Run discards on the state-driven coordinator

internal/store/coordinate.go

@@ -0,0 +1,69 @@
+package store
+
+import (
+	"context"
+	"database/sql"
+)
+
+type Work struct {
+	AbandonedMerges []string
+	StartMerges     []ClaimedMerge
+	FinalizeMerges  []FinalizingMerge
+	StartDiscards   []string
+	FinishDiscards  []string
+}
+
+func (s *Store) Coordinate(ctx context.Context) (Work, error) {
+	work := Work{}
+	err := s.write(ctx, func(tx *sql.Tx, emit emitFunc) error {
+		var err error
+		work.AbandonedMerges, err = abandonMerges(ctx, tx, emit)
+		if err != nil {
+			return err
+		}
+		err = claimHeldMerges(ctx, tx, emit)
+		if err != nil {
+			return err
+		}
+		work.StartMerges, err = startableMerges(ctx, tx)
+		if err != nil {
+			return err
+		}
+		work.FinalizeMerges, err = finalizingMerges(ctx, tx)
+		if err != nil {
+			return err
+		}
+		_, err = tx.ExecContext(ctx, `UPDATE tasks SET discard_state = 'closing'
+			WHERE status = 'active' AND discard_state = 'running'
+				AND NOT EXISTS (SELECT 1 FROM agent_sessions s WHERE s.id = tasks.discard_session AND s.state = 'running')`)
+		if err != nil {
+			return err
+		}
+		work.StartDiscards, err = queryIDs(ctx, tx, `SELECT id FROM tasks WHERE status = 'active' AND discard_state = 'held' AND NOT `+implementerRunning)
+		if err != nil {
+			return err
+		}
+		work.FinishDiscards, err = queryIDs(ctx, tx, `SELECT id FROM tasks WHERE status = 'active' AND discard_state = 'closing'`)
+		return err
+	})
+	return work, err
+}
+
+func queryIDs(ctx context.Context, tx *sql.Tx, query string) ([]string, error) {
+	rows, err := tx.QueryContext(ctx, query)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	ids := []string{}
+	for rows.Next() {
+		id := ""
+		err = rows.Scan(&id)
+		if err != nil {
+			return nil, err
+		}
+		ids = append(ids, id)
+	}
+	return ids, rows.Err()
+}