Make a light weight version (default) of DEBUG OBJECT

The light version only shows the light weight infomation,
which mostly O(1). The pre-existing version that show more
stats such as serializedlength is reachable with the `full`
argument.

This should allow looking into debug stats (the key expired
but not deleted), even on huge object, on which we're afraid
to run the command for fear of causing a server freeze.

Like 3ca451c.

Signed-off-by: Binbin <[email protected]>

src/debug.c

@@ -426,7 +426,7 @@ void debugCommand(client *c) {
             "MALLCTL-STR <key> [<val>]",
             "    Get or set a malloc tuning string.",
 #endif
-            "OBJECT <key>",
+            "OBJECT <key> [full]",
             "    Show low level info about `key` and associated value.",
             "DROP-CLUSTER-PACKET-FILTER <packet-type>",
             "    Drop all packets that match the filtered type. Set to -1 allow all packets.",
@@ -604,11 +604,14 @@ void debugCommand(client *c) {
     } else if (!strcasecmp(c->argv[1]->ptr, "close-cluster-link-on-packet-drop") && c->argc == 3) {
         server.debug_cluster_close_link_on_packet_drop = atoi(c->argv[2]->ptr);
         addReply(c, shared.ok);
-    } else if (!strcasecmp(c->argv[1]->ptr, "object") && c->argc == 3) {
+    } else if (!strcasecmp(c->argv[1]->ptr, "object") && (c->argc == 3 || c->argc == 4)) {
         dictEntry *de;
         robj *val;
         char *strenc;
 
+        int full = 0;
+        if (c->argc == 4 && !strcasecmp(c->argv[3]->ptr, "full")) full = 1;
+
         if ((de = dbFind(c->db, c->argv[2]->ptr)) == NULL) {
             addReplyErrorObject(c, shared.nokeyerr);
             return;
@@ -639,22 +642,25 @@ void debugCommand(client *c) {
             used = snprintf(nextra, remaining, " ql_compressed:%d", compressed);
             nextra += used;
             remaining -= used;
-            /* Add total uncompressed size */
-            unsigned long sz = 0;
-            for (quicklistNode *node = ql->head; node; node = node->next) {
-                sz += node->sz;
+            if (full) {
+                /* Add total uncompressed size */
+                unsigned long sz = 0;
+                for (quicklistNode *node = ql->head; node; node = node->next) {
+                    sz += node->sz;
+                }
+                used = snprintf(nextra, remaining, " ql_uncompressed_size:%lu", sz);
+                nextra += used;
+                remaining -= used;
             }
-            used = snprintf(nextra, remaining, " ql_uncompressed_size:%lu", sz);
-            nextra += used;
-            remaining -= used;
         }
 
-        addReplyStatusFormat(c,
-                             "Value at:%p refcount:%d "
-                             "encoding:%s serializedlength:%zu "
-                             "lru:%d lru_seconds_idle:%llu%s",
-                             (void *)val, val->refcount, strenc, rdbSavedObjectLen(val, c->argv[2], c->db->id),
-                             val->lru, estimateObjectIdleTime(val) / 1000, extra);
+        sds s = sdsempty();
+        s = sdscatprintf(s, "Value at:%p refcount:%d encoding:%s", (void *)val, val->refcount, strenc);
+        if (full) s = sdscatprintf(s, " serializedlength:%zu", rdbSavedObjectLen(val, c->argv[2], c->db->id));
+        s = sdscatprintf(s, " lru:%d lru_seconds_idle:%llu", val->lru, estimateObjectIdleTime(val) / 1000);
+        s = sdscatprintf(s, "%s", extra);
+        addReplyStatusLength(c, s, sdslen(s));
+        sdsfree(s);
     } else if (!strcasecmp(c->argv[1]->ptr, "sdslen") && c->argc == 3) {
         dictEntry *de;
         robj *val;