Forked from stevekrouse/dlock
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Forked from @stevekrouse/dlock! 🙏
Create valimport { acquireLock } from "https://esm.town/v/postpostscript/lock";
using exampleLock = await acquireLock();
// lock will be released when it goes out of context
Create valusing exampleLock = await acquireLock({
id: "lockExample",
retries: 0,
ttl: 5, // seconds
retryTimeout: 1000, // ms
});1
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import { sleep } from "https://deno.land/x/sleep/mod.ts";
import { fetchJSON } from "https://esm.town/v/stevekrouse/fetchJSON";
import { parentReference } from "https://esm.town/v/stevekrouse/parentReference";
import { searchParams } from "https://esm.town/v/stevekrouse/searchParams";
export async function acquireLock(opts?: LockOptions): Promise<{
release: () => Promise<LockResponse | undefined>;
}> {
let id = opts?.id ?? parentReference().userHandle + "-" + parentReference().valName;
id = id.replace(/[^\w]+/g, "_");
const ttl = opts?.ttl ?? 3;
async function handleError(error: string) {
if (typeof opts.retries === "number" && (opts.retry ?? 0) >= opts.retries) {
throw new LockError(`LockError: failed with message "${error || "unknown error"}"`);
}
await sleep((opts?.retryTimeout ?? 1000) / 1000);
return acquireLock({
...opts,
id,
ttl,
retry: (opts.retry ?? 0) + 1,
});
}
const res = await makeRequest(id, "acquire", {
ttl,
});
const { lease } = res;
if (!lease) {
return handleError(res.error);
}
const acquired = await makeRequest(id, "acquire", {
ttl,
lease,
});
if (!acquired.lease) {
return handleError(res.error);
}
let released = false;
async function release(): Promise<LockResponse | undefined> {
if (released) return;
released = true;
return makeRequest(id, "release", {
lease,
});
}
return {
release,
[Symbol.dispose]: release,
};
}
export class LockError extends Error {}
export type LockOptions = {
id?: string;
ttl?: number;
retry?: number;
retries?: number;
retryTimeout?: number;
};
export type LockResponse = {
lease?: number;
deadline: number;
error?: "string";
};
export async function makeRequest(id: string, method: "release" | "acquire", params): Promise<LockResponse> {
return fetchJSON(
`https://dlock.univalent.net/lock/${id}/${method}?${searchParams(params)}`,
);
}
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