lightningd: fix race where we do rescan before all plugins finish init.

The symptom (under heavy load and valgrind) in test_plugin_command:

	lightningd: common/json_stream.c:237: json_stream_output_: Assertion `!js->reader' failed.

This is because we try to call `getmanifest` again on `pay` which has not yet
responded to init.

The minimal fix for this is to keep proper state, so we can tell the
difference between "not yet called getmanifest" and "not yet finished
init".

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

lightningd/bitcoind.c

@@ -47,7 +47,7 @@ static void plugin_config_cb(const char *buffer,
 			     const jsmntok_t *idtok,
 			     struct plugin *plugin)
 {
-	plugin->plugin_state = CONFIGURED;
+	plugin->plugin_state = INIT_COMPLETE;
 	io_break(plugin);
 }
 
@@ -77,8 +77,9 @@ static void wait_plugin(struct bitcoind *bitcoind, const char *method,
 	 * before responding to `init`).
 	 * Note that lightningd/plugin will not send `init` to an already
 	 * configured plugin. */
-	if (p->plugin_state != CONFIGURED)
+	if (p->plugin_state == NEEDS_INIT)
 		config_plugin(p);
+
 	strmap_add(&bitcoind->pluginsmap, method, p);
 }
 

lightningd/plugin.c

@@ -969,6 +969,7 @@ bool plugin_parse_getmanifest_response(const char *buffer,
 	    !plugin_hooks_add(plugin, buffer, resulttok))
 		return false;
 
+	plugin->plugin_state = NEEDS_INIT;
 	return true;
 }
 
@@ -1167,7 +1168,7 @@ static void plugin_config_cb(const char *buffer,
 			     const jsmntok_t *idtok,
 			     struct plugin *plugin)
 {
-	plugin->plugin_state = CONFIGURED;
+	plugin->plugin_state = INIT_COMPLETE;
 }
 
 void
@@ -1240,7 +1241,7 @@ void plugins_config(struct plugins *plugins)
 {
 	struct plugin *p;
 	list_for_each(&plugins->plugins, p, list) {
-		if (p->plugin_state == UNCONFIGURED)
+		if (p->plugin_state == NEEDS_INIT)
 			plugin_config(p);
 	}
 

lightningd/plugin.h

@@ -22,8 +22,14 @@
 
 
 enum plugin_state {
+	/* We have to ask getmanifest */
 	UNCONFIGURED,
-	CONFIGURED
+	/* Got `getmanifest` reply, now we need to send `init`. */
+	NEEDS_INIT,
+	/* We have to get `init` response */
+	AWAITING_INIT_RESPONSE,
+	/* We have `init` response. */
+	INIT_COMPLETE
 };
 
 /**

lightningd/plugin_control.c

@@ -25,7 +25,7 @@ static struct command_result *plugin_dynamic_list_plugins(struct command *cmd)
 		json_object_start(response, NULL);
 		json_add_string(response, "name", p->cmd);
 		json_add_bool(response, "active",
-		              p->plugin_state == CONFIGURED);
+		              p->plugin_state == INIT_COMPLETE);
 		json_object_end(response);
 	}
 	json_array_end(response);
@@ -69,14 +69,14 @@ static void plugin_dynamic_config_callback(const char *buffer,
 {
 	struct plugin *p;
 
-	dp->plugin->plugin_state = CONFIGURED;
+	dp->plugin->plugin_state = INIT_COMPLETE;
 	/* Reset the timer only now so that we are either configured, or
 	 * killed. */
 	tal_free(dp->plugin->timeout_timer);
 	tal_del_destructor2(dp->plugin, plugin_dynamic_crash, dp);
 
 	list_for_each(&dp->plugin->plugins->plugins, p, list) {
-		if (p->plugin_state != CONFIGURED)
+		if (p->plugin_state != INIT_COMPLETE)
 			return;
 	}