MINOR: cli/pools: add pool name filtering capability to "show pools"

Now it becomes possible to match a pool name's prefix, for example:

  $ socat - /tmp/haproxy.sock <<< "show pools match quic byusage"
  Dumping pools usage. Use SIGQUIT to flush them.
    - Pool quic_conn_r (65560 bytes) : 1337 allocated (87653720 bytes), ...
    - Pool quic_crypto (1048 bytes) : 6685 allocated (7005880 bytes), ...
    - Pool quic_conn (4056 bytes) : 1337 allocated (5422872 bytes), ...
    - Pool quic_rxbuf (262168 bytes) : 8 allocated (2097344 bytes), ...
    - Pool quic_connne (184 bytes) : 9359 allocated (1722056 bytes), ...
    - Pool quic_frame (184 bytes) : 7938 allocated (1460592 bytes), ...
    - Pool quic_tx_pac (152 bytes) : 6454 allocated (981008 bytes), ...
    - Pool quic_tls_ke (56 bytes) : 12033 allocated (673848 bytes), ...
    - Pool quic_rx_pac (408 bytes) : 1596 allocated (651168 bytes), ...
    - Pool quic_tls_se (88 bytes) : 6685 allocated (588280 bytes), ...
    - Pool quic_cstrea (88 bytes) : 4011 allocated (352968 bytes), ...
    - Pool quic_tls_iv (24 bytes) : 12033 allocated (288792 bytes), ...
    - Pool quic_dgram (344 bytes) : 732 allocated (251808 bytes), ...
    - Pool quic_arng (56 bytes) : 4011 allocated (224616 bytes), ...
    - Pool quic_conn_c (152 bytes) : 1337 allocated (203224 bytes), ...
  Total: 15 pools, 109578176 bytes allocated, 109578176 used ...

In this case the reported total only concerns the dumped ones.

doc/management.txt

@@ -2897,7 +2897,7 @@ show peers [dict|-] [<peers section>]
             table:0x55871b5b46a0 id=stkt update=1 localupdate=0 \
               commitupdate=0 syncing=0
 
-show pools [byname|bysize|byusage] [<nb>]
+show pools [byname|bysize|byusage] [match <pfx>] [<nb>]
   Dump the status of internal memory pools. This is useful to track memory
   usage when suspecting a memory leak for example. It does exactly the same
   as the SIGQUIT when running in foreground except that it does not flush the
@@ -2905,7 +2905,29 @@ show pools [byname|bysize|byusage] [<nb>]
   sorted by pool name; if "bysize" is specified, it is sorted by item size in
   reverse order; if "byusage" is specified, it is sorted by total usage in
   reverse order, and only used entries are shown. It is also possible to limit
-  the output to the <nb> first entries (e.g. when sorting by usage).
+  the output to the <nb> first entries (e.g. when sorting by usage). Finally,
+  if "match" followed by a prefix is specified, then only pools whose name
+  starts with this prefix will be shown. The reported total only concerns pools
+  matching the filtering criteria. Example:
+
+    $ socat - /tmp/haproxy.sock <<< "show pools match quic byusage"
+    Dumping pools usage. Use SIGQUIT to flush them.
+      - Pool quic_conn_r (65560 bytes) : 1337 allocated (87653720 bytes), ...
+      - Pool quic_crypto (1048 bytes) : 6685 allocated (7005880 bytes), ...
+      - Pool quic_conn (4056 bytes) : 1337 allocated (5422872 bytes), ...
+      - Pool quic_rxbuf (262168 bytes) : 8 allocated (2097344 bytes), ...
+      - Pool quic_connne (184 bytes) : 9359 allocated (1722056 bytes), ...
+      - Pool quic_frame (184 bytes) : 7938 allocated (1460592 bytes), ...
+      - Pool quic_tx_pac (152 bytes) : 6454 allocated (981008 bytes), ...
+      - Pool quic_tls_ke (56 bytes) : 12033 allocated (673848 bytes), ...
+      - Pool quic_rx_pac (408 bytes) : 1596 allocated (651168 bytes), ...
+      - Pool quic_tls_se (88 bytes) : 6685 allocated (588280 bytes), ...
+      - Pool quic_cstrea (88 bytes) : 4011 allocated (352968 bytes), ...
+      - Pool quic_tls_iv (24 bytes) : 12033 allocated (288792 bytes), ...
+      - Pool quic_dgram (344 bytes) : 732 allocated (251808 bytes), ...
+      - Pool quic_arng (56 bytes) : 4011 allocated (224616 bytes), ...
+      - Pool quic_conn_c (152 bytes) : 1337 allocated (203224 bytes), ...
+    Total: 15 pools, 109578176 bytes allocated, 109578176 used ...
 
