Implement subscriptions based on ethereumjs-blockstream

12 files changed, 376 insertions, 401 deletions

diff --git a/package.json b/package.json
index 011e974c0..59b0c9cf9 100644
--- a/package.json
+++ b/package.json
@@ -56,6 +56,7 @@
     "@types/mocha": "^2.2.41",
     "@types/node": "^8.0.1",
     "@types/sinon": "^2.2.2",
+    "@types/uuid": "^3.4.2",
     "awesome-typescript-loader": "^3.1.3",
     "bignumber.js": "^4.0.2",
     "chai": "^4.0.1",
@@ -100,6 +101,7 @@
     "find-versions": "^2.0.0",
     "lodash": "^4.17.4",
     "publish-release": "^1.3.3",
+    "uuid": "^3.1.0",
     "web3": "^0.20.0"
   }
 }
diff --git a/src/contract_wrappers/contract_wrapper.ts b/src/contract_wrappers/contract_wrapper.ts
index 927a09b52..6f22f5bdb 100644
--- a/src/contract_wrappers/contract_wrapper.ts
+++ b/src/contract_wrappers/contract_wrapper.ts
@@ -1,10 +1,10 @@
 import * as _ from 'lodash';
 import * as Web3 from 'web3';
-import * as ethUtil from 'ethereumjs-util';
-import {BlockAndLogStreamer} from 'ethereumjs-blockstream';
+import {BlockAndLogStreamer, Block} from 'ethereumjs-blockstream';
 import {Web3Wrapper} from '../web3_wrapper';
 import {AbiDecoder} from '../utils/abi_decoder';
 import {
+    ZeroExError,
     InternalZeroExError,
     Artifact,
     LogWithDecodedArgs,
@@ -12,38 +12,73 @@ import {
     ContractEvents,
     SubscriptionOpts,
     IndexedFilterValues,
+    EventCallback,
 } from '../types';
 import {utils} from '../utils/utils';
-
-const TOPIC_LENGTH = 32;
+import {constants} from '../utils/constants';
+import {intervalUtils} from '../utils/interval_utils';
+import {filterUtils} from '../utils/filter_utils';
 
 export class ContractWrapper {
     protected _web3Wrapper: Web3Wrapper;
     private _abiDecoder?: AbiDecoder;
     private _blockAndLogStreamer: BlockAndLogStreamer;
+    private _blockAndLogStreamInterval: NodeJS.Timer;
+    private _activeFilters: number;
+    private _filters: {[filterToken: string]: Web3.FilterObject};
+    private _filterCallbacks: {[filterToken: string]: EventCallback};
+    private _onLogAddedSubscriptionToken: string|undefined;
+    private _onLogRemovedSubscriptionToken: string|undefined;
     constructor(web3Wrapper: Web3Wrapper, abiDecoder?: AbiDecoder) {
         this._web3Wrapper = web3Wrapper;
         this._abiDecoder = abiDecoder;
-        const getBlockAsync = async (hash: string) => this._web3Wrapper.getBlockAsync(hash);
-        this._blockAndLogStreamer = new BlockAndLogStreamer(
-            this._web3Wrapper.getBlockAsync.bind(this._web3Wrapper),
-            this._web3Wrapper.getLogsAsync.bind(this._web3Wrapper),
+        this._activeFilters = 0;
+        this._filters = {};
+        this._filterCallbacks = {};
+        this._onLogAddedSubscriptionToken = undefined;
+        this._onLogRemovedSubscriptionToken = undefined;
+    }
+    protected _subscribe(address: string, eventName: ContractEvents,
+                         indexFilterValues: IndexedFilterValues, abi: Web3.ContractAbi,
+                         callback: EventCallback): string {
+        const filter = filterUtils.getFilter(
+            this._web3Wrapper.keccak256.bind(this._web3Wrapper), address, eventName, indexFilterValues, abi,
         );
+        if (_.isEmpty(this._filters)) {
+            this._startBlockAndLogStream();
+            let removed = false;
+            this._onLogAddedSubscriptionToken = this._blockAndLogStreamer.subscribeToOnLogAdded(
+                this._onLogStateChanged.bind(this, removed),
+            );
+            removed = true;
+            this._onLogRemovedSubscriptionToken = this._blockAndLogStreamer.subscribeToOnLogRemoved(
+                this._onLogStateChanged.bind(this, removed),
+            );
+        }
+        const filterToken = filterUtils.generateUUID();
