lightningd: instantiate watchman at startup

Create watchman after setup_topology so it can queue bwatch RPC requests
and replay pending ops once the plugin is ready.  No subsystems register
watches yet — that lands in the wallet migration PR.

Author: sangbida

lightningd/lightningd.c

@@ -75,6 +75,7 @@
 #include <lightningd/plugin_hook.h>
 #include <lightningd/runes.h>
 #include <lightningd/subd.h>
+#include <lightningd/watchman.h>
 #include <sys/resource.h>
 #include <wallet/invoices.h>
 #include <wally_bip32.h>
@@ -1347,6 +1348,10 @@ int main(int argc, char *argv[])
 	setup_topology(ld->topology);
 	trace_span_end(ld->topology);
 
+	/*~ Stand up the watchman: it queues bwatch RPC requests until the
+	 * bwatch plugin reports ready, then replays them. */
+	ld->watchman = watchman_new(ld, ld);
+
 	db_begin_transaction(ld->wallet->db);
 	trace_span_start("delete_old_htlcs", ld->wallet);
 	wallet_delete_old_htlcs(ld->wallet);

lightningd/plugin.c

@@ -29,6 +29,7 @@
 #include <lightningd/plugin_control.h>
 #include <lightningd/plugin_hook.h>
 #include <lightningd/subd.h>
+#include <lightningd/watchman.h>
 
 /* Only this file can include this generated header! */
 # include <plugins/list_of_builtin_plugins_gen.h>
@@ -2087,6 +2088,7 @@ static void plugin_config_cb(const char *buffer,
 	}
 	if (tal_count(plugin->custom_msgs))
 		tell_connectd_custommsgs(plugin->plugins);
+	watchman_notify_plugin_ready(plugin->plugins->ld, plugin);
 	notify_plugin_started(plugin->plugins->ld, plugin);
 	check_plugins_initted(plugin->plugins);
 }

lightningd/test/run-find_my_abspath.c

@@ -222,6 +222,9 @@ struct wallet *wallet_new(struct lightningd *ld UNNEEDED, struct timers *timers
 /* Generated stub for wallet_sanity_check */
 bool wallet_sanity_check(struct wallet *w UNNEEDED)
 { fprintf(stderr, "wallet_sanity_check called!\n"); abort(); }
+/* Generated stub for watchman_new */
+struct watchman *watchman_new(const tal_t *ctx UNNEEDED, struct lightningd *ld UNNEEDED)
+{ fprintf(stderr, "watchman_new called!\n"); abort(); }
 /* AUTOGENERATED MOCKS END */
 
 struct logger *crashlog;

lightningd/watchman.c

@@ -135,8 +135,6 @@ static void load_pending_ops(struct watchman *wm)
 	}
 }
 
-static void watchman_on_plugin_ready(struct lightningd *ld, struct plugin *plugin);
-
 /* Apply --rescan: negative means absolute height (only go back),
  * positive means relative (go back N blocks from stored tip). */
 static void apply_rescan(struct watchman *wm, struct lightningd *ld)
@@ -167,16 +165,15 @@ struct watchman *watchman_new(const tal_t *ctx, struct lightningd *ld)
 	wm->ld = ld;
 	wm->pending_ops = tal_arr(wm, struct pending_op *, 0);
 
+	db_begin_transaction(ld->wallet->db);
 	load_pending_ops(wm);
 	load_tip(wm);
+	db_commit_transaction(ld->wallet->db);
 	apply_rescan(wm, ld);
 
 	log_info(ld->log, "Watchman: height=%u, %zu pending ops",
 		 wm->last_processed_height, tal_count(wm->pending_ops));
 
-	/* Replay pending ops exactly when bwatch transitions to INIT_COMPLETE. */
-	ld->plugins->on_plugin_ready = watchman_on_plugin_ready;
-
 	return wm;
 }
 
@@ -359,7 +356,7 @@ void watchman_replay_pending(struct lightningd *ld)
 
 /* Replay pending ops when bwatch is ready.  On a fresh node current_height
  * is still 0, so we defer to json_block_processed where it's guaranteed > 0. */
-static void watchman_on_plugin_ready(struct lightningd *ld, struct plugin *plugin)
+void watchman_notify_plugin_ready(struct lightningd *ld, struct plugin *plugin)
 {
 	struct watchman *wm = ld->watchman;
 

lightningd/watchman.h

@@ -7,6 +7,7 @@
 
 struct lightningd;
 struct pending_op;
+struct plugin;
 struct short_channel_id;
 
 /* lightningd's view of bwatch.  bwatch lives in a separate process and tells
@@ -58,6 +59,14 @@ typedef void (*depth_found_fn)(struct lightningd *ld,
 			       u32 depth,
 			       u32 blockheight);
 
+/**
+ * watchman_notify_plugin_ready - Called by plugin.c when any plugin reaches INIT_COMPLETE
+ *
+ * Checks whether the newly-ready plugin is bwatch and, if so, replays any
+ * pending watch operations that were queued before bwatch was available.
+ */
+void watchman_notify_plugin_ready(struct lightningd *ld, struct plugin *plugin);
+
 /**
  * watchman_new - Create and initialize a new watchman instance
  * @ctx: tal context to allocate from