adding CANCELED to AsyncSocketExceptionType

Summary: adding CANCELED to AsyncSocketExceptionType

Reviewed By: yfeldblum

Differential Revision: D22345735

fbshipit-source-id: 73c61b409531d71a39d82a46d9c0ebc720801c45

folly/io/async/AsyncSocketException.cpp

@@ -54,6 +54,8 @@ namespace folly {
       return "Network error";
     case EARLY_DATA_REJECTED:
       return "Early data rejected";
+    case CANCELED:
+      return "IO operation was canceled";
     default:
       return "(Invalid exception type)";
   }

folly/io/async/AsyncSocketException.h

@@ -43,6 +43,7 @@ class FOLLY_EXPORT AsyncSocketException : public std::runtime_error {
     // SASL_HANDSHAKE_TIMEOUT = 14, // no longer used
     NETWORK_ERROR = 15,
     EARLY_DATA_REJECTED = 16,
+    CANCELED = 17,
   };
 
   AsyncSocketException(