+        this._filters[filterToken] = filter;
+        this._filterCallbacks[filterToken] = callback;
+        return filterToken;
+    }
+    protected _unsubscribe(filterToken: string): void {
+        if (_.isUndefined(this._filters[filterToken])) {
+            throw new Error(ZeroExError.SubscriptionNotFound);
+        }
+        delete this._filters[filterToken];
+        delete this._filterCallbacks[filterToken];
+        if (_.isEmpty(this._filters)) {
+            this._blockAndLogStreamer.unsubscribeFromOnLogAdded(this._onLogAddedSubscriptionToken as string);
+            this._blockAndLogStreamer.unsubscribeFromOnLogRemoved(this._onLogRemovedSubscriptionToken as string);
+            this._stopBlockAndLogStream();
+        }
     }
     protected async _getLogsAsync(address: string, eventName: ContractEvents, subscriptionOpts: SubscriptionOpts,
                                   indexFilterValues: IndexedFilterValues,
                                   abi: Web3.ContractAbi): Promise<LogWithDecodedArgs[]> {
-        const eventAbi = _.find(abi, {name: eventName}) as Web3.EventAbi;
-        const eventSignature = this._getEventSignatureFromAbiByName(eventAbi, eventName);
-        const topicForEventSignature = this._web3Wrapper.keccak256(eventSignature);
-        const topicsForIndexedArgs = this._getTopicsForIndexedArgs(eventAbi, indexFilterValues);
-        const topics = [topicForEventSignature, ...topicsForIndexedArgs];
-        const filter = {
-            fromBlock: subscriptionOpts.fromBlock,
-            toBlock: subscriptionOpts.toBlock,
-            address,
-            topics,
-        };
+        const filter = filterUtils.getFilter(
+            this._web3Wrapper.keccak256.bind(this._web3Wrapper), address, eventName, indexFilterValues, abi,
+            subscriptionOpts,
+        );
         const logs = await this._web3Wrapper.getLogsAsync(filter);
         const logsWithDecodedArguments = _.map(logs, this._tryToDecodeLogOrNoop.bind(this));
         return logsWithDecodedArguments;
@@ -62,27 +97,34 @@ export class ContractWrapper {
             await this._web3Wrapper.getContractInstanceFromArtifactAsync<A>(artifact, addressIfExists);
         return contractInstance;
     }
-    protected _getEventSignatureFromAbiByName(eventAbi: Web3.EventAbi, eventName: ContractEvents): string {
-        const types = _.map(eventAbi.inputs, 'type');
-        const signature = `${eventAbi.name}(${types.join(',')})`;
-        return signature;
-    }
-    private _getTopicsForIndexedArgs(abi: Web3.EventAbi, indexFilterValues: IndexedFilterValues): Array<string|null> {
-        const topics: Array<string|null> = [];
-        for (const eventInput of abi.inputs) {
-            if (!eventInput.indexed) {
-                continue;
+    private _onLogStateChanged(removed: boolean, log: Web3.LogEntry): void {
+        _.forEach(this._filters, (filter: Web3.FilterObject, filterToken: string) => {
+            if (filterUtils.matchesFilter(log, filter)) {
+                const decodedLog = this._tryToDecodeLogOrNoop(log) as LogWithDecodedArgs;
+                const logEvent = {
+                    ...decodedLog,
+                    removed,
+                };
+                this._filterCallbacks[filterToken](logEvent);
             }
-            if (_.isUndefined(indexFilterValues[eventInput.name])) {
-                topics.push(null);
-            } else {
-                const value = indexFilterValues[eventInput.name] as string;
-                const buffer = ethUtil.toBuffer(value);
-                const paddedBuffer = ethUtil.setLengthLeft(buffer, TOPIC_LENGTH);
-                const topic = ethUtil.bufferToHex(paddedBuffer);
-                topics.push(topic);
-            }
-        }
-        return topics;
