From ee0c13eefe442de69c27a23f7cd557b4970c532d Mon Sep 17 00:00:00 2001
From: ZmnSCPxj jxPCSnmZ <zmnscpxj@protonmail.com>
Date: Mon, 23 Nov 2020 11:46:13 +0800
Subject: [PATCH] lightningd/plugin.c: Make plugin-exclusive loop support
 multiple plugins.

---
 lightningd/plugin.c      | 20 ++++++++++++++------
 lightningd/plugin.h      | 10 +++++++---
 lightningd/plugin_hook.c | 15 +++++++++++----
 3 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/lightningd/plugin.c b/lightningd/plugin.c
index 75d12a8a299e..f28ab277efc2 100644
--- a/lightningd/plugin.c
+++ b/lightningd/plugin.c
@@ -1715,20 +1715,28 @@ void plugin_request_send(struct plugin *plugin,
 	req->stream = NULL;
 }
 
-void *plugin_exclusive_loop(struct plugin *plugin)
+void *plugins_exclusive_loop(struct plugin **plugins)
 {
 	void *ret;
+	size_t i;
+	bool last = false;
+	assert(tal_count(plugins) != 0);
 
-	io_conn_out_exclusive(plugin->stdin_conn, true);
-	io_conn_exclusive(plugin->stdout_conn, true);
+	for (i = 0; i < tal_count(plugins); ++i) {
+		io_conn_out_exclusive(plugins[i]->stdin_conn, true);
+		io_conn_exclusive(plugins[i]->stdout_conn, true);
+	}
 
 	/* We don't service timers here, either! */
 	ret = io_loop(NULL, NULL);
 
-	io_conn_out_exclusive(plugin->stdin_conn, false);
-	if (io_conn_exclusive(plugin->stdout_conn, false))
+	for (i = 0; i < tal_count(plugins); ++i) {
+		io_conn_out_exclusive(plugins[i]->stdin_conn, false);
+		last = io_conn_exclusive(plugins[i]->stdout_conn, false);
+	}
+	if (last)
 		fatal("Still io_exclusive after removing plugin %s?",
-		      plugin->cmd);
+		      plugins[tal_count(plugins) - 1]->cmd);
 
 	return ret;
 }
diff --git a/lightningd/plugin.h b/lightningd/plugin.h
index 070c0184ad8e..6f9c7ab667ea 100644
--- a/lightningd/plugin.h
+++ b/lightningd/plugin.h
@@ -304,12 +304,16 @@ void json_add_opt_disable_plugins(struct json_stream *response,
 				  const struct plugins *plugins);
 
 /**
- * Used by db hooks which can't have any other I/O while talking to plugin.
+ * Used by db hooks which can't have any other I/O while talking to
+ * hooked plugins.
  *
- * Returns output of io_loop() (ie. whatever gets passed to io_break()
+ * @param plugins - a `tal`-allocated array of plugins that are the
+ * only ones we talk to.
+ *
+ * @return output of io_loop() (ie. whatever gets passed to io_break()
  * to end exclusive loop).
  */
-void *plugin_exclusive_loop(struct plugin *plugin);
+void *plugins_exclusive_loop(struct plugin **plugins);
 
 /**
  * Add a directory to the plugin path to automatically load plugins.
diff --git a/lightningd/plugin_hook.c b/lightningd/plugin_hook.c
index 321cb75fec53..9413fa3047b8 100644
--- a/lightningd/plugin_hook.c
+++ b/lightningd/plugin_hook.c
@@ -330,12 +330,18 @@ void plugin_hook_db_sync(struct db *db)
 	struct jsonrpc_request *req;
 	struct plugin_hook_request *ph_req;
 	void *ret;
-	struct plugin *plugin;
+	struct plugin **plugins;
+	size_t i;
 
 	const char **changes = db_changes(db);
 	if (tal_count(hook->hooks) == 0)
 		return;
 
+	plugins = notleak(tal_arr(NULL, struct plugin *,
+				  tal_count(hook->hooks)));
+	for (i = 0; i < tal_count(hook->hooks); ++i)
+		plugins[i] = hook->hooks[i]->plugin;
+
 	ph_req = notleak(tal(hook->hooks, struct plugin_hook_request));
 	/* FIXME: do IO logging for this! */
 	req = jsonrpc_request_start(NULL, hook->name, NULL, NULL,
@@ -344,7 +350,7 @@ void plugin_hook_db_sync(struct db *db)
 
 	ph_req->hook = hook;
 	ph_req->db = db;
-	plugin = ph_req->plugin = hook->hooks[0]->plugin;
+	ph_req->plugin = hook->hooks[0]->plugin;
 
 	json_add_num(req->stream, "data_version", db_data_version_get(db));
 
@@ -359,12 +365,13 @@ void plugin_hook_db_sync(struct db *db)
 	/* We can be called on way out of an io_loop, which is already breaking.
 	 * That will make this immediately return; save the break value and call
 	 * again, then hand it onwards. */
-	ret = plugin_exclusive_loop(plugin);
+	ret = plugins_exclusive_loop(plugins);
 	if (ret != ph_req) {
-		void *ret2 = plugin_exclusive_loop(plugin);
+		void *ret2 = plugins_exclusive_loop(plugins);
 		assert(ret2 == ph_req);
 		io_break(ret);
 	}
+	tal_free(plugins);
 }
 
 static void add_deps(const char ***arr,