lightningd: move the state changes into struct channel.

And instead of loading them in listpeerchannels, use them.  This means
listpeerchannels no longer touches the db.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Fixed: JSONRPC: `listpeerchannels` (and thus, pay) sped up on very large nodes.

lightningd/channel.c

@@ -312,6 +312,7 @@ struct channel *new_unsaved_channel(struct peer *peer,
 	channel->stable_conn_timer = NULL;
 	/* Nothing happened yet */
 	memset(&channel->stats, 0, sizeof(channel->stats));
+	channel->state_changes = tal_arr(channel, struct state_change_entry, 0);
 
 	/* No shachain yet */
 	channel->their_shachain.id = 0;
@@ -448,7 +449,8 @@ struct channel *new_channel(struct peer *peer, u64 dbid,
 			    /* NULL or stolen */
 			    struct peer_update *peer_update STEALS,
 			    u64 last_stable_connection,
-			    const struct channel_stats *stats)
+			    const struct channel_stats *stats,
+			    struct state_change_entry *state_changes STEALS)
 {
 	struct channel *channel = tal(peer->ld, struct channel);
 	struct amount_msat htlc_min, htlc_max;
@@ -606,6 +608,8 @@ struct channel *new_channel(struct peer *peer, u64 dbid,
 	channel->last_stable_connection = last_stable_connection;
 	channel->stable_conn_timer = NULL;
 	channel->stats = *stats;
+	channel->state_changes = tal_steal(channel, state_changes);
+
  	/* Populate channel->channel_gossip */
 	channel_gossip_init(channel, take(peer_update));
 
@@ -836,8 +840,6 @@ void channel_set_state(struct channel *channel,
 		       enum state_change reason,
 		       char *why)
 {
-	struct timeabs timestamp;
-
 	/* set closer, if known */
 	if (channel_state_closing(state) && channel->closer == NUM_SIDES) {
 		if (reason == REASON_LOCAL)   channel->closer = LOCAL;
@@ -865,10 +867,17 @@ void channel_set_state(struct channel *channel,
 
 	/* plugin notification channel_state_changed and DB entry */
 	if (state != old_state) {  /* see issue #4029 */
-		timestamp = time_now();
+		struct state_change_entry change;
+		change.timestamp = time_now();
+		change.old_state = old_state;
+		change.new_state = state;
+		change.cause = reason;
+		change.message = tal_strdup(channel->state_changes, why);
+		tal_arr_expand(&channel->state_changes, change);
+
 		wallet_state_change_add(channel->peer->ld->wallet,
 					channel->dbid,
-					timestamp,
+					change.timestamp,
 					old_state,
 					state,
 					reason,
@@ -877,7 +886,7 @@ void channel_set_state(struct channel *channel,
 					     &channel->peer->id,
 					     &channel->cid,
 					     channel->scid,
-					     timestamp,
+					     change.timestamp,
 					     old_state,
 					     state,
 					     reason,

lightningd/channel.h

@@ -325,6 +325,9 @@ struct channel {
 
 	/* Our stats */
 	struct channel_stats stats;
+
+	/* Our change history. */
+	struct state_change_entry *state_changes;
 };
 
 /* Is channel owned (and should be talking to peer) */
@@ -407,7 +410,8 @@ struct channel *new_channel(struct peer *peer, u64 dbid,
 			    /* NULL or stolen */
 			    struct peer_update *peer_update STEALS,
 			    u64 last_stable_connection,
-			    const struct channel_stats *stats);
+			    const struct channel_stats *stats,
+			    struct state_change_entry *state_changes STEALS);
 
 /* new_inflight - Create a new channel_inflight for a channel */
 struct channel_inflight *new_inflight(struct channel *channel,

lightningd/opening_control.c

@@ -220,7 +220,8 @@ wallet_commit_channel(struct lightningd *ld,
 			      ld->config.ignore_fee_limits,
 			      NULL,
 			      0,
-			      &zero_channel_stats);
+			      &zero_channel_stats,
+			      tal_arr(NULL, struct state_change_entry, 0));
 
 	/* Now we finally put it in the database. */
 	wallet_channel_insert(ld->wallet, channel);
@@ -1598,7 +1599,8 @@ static struct channel *stub_chan(struct command *cmd,
 			      false,
 			      NULL,
 			      0,
-			      &zero_channel_stats);
+			      &zero_channel_stats,
+			      tal_arr(NULL, struct state_change_entry, 0));
 