+        });
+    }
+    private _startBlockAndLogStream(): void {
+        this._blockAndLogStreamer = new BlockAndLogStreamer(
+            this._web3Wrapper.getBlockAsync.bind(this._web3Wrapper),
+            this._web3Wrapper.getLogsAsync.bind(this._web3Wrapper),
+        );
+        this._blockAndLogStreamer.addLogFilter({});
+        this._blockAndLogStreamInterval = intervalUtils.setAsyncExcludingInterval(
+            this._reconcileBlockAsync.bind(this), constants.DEFAULT_BLOCK_POLLING_INTERVAL,
+        );
+    }
+    private _stopBlockAndLogStream(): void {
+        intervalUtils.clearAsyncExcludingInterval(this._blockAndLogStreamInterval);
+        delete this._blockAndLogStreamer;
+    }
+    private async _reconcileBlockAsync(): Promise<void> {
+        const latestBlock = await this._web3Wrapper.getBlockAsync('latest');
+        this._blockAndLogStreamer.reconcileNewBlock(latestBlock as any as Block);
     }
 }
diff --git a/src/contract_wrappers/exchange_wrapper.ts b/src/contract_wrappers/exchange_wrapper.ts
index 32eaa590c..e5f190864 100644
--- a/src/contract_wrappers/exchange_wrapper.ts
+++ b/src/contract_wrappers/exchange_wrapper.ts
@@ -16,11 +16,8 @@ import {
     SignedOrder,
     ContractEvent,
     ExchangeEvents,
-    ContractEventEmitter,
     SubscriptionOpts,
     IndexedFilterValues,
-    CreateContractEvent,
-    ContractEventObj,
     OrderCancellationRequest,
     OrderFillRequest,
     LogErrorContractEventArgs,
@@ -31,10 +28,10 @@ import {
     ValidateOrderFillableOpts,
     OrderTransactionOpts,
     RawLog,
+    EventCallback,
 } from '../types';
 import {assert} from '../utils/assert';
 import {utils} from '../utils/utils';
-import {eventUtils} from '../utils/event_utils';
 import {OrderValidationUtils} from '../utils/order_validation_utils';
 import {ContractWrapper} from './contract_wrapper';
 import {constants} from '../utils/constants';
@@ -51,7 +48,7 @@ const SHOULD_VALIDATE_BY_DEFAULT = true;
  */
 export class ExchangeWrapper extends ContractWrapper {
     private _exchangeContractIfExists?: ExchangeContract;
-    private _exchangeLogEventEmitters: ContractEventEmitter[];
+    private _activeSubscriptions: string[];
     private _orderValidationUtils: OrderValidationUtils;
     private _tokenWrapper: TokenWrapper;
     private _exchangeContractErrCodesToMsg = {
@@ -86,7 +83,7 @@ export class ExchangeWrapper extends ContractWrapper {
         super(web3Wrapper, abiDecoder);
         this._tokenWrapper = tokenWrapper;
         this._orderValidationUtils = new OrderValidationUtils(tokenWrapper, this);
-        this._exchangeLogEventEmitters = [];
+        this._activeSubscriptions = [];
         this._contractAddressIfExists = contractAddressIfExists;
     }
     /**
@@ -622,41 +619,32 @@ export class ExchangeWrapper extends ContractWrapper {
         return txHash;
     }
     /**
-     * Subscribe to an event type emitted by the Exchange smart contract
-     * @param   eventName               The exchange contract event you would like to subscribe to.
-     * @param   subscriptionOpts        Subscriptions options that let you configure the subscription.
-     * @param   indexFilterValues       An object where the keys are indexed args returned by the event and
-     *                                  the value is the value you are interested in. E.g `{maker: aUserAddressHex}`
-     * @param   exchangeContractAddress The hex encoded address of the Exchange contract to call.
-     * @return                      ContractEventEmitter object
+     * Subscribe to an event type emitted by the Exchange contract.
+     * @param   tokenAddress        The hex encoded address where the ERC20 token is deployed.
+     * @param   eventName           The exchange contract event you would like to subscribe to.
