redis-cli: interactive reconnection for latency modes.

--stat mode already used to reconnect automatically if the server is no
longer available. This is useful since this is an interactive mode used
for debugging, however the same applies to --latency and --latency-dist
modes, so now both use the reconnecting command execution as well.

The reconnection code was modified to use basic VT100 escape sequences
in order to play better with different kinds of output on the screen
when the reconnection happens, and to hide the reconnection attempt
output when finally the reconnection happens.

src/redis-cli.c

@@ -673,16 +673,17 @@ static int cliSendCommand(int argc, char **argv, int repeat) {
     return REDIS_OK;
 }
 
-/* Send the INFO command, reconnecting the link if needed. */
-static redisReply *reconnectingInfo(void) {
-    redisContext *c = context;
+/* Send a command reconnecting the link if needed. */
+static redisReply *reconnectingRedisCommand(redisContext *c, const char *fmt, ...) {
     redisReply *reply = NULL;
     int tries = 0;
+    va_list ap;
 
     assert(!c->err);
     while(reply == NULL) {
         while (c->err & (REDIS_ERR_IO | REDIS_ERR_EOF)) {
-            printf("Reconnecting (%d)...\r", ++tries);
+            printf("\r\x1b[0K"); /* Cursor to left edge + clear line. */
+            printf("Reconnecting... %d\r", ++tries);
             fflush(stdout);
 
             redisFree(c);
@@ -690,12 +691,15 @@ static redisReply *reconnectingInfo(void) {
             usleep(1000000);
         }
 
-        reply = redisCommand(c,"INFO");
+        va_start(ap,fmt);
+        reply = redisvCommand(c,fmt,ap);
+        va_end(ap);
+
         if (c->err && !(c->err & (REDIS_ERR_IO | REDIS_ERR_EOF))) {
             fprintf(stderr, "Error: %s\n", c->errstr);
             exit(1);
         } else if (tries > 0) {
-            printf("\n");
+            printf("\r\x1b[0K"); /* Cursor to left edge + clear line. */
         }
     }
 
@@ -1047,7 +1051,7 @@ static void latencyMode(void) {
     if (!context) exit(1);
     while(1) {
         start = mstime();
-        reply = redisCommand(context,"PING");
+        reply = reconnectingRedisCommand(context,"PING");
         if (reply == NULL) {
             fprintf(stderr,"\nI/O error\n");
             exit(1);
@@ -1197,7 +1201,7 @@ static void latencyDistMode(void) {
     if (!context) exit(1);
     while(1) {
         start = ustime();
-        reply = redisCommand(context,"PING");
+        reply = reconnectingRedisCommand(context,"PING");
         if (reply == NULL) {
             fprintf(stderr,"\nI/O error\n");
             exit(1);
@@ -1845,7 +1849,7 @@ static void statMode(void) {
         char buf[64];
         int j;
 
-        reply = reconnectingInfo();
+        reply = reconnectingRedisCommand(context,"INFO");
         if (reply->type == REDIS_REPLY_ERROR) {
             printf("ERROR: %s\n", reply->str);
             exit(1);