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import {intervalUtils} from '@0xproject/utils';
import {BigNumber} from 'bignumber.js';
import {RBTree} from 'bintrees';
import * as _ from 'lodash';
import {ZeroEx} from '../0x';
import {SignedOrder, 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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