Organize async task queues by network

6 files changed, 156 insertions, 171 deletions

diff --git a/packages/testnet-faucets/src/ts/dispatch_queue.ts b/packages/testnet-faucets/src/ts/dispatch_queue.ts
new file mode 100644
index 000000000..94d094203
--- /dev/null
+++ b/packages/testnet-faucets/src/ts/dispatch_queue.ts
@@ -0,0 +1,47 @@
+import { intervalUtils } from '@0xproject/utils';
+import * as _ from 'lodash';
+
+const MAX_QUEUE_SIZE = 500;
+const DEFAULT_QUEUE_INTERVAL_MS = 1000;
+
+export class DispatchQueue {
+    private _queueIntervalMs: number;
+    private _queue: Array<() => Promise<void>>;
+    private _queueIntervalIdIfExists?: NodeJS.Timer;
+    constructor() {
+        this._queueIntervalMs = DEFAULT_QUEUE_INTERVAL_MS;
+        this._queue = [];
+        this._start();
+    }
+    public add(task: () => Promise<void>): boolean {
+        if (this.isFull()) {
+            return false;
+        }
+        this._queue.push(task);
+        return true;
+    }
+    public size(): number {
+        return this._queue.length;
+    }
+    public isFull(): boolean {
+        return this.size() >= MAX_QUEUE_SIZE;
+    }
+    public stop() {
+        if (!_.isUndefined(this._queueIntervalIdIfExists)) {
+            intervalUtils.clearAsyncExcludingInterval(this._queueIntervalIdIfExists);
+        }
+    }
+    private _start() {
+        this._queueIntervalIdIfExists = intervalUtils.setAsyncExcludingInterval(
+            async () => {
+                const task = this._queue.shift();
+                if (_.isUndefined(task)) {
+                    return Promise.resolve();
+                }
+                await task();
+            },
+            this._queueIntervalMs,
+            _.noop,
+        );
+    }
+}
diff --git a/packages/testnet-faucets/src/ts/dispense_asset_tasks.ts b/packages/testnet-faucets/src/ts/dispense_asset_tasks.ts
new file mode 100644
index 000000000..c70458fbe
--- /dev/null
+++ b/packages/testnet-faucets/src/ts/dispense_asset_tasks.ts
@@ -0,0 +1,54 @@
+import { ZeroEx } from '0x.js';
+import { BigNumber, promisify } from '@0xproject/utils';
+import * as _ from 'lodash';
+import * as Web3 from 'web3';
+
+import { configs } from './configs';
+import { errorReporter } from './error_reporter';
+import { utils } from './utils';
+
+const DISPENSE_AMOUNT_ETHER = 0.1;
+const DISPENSE_AMOUNT_TOKEN = 0.1;
+
+export const dispenseAssetTasks = {
+    dispenseEtherTask(recipientAddress: string, web3: Web3) {
+        return async () => {
+            utils.consoleLog(`Processing ETH ${recipientAddress}`);
+            const sendTransactionAsync = promisify(web3.eth.sendTransaction);
+            try {
+                const txHash = await sendTransactionAsync({
+                    from: configs.DISPENSER_ADDRESS,
+                    to: recipientAddress,
+                    value: web3.toWei(DISPENSE_AMOUNT_ETHER, 'ether'),
+                });
+                utils.consoleLog(`Sent ${DISPENSE_AMOUNT_ETHER} ETH to ${recipientAddress} tx: ${txHash}`);
+            } catch (err) {
+                utils.consoleLog(`Unexpected err: ${err} - ${JSON.stringify(err)}`);
+                await errorReporter.reportAsync(err);
+            }
+        };
+    },
+    dispenseTokenTask(recipientAddress: string, tokenSymbol: string, zeroEx: ZeroEx) {
+        return async () => {
+            utils.consoleLog(`Processing ${tokenSymbol} ${recipientAddress}`);
+            const amountToDispense = new BigNumber(DISPENSE_AMOUNT_TOKEN);
+            try {
+                const token = await zeroEx.tokenRegistry.getTokenBySymbolIfExistsAsync(tokenSymbol);
+                if (_.isUndefined(token)) {
+                    throw new Error(`Unsupported asset type: ${tokenSymbol}`);
+                }
+                const baseUnitAmount = ZeroEx.toBaseUnitAmount(amountToDispense, token.decimals);
+                const txHash = await zeroEx.token.transferAsync(
+                    token.address,
