MINOR: peers/cli: do not dump the peers dictionaries by default on "show peers"

The "show peers" output has become huge due to the dictionaries making it
less readable. Now this feature has reached a certain level of maturity
which doesn't warrant to dump it all the time, given that it was essentially
needed by developers. Let's make it optional, and disabled by default, only
when "show peers dict" is requested. The default output reminds about the
command. The output has been divided by 5 :

  $ socat - /tmp/sock1  <<< "show peers dict" | wc -l
  125
  $ socat - /tmp/sock1  <<< "show peers" | wc -l
  26

It could be useful to backport this to recent stable versions.

doc/management.txt

@@ -2259,11 +2259,13 @@ show map [<map>]
   are not directly a list of available maps, but are the list of all patterns
   composing any map. Many of these patterns can be shared with ACL.
 
-show peers [<peers section>]
+show peers [dict|-] [<peers section>]
   Dump info about the peers configured in "peers" sections. Without argument,
   the list of the peers belonging to all the "peers" sections are listed. If
   <peers section> is specified, only the information about the peers belonging
-  to this "peers" section are dumped.
+  to this "peers" section are dumped. When "dict" is specified before the peers
+  section name, the entire Tx/Rx dictionary caches will also be dumped (very
+  large). Passing "-" may be required to dump a peers section called "dict".
 
   Here are two examples of outputs where hostA, hostB and hostC peers belong to
   "sharedlb" peers sections. Only hostA and hostB are connected. Only hostA has

include/haproxy/applet-t.h

@@ -171,6 +171,7 @@ struct appctx {
 			void *target;
 			struct peers *peers; /* "peers" section being currently dumped. */
 			struct peer *peer;   /* "peer" being currently dumped. */
+			int flags;           /* non-zero if "dict" dump requested */
 		} cfgpeers;
 		struct {
 			char *path;

src/peers.c

@@ -89,6 +89,9 @@
 #define PEER_RECONNECT_TIMEOUT      5000 /* 5 seconds */
 #define PEER_HEARTBEAT_TIMEOUT      3000 /* 3 seconds */
 
+/* flags for "show peers" */
+#define PEERS_SHOW_F_DICT           0x00000001 /* also show the contents of the dictionary */
+
 /*****************************/
 /* Sync message class        */
 /*****************************/
@@ -3313,6 +3316,13 @@ static int cli_parse_show_peers(char **args, char *payload, struct appctx *appct
 {
 	appctx->ctx.cfgpeers.target = NULL;
 
+	if (strcmp(args[2], "dict") == 0) {
+		/* show the dictionaries (large dump) */
+		appctx->ctx.cfgpeers.flags |= PEERS_SHOW_F_DICT;
+		args++;
+	} else if (strcmp(args[2], "-") == 0)
+		args++; // allows to show a section called "dict"
+
 	if (*args[2]) {
 		struct peers *p;
 
@@ -3364,7 +3374,7 @@ static int peers_dump_head(struct buffer *msg, struct stream_interface *si, stru
  * Returns 0 if the output buffer is full and needs to be called again, non-zero
  * if not. Dedicated to be called by cli_io_handler_show_peers() cli I/O handler.
  */
-static int peers_dump_peer(struct buffer *msg, struct stream_interface *si, struct peer *peer)
+static int peers_dump_peer(struct buffer *msg, struct stream_interface *si, struct peer *peer, int flags)
 {
 	struct connection *conn;
 	char pn[INET6_ADDRSTRLEN];
@@ -3480,6 +3490,7 @@ static int peers_dump_peer(struct buffer *msg, struct stream_interface *si, stru
 			chunk_appendf(&trash, "\n              table:%p id=%s update=%u localupdate=%u"
 			              " commitupdate=%u syncing=%u",
 			              t, t->id, t->update, t->localupdate, t->commitupdate, t->syncing);
+			if (flags & PEERS_SHOW_F_DICT) {
 				chunk_appendf(&trash, "\n        TX dictionary cache:");
 				count = 0;
 				for (i = 0; i < dcache->max_entries; i++) {
@@ -3506,6 +3517,9 @@ static int peers_dump_peer(struct buffer *msg, struct stream_interface *si, stru
 						      (char *)dcache->rx[i].de->value.key : "-");
 					count &= 0x3;
 				}
+			} else {
+				chunk_appendf(&trash, "\n        Dictionary cache not dumped (use \"show peers dict\")");
+			}
 		}
 	}
 
@@ -3576,7 +3590,7 @@ static int cli_io_handler_show_peers(struct appctx *appctx)
 					appctx->st2 = STAT_ST_END;
 			}
 			else {
-				if (!peers_dump_peer(&trash, si, appctx->ctx.cfgpeers.peer))
+				if (!peers_dump_peer(&trash, si, appctx->ctx.cfgpeers.peer, appctx->ctx.cfgpeers.flags))
 					goto out;
 
 				appctx->ctx.cfgpeers.peer = appctx->ctx.cfgpeers.peer->next;