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WIP: Web Locks API initial implementation #417

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tshemsedinov
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Refs: #416

@belochub
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@tshemsedinov isn't it supposed to be compliant with the spec for Web Locks API? It defines two interfaces: LockManager and Lock, both of which are not present in the implementation in this PR. Thus I don't think it should be called 'Web Locks API implementation' unless you implement the interfaces mentioned above.

@tshemsedinov
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Yes, but it's just proof of concept and WIP. @belochub I'll implement also
options: { mode: "exclusive" | "shared", signal <AbortSignal>, ifAvailable <boolean> } and extend specification with timeout, recursive locking and locking queue in each thread, error handling in critical section, etc.

lib/locks.js Outdated Show resolved Hide resolved
lib/locks.js Outdated Show resolved Hide resolved
const prev = Atomics.exchange(this.flag, 0, LOCKED);
if (prev === LOCKED) return;
this.owner = true;
this.trying = false;
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Is this.trying needed?

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We can use mutex.queue.length > 0 instead

return this.tryEnter();
}

tryEnter() {
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Perhaps we can merge tryEnter and enterIfAvailable by adding lock argument and a few checks?

lib/locks.js Outdated
enterIfAvailable(lock) {
if (this.owner) return lock.callback();
const prev = Atomics.exchange(this.flag, 0, LOCKED);
if (prev === LOCKED) return lock.callback();
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According to https://wicg.github.io/web-locks/#api-lock-manager-request when ifAvailable is true the callback must be passed a lock (boolean) argument that signifies whether it got the lock or not.

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In new implementation:

  • Mutex class is merged into Lock class
  • Added: AbortError, AbortSignal, AbortController

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3 participants