API reference › @evolu/common › Task

JavaScript-native structured concurrency.

Core Types

Name	Description
AbortError	Error returned when a Task is aborted via AbortSignal.
Fiber	Fiber is a handle to a running Task that can be awaited, aborted, or disposed.
Run	Runs a Task with structured concurrency semantics.
RunSnapshot	A recursive snapshot of a Run tree.
NextTask	A Task that can complete with a value, signal done, or fail.
RunState	The lifecycle state of a Run.
Task	JavaScript-native structured concurrency.
AbortError	Error returned when a Task is aborted via AbortSignal.

Creating Run

Name	Description
CreateRun	Factory type for creating root Run instances.
RunStoppedError	Abort reason indicating a Run can no longer start new Tasks.
createRun	Creates root Run.
runStoppedError	Shared RunStoppedError instance used as the default AbortError.reason when a Task is started on a non-running Run.
RunStoppedError	Abort reason indicating a Run can no longer start new Tasks.

Abort masking

Name	Description
AbortMask	Abort mask depth for a Run or Fiber.
AbortMask	Abort mask depth for a Run or Fiber.
unabortable	Makes a Task unabortable.
unabortableMask	Like unabortable, but provides restore to restore abortability for specific tasks.

Composition

Name	Description
AllAbortError	Abort reason used by all when aborting remaining tasks.
AllSettledAbortError	Abort reason used by allSettled when aborted externally.
AnyAbortError	Abort reason used by any when aborting remaining tasks.
CollectOptions	Options for all, allSettled, map, and mapSettled.
FetchError	Error returned when a fetch Task fails.
MapAbortError	Abort reason used by map when aborting remaining tasks.
RaceLostError	Abort reason for tasks that lose a race.
RepeatAttempt	Info passed to repeat RepeatOptions.onRepeat callback.
RepeatOptions	Options for repeat.
RetryAttempt	Info passed to retry RetryOptions.onRetry callback.
RetryError	Error returned when all retry attempts are exhausted.
RetryOptions	Options for retry.
TimeoutError	Typed error returned by timeout when a task exceeds its time limit.
allAbortError	AllAbortError used as abort reason in all.
AllAbortError	Abort reason used by all when aborting remaining tasks.
allSettledAbortError	AllSettledAbortError used as abort reason in allSettled.
AllSettledAbortError	Abort reason used by allSettled when aborted externally.
anyAbortError	AnyAbortError used as abort reason in any.
AnyAbortError	Abort reason used by any when aborting remaining tasks.
FetchError	Error returned when a fetch Task fails.
mapAbortError	MapAbortError used as abort reason in map.
MapAbortError	Abort reason used by map when aborting remaining tasks.
raceLostError	RaceLostError used as abort reason in race.
RaceLostError	Abort reason for tasks that lose a race.
timeoutError	TimeoutError used as abort reason in timeout.
TimeoutError	Typed error returned by timeout when a task exceeds its time limit.
yieldNow	Yields execution to allow other work to proceed.
all	Fails fast on first error across multiple Tasks.
allSettled	Completes all Tasks regardless of individual failures.
any	Returns the first Task that succeeds.
callback	Creates a Task from a callback-based API.
concurrently	Runs tasks concurrently instead of sequentially.
fetch	Creates a Task that wraps the native Fetch API.
map	Maps values to Tasks, failing fast on first error.
mapSettled	Maps values to Tasks, completing all regardless of failures.
race	Returns a Task that completes first.
repeat	Repeats a Task according to a Schedule.
retry	Wraps a Task with retry logic.
sleep	Pauses execution for a specified duration.
timeout	Wraps a Task with a time limit.

Concurrency primitives

Name	Description
Deferred	A value that can be resolved later.
DeferredDisposedError	Abort reason used when a Deferred is disposed.
Gate	A blocking Task — like a gate.
LeaderLock	Cross-platform leader lock abstraction.
LeaderLockDep	-
Mutex	A mutex (mutual exclusion) that ensures only one Task runs at a time.
MutexByKey	A keyed Mutex registry.
MutexRef	Ref protected by a Mutex.
Semaphore	A semaphore that limits the number of concurrent Tasks.
SemaphoreByKey	A keyed Semaphore registry.
SemaphoreDisposedError	Abort reason used when a Semaphore is disposed.
Concurrency	Maximum number of concurrent Tasks.
deferredDisposedError	DeferredDisposedError used as abort reason in createDeferred.
DeferredDisposedError	Abort reason used when a Deferred is disposed.
semaphoreDisposedError	SemaphoreDisposedError used as abort reason in createSemaphore.
SemaphoreDisposedError	Abort reason used when a Semaphore is disposed.
createDeferred	Creates a Deferred.
createGate	Creates a Gate that starts closed.
createInMemoryLeaderLock	Creates an in-process LeaderLock.
createMutex	Creates a Mutex.
createMutexByKey	Creates a MutexByKey.
createMutexRef	Creates a MutexRef with the given initial immutable value.
createSemaphore	Creates a Semaphore that limits concurrent Tasks.
createSemaphoreByKey	Creates a SemaphoreByKey.

Monitoring

Name	Description
RunConfig	Configuration for Run behavior.
RunEvent	Events emitted by a Run for monitoring and debugging.
RunEventData	The event-specific payload of a RunEvent.
RunSnapshotState	RunSnapshot state Type.
RunEvent	Events emitted by a Run for monitoring and debugging.
RunEventData	The event-specific payload of a RunEvent.
RunSnapshotState	RunSnapshot state Type.

Type utilities

Type Alias	Description
AnyTask	Shorthand for a Task with any type parameters.
InferFiberDeps	Extracts the deps type from a Fiber.
InferFiberErr	Extracts the error type from a Fiber.
InferFiberOk	Extracts the value type from a Fiber.
InferTaskDeps	Extracts the deps type from a Task.
InferTaskDone	Extracts the done value type from a NextTask.
InferTaskErr	Extracts the error type from a Task.
InferTaskOk	Extracts the value type from a Task.

Interfaces

Interface	Description
CreateMutexByKeyOptions	Options for createMutexByKey.
CreateSemaphoreByKeyOptions	Options for createSemaphoreByKey.
RunConfigDep	-
RunStateDisposing	Base interface for objects with a discriminant type property.
RunStateRunning	Base interface for objects with a discriminant type property.
RunStateSettled	Base interface for objects with a discriminant type property.
SemaphoreSnapshot	Snapshot returned by Semaphore.snapshot.

Type Aliases

Type Alias	Description
AnyAllFailed	Tie-breaker for any when all tasks fail.
RunDeps	Default deps provided by createRun.