| [a762898] | 1 | /**
|
|---|
| 2 | * A counting semaphore for async functions that manages available permits.
|
|---|
| 3 | * Semaphores are mainly used to limit the number of concurrent async tasks.
|
|---|
| 4 | *
|
|---|
| 5 | * Each `acquire` operation takes a permit or waits until one is available.
|
|---|
| 6 | * Each `release` operation adds a permit, potentially allowing a waiting task to proceed.
|
|---|
| 7 | *
|
|---|
| 8 | * The semaphore ensures fairness by maintaining a FIFO (First In, First Out) order for acquirers.
|
|---|
| 9 | *
|
|---|
| 10 | * @example
|
|---|
| 11 | * const sema = new Semaphore(2);
|
|---|
| 12 | *
|
|---|
| 13 | * async function task() {
|
|---|
| 14 | * await sema.acquire();
|
|---|
| 15 | * try {
|
|---|
| 16 | * // This code can only be executed by two tasks at the same time
|
|---|
| 17 | * } finally {
|
|---|
| 18 | * sema.release();
|
|---|
| 19 | * }
|
|---|
| 20 | * }
|
|---|
| 21 | *
|
|---|
| 22 | * task();
|
|---|
| 23 | * task();
|
|---|
| 24 | * task(); // This task will wait until one of the previous tasks releases the semaphore.
|
|---|
| 25 | */
|
|---|
| 26 | declare class Semaphore {
|
|---|
| 27 | /**
|
|---|
| 28 | * The maximum number of concurrent operations allowed.
|
|---|
| 29 | * @type {number}
|
|---|
| 30 | */
|
|---|
| 31 | capacity: number;
|
|---|
| 32 | /**
|
|---|
| 33 | * The number of available permits.
|
|---|
| 34 | * @type {number}
|
|---|
| 35 | */
|
|---|
| 36 | available: number;
|
|---|
| 37 | private deferredTasks;
|
|---|
| 38 | /**
|
|---|
| 39 | * Creates an instance of Semaphore.
|
|---|
| 40 | * @param {number} capacity - The maximum number of concurrent operations allowed.
|
|---|
| 41 | *
|
|---|
| 42 | * @example
|
|---|
| 43 | * const sema = new Semaphore(3); // Allows up to 3 concurrent operations.
|
|---|
| 44 | */
|
|---|
| 45 | constructor(capacity: number);
|
|---|
| 46 | /**
|
|---|
| 47 | * Acquires a semaphore, blocking if necessary until one is available.
|
|---|
| 48 | * @returns {Promise<void>} A promise that resolves when the semaphore is acquired.
|
|---|
| 49 | *
|
|---|
| 50 | * @example
|
|---|
| 51 | * const sema = new Semaphore(1);
|
|---|
| 52 | *
|
|---|
| 53 | * async function criticalSection() {
|
|---|
| 54 | * await sema.acquire();
|
|---|
| 55 | * try {
|
|---|
| 56 | * // This code section cannot be executed simultaneously
|
|---|
| 57 | * } finally {
|
|---|
| 58 | * sema.release();
|
|---|
| 59 | * }
|
|---|
| 60 | * }
|
|---|
| 61 | */
|
|---|
| 62 | acquire(): Promise<void>;
|
|---|
| 63 | /**
|
|---|
| 64 | * Releases a semaphore, allowing one more operation to proceed.
|
|---|
| 65 | *
|
|---|
| 66 | * @example
|
|---|
| 67 | * const sema = new Semaphore(1);
|
|---|
| 68 | *
|
|---|
| 69 | * async function task() {
|
|---|
| 70 | * await sema.acquire();
|
|---|
| 71 | * try {
|
|---|
| 72 | * // This code can only be executed by two tasks at the same time
|
|---|
| 73 | * } finally {
|
|---|
| 74 | * sema.release(); // Allows another waiting task to proceed.
|
|---|
| 75 | * }
|
|---|
| 76 | * }
|
|---|
| 77 | */
|
|---|
| 78 | release(): void;
|
|---|
| 79 | }
|
|---|
| 80 |
|
|---|
| 81 | export { Semaphore };
|
|---|