+     * @param   indexFilterValues   An object where the keys are indexed args returned by the event and
+     *                              the value is the value you are interested in. E.g `{maker: aUserAddressHex}`
+     * @param   callback            Callback that gets called when a log is added/removed
+     * @return ContractEventEmitter object
      */
-    public async subscribeAsync(eventName: ExchangeEvents, subscriptionOpts: SubscriptionOpts,
-                                indexFilterValues: IndexedFilterValues, exchangeContractAddress: string):
-                                Promise<ContractEventEmitter> {
-        assert.isETHAddressHex('exchangeContractAddress', exchangeContractAddress);
+    public async subscribeAsync(eventName: ExchangeEvents, indexFilterValues: IndexedFilterValues,
+                                callback: EventCallback): Promise<string> {
         assert.doesBelongToStringEnum('eventName', eventName, ExchangeEvents);
-        assert.doesConformToSchema('subscriptionOpts', subscriptionOpts, schemas.subscriptionOptsSchema);
         assert.doesConformToSchema('indexFilterValues', indexFilterValues, schemas.indexFilterValuesSchema);
-        const exchangeContract = await this._getExchangeContractAsync();
-        let createLogEvent: CreateContractEvent;
-        switch (eventName) {
-            case ExchangeEvents.LogFill:
-                createLogEvent = exchangeContract.LogFill;
-                break;
-            case ExchangeEvents.LogError:
-                createLogEvent = exchangeContract.LogError;
-                break;
-            case ExchangeEvents.LogCancel:
-                createLogEvent = exchangeContract.LogCancel;
-                break;
-            default:
-                throw utils.spawnSwitchErr('ExchangeEvents', eventName);
-        }
-
-        const logEventObj: ContractEventObj = createLogEvent(indexFilterValues, subscriptionOpts);
-        const eventEmitter = eventUtils.wrapEventEmitter(logEventObj);
-        this._exchangeLogEventEmitters.push(eventEmitter);
-        return eventEmitter;
+        const exchangeContractAddress = await this.getContractAddressAsync();
+        const subscriptionToken = this._subscribe(
+            exchangeContractAddress, eventName, indexFilterValues, artifacts.ExchangeArtifact.abi, callback,
+        );
+        this._activeSubscriptions.push(subscriptionToken);
+        return subscriptionToken;
+    }
+    /**
+     * Cancel a subscription
+     * @param   subscriptionToken Subscription token returned by `subscribe()`
+     */
+    public unsubscribe(subscriptionToken: string): void {
+        _.pull(this._activeSubscriptions, subscriptionToken);
+        this._unsubscribe(subscriptionToken);
     }
     /**
      * Gets historical logs without creating a subscription
@@ -678,15 +666,6 @@ export class ExchangeWrapper extends ContractWrapper {
         return logs;
     }
     /**
-     * Stops watching for all exchange events
-     */
-    public async stopWatchingAllEventsAsync(): Promise<void> {
-        const stopWatchingPromises = _.map(this._exchangeLogEventEmitters,
-                                           logEventObj => logEventObj.stopWatchingAsync());
-        await Promise.all(stopWatchingPromises);
-        this._exchangeLogEventEmitters = [];
-    }
-    /**
      * Retrieves the Ethereum address of the Exchange contract deployed on the network
      * that the user-passed web3 provider is connected to.
      * @returns The Ethereum address of the Exchange contract being used.
@@ -809,8 +788,15 @@ export class ExchangeWrapper extends ContractWrapper {
         const ZRXtokenAddress = await exchangeInstance.ZRX_TOKEN_CONTRACT.callAsync();
         return ZRXtokenAddress;
     }
+    /**
+     * Cancels all existing subscriptions
+     */
+    public unsubscribeAll(): void {
+        _.forEach(this._activeSubscriptions, this._unsubscribe.bind(this));
+        this._activeSubscriptions = [];
+    }
     private async _invalidateContractInstancesAsync(): Promise<void> {
-        await this.stopWatchingAllEventsAsync();
+        this.unsubscribeAll();
         delete this._exchangeContractIfExists;
     }
     private async _isValidSignatureUsingContractCallAsync(dataHex: string, ecSignature: ECSignature,
diff --git a/src/contract_wrappers/token_wrapper.ts b/src/contract_wrappers/token_wrapper.ts
index f988e6ece..d2b1ccf96 100644
--- a/src/contract_wrappers/token_wrapper.ts
+++ b/src/contract_wrappers/token_wrapper.ts
@@ -4,7 +4,6 @@ import {SchemaValidator, schemas} from '0x-json-schemas';
 import {Web3Wrapper} from '../web3_wrapper';
 import {assert} from '../utils/assert';
 import {utils} from '../utils/utils';
-import {eventUtils} from '../utils/event_utils';
 import {constants} from '../utils/constants';
 import {ContractWrapper} from './contract_wrapper';
 import {AbiDecoder} from '../utils/abi_decoder';
@@ -15,12 +14,10 @@ import {
     TokenEvents,
     IndexedFilterValues,
     SubscriptionOpts,
-    CreateContractEvent,
-    ContractEventEmitter,
-    ContractEventObj,
     MethodOpts,
     LogWithDecodedArgs,
     RawLog,
+    EventCallback,
 } from '../types';
 
 const ALLOWANCE_TO_ZERO_GAS_AMOUNT = 47155;
@@ -33,13 +30,13 @@ const ALLOWANCE_TO_ZERO_GAS_AMOUNT = 47155;
 export class TokenWrapper extends ContractWrapper {
     public UNLIMITED_ALLOWANCE_IN_BASE_UNITS = constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS;
     private _tokenContractsByAddress: {[address: string]: TokenContract};
-    private _tokenLogEventEmitters: ContractEventEmitter[];
+    private _activeSubscriptions: string[];
     private _tokenTransferProxyContractAddressFetcher: () => Promise<string>;
     constructor(web3Wrapper: Web3Wrapper, abiDecoder: AbiDecoder,
                 tokenTransferProxyContractAddressFetcher: () => Promise<string>) {
         super(web3Wrapper, abiDecoder);
         this._tokenContractsByAddress = {};
-        this._tokenLogEventEmitters = [];
+        this._activeSubscriptions = [];
         this._tokenTransferProxyContractAddressFetcher = tokenTransferProxyContractAddressFetcher;
     }
     /**
@@ -251,34 +248,29 @@ export class TokenWrapper extends ContractWrapper {
      * Subscribe to an event type emitted by the Token contract.
