Documentation
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Overview ¶
Package postgres provides transactional completion adapters for dureq handlers whose business state lives in PostgreSQL. By committing a business write and the dureq completion marker in the same SQL transaction, handlers achieve exactly-once outcome semantics — even under retries and crashes.
Usage:
func handleOrder(ctx context.Context, order OrderPayload) error {
tx, _ := db.BeginTx(ctx, nil)
defer tx.Rollback()
// Business write.
tx.ExecContext(ctx, "INSERT INTO orders (...) VALUES (...)", ...)
// Mark this run as completed — same TX.
if err := postgres.CompleteTx(ctx, tx); err != nil {
return err // already completed on a previous attempt
}
return tx.Commit()
}
Index ¶
- Variables
- func CheckpointTx(ctx context.Context, tx *sql.Tx, step string, data []byte) error
- func CompleteTx(ctx context.Context, tx *sql.Tx) error
- func EnsureTable(ctx context.Context, db *sql.DB) error
- func FailTx(ctx context.Context, tx *sql.Tx, err error) error
- func IsCheckpointed(ctx context.Context, db *sql.DB, step string) (bool, []byte, error)
- func IsCompleted(ctx context.Context, db *sql.DB) (bool, error)
Constants ¶
This section is empty.
Variables ¶
var ErrAlreadyCompleted = errors.New("dureq: run already completed")
ErrAlreadyCompleted is returned when a run has already been marked as completed. The handler should treat this as a successful no-op (the previous attempt committed).
Functions ¶
func CheckpointTx ¶
CheckpointTx records an intermediate checkpoint within a long-running handler. The step name distinguishes different checkpoints within the same run. On retry, the handler can call IsCheckpointed to skip already-completed steps.
func CompleteTx ¶
CompleteTx inserts a completion marker for the current run inside the given transaction. If the run was already completed (duplicate), ErrAlreadyCompleted is returned and the caller should skip further work (or commit as no-op).
The run ID and job ID are extracted from the context (set by the dureq worker).
func EnsureTable ¶
EnsureTable creates the dureq_completions table if it does not exist. Call this once during application startup or in a migration.
func FailTx ¶
FailTx records a failure marker for the current run. This is useful when the handler wants to record that it attempted but failed, preventing re-execution of side effects on retry.
func IsCheckpointed ¶
IsCheckpointed checks whether a specific checkpoint step has been recorded.
Types ¶
This section is empty.
Source Files