Create a new IterableQueueMapperSimple
Function which is called for every item in input.
Expected to return a Promise or value.
The mapper should handle all errors and not allow an error to be thrown
out of the mapper function as this enables the best handling of errors
closest to the time that they occur.
If the mapper function does allow an error to be thrown then the
errors will be accumulated in the errors property.
IterableQueueMapperSimple options
Optional concurrency?: numberNumber of items to accept for mapping before requiring the caller to wait for one to complete.
4
Private Readonly _donePrivate Readonly _errorsPrivate _isPrivate Readonly _mapperPrivate Readonly _writerAccumulated errors from background mapperss
Reference to the errors array
Note that this property can be periodically checked
during processing and errors can be .pop()'d off of the array
and logged / handled as desired. Errors .pop()'d off of the array
will no longer be available in the array on the next check.
Indicates if all background mappers have finished.
true if .onIdle() has been called and finished all background writes
Private discardAccept a request for sending in the background if a concurrency slot is available. Else, do not return until a concurrency slot is freed up. This provides concurrency background writes with back pressure to prevent the caller from getting too far ahead.
MUST await onIdle for background mapperss to finish
Private workerGenerated using TypeDoc
Accepts queue items via
enqueueand calls themapperon them with specified concurrency, storing themapperresult in a queue of specified max size, before being iterated / read by the caller. Theenqueuemethod will block if the queue is full, until an item is read.Remarks
Note: the name is somewhat of a misnomer as this wraps
IterableQueueMapperbut is not itself anIterable.Accepts items for mapping in the background, discards the results, but accumulates exceptions in the
errorsproperty.Allows up to
concurrencymappers to be in progress beforeenqueuewill block until a mapper completes.