      * @param   tokenAddress        The hex encoded address where the ERC20 token is deployed.
      * @param   eventName           The token contract event you would like to subscribe to.
-     * @param   subscriptionOpts    Subscriptions options that let you configure the subscription.
      * @param   indexFilterValues   An object where the keys are indexed args returned by the event and
      *                              the value is the value you are interested in. E.g `{maker: aUserAddressHex}`
+     * @param   callback            Callback that gets called when a log is added/removed
      * @return ContractEventEmitter object
      */
-    public async subscribeAsync(tokenAddress: string, eventName: TokenEvents, subscriptionOpts: SubscriptionOpts,
-                                indexFilterValues: IndexedFilterValues): Promise<ContractEventEmitter> {
+    public subscribe(tokenAddress: string, eventName: TokenEvents, indexFilterValues: IndexedFilterValues,
+                     callback: EventCallback): string {
         assert.isETHAddressHex('tokenAddress', tokenAddress);
         assert.doesBelongToStringEnum('eventName', eventName, TokenEvents);
-        assert.doesConformToSchema('subscriptionOpts', subscriptionOpts, schemas.subscriptionOptsSchema);
         assert.doesConformToSchema('indexFilterValues', indexFilterValues, schemas.indexFilterValuesSchema);
-        const tokenContract = await this._getTokenContractAsync(tokenAddress);
-        let createLogEvent: CreateContractEvent;
-        switch (eventName) {
-            case TokenEvents.Approval:
-                createLogEvent = tokenContract.Approval;
-                break;
-            case TokenEvents.Transfer:
-                createLogEvent = tokenContract.Transfer;
-                break;
-            default:
-                throw utils.spawnSwitchErr('TokenEvents', eventName);
-        }
-
-        const logEventObj: ContractEventObj = createLogEvent(indexFilterValues, subscriptionOpts);
-        const eventEmitter = eventUtils.wrapEventEmitter(logEventObj);
-        this._tokenLogEventEmitters.push(eventEmitter);
-        return eventEmitter;
+        const subscriptionToken = this._subscribe(
+            tokenAddress, eventName, indexFilterValues, artifacts.TokenArtifact.abi, callback,
+        );
+        this._activeSubscriptions.push(subscriptionToken);
+        return subscriptionToken;
+    }
+    /**
+     * Cancel a subscription
+     * @param   subscriptionToken Subscription token returned by `subscribe()`
+     */
+    public unsubscribe(subscriptionToken: string): void {
+        _.pull(this._activeSubscriptions, subscriptionToken);
+        this._unsubscribe(subscriptionToken);
     }
     /**
      * Gets historical logs without creating a subscription
@@ -301,16 +293,14 @@ export class TokenWrapper extends ContractWrapper {
         return logs;
     }
     /**
-     * Stops watching for all token events
+     * Cancels all existing subscriptions
      */
-    public async stopWatchingAllEventsAsync(): Promise<void> {
-        const stopWatchingPromises = _.map(this._tokenLogEventEmitters,
-                                           logEventObj => logEventObj.stopWatchingAsync());
-        await Promise.all(stopWatchingPromises);
-        this._tokenLogEventEmitters = [];
+    public unsubscribeAll(): void {
+        _.forEach(this._activeSubscriptions, this._unsubscribe.bind(this));
+        this._activeSubscriptions = [];
