Add CLIENT INFO and CLIENT LIST [id]. (#8113)

* Add CLIENT INFO subcommand.

The output is identical to CLIENT LIST but provides a single line for
the current client only.

* Add CLIENT LIST ID [id...].

Co-authored-by: Itamar Haber <itamar@redislabs.com>

src/networking.c

@@ -2331,6 +2331,7 @@ void clientCommand(client *c) {
     if (c->argc == 2 && !strcasecmp(c->argv[1]->ptr,"help")) {
         const char *help[] = {
 "ID                     -- Return the ID of the current connection.",
+"INFO                   -- Return information about the current client connection.",
 "GETNAME                -- Return the name of the current connection.",
 "KILL <ip:port>         -- Kill connection made from <ip:port>.",
 "KILL <option> <value> [option value ...] -- Kill connections. Options are:",
@@ -2341,6 +2342,7 @@ void clientCommand(client *c) {
 "     SKIPME (yes|no)   -- Skip killing current connection (default: yes).",
 "LIST [options ...]     -- Return information about client connections. Options:",
 "     TYPE (normal|master|replica|pubsub) -- Return clients of specified type.",
+"     ID id [id ...]                      -- Return clients of specified IDs only.",
 "PAUSE <timeout>        -- Suspend all Redis clients for <timout> milliseconds.",
 "REPLY (on|off|skip)    -- Control the replies sent to the current connection.",
 "SETNAME <name>         -- Assign the name <name> to the current connection.",
@@ -2354,21 +2356,46 @@ NULL
     } else if (!strcasecmp(c->argv[1]->ptr,"id") && c->argc == 2) {
         /* CLIENT ID */
         addReplyLongLong(c,c->id);
+    } else if (!strcasecmp(c->argv[1]->ptr,"info") && c->argc == 2) {
+        /* CLIENT INFO */
+        sds o = catClientInfoString(sdsempty(), c);
+        o = sdscatlen(o,"\n",1);
+        addReplyVerbatim(c,o,sdslen(o),"txt");
+        sdsfree(o);
     } else if (!strcasecmp(c->argv[1]->ptr,"list")) {
         /* CLIENT LIST */
         int type = -1;
+        sds o = NULL;
         if (c->argc == 4 && !strcasecmp(c->argv[2]->ptr,"type")) {
             type = getClientTypeByName(c->argv[3]->ptr);
             if (type == -1) {
                 addReplyErrorFormat(c,"Unknown client type '%s'",
                     (char*) c->argv[3]->ptr);
                 return;
-             }
+            }
+        } else if (c->argc > 3 && !strcasecmp(c->argv[2]->ptr,"id")) {
+            int j;
+            o = sdsempty();
+            for (j = 3; j < c->argc; j++) {
+                long long cid;
+                if (getLongLongFromObjectOrReply(c, c->argv[j], &cid,
+                            "Invalid client ID")) {
+                    sdsfree(o);
+                    return;
+                }
+                client *cl = lookupClientByID(cid);
+                if (cl) {
+                    o = catClientInfoString(o, cl);
+                    o = sdscatlen(o, "\n", 1);
+                }
+            }
         } else if (c->argc != 2) {
             addReply(c,shared.syntaxerr);
             return;
         }
-        sds o = getAllClientsInfoString(type);
+
+        if (!o)
+            o = getAllClientsInfoString(type);
         addReplyVerbatim(c,o,sdslen(o),"txt");
         sdsfree(o);
     } else if (!strcasecmp(c->argv[1]->ptr,"reply") && c->argc == 3) {

src/redis-cli.c

@@ -1304,7 +1304,8 @@ static int cliSendCommand(int argc, char **argv, long repeat) {
                       (!strcasecmp(argv[1],"nodes") ||
                        !strcasecmp(argv[1],"info"))) ||
         (argc >= 2 && !strcasecmp(command,"client") &&
-                       !strcasecmp(argv[1],"list")) ||
+                       (!strcasecmp(argv[1],"list") ||
+                        !strcasecmp(argv[1],"info"))) ||
         (argc == 3 && !strcasecmp(command,"latency") &&
                        !strcasecmp(argv[1],"graph")) ||
         (argc == 2 && !strcasecmp(command,"latency") &&

tests/unit/introspection.tcl

@@ -3,6 +3,16 @@ start_server {tags {"introspection"}} {
         r client list
     } {*addr=*:* fd=* age=* idle=* flags=N db=9 sub=0 psub=0 multi=-1 qbuf=26 qbuf-free=* argv-mem=* obl=0 oll=0 omem=0 tot-mem=* events=r cmd=client*}
 
+    test {CLIENT LIST with IDs} {
+        set myid [r client id]
+        set cl [split [r client list id $myid] "\r\n"]
+        assert_match "id=$myid*" [lindex $cl 0]
+    }
+
+    test {CLIENT INFO} {
+        r client info
+    } {*addr=*:* fd=* age=* idle=* flags=N db=9 sub=0 psub=0 multi=-1 qbuf=26 qbuf-free=* argv-mem=* obl=0 oll=0 omem=0 tot-mem=* events=r cmd=client*}
+
     test {MONITOR can log executed commands} {
         set rd [redis_deferring_client]
         $rd monitor