+                    configs.DISPENSER_ADDRESS,
+                    recipientAddress,
+                    baseUnitAmount,
+                );
+                utils.consoleLog(`Sent ${amountToDispense} ZRX to ${recipientAddress} tx: ${txHash}`);
+            } catch (err) {
+                utils.consoleLog(`Unexpected err: ${err} - ${JSON.stringify(err)}`);
+                await errorReporter.reportAsync(err);
+            }
+        };
+    },
+};
diff --git a/packages/testnet-faucets/src/ts/ether_request_queue.ts b/packages/testnet-faucets/src/ts/ether_request_queue.ts
deleted file mode 100644
index 710d49f39..000000000
--- a/packages/testnet-faucets/src/ts/ether_request_queue.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-import { promisify } from '@0xproject/utils';
-import * as _ from 'lodash';
-
-import { configs } from './configs';
-import { errorReporter } from './error_reporter';
-import { RequestQueue } from './request_queue';
-import { utils } from './utils';
-
-const DISPENSE_AMOUNT_ETHER = 0.1;
-
-export class EtherRequestQueue extends RequestQueue {
-    protected async _processNextRequestFireAndForgetAsync(recipientAddress: string) {
-        utils.consoleLog(`Processing ETH ${recipientAddress}`);
-        const sendTransactionAsync = promisify(this._web3.eth.sendTransaction);
-        try {
-            const txHash = await sendTransactionAsync({
-                from: configs.DISPENSER_ADDRESS,
-                to: recipientAddress,
-                value: this._web3.toWei(DISPENSE_AMOUNT_ETHER, 'ether'),
-            });
-            utils.consoleLog(`Sent ${DISPENSE_AMOUNT_ETHER} ETH to ${recipientAddress} tx: ${txHash}`);
-        } catch (err) {
-            utils.consoleLog(`Unexpected err: ${err} - ${JSON.stringify(err)}`);
-            await errorReporter.reportAsync(err);
-        }
-    }
-}
diff --git a/packages/testnet-faucets/src/ts/handler.ts b/packages/testnet-faucets/src/ts/handler.ts
index d96b90802..ce7a81eba 100644
--- a/packages/testnet-faucets/src/ts/handler.ts
+++ b/packages/testnet-faucets/src/ts/handler.ts
@@ -1,5 +1,4 @@
 import { Order, SignedOrder, ZeroEx } from '0x.js';
-import { NonceTrackerSubprovider } from '@0xproject/subproviders';
 import { BigNumber } from '@0xproject/utils';
 import * as express from 'express';
 import * as _ from 'lodash';
@@ -10,17 +9,23 @@ import * as Web3 from 'web3';
 // we are not running in a browser env.
 // Filed issue: https://github.com/ethereum/web3.js/issues/844
 (global as any).XMLHttpRequest = undefined;
+import { NonceTrackerSubprovider } from '@0xproject/subproviders';
 import ProviderEngine = require('web3-provider-engine');
 import HookedWalletSubprovider = require('web3-provider-engine/subproviders/hooked-wallet');
 import RpcSubprovider = require('web3-provider-engine/subproviders/rpc');
 
 import { configs } from './configs';
-import { EtherRequestQueue } from './ether_request_queue';
+import { DispatchQueue } from './dispatch_queue';
+import { dispenseAssetTasks } from './dispense_asset_tasks';
 import { idManagement } from './id_management';
-import { RequestQueue } from './request_queue';
 import { rpcUrls } from './rpc_urls';
 import { utils } from './utils';
-import { ZRXRequestQueue } from './zrx_request_queue';
+
+interface NetworkConfig {
+    dispatchQueue: DispatchQueue;
+    web3: Web3;
+    zeroEx: ZeroEx;
+}
 
 interface ItemByNetworkId<T> {
     [networkId: string]: T;
@@ -35,30 +40,7 @@ enum RequestedAssetType {
 const FIVE_DAYS_IN_MS = 4.32e8; // TODO: make this configurable
 
 export class Handler {
-    private _zeroExByNetworkId: ItemByNetworkId<ZeroEx> = {};
-    private _etherRequestQueueByNetworkId: ItemByNetworkId<RequestQueue> = {};
-    private _zrxRequestQueueByNetworkId: ItemByNetworkId<RequestQueue> = {};
-    private static _dispenseAsset(
-        req: express.Request,
-        res: express.Response,
-        requestQueueByNetworkId: ItemByNetworkId<RequestQueue>,