     }
-    private async _invalidateContractInstancesAsync(): Promise<void> {
-        await this.stopWatchingAllEventsAsync();
+    private _invalidateContractInstancesAsync(): void {
+        this.unsubscribeAll();
         this._tokenContractsByAddress = {};
     }
     private async _getTokenContractAsync(tokenAddress: string): Promise<TokenContract> {
diff --git a/src/index.ts b/src/index.ts
index 3359743e9..97ab084b7 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -19,7 +19,6 @@ export {
     OrderFillOrKillRequest,
     OrderCancellationRequest,
     OrderFillRequest,
-    ContractEventEmitter,
     LogErrorContractEventArgs,
     LogCancelContractEventArgs,
     LogFillContractEventArgs,
@@ -36,4 +35,5 @@ export {
     MethodOpts,
     OrderTransactionOpts,
     FilterObject,
+    LogEvent,
 } from './types';
diff --git a/src/types.ts b/src/types.ts
index 35bb6af78..f0f37bfca 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -14,6 +14,7 @@ export enum ZeroExError {
     InvalidJump = 'INVALID_JUMP',
     OutOfGas = 'OUT_OF_GAS',
     NoNetworkId = 'NO_NETWORK_ID',
+    SubscriptionNotFound = 'SUBSCRIPTION_NOT_FOUND',
 }
 
 export enum InternalZeroExError {
@@ -35,23 +36,17 @@ export type OrderAddresses = [string, string, string, string, string];
 export type OrderValues = [BigNumber.BigNumber, BigNumber.BigNumber, BigNumber.BigNumber,
                            BigNumber.BigNumber, BigNumber.BigNumber, BigNumber.BigNumber];
 
-export type EventCallbackAsync = (err: Error, event: ContractEvent) => Promise<void>;
-export type EventCallbackSync = (err: Error, event: ContractEvent) => void;
-export type EventCallback = EventCallbackSync|EventCallbackAsync;
-export interface ContractEventObj {
-    watch: (eventWatch: EventCallback) => void;
-    stopWatching: () => void;
+export interface LogEvent extends LogWithDecodedArgs {
+    removed: boolean;
 }
-export type CreateContractEvent = (indexFilterValues: IndexedFilterValues,
-                                   subscriptionOpts: SubscriptionOpts) => ContractEventObj;
+export type EventCallbackAsync = (log: LogEvent) => Promise<void>;
+export type EventCallbackSync = (log: LogEvent) => void;
+export type EventCallback = EventCallbackSync|EventCallbackAsync;
 export interface ExchangeContract extends Web3.ContractInstance {
     isValidSignature: {
         callAsync: (signerAddressHex: string, dataHex: string, v: number, r: string, s: string,
                     txOpts?: TxOpts) => Promise<boolean>;
     };
-    LogFill: CreateContractEvent;
-    LogCancel: CreateContractEvent;
-    LogError: CreateContractEvent;
     ZRX_TOKEN_CONTRACT: {
         callAsync: () => Promise<string>;
     };
@@ -137,8 +132,6 @@ export interface ExchangeContract extends Web3.ContractInstance {
 }
 
 export interface TokenContract extends Web3.ContractInstance {
-    Transfer: CreateContractEvent;
-    Approval: CreateContractEvent;
     balanceOf: {
         callAsync: (address: string, defaultBlock?: Web3.BlockParam) => Promise<BigNumber.BigNumber>;
     };
@@ -378,11 +371,6 @@ export interface OrderFillRequest {
 
 export type AsyncMethod = (...args: any[]) => Promise<any>;
 
-export interface ContractEventEmitter {
-    watch: (eventCallback: EventCallback) => void;
-    stopWatchingAsync: () => Promise<void>;
-}
-
 /**
  * We re-export the `Web3.Provider` type specified in the Web3 Typescript typings
  * since it is the type of the `provider` argument to the `ZeroEx` constructor.
