db: add column for first block of channel.

This determines how far we go back.

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

wallet/db.c

@@ -145,6 +145,11 @@ char *dbmigrations[] = {
     "  VALUES('next_pay_index', "
     "    COALESCE((SELECT MAX(pay_index) FROM invoices WHERE state=1), 0) + 1"
     "  );",
+    /* Create first_block field; initialize from channel id if any.
+     * This fails for channels still awaiting lockin, but that only applies to
+     * pre-release software, so it's forgivable. */
+    "ALTER TABLE channels ADD first_blocknum INTEGER;",
+    "UPDATE channels SET first_blocknum=CAST(short_channel_id AS INTEGER) WHERE short_channel_id IS NOT NULL;",
     NULL,
 };
 

wallet/wallet.c

@@ -597,6 +597,25 @@ bool wallet_channels_load_active(struct wallet *w, struct list_head *peers)
 	return ok;
 }
 
+u32 wallet_channels_first_blocknum(struct wallet *w)
+{
+	int err;
+	u32 first_blocknum;
+	sqlite3_stmt *stmt =
+	    db_query(__func__, w->db,
+		     "SELECT MIN(first_blocknum) FROM channels WHERE state >= %d AND state != %d;",
+		     OPENINGD, CLOSINGD_COMPLETE);
+
+	err = sqlite3_step(stmt);
+	if (err == SQLITE_ROW && sqlite3_column_type(stmt, 1) != SQLITE_NULL)
+		first_blocknum = sqlite3_column_int(stmt, 1);
+	else
+		first_blocknum = UINT32_MAX;
+
+	sqlite3_finalize(stmt);
+	return first_blocknum;
+}
+
 void wallet_channel_config_save(struct wallet *w, struct channel_config *cc)
 {
 	sqlite3_stmt *stmt;

wallet/wallet.h

@@ -242,6 +242,15 @@ bool wallet_peer_by_nodeid(struct wallet *w, const struct pubkey *nodeid,
  */
 bool wallet_channels_load_active(struct wallet *w, struct list_head *peers);
 
+/**
+ * wallet_channels_first_blocknum - get first block we're interested in.
+ *
+ * @w: wallet to load from.
+ *
+ * Returns UINT32_MAX if nothing interesting.
+ */
+u32 wallet_channels_first_blocknum(struct wallet *w);
+
 /**
  * wallet_extract_owned_outputs - given a tx, extract all of our outputs
  */