unleash-server/dist/lib/util/db-lock.js

Unleash is an enterprise ready feature flag service. It provides different strategies for handling feature flags.

import pg from 'pg';
const { Client } = pg;
export const defaultLockKey = 479341;
export const defaultTimeout = 30 * 60000;
const defaultOptions = {
    timeout: defaultTimeout,
    lockKey: defaultLockKey,
    logger: { ...console, fatal: console.error },
};
export const withDbLock = (dbConfig, config = defaultOptions) => (fn) => async (...args) => {
    const client = new Client({
        ...dbConfig,
    });
    let lockAcquired = false;
    try {
        await client.connect();
        // wait to obtain a lock
        await client.query('SELECT pg_advisory_lock($1)', [config.lockKey]);
        lockAcquired = true;
        const promise = fn(...args);
        const timeoutPromise = new Promise((_, reject) => setTimeout(() => reject(new Error('Query read timeout')), config.timeout));
        const result = (await Promise.race([promise, timeoutPromise]));
        return result;
    }
    catch (e) {
        config.logger.error(`Locking error: ${e.message}`);
        throw e;
    }
    finally {
        if (lockAcquired) {
            await client.query('SELECT pg_advisory_unlock($1)', [
                config.lockKey,
            ]);
        }
        await client.end();
    }
};
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