diff --git a/src/utils/constants.ts b/src/utils/constants.ts
index 1b11d7055..a066fe869 100644
--- a/src/utils/constants.ts
+++ b/src/utils/constants.ts
@@ -7,4 +7,5 @@ export const constants = {
     INVALID_JUMP_PATTERN: 'invalid JUMP at',
     OUT_OF_GAS_PATTERN: 'out of gas',
     UNLIMITED_ALLOWANCE_IN_BASE_UNITS: new BigNumber(2).pow(256).minus(1),
+    DEFAULT_BLOCK_POLLING_INTERVAL: 1000,
 };
diff --git a/src/utils/event_utils.ts b/src/utils/event_utils.ts
deleted file mode 100644
index e8f30e1a8..000000000
--- a/src/utils/event_utils.ts
+++ /dev/null
@@ -1,41 +0,0 @@
-import * as _ from 'lodash';
-import {EventCallback, ContractEventArg, ContractEvent, ContractEventObj, ContractEventEmitter} from '../types';
-import * as BigNumber from 'bignumber.js';
-import promisify = require('es6-promisify');
-
-export const eventUtils = {
-    wrapEventEmitter(event: ContractEventObj): ContractEventEmitter {
-        const watch = (eventCallback: EventCallback) => {
-            const bignumberWrappingEventCallback = eventUtils._getBigNumberWrappingEventCallback(eventCallback);
-            event.watch(bignumberWrappingEventCallback);
-        };
-        const zeroExEvent = {
-            watch,
-            stopWatchingAsync: async () => {
-                await promisify(event.stopWatching, event)();
-            },
-        };
-        return zeroExEvent;
-    },
-    /**
-     * Wraps eventCallback function so that all the BigNumber arguments are wrapped in a newer version of BigNumber.
-     * @param eventCallback     Event callback function to be wrapped
-     * @return Wrapped event callback function
-     */
-    _getBigNumberWrappingEventCallback(eventCallback: EventCallback): EventCallback {
-        const bignumberWrappingEventCallback = (err: Error, event: ContractEvent) => {
-            if (_.isNull(err)) {
-                const wrapIfBigNumber = (value: ContractEventArg): ContractEventArg => {
-                    // HACK: The old version of BigNumber used by Web3@0.19.0 does not support the `isBigNumber`
-                    // and checking for a BigNumber instance using `instanceof` does not work either. We therefore
-                    // check if the value constructor is a bignumber constructor.
-                    const isWeb3BigNumber = _.startsWith(value.constructor.toString(), 'function BigNumber(');
-                    return isWeb3BigNumber ?  new BigNumber(value) : value;
-                };
-                event.args = _.mapValues(event.args, wrapIfBigNumber);
-            }
-            eventCallback(err, event);
-        };
-        return bignumberWrappingEventCallback;
-    },
-};
diff --git a/src/utils/filter_utils.ts b/src/utils/filter_utils.ts
new file mode 100644
index 000000000..ee39b6836
--- /dev/null
+++ b/src/utils/filter_utils.ts
@@ -0,0 +1,80 @@
+import * as _ from 'lodash';
+import * as Web3 from 'web3';
+import * as uuid from 'uuid/v4';
+import * as ethUtil from 'ethereumjs-util';
+import {ContractEvents, IndexedFilterValues, SubscriptionOpts} from '../types';
+
+const TOPIC_LENGTH = 32;
+
+export const filterUtils = {
+    generateUUID(): string {
+        return uuid();
+    },
+    getFilter(keccak256: (data: string) => string, address: string, eventName: ContractEvents,
+              indexFilterValues: IndexedFilterValues, abi: Web3.ContractAbi,
+              subscriptionOpts?: SubscriptionOpts): Web3.FilterObject {
+        const eventAbi = _.find(abi, {name: eventName}) as Web3.EventAbi;
+        const eventSignature = filterUtils.getEventSignatureFromAbiByName(eventAbi, eventName);
+        const topicForEventSignature = keccak256(eventSignature);
+        const topicsForIndexedArgs = filterUtils.getTopicsForIndexedArgs(eventAbi, indexFilterValues);
+        const topics = [topicForEventSignature, ...topicsForIndexedArgs];
+        let filter: Web3.FilterObject = {
+            address,
+            topics,
+        };
+        if (!_.isUndefined(subscriptionOpts)) {
+            filter = {
+                ...subscriptionOpts,
+                ...filter,
+            };
+        }
+        return filter;
+    },
+    getEventSignatureFromAbiByName(eventAbi: Web3.EventAbi, eventName: ContractEvents): string {
+        const types = _.map(eventAbi.inputs, 'type');
+        const signature = `${eventAbi.name}(${types.join(',')})`;
+        return signature;
+    },
+    getTopicsForIndexedArgs(abi: Web3.EventAbi, indexFilterValues: IndexedFilterValues): Array<string|null> {
