TxSemaphore.tryAcquireN — API

TxSemaphore.tryAcquireNconsteffect/TxSemaphore.ts:380

(self: TxSemaphore, n: number): Effect.Effect<boolean>

Tries to acquire the specified number of permits from the semaphore without blocking, returning true if successful or false if not enough permits are available.

When to use

Use to attempt a multi-permit acquisition without retrying when not enough permits are available.

Example (Trying to acquire multiple permits)

import { Console, Effect, TxSemaphore } from "effect"

const program = Effect.gen(function*() {
  const semaphore = yield* TxSemaphore.make(3)

  // Try to acquire 2 permits (should succeed)
  const first = yield* TxSemaphore.tryAcquireN(semaphore, 2)
  yield* Console.log(`First try (2 permits): ${first}`) // true

  // Try to acquire 2 more permits (should fail, only 1 left)
  const second = yield* TxSemaphore.tryAcquireN(semaphore, 2)
  yield* Console.log(`Second try (2 permits): ${second}`) // false
})

combinatorsacquireN tryAcquire

Source effect/TxSemaphore.ts:38011 lines

export const tryAcquireN = (self: TxSemaphore, n: number): Effect.Effect<boolean> => {
  if (n <= 0) {
    return Effect.die(new Error("Number of permits must be positive"))
  }
  return TxRef.modify(self.permitsRef, (permits: number) => {
    if (permits >= n) {
      return [true, permits - n]
    }
    return [false, permits]
  })
}