You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
52 lines
1.4 KiB
JavaScript
52 lines
1.4 KiB
JavaScript
const db = require('../service/db.js');
|
|
|
|
const coll = db.collection('system');
|
|
|
|
async function get(_id) {
|
|
const doc = await coll.findOne({ _id });
|
|
if (doc) return doc.value;
|
|
return null;
|
|
}
|
|
async function update(_id, update, config) {
|
|
await coll.findOneAndUpdate({ _id }, update, config);
|
|
return get(_id);
|
|
}
|
|
/**
|
|
* Increments the user counter.
|
|
* @returns {number} Integer value after increment.
|
|
*/
|
|
function incUserCounter() {
|
|
return update('userCounter', { $inc: { value: 1 } }, { upsert: true });
|
|
}
|
|
/**
|
|
* Increments the problem ID counter.
|
|
* @returns {number} Integer value before increment.
|
|
*/
|
|
function incPidCounter() {
|
|
return update('userCounter', { $inc: { value: 1 } }, { upsert: true });
|
|
}
|
|
async function acquireLock(name) {
|
|
const value = Math.floor(Math.random() * 0xFFFFFFFF);
|
|
try {
|
|
await coll.updateOne({ _id: `lock_${name}`, value: 0 }, { $set: { value } }, { upsert: true });
|
|
} catch (e) { return null; }
|
|
return value;
|
|
}
|
|
async function releaseLock(name, value) {
|
|
const result = await coll.updateOne({ _id: `lock_${name}`, value }, { $set: { value: 0 } });
|
|
return !!result.matchedCount;
|
|
}
|
|
async function releaseLockAnyway(name) {
|
|
await coll.updateOne({ _id: `lock_${name}` }, { $set: { value: 0 } });
|
|
return true;
|
|
}
|
|
module.exports = {
|
|
get,
|
|
update,
|
|
incPidCounter,
|
|
incUserCounter,
|
|
acquireLock,
|
|
releaseLock,
|
|
releaseLockAnyway,
|
|
};
|