bkpr: annotate an account with the block at which it's been resolved

Due to the way that onchain channel closes work, there is often a delay
between when the funding output is spent and the channel is considered
'closed'.

Once *every* downstream utxo of a channel has landed on chain, we
annotate the account with the resolving blockheight.

This gives us some insight into whether or not the chain fees etc of a
channel are going to update further and allows for a natural marker to
prune data (at a later date)

plugins/bkpr/bookkeeper.c

@@ -756,7 +756,11 @@ listpeers_done(struct command *cmd, const char *buf,
 			   "Unable to find account %s in listpeers",
 			   info->acct->name);
 
-	/* FIXME: maybe mark channel as 'onchain_resolved' */
+	/* Maybe mark acct as onchain resolved */
+	db_begin_transaction(db);
+	if (info->acct->closed_event_db_id)
+		maybe_mark_account_onchain(db, info->acct);
+	db_commit_transaction(db);
 	return notification_handled(cmd);
 }
 
@@ -1078,9 +1082,11 @@ parse_and_log_chain_move(struct command *cmd,
 		return command_still_pending(cmd);
 	}
 
-	/* FIXME: maybe mark channel as 'onchain_resolved' */
-	if (err)
-		plugin_err(cmd->plugin, err);
+	/* Maybe mark acct as onchain resolved */
+	db_begin_transaction(db);
+	if (acct->closed_event_db_id)
+		maybe_mark_account_onchain(db, acct);
+	db_commit_transaction(db);
 
 	return notification_handled(cmd);;
 }

plugins/bkpr/recorder.c

@@ -334,7 +334,8 @@ bool find_txo_chain(const tal_t *ctx,
 	open_ev = find_chain_event_by_id(ctx, db,
 					 *acct->open_event_db_id);
 
-	*sets = tal_arr(ctx, struct txo_set *, 0);
+	if (sets)
+		*sets = tal_arr(ctx, struct txo_set *, 0);
 	txids = tal_arr(ctx, struct bitcoin_txid *, 0);
 	tal_arr_expand(&txids, &open_ev->outpoint.txid);
 
@@ -379,12 +380,51 @@ bool find_txo_chain(const tal_t *ctx,
 			}
 		}
 
-		tal_arr_expand(sets, set);
+		if (sets)
+			tal_arr_expand(sets, set);
 	}
 
 	return is_complete;
 }
 
+void maybe_mark_account_onchain(struct db *db, struct account *acct)
+{
+	const u8 *ctx = tal(NULL, u8);
+	if (find_txo_chain(ctx, db, acct, NULL)) {
+		/* Ok now we find the max block height of the
+		 * spending chain_events for this channel */
+		bool ok;
+
+		struct db_stmt *stmt = db_prepare_v2(db,
+				SQL("SELECT"
+				    " blockheight"
+				    " FROM chain_events"
+				    " WHERE account_id = ?"
+				    "  AND spending_txid IS NOT NULL"
+				    " ORDER BY blockheight DESC"
+				    " LIMIT 1"));
+
+		db_bind_u64(stmt, 0, acct->db_id);
+		db_query_prepared(stmt);
+		ok = db_step(stmt);
+		assert(ok);
+
+		acct->onchain_resolved_block = db_col_int(stmt, "blockheight");
+		tal_free(stmt);
+
+		/* Ok, now we update the account with this blockheight */
+		stmt = db_prepare_v2(db, SQL("UPDATE accounts SET"
+					     "  onchain_resolved_block = ?"
+					     " WHERE"
+					     " id = ?"));
+		db_bind_int(stmt, 0, acct->onchain_resolved_block);
+		db_bind_u64(stmt, 1, acct->db_id);
+		db_exec_prepared_v2(take(stmt));
+	}
+
+	tal_free(ctx);
+}
+
 struct chain_event *find_chain_event_by_id(const tal_t *ctx,
 					   struct db *db,
 					   u64 event_db_id)

plugins/bkpr/recorder.h

@@ -117,6 +117,13 @@ char *maybe_update_onchain_fees(const tal_t *ctx,
 			        struct db *db,
 			        struct bitcoin_txid *txid);
 
+/* Have all the outputs for this account's close tx
+ * been resolved onchain? If so, update the account with the
+ * highest blockheight that has a resolving tx in it.
+ *
+ * The point of this is to allow us to prune data, eventually */
+void maybe_mark_account_onchain(struct db *db, struct account *acct);
+
 /* Log a channel event */
 void log_channel_event(struct db *db,
 		       const struct account *acct,