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import {intervalUtils} from '@0xproject/utils';
import {BigNumber} from 'bignumber.js';
import {RBTree} from 'bintrees';
import * as _ from 'lodash';
import {ZeroExError} from '../types';
import {utils} from '../utils/utils';
const DEFAULT_EXPIRATION_MARGIN_MS = 0;
const DEFAULT_ORDER_EXPIRATION_CHECKING_INTERVAL_MS = 50;
/**
* This class includes the functionality to detect expired orders.
* It stores them in a min heap by expiration time and checks for expired ones every `orderExpirationCheckingIntervalMs`
*/
export class ExpirationWatcher {
private _orderHashByExpirationRBTree: RBTree<string>;
private _expiration: {[orderHash: string]: BigNumber} = {};
private _orderExpirationCheckingIntervalMs: number;
private _expirationMarginMs: number;
private _orderExpirationCheckingIntervalIdIfExists?: NodeJS.Timer;
constructor(expirationMarginIfExistsMs?: number,
orderExpirationCheckingIntervalIfExistsMs?: number) {
this._expirationMarginMs = expirationMarginIfExistsMs ||
DEFAULT_EXPIRATION_MARGIN_MS;
this._orderExpirationCheckingIntervalMs = expirationMarginIfExistsMs ||
DEFAULT_ORDER_EXPIRATION_CHECKING_INTERVAL_MS;
const scoreFunction = (orderHash: string) => this._expiration[orderHash].toNumber();
const comparator = (lhs: string, rhs: string) => scoreFunction(lhs) - scoreFunction(rhs);
this._orderHashByExpirationRBTree = new RBTree(comparator);
}
public subscribe(callback: (orderHash: string) => void): void {
if (!_.isUndefined(this._orderExpirationCheckingIntervalIdIfExists)) {
throw new Error(ZeroExError.SubscriptionAlreadyPresent);
}
this._orderExpirationCheckingIntervalIdIfExists = intervalUtils.setAsyncExcludingInterval(
this._pruneExpiredOrders.bind(this, callback), this._orderExpirationCheckingIntervalMs,
);
}
public unsubscribe(): void {
if (_.isUndefined(this._orderExpirationCheckingIntervalIdIfExists)) {
throw new Error(ZeroExError.SubscriptionNotFound);
}
intervalUtils.clearAsyncExcludingInterval(this._orderExpirationCheckingIntervalIdIfExists);
delete this._orderExpirationCheckingIntervalIdIfExists;
}
public addOrder(orderHash: string, expirationUnixTimestampMs: BigNumber): void {
this._expiration[orderHash] = expirationUnixTimestampMs;
this._orderHashByExpirationRBTree.insert(orderHash);
}
public removeOrder(orderHash: string): void {
this._orderHashByExpirationRBTree.remove(orderHash);
delete this._expiration[orderHash];
}
private _pruneExpiredOrders(callback: (orderHash: string) => void): void {
const currentUnixTimestampMs = utils.getCurrentUnixTimestampMs();
while (true) {
const hasTrakedOrders = this._orderHashByExpirationRBTree.size === 0;
if (hasTrakedOrders) {
break;
}
const nextOrderHashToExpire = this._orderHashByExpirationRBTree.min();
const hasNoExpiredOrders = this._expiration[nextOrderHashToExpire].greaterThan(
currentUnixTimestampMs.plus(this._expirationMarginMs),
);
const isSubscriptionActive = _.isUndefined(this._orderExpirationCheckingIntervalIdIfExists);
if (hasNoExpiredOrders || isSubscriptionActive) {
break;
}
const orderHash = this._orderHashByExpirationRBTree.min();
this._orderHashByExpirationRBTree.remove(orderHash);
delete this._expiration[orderHash];
callback(orderHash);
}
}
}
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