pytest: don't checksum plugins on startup in VALGRIND developer mode.

This loads up 20MB of plugins temporarily; we seem to be getting OOM
killed under CI and I wonder if this is contributing.

Doesn't significantly reduce runtime here, but I have lots of memory.

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

contrib/pyln-testing/pyln/testing/utils.py

@@ -675,6 +675,7 @@ class LightningNode(object):
                 self.daemon.opts["dev-debugger"] = os.getenv("DEBUG_SUBD")
             if valgrind:
                 self.daemon.env["LIGHTNINGD_DEV_NO_BACKTRACE"] = "1"
+                self.daemon.opts["dev-no-plugin-checksum"] = None
             else:
                 # Under valgrind, scanning can access uninitialized mem.
                 self.daemon.env["LIGHTNINGD_DEV_MEMLEAK"] = "1"

lightningd/lightningd.c

@@ -114,6 +114,7 @@ static struct lightningd *new_lightningd(const tal_t *ctx)
 	 * same exact code users will be running. */
 #if DEVELOPER
 	ld->dev_debug_subprocess = NULL;
+	ld->dev_no_plugin_checksum = false;
 	ld->dev_disconnect_fd = -1;
 	ld->dev_subdaemon_fail = false;
 	ld->dev_allow_localhost = false;

lightningd/lightningd.h

@@ -207,6 +207,9 @@ struct lightningd {
 	/* If we want to debug a subdaemon/plugin. */
 	const char *dev_debug_subprocess;
 
+	/* If we have --dev-no-plugin-checksum */
+	bool dev_no_plugin_checksum;
+
 	/* If we have a --dev-disconnect file */
 	int dev_disconnect_fd;
 

lightningd/options.c

@@ -584,6 +584,10 @@ static void dev_register_opts(struct lightningd *ld)
 	opt_register_early_arg("--dev-debugger=<subprocess>", opt_subprocess_debug, NULL,
 			 ld, "Invoke gdb at start of <subprocess>");
 
+	opt_register_early_noarg("--dev-no-plugin-checksum", opt_set_bool,
+				 &ld->dev_no_plugin_checksum,
+				 "Don't checksum plugins to detect changes");
+
 	opt_register_noarg("--dev-no-reconnect", opt_set_invbool,
 			   &ld->reconnect,
 			   "Disable automatic reconnect-attempts by this node, but accept incoming");

lightningd/plugin.c

@@ -209,9 +209,14 @@ static void destroy_plugin(struct plugin *p)
 	}
 }
 
-static u32 file_checksum(const char* path)
+static u32 file_checksum(struct lightningd *ld, const char *path)
 {
-	char *content = grab_file(tmpctx, path);
+	char *content;
+
+	if (IFDEV(ld->dev_no_plugin_checksum, false))
+		return 0;
+
+	content = grab_file(tmpctx, path);
 	if (content == NULL) return 0;
 	return crc32c(0, content, tal_count(content));
 }
@@ -231,7 +236,7 @@ struct plugin *plugin_register(struct plugins *plugins, const char* path TAKES,
 			if (important)
 				p_temp->important = true;
 			/* stop and restart plugin on different checksum */
-			chksum = file_checksum(path);
+			chksum = file_checksum(plugins->ld, path);
 			if (p_temp->checksum != chksum && !p_temp->important) {
 				plugin_kill(p_temp, LOG_INFORM,
 					    "Plugin changed, needs restart.");
@@ -246,7 +251,7 @@ struct plugin *plugin_register(struct plugins *plugins, const char* path TAKES,
 	p = tal(plugins, struct plugin);
 	p->plugins = plugins;
 	p->cmd = tal_strdup(p, path);
-	p->checksum = file_checksum(p->cmd);
+	p->checksum = file_checksum(plugins->ld, p->cmd);
 	p->shortname = path_basename(p, p->cmd);
 	p->start_cmd = start_cmd;
 

tests/test_plugin.py

@@ -2520,6 +2520,9 @@ plugin.run()
 
     # get a node that is not started so we can put a plugin in its lightning_dir
     n = node_factory.get_node(start=False)
+    if "dev-no-plugin-checksum" in n.daemon.opts:
+        del n.daemon.opts["dev-no-plugin-checksum"]
+
     lndir = n.daemon.lightning_dir
 
     # write hello world plugin to lndir/plugins