 	/* We don't want to gossip about this, ever. */
 	channel->channel_gossip = tal_free(channel->channel_gossip);

lightningd/peer_control.c

@@ -820,7 +820,6 @@ static void NON_NULL_ARGS(1, 2, 4, 5) json_add_channel(struct command *cmd,
 	struct lightningd *ld = cmd->ld;
 	struct amount_msat funding_msat;
 	struct amount_sat peer_funded_sats;
-	struct state_change_entry *state_changes;
 	const struct peer_update *peer_update;
 	u32 feerate;
 
@@ -1161,19 +1160,18 @@ static void NON_NULL_ARGS(1, 2, 4, 5) json_add_channel(struct command *cmd,
 	json_add_num(response, "max_accepted_htlcs",
 		     channel->our_config.max_accepted_htlcs);
 
-	state_changes = wallet_state_change_get(tmpctx, ld->wallet, channel->dbid);
 	json_array_start(response, "state_changes");
-	for (size_t i = 0; i < tal_count(state_changes); i++) {
+	for (size_t i = 0; i < tal_count(channel->state_changes); i++) {
 		json_object_start(response, NULL);
 		json_add_timeiso(response, "timestamp",
-				 state_changes[i].timestamp);
+				 channel->state_changes[i].timestamp);
 		json_add_string(response, "old_state",
-				channel_state_str(state_changes[i].old_state));
+				channel_state_str(channel->state_changes[i].old_state));
 		json_add_string(response, "new_state",
-				channel_state_str(state_changes[i].new_state));
+				channel_state_str(channel->state_changes[i].new_state));
 		json_add_string(response, "cause",
-				channel_change_state_reason_str(state_changes[i].cause));
-		json_add_string(response, "message", state_changes[i].message);
+				channel_change_state_reason_str(channel->state_changes[i].cause));
+		json_add_string(response, "message", channel->state_changes[i].message);
 		json_object_end(response);
 	}
 	json_array_end(response);

wallet/test/run-db.c

@@ -192,7 +192,8 @@ struct channel *new_channel(struct peer *peer UNNEEDED, u64 dbid UNNEEDED,
 			    /* NULL or stolen */
 			    struct peer_update *peer_update STEALS UNNEEDED,
 			    u64 last_stable_connection UNNEEDED,
-			    const struct channel_stats *stats UNNEEDED)
+			    const struct channel_stats *stats UNNEEDED,
+			    struct state_change_entry *state_changes STEALS UNNEEDED)
 { fprintf(stderr, "new_channel called!\n"); abort(); }
 /* Generated stub for new_coin_wallet_deposit */
 struct chain_coin_mvt *new_coin_wallet_deposit(const tal_t *ctx UNNEEDED,

wallet/test/run-wallet.c

@@ -1997,7 +1997,8 @@ static bool test_channel_inflight_crud(struct lightningd *ld, const tal_t *ctx)
 			   false,
 			   NULL,
 			   0,
-			   stats);
+			   stats,
+			   tal_arr(NULL, struct state_change_entry, 0));
 	db_begin_transaction(w->db);
 	CHECK(!wallet_err);
 	wallet_channel_insert(w, chan);

wallet/wallet.c

@@ -1522,6 +1522,7 @@ static struct channel *wallet_stmt2channel(struct wallet *w, struct db_stmt *stm
 	bool ignore_fee_limits;
 	struct peer_update *remote_update;
 	struct channel_stats stats;
+	struct state_change_entry *state_changes;
 
 	peer_dbid = db_col_u64(stmt, "peer_id");
 	peer = find_peer_by_dbid(w->ld, peer_dbid);
@@ -1725,6 +1726,8 @@ static struct channel *wallet_stmt2channel(struct wallet *w, struct db_stmt *stm
 				      &stats.out_msatoshi_fulfilled,
 				      AMOUNT_MSAT(0));
 
+	/* Stolen by new_channel */
+	state_changes = wallet_state_change_get(NULL, w, db_col_u64(stmt, "id"));
 	chan = new_channel(peer, db_col_u64(stmt, "id"),
 			   &wshachain,
 			   channel_state_in_db(db_col_int(stmt, "state")),
@@ -1787,7 +1790,8 @@ static struct channel *wallet_stmt2channel(struct wallet *w, struct db_stmt *stm
 			   ignore_fee_limits,
 			   remote_update,
 			   db_col_u64(stmt, "last_stable_connection"),
-			   &stats);
+			   &stats,
+			   state_changes);
 
 	if (!wallet_channel_load_inflights(w, chan)) {
 		tal_free(chan);