56,10 @@ enum class WriteFlags : uint32_t {
    * will be acknowledged.
    */
   EOR = 0x02,
+  /*
+   * this indicates that only the write side of socket should be shutdown
+   */
+  WRITE_SHUTDOWN = 0x04,
 };
 
 /*