snapshot of https://github.com/ThreeDotsLabs/watermill.git (master, 2026-09-15; blobs > 131072B omitted)

tools/pq/backend/postgres.go

@@ -0,0 +1,99 @@
+package backend
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/jmoiron/sqlx"
+	_ "github.com/lib/pq"
+
+	"github.com/ThreeDotsLabs/watermill/components/delay"
+	"github.com/ThreeDotsLabs/watermill/tools/pq/cli"
+)
+
+type PostgresMessage struct {
+	Offset   int    `db:"offset"`
+	UUID     string `db:"uuid"`
+	Payload  string `db:"payload"`
+	Metadata string `db:"metadata"`
+}
+
+type PostgresBackend struct {
+	db     *sqlx.DB
+	config cli.BackendConfig
+}
+
+func NewPostgresBackend(ctx context.Context, config cli.BackendConfig) (*PostgresBackend, error) {
+	dbURL := os.Getenv("DATABASE_URL")
+	if dbURL == "" {
+		return nil, fmt.Errorf("missing DATABASE_URL")
+	}
+
+	db, err := sqlx.Connect("postgres", dbURL)
+	if err != nil {
+		return nil, err
+	}
+
+	return &PostgresBackend{
+		db:     db,
+		config: config,
+	}, nil
+}
+
+func (r *PostgresBackend) AllMessages(ctx context.Context) ([]cli.Message, error) {
+	var dbMessages []PostgresMessage
+	err := r.db.SelectContext(ctx, &dbMessages, fmt.Sprintf(`SELECT "offset", uuid, payload, metadata FROM %v WHERE acked = false ORDER BY "offset"`, r.topic()))
+	if err != nil {
+		return nil, err
+	}
+
+	var messages []cli.Message
+
+	for _, dbMsg := range dbMessages {
+		var metadata map[string]string
+		err := json.Unmarshal([]byte(dbMsg.Metadata), &metadata)
+		if err != nil {
+			return nil, err
+		}
+
+		msg, err := cli.NewMessage(fmt.Sprint(dbMsg.Offset), dbMsg.UUID, dbMsg.Payload, metadata)
+		if err != nil {
+			return nil, err
+		}
+
+		messages = append(messages, msg)
+	}
+
+	return messages, nil
+}
+
+func (r *PostgresBackend) Requeue(ctx context.Context, msg cli.Message) error {
+	_, err := r.db.ExecContext(ctx, fmt.Sprintf(`UPDATE %v SET metadata = metadata::jsonb || jsonb_build_object($1::text, $2::text) WHERE "offset" = $3`, r.topic()),
+		delay.DelayedUntilKey, time.Now().UTC().Format(time.RFC3339), msg.ID,
+	)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (r *PostgresBackend) Ack(ctx context.Context, msg cli.Message) error {
+	_, err := r.db.ExecContext(ctx, fmt.Sprintf(`UPDATE %v SET acked = true WHERE "offset" = %v`, r.topic(), msg.ID))
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (r *PostgresBackend) topic() string {
+	if r.config.Topic != "" {
+		return fmt.Sprintf(`"watermill_%v"`, r.config.Topic)
+	}
+
+	return fmt.Sprintf(`"%v"`, r.config.RawTopic)
+}