Documentation
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Overview ¶
Package lifecycle is the one way an entity's states are declared (ADR 0046): a thin constructor over github.com/qmuntal/stateless with external storage. The transition table (Configure(...).Permit(...)) stays in the module that owns the entity; this package gives it the storage seam and the single error.
A move fails with ErrInvalidTransition in two cases, and callers handle one: the trigger is not permitted from the state the machine read, or the storage write reports a compare-and-swap miss (the row changed after it was read). A worker treats the error as a stale event and finishes the job without a retry; an API handler answers 409. It is never swallowed.
Exit actions carry no side effects. stateless runs them before the write and does not roll them back, so an exit action that sends mail or enqueues a job would do so for a move that the write then refuses. Put effects in the same transaction as the write, after the move.
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ErrInvalidTransition = errors.New("invalid transition")
ErrInvalidTransition is returned by a fire call that no legal move satisfies: an unpermitted trigger, or a write that lost the compare-and-swap.
Functions ¶
func New ¶
func New[S comparable](storage Storage[S]) *stateless.StateMachine
New returns a state machine over the storage, with no states configured. Build one per entity use: it remembers the state it read to make the write conditional on it.
Types ¶
type Storage ¶
type Storage[S comparable] struct { Read func(ctx context.Context) (S, error) Write func(ctx context.Context, from, to S) (swapped bool, err error) }
Storage is where an entity's state lives. Write is the compare-and-swap: a conditional update that stores to only while the row is still in from (the state Read returned), and reports whether it did. A miss is (false, nil); a database fault is the error.
Source Files