transmit_result enum instead of macro defines

memcached.c

@@ -91,7 +91,6 @@ static bool update_event(conn *c, const int new_flags);
 static void complete_nread(conn *c);
 static void process_command(conn *c, char *command);
 static void write_and_free(conn *c, char *buf, int bytes);
-static int transmit(conn *c);
 static int ensure_iov_space(conn *c);
 static int add_iov(conn *c, const void *buf, int len);
 static int add_msghdr(conn *c);
@@ -113,10 +112,14 @@ time_t process_started;     /* when the process was started */
 static conn *listen_conn = NULL;
 static struct event_base *main_base;
 
-#define TRANSMIT_COMPLETE   0
-#define TRANSMIT_INCOMPLETE 1
-#define TRANSMIT_SOFT_ERROR 2
-#define TRANSMIT_HARD_ERROR 3
+enum transmit_result {
+    TRANSMIT_COMPLETE,   /** All done writing. */
+    TRANSMIT_INCOMPLETE, /** More data remaining to write. */
+    TRANSMIT_SOFT_ERROR, /** Can't write any more right now. */
+    TRANSMIT_HARD_ERROR  /** Can't write (c->state is set to conn_closing) */
+};
+
+static enum transmit_result transmit(conn *c);
 
 #define REALTIME_MAXDELTA 60*60*24*30
 
@@ -3240,7 +3243,7 @@ void accept_new_conns(const bool do_accept) {
  *   TRANSMIT_SOFT_ERROR Can't write any more right now.
  *   TRANSMIT_HARD_ERROR Can't write (c->state is set to conn_closing)
  */
-static int transmit(conn *c) {
+static enum transmit_result transmit(conn *c) {
     assert(c != NULL);
 
     if (c->msgcurr < c->msgused &&