9 declarations
Async semaphore for concurrency limiting.
With Infinity permits, acquire() always resolves immediately.
constructortype new (permits: number): AsyncSemaphore
permitsnumberacquiretype (): Promise<void>
Promise<void>releasetype (): void
voidAsyncStatus <T>(): Deferred<T> Creates an object with a promise and its resolve/reject handlers.
Deferred<T> Deferred<T> A deferred object with a promise and its resolve/reject handlers.
TpromisePromise<T>resolve(value: T) => voidreject(reason: any) => void<T>(items: Iterable<T>, concurrency: number, fn: (item: T, index: number) => void | Promise<void>, signal?: AbortSignal | undefined): Promise<...> Runs a function on each item with controlled concurrency. Like map_concurrent but doesn't collect results (more efficient for side effects).
itemsitems to process
Iterable<T>concurrencymaximum number of concurrent operations
numberfnfunction to apply to each item
(item: T, index: number) => void | Promise<void>signal?optional AbortSignal to cancel processing
AbortSignal | undefinedPromise<void> await each_concurrent(
file_paths,
5, // max 5 concurrent deletions
async (path) => { await unlink(path); },
);(value: unknown): value is Promise<unknown> Checks if value is a Promise (or thenable).
valueunknownboolean <T, R>(items: Iterable<T>, concurrency: number, fn: (item: T, index: number) => R | Promise<R>, signal?: AbortSignal | undefined): Promise<...> Maps over items with controlled concurrency, preserving input order.
itemsitems to process
Iterable<T>concurrencymaximum number of concurrent operations
numberfnfunction to apply to each item
(item: T, index: number) => R | Promise<R>signal?optional AbortSignal to cancel processing
AbortSignal | undefinedPromise<R[]> promise resolving to array of results in same order as input
const results = await map_concurrent(
file_paths,
5, // max 5 concurrent reads
async (path) => readFile(path, 'utf8'),
);<T, R>(items: Iterable<T>, concurrency: number, fn: (item: T, index: number) => R | Promise<R>, signal?: AbortSignal | undefined): Promise<...> Like map_concurrent but collects all results/errors instead of failing fast.
Returns an array of settlement objects matching the Promise.allSettled pattern.
On abort, resolves with partial results: completed items keep their real settlements, in-flight and un-started items are settled as rejected with the abort reason.
itemsitems to process
Iterable<T>concurrencymaximum number of concurrent operations
numberfnfunction to apply to each item
(item: T, index: number) => R | Promise<R>signal?optional AbortSignal to cancel processing
AbortSignal | undefinedPromise<PromiseSettledResult<R>[]> promise resolving to array of PromiseSettledResult objects in input order
const results = await map_concurrent_settled(urls, 5, fetch);
for (const [i, result] of results.entries()) {
if (result.status === 'fulfilled') {
console.log(`${urls[i]}: ${result.value.status}`);
} else {
console.error(`${urls[i]}: ${result.reason}`);
}
}(duration?: number): Promise<void> Waits for the given duration before resolving.
durationnumber0Promise<void>