1 files changed, 58 insertions, 0 deletions
diff --git a/packages/0x.js/src/order_watcher/expiration_watcher.ts b/packages/0x.js/src/order_watcher/expiration_watcher.ts
new file mode 100644
index 000000000..1a9e9a418
--- /dev/null
+++ b/packages/0x.js/src/order_watcher/expiration_watcher.ts
@@ -0,0 +1,58 @@
+import * as _ from 'lodash';
+import {BigNumber} from 'bignumber.js';
+import {utils} from '../utils/utils';
+import {intervalUtils} from '../utils/interval_utils';
+import {SignedOrder} from '../types';
+import {Heap} from '../utils/heap';
+import {ZeroEx} from '../0x';
+
+// Order prunning is very fast
+const DEFAULT_ORDER_EXPIRATION_CHECKING_INTERVAL_MS = 50;
+
+/**
+ * This class includes all the functionality related to prunning expired orders
+ */
+export class ExpirationWatcher {
+    private orderHashHeapByExpiration: Heap<string>;
+    private expiration: {[orderHash: string]: BigNumber};
+    private callbackIfExists?: (orderHash: string) => void;
+    private orderExpirationCheckingIntervalMs: number;
+    private orderExpirationCheckingIntervalIdIfExists?: NodeJS.Timer;
+    constructor(orderExpirationCheckingIntervalMs?: number) {
+        this.orderExpirationCheckingIntervalMs = orderExpirationCheckingIntervalMs ||
+                                                 DEFAULT_ORDER_EXPIRATION_CHECKING_INTERVAL_MS;
+        this.expiration = {};
+        const scoreFunction = ((orderHash: string) => {
+            return this.expiration[orderHash].toNumber();
+        }).bind(this);
+        this.orderHashHeapByExpiration = new Heap(scoreFunction);
+    }
+    public subscribe(callback: (orderHash: string) => void): void {
+        this.callbackIfExists = callback;
+        this.orderExpirationCheckingIntervalIdIfExists = intervalUtils.setAsyncExcludingInterval(
+            this.pruneExpiredOrders.bind(this), this.orderExpirationCheckingIntervalMs,
+        );
+    }
+    public unsubscribe(): void {
+        intervalUtils.clearAsyncExcludingInterval(this.orderExpirationCheckingIntervalIdIfExists as NodeJS.Timer);
+        delete this.callbackIfExists;
+    }
+    public addOrder(orderHash: string, expirationUnixTimestampSec: BigNumber): void {
+        this.expiration[orderHash] = expirationUnixTimestampSec;
+        // We don't remove hashes on order remove because it's slow (linear).
+        // We just skip them later if the order was already removed from the order watcher.
+        this.orderHashHeapByExpiration.push(orderHash);
+    }
+    private pruneExpiredOrders(): void {
+        const currentUnixTimestampSec = utils.getCurrentUnixTimestamp();
+        while (
+            this.orderHashHeapByExpiration.size() !== 0 &&
+            this.expiration[this.orderHashHeapByExpiration.head()].lessThan(currentUnixTimestampSec) &&
+            !_.isUndefined(this.callbackIfExists)
+        ) {
+            const orderHash = this.orderHashHeapByExpiration.pop();
+            delete this.expiration[orderHash];
+            this.callbackIfExists(orderHash);
+        }
+    }
+}