 show profiling [{all | status | tasks | memory}] [byaddr|bytime|aggr|<max_lines>]*
   Dumps the current profiling settings, one per line, as well as the command

src/pool.c

@@ -95,6 +95,7 @@ struct pool_dump_info {
 
 /* context used by "show pools" */
 struct show_pools_ctx {
+	char *prefix;  /* if non-null, match this prefix name for the pool */
 	int by_what; /* 0=no sort, 1=by name, 2=by item size, 3=by total alloc */
 	int maxcnt;  /* 0=no limit, other=max number of output entries */
 };
@@ -929,9 +930,10 @@ static int cmp_dump_pools_usage(const void *a, const void *b)
 
 /* This function dumps memory usage information into the trash buffer.
  * It may sort by a criterion if <by_what> is non-zero, and limit the
- * number of output lines if <max> is non-zero.
+ * number of output lines if <max> is non-zero. It may limit only to
+ * pools whose names start with <pfx> if <pfx> is non-null.
  */
-void dump_pools_to_trash(int by_what, int max)
+void dump_pools_to_trash(int by_what, int max, const char *pfx)
 {
 	struct pool_dump_info pool_info[POOLS_MAX_DUMPED_ENTRIES];
 	struct pool_head *entry;
@@ -950,6 +952,10 @@ void dump_pools_to_trash(int by_what, int max)
 		if (by_what == 3 && !entry->allocated)
 			continue;
 
+		/* verify the pool name if a prefix is requested */
+		if (pfx && strncmp(entry->name, pfx, strlen(pfx)) != 0)
+			continue;
+
 		if (!(pool_debugging & POOL_DBG_NO_CACHE)) {
 			for (cached = i = 0; i < global.nbthread; i++)
 				cached += entry->cache[i].count;
@@ -1004,7 +1010,7 @@ void dump_pools_to_trash(int by_what, int max)
 /* Dump statistics on pools usage. */
 void dump_pools(void)
 {
-	dump_pools_to_trash(0, 0);
+	dump_pools_to_trash(0, 0, NULL);
 	qfprintf(stderr, "%s", trash.area);
 }
 
@@ -1136,15 +1142,27 @@ static int cli_parse_show_pools(char **args, char *payload, struct appctx *appct
 		else if (strcmp(args[arg], "byusage") == 0) {
 			ctx->by_what = 3; // sort output by total allocated size
 		}
+		else if (strcmp(args[arg], "match") == 0 && *args[arg+1]) {
+			ctx->prefix = strdup(args[arg+1]); // only pools starting with this
+			arg++;
+		}
 		else if (isdigit((unsigned char)*args[arg])) {
 			ctx->maxcnt = atoi(args[arg]); // number of entries to dump
 		}
 		else
-			return cli_err(appctx, "Expects either 'byname', 'bysize', 'byusage', or a max number of output lines.\n");
+			return cli_err(appctx, "Expects either 'byname', 'bysize', 'byusage', 'match <pfx>', or a max number of output lines.\n");
 	}
 	return 0;
 }
 
+/* release the "show pools" context */
+static void cli_release_show_pools(struct appctx *appctx)
+{
+	struct show_pools_ctx *ctx = appctx->svcctx;
+
+	ha_free(&ctx->prefix);
+}
+
 /* This function dumps memory usage information onto the stream connector's
  * read buffer. It returns 0 as long as it does not complete, non-zero upon
  * completion. No state is used.
@@ -1153,7 +1171,7 @@ static int cli_io_handler_dump_pools(struct appctx *appctx)
 {
 	struct show_pools_ctx *ctx = appctx->svcctx;
 
-	dump_pools_to_trash(ctx->by_what, ctx->maxcnt);
+	dump_pools_to_trash(ctx->by_what, ctx->maxcnt, ctx->prefix);
 	if (applet_putchk(appctx, &trash) == -1)
 		return 0;
 	return 1;
@@ -1200,7 +1218,7 @@ INITCALL0(STG_REGISTER, pools_register_build_options);
 
 /* register cli keywords */
 static struct cli_kw_list cli_kws = {{ },{
-	{ { "show", "pools",  NULL }, "show pools [byname|bysize|byusage] [nb] : report information about the memory pools usage", cli_parse_show_pools, cli_io_handler_dump_pools },
+	{ { "show", "pools",  NULL }, "show pools [by*] [match <pfx>] [nb]     : report information about the memory pools usage", cli_parse_show_pools, cli_io_handler_dump_pools, cli_release_show_pools },
 	{{},}
 }};