-        requestedAssetType: RequestedAssetType,
-    ) {
-        const requestQueue = _.get(requestQueueByNetworkId, req.params.networkId);
-        if (_.isUndefined(requestQueue)) {
-            res.status(400).send('UNSUPPORTED_NETWORK_ID');
-            return;
-        }
-        const didAddToQueue = requestQueue.add(req.params.recipient);
-        if (!didAddToQueue) {
-            res.status(503).send('QUEUE_IS_FULL');
-            return;
-        }
-        utils.consoleLog(
-            `Added ${req.params.recipient} to queue: ${requestedAssetType} networkId: ${req.params.networkId}`,
-        );
-        res.status(200).end();
-    }
+    private _networkConfigByNetworkId: ItemByNetworkId<NetworkConfig> = {};
     private static _createProviderEngine(rpcUrl: string) {
         const engine = new ProviderEngine();
         engine.addProvider(new NonceTrackerSubprovider());
@@ -79,35 +61,31 @@ export class Handler {
                 networkId: +networkId,
             };
             const zeroEx = new ZeroEx(web3.currentProvider, zeroExConfig);
-            this._zeroExByNetworkId[networkId] = zeroEx;
-            this._etherRequestQueueByNetworkId[networkId] = new EtherRequestQueue(web3);
-            this._zrxRequestQueueByNetworkId[networkId] = new ZRXRequestQueue(web3, zeroEx);
+            const dispatchQueue = new DispatchQueue();
+            this._networkConfigByNetworkId[networkId] = {
+                dispatchQueue,
+                web3,
+                zeroEx,
+            };
         });
     }
     public getQueueInfo(req: express.Request, res: express.Response) {
         res.setHeader('Content-Type', 'application/json');
         const queueInfo = _.mapValues(rpcUrls, (rpcUrl: string, networkId: string) => {
-            const etherRequestQueue = this._etherRequestQueueByNetworkId[networkId];
-            const zrxRequestQueue = this._zrxRequestQueueByNetworkId[networkId];
+            const dispatchQueue = this._networkConfigByNetworkId[networkId].dispatchQueue;
             return {
-                ether: {
-                    full: etherRequestQueue.isFull(),
-                    size: etherRequestQueue.size(),
-                },
-                zrx: {
-                    full: zrxRequestQueue.isFull(),
-                    size: zrxRequestQueue.size(),
-                },
+                full: dispatchQueue.isFull(),
+                size: dispatchQueue.size(),
             };
         });
         const payload = JSON.stringify(queueInfo);
         res.status(200).send(payload);
     }
     public dispenseEther(req: express.Request, res: express.Response) {
-        Handler._dispenseAsset(req, res, this._etherRequestQueueByNetworkId, RequestedAssetType.ETH);
+        this._dispenseAsset(req, res, RequestedAssetType.ETH);
     }
     public dispenseZRX(req: express.Request, res: express.Response) {
-        Handler._dispenseAsset(req, res, this._zrxRequestQueueByNetworkId, RequestedAssetType.ZRX);
+        this._dispenseAsset(req, res, RequestedAssetType.ZRX);
     }
     public async dispenseWETHOrder(req: express.Request, res: express.Response) {
         await this._dispenseOrder(req, res, RequestedAssetType.WETH);
@@ -115,12 +93,44 @@ export class Handler {
     public async dispenseZRXOrder(req: express.Request, res: express.Response, next: express.NextFunction) {
         await this._dispenseOrder(req, res, RequestedAssetType.ZRX);
     }
+    private _dispenseAsset(req: express.Request, res: express.Response, requestedAssetType: RequestedAssetType) {
+        const networkId = req.params.networkId;
+        const recipient = req.params.recipient;
+        const networkConfig = _.get(this._networkConfigByNetworkId, networkId);
+        if (_.isUndefined(networkConfig)) {
+            res.status(400).send('UNSUPPORTED_NETWORK_ID');
+            return;
+        }
+        let dispenserTask;
+        switch (requestedAssetType) {
