Dont log error in case of eof error for async_read

async_read returns eof to indicate that the other side has closed the socket.
This is a way for other side to know that socket should be closed now. There
is no need to log since it is not an error condition

Closes-Bug: 1506795

Change-Id: I5dc5dc0cb9a909d97dacff8ceef89c863a7536c7
(cherry picked from commit ef96e3d)

src/io/tcp_session.cc

@@ -427,9 +427,12 @@ void TcpSession::AsyncReadHandler(
 
     if (IsSocketErrorHard(error)) {
         session->ReleaseBufferLocked(buffer);
-        TCP_SESSION_LOG_ERROR(session, TCP_DIR_IN,
+	// eof is returned when the peer closed the socket, no need to log err
+	if (error != error::eof) {
+	    TCP_SESSION_LOG_ERROR(session, TCP_DIR_IN,
                               "Read failed due to error " << error.value()
                               << " : " << error.message());
+	}
         lock.release();
         session->CloseInternal(error, true);
         return;
@@ -440,9 +443,12 @@ void TcpSession::AsyncReadHandler(
         // check error code if session needs to be closed
         if (IsSocketErrorHard(err)) {
             session->ReleaseBufferLocked(buffer);
-            TCP_SESSION_LOG_ERROR(session, TCP_DIR_IN,
+	    // eof is returned when the peer has closed the socket
+	    if (error != error::eof) {
+		TCP_SESSION_LOG_ERROR(session, TCP_DIR_IN,
                                   "Read failed due to error " << err.value()
                                   << " : " << err.message());
+	    }
             lock.release();
             session->CloseInternal(err, true);
             return;