lightningd: require explicit LIGHTNINGD_DEV_MEMLEAK env var to do memleak.

Otherwise every allocation and free is slowed down.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/lightningd.c

@@ -74,7 +74,8 @@ static struct lightningd *new_lightningd(const tal_t *ctx,
 	ld->dev_disconnect_fd = -1;
 	ld->dev_hsm_seed = NULL;
 	ld->dev_subdaemon_fail = false;
-	memleak_init(ld, backtrace_state);
+	if (getenv("LIGHTNINGD_DEV_MEMLEAK"))
+		memleak_init(ld, backtrace_state);
 #endif
 
 	list_head_init(&ld->peers);

lightningd/memdump.c

@@ -144,6 +144,10 @@ static void json_memleak(struct command *cmd,
 {
 	struct json_result *response = new_json_result(cmd);
 
+	if (!getenv("LIGHTNINGD_DEV_MEMLEAK"))
+		command_fail(cmd,
+			     "Leak detection needs $LIGHTNINGD_DEV_MEMLEAK");
+
 	json_object_start(response, NULL);
 	scan_mem(cmd, response, cmd->ld);
 	json_object_end(response);

tests/test_lightningd.py

@@ -108,6 +108,7 @@ class NodeFactory(object):
             daemon.cmd_line.append("--dev-disconnect=dev_disconnect")
         if DEVELOPER:
             daemon.cmd_line.append("--dev-fail-on-subdaemon-fail")
+            daemon.env["LIGHTNINGD_DEV_MEMLEAK"] = "1"
             if VALGRIND:
                 daemon.env["LIGHTNINGD_DEV_NO_BACKTRACE"] = "1"
         opts = [] if options is None else options