+            case RequestedAssetType.ETH:
+                dispenserTask = dispenseAssetTasks.dispenseEtherTask(recipient, networkConfig.web3);
+                break;
+            case RequestedAssetType.WETH:
+                dispenserTask = dispenseAssetTasks.dispenseTokenTask(recipient, requestedAssetType, networkConfig.zeroEx);
+                break;
+            case RequestedAssetType.ZRX:
+                dispenserTask = dispenseAssetTasks.dispenseTokenTask(recipient, requestedAssetType, networkConfig.zeroEx);
+                break;
+            default:
+                throw new Error(`Unsupported asset type: ${requestedAssetType}`);
+        }
+
+        const didAddToQueue = networkConfig.dispatchQueue.add(dispenserTask);
+        if (!didAddToQueue) {
+            res.status(503).send('QUEUE_IS_FULL');
+            return;
+        }
+        utils.consoleLog(`Added ${recipient} to queue: ${requestedAssetType} networkId: ${networkId}`);
+        res.status(200).end();
+    }
     private async _dispenseOrder(req: express.Request, res: express.Response, requestedAssetType: RequestedAssetType) {
-        const zeroEx = _.get(this._zeroExByNetworkId, req.params.networkId);
-        if (_.isUndefined(zeroEx)) {
+        const networkConfig = _.get(this._networkConfigByNetworkId, req.params.networkId);
+        if (_.isUndefined(networkConfig)) {
             res.status(400).send('UNSUPPORTED_NETWORK_ID');
             return;
         }
+        const zeroEx = networkConfig.zeroEx;
         res.setHeader('Content-Type', 'application/json');
         const makerTokenAddress = await zeroEx.tokenRegistry.getTokenAddressBySymbolIfExistsAsync(requestedAssetType);
         if (_.isUndefined(makerTokenAddress)) {
diff --git a/packages/testnet-faucets/src/ts/request_queue.ts b/packages/testnet-faucets/src/ts/request_queue.ts
deleted file mode 100644
index 718f8be0c..000000000
--- a/packages/testnet-faucets/src/ts/request_queue.ts
+++ /dev/null
@@ -1,56 +0,0 @@
-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() {
-        if (!_.isUndefined(this._queueIntervalId)) {
-            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');
-    }
-}
diff --git a/packages/testnet-faucets/src/ts/zrx_request_queue.ts b/packages/testnet-faucets/src/ts/zrx_request_queue.ts
deleted file mode 100644
index 3659f4856..000000000
--- a/packages/testnet-faucets/src/ts/zrx_request_queue.ts
+++ /dev/null
@@ -1,43 +0,0 @@
-import { ZeroEx } from '0x.js';
-import { BigNumber } from '@0xproject/utils';
-import * as _ from 'lodash';
-
-import { configs } from './configs';
-import { errorReporter } from './error_reporter';
-import { RequestQueue } from './request_queue';
-import { utils } from './utils';
-
-// 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 DISPENSE_AMOUNT_ZRX = new BigNumber(0.1);
-const QUEUE_INTERVAL_MS = 5000;
-
-export class ZRXRequestQueue extends RequestQueue {
-    private _zeroEx: ZeroEx;
-    constructor(web3: Web3, zeroEx: ZeroEx) {
-        super(web3);
-        this._queueIntervalMs = QUEUE_INTERVAL_MS;
-        this._zeroEx = zeroEx;
-    }
-    protected async _processNextRequestFireAndForgetAsync(recipientAddress: string) {
-        utils.consoleLog(`Processing ZRX ${recipientAddress}`);
-        const baseUnitAmount = ZeroEx.toBaseUnitAmount(DISPENSE_AMOUNT_ZRX, 18);
-        try {
-            const zrxTokenAddress = this._zeroEx.exchange.getZRXTokenAddress();
-            const txHash = await this._zeroEx.token.transferAsync(
-                zrxTokenAddress,
-                configs.DISPENSER_ADDRESS,
-                recipientAddress,
-                baseUnitAmount,
-            );
-            utils.consoleLog(`Sent ${DISPENSE_AMOUNT_ZRX} ZRX to ${recipientAddress} tx: ${txHash}`);
-        } catch (err) {
-            utils.consoleLog(`Unexpected err: ${err} - ${JSON.stringify(err)}`);
-            await errorReporter.reportAsync(err);
-        }
-    }
-}