1 files changed, 56 insertions, 0 deletions
diff --git a/packages/testnet-faucets/src/ts/request_queue.ts b/packages/testnet-faucets/src/ts/request_queue.ts
new file mode 100644
index 000000000..20f2833a1
--- /dev/null
+++ b/packages/testnet-faucets/src/ts/request_queue.ts
@@ -0,0 +1,56 @@
+import * as _ from 'lodash';
+import * as timers from 'timers';
+
+// HACK: web3 leaks XMLHttpRequest into the global scope and causes requests to hang
+// because they are using the wrong XHR package.
+// Filed issue: https://github.com/ethereum/web3.js/issues/844
+// tslint:disable-next-line:ordered-imports
+import * as Web3 from 'web3';
+
+const MAX_QUEUE_SIZE = 500;
+const DEFAULT_QUEUE_INTERVAL_MS = 1000;
+
+export class RequestQueue {
+    protected queueIntervalMs: number;
+    protected queue: string[];
+    protected queueIntervalId: NodeJS.Timer;
+    protected web3: Web3;
+    constructor(web3: any) {
+        this.queueIntervalMs = DEFAULT_QUEUE_INTERVAL_MS;
+        this.queue = [];
+
+        this.web3 = web3;
+
+        this.start();
+    }
+    public add(recipientAddress: string): boolean {
+        if (this.isFull()) {
+            return false;
+        }
+        this.queue.push(recipientAddress);
+        return true;
+    }
+    public size(): number {
+        return this.queue.length;
+    }
+    public isFull(): boolean {
+        return this.size() >= MAX_QUEUE_SIZE;
+    }
+    protected start() {
+        this.queueIntervalId = timers.setInterval(() => {
+            const recipientAddress = this.queue.shift();
+            if (_.isUndefined(recipientAddress)) {
+                return;
+            }
+            // tslint:disable-next-line:no-floating-promises
+            this.processNextRequestFireAndForgetAsync(recipientAddress);
+        }, this.queueIntervalMs);
+    }
+    protected stop() {
+        clearInterval(this.queueIntervalId);
+    }
+    // tslint:disable-next-line:prefer-function-over-method
+    protected async processNextRequestFireAndForgetAsync(recipientAddress: string) {
+        throw new Error('Expected processNextRequestFireAndForgetAsync to be implemented by a subclass');
+    }
+}