first commit

backend/internal/service/ops_advisory_lock.go

@@ -0,0 +1,46 @@
+package service
+
+import (
+	"context"
+	"database/sql"
+	"hash/fnv"
+	"time"
+)
+
+func hashAdvisoryLockID(key string) int64 {
+	h := fnv.New64a()
+	_, _ = h.Write([]byte(key))
+	return int64(h.Sum64())
+}
+
+func tryAcquireDBAdvisoryLock(ctx context.Context, db *sql.DB, lockID int64) (func(), bool) {
+	if db == nil {
+		return nil, false
+	}
+	if ctx == nil {
+		ctx = context.Background()
+	}
+
+	conn, err := db.Conn(ctx)
+	if err != nil {
+		return nil, false
+	}
+
+	acquired := false
+	if err := conn.QueryRowContext(ctx, "SELECT pg_try_advisory_lock($1)", lockID).Scan(&acquired); err != nil {
+		_ = conn.Close()
+		return nil, false
+	}
+	if !acquired {
+		_ = conn.Close()
+		return nil, false
+	}
+
+	release := func() {
+		unlockCtx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+		defer cancel()
+		_, _ = conn.ExecContext(unlockCtx, "SELECT pg_advisory_unlock($1)", lockID)
+		_ = conn.Close()
+	}
+	return release, true
+}