+        const topics: Array<string|null> = [];
+        for (const eventInput of abi.inputs) {
+            if (!eventInput.indexed) {
+                continue;
+            }
+            if (_.isUndefined(indexFilterValues[eventInput.name])) {
+                topics.push(null);
+            } else {
+                const value = indexFilterValues[eventInput.name] as string;
+                const buffer = ethUtil.toBuffer(value);
+                const paddedBuffer = ethUtil.setLengthLeft(buffer, TOPIC_LENGTH);
+                const topic = ethUtil.bufferToHex(paddedBuffer);
+                topics.push(topic);
+            }
+        }
+        return topics;
+    },
+    matchesFilter(log: Web3.LogEntry, filter: Web3.FilterObject): boolean {
+        if (!_.isUndefined(filter.address) && log.address !== filter.address) {
+            return false;
+        }
+        if (!_.isUndefined(filter.topics)) {
+            return filterUtils.matchesTopics(log.topics, filter.topics);
+        }
+        return true;
+    },
+    matchesTopics(logTopics: string[], filterTopics: Array<string[]|string|null>): boolean {
+        const matchesTopic = _.zipWith(logTopics, filterTopics, filterUtils.matchesTopic.bind(filterUtils));
+        const matchesTopics = _.every(matchesTopic);
+        return matchesTopics;
+    },
+    matchesTopic(logTopic: string, filterTopic: string[]|string|null): boolean {
+        if (_.isArray(filterTopic)) {
+            return _.includes(filterTopic, logTopic);
+        }
+        if (_.isString(filterTopic)) {
+            return filterTopic === logTopic;
+        }
+        // null topic is a wildcard
+        return true;
+    },
+};
diff --git a/test/exchange_wrapper_test.ts b/test/exchange_wrapper_test.ts
index 71c5713ad..51d6957d5 100644
--- a/test/exchange_wrapper_test.ts
+++ b/test/exchange_wrapper_test.ts
@@ -19,6 +19,7 @@ import {
     OrderFillRequest,
     LogFillContractEventArgs,
     OrderFillOrKillRequest,
+    LogEvent,
 } from '../src';
 import {DoneCallback} from '../src/types';
 import {FillScenarios} from './utils/fill_scenarios';
@@ -616,7 +617,7 @@ describe('ExchangeWrapper', () => {
             });
         });
     });
-    describe('#subscribeAsync', () => {
+    describe('#subscribe', () => {
         const indexFilterValues = {};
         const shouldThrowOnInsufficientBalanceOrAllowance = true;
         let makerTokenAddress: string;
@@ -626,10 +627,6 @@ describe('ExchangeWrapper', () => {
         let makerAddress: string;
         let fillableAmount: BigNumber.BigNumber;
         let signedOrder: SignedOrder;
-        const subscriptionOpts: SubscriptionOpts = {
-            fromBlock: 0,
-            toBlock: 'latest',
-        };
         const fillTakerAmountInBaseUnits = new BigNumber(1);
         const cancelTakerAmountInBaseUnits = new BigNumber(1);
         before(() => {
@@ -645,24 +642,22 @@ describe('ExchangeWrapper', () => {
             );
         });
         afterEach(async () => {
-            await zeroEx.exchange.stopWatchingAllEventsAsync();
+            zeroEx.exchange.unsubscribeAll();
         });
         // Hack: Mocha does not allow a test to be both async and have a `done` callback
-        // Since we need to await the receipt of the event in the `subscribeAsync` callback,
+        // Since we need to await the receipt of the event in the `subscribe` callback,
         // we do need both. A hack is to make the top-level a sync fn w/ a done callback and then
         // wrap the rest of the test in an async block
         // Source: https://github.com/mochajs/mocha/issues/2407
         it('Should receive the LogFill event when an order is filled', (done: DoneCallback) => {
             (async () => {
-                const zeroExEvent = await zeroEx.exchange.subscribeAsync(
-                    ExchangeEvents.LogFill, subscriptionOpts, indexFilterValues, exchangeContractAddress,
-                );
-                zeroExEvent.watch((err: Error, event: ContractEvent) => {
-                    expect(err).to.be.null();
-                    expect(event).to.not.be.undefined();
-                    expect(event.event).to.be.equal('LogFill');
+                const callback = (logEvent: LogEvent) => {
+                    expect(logEvent.event).to.be.equal(ExchangeEvents.LogFill);
                     done();
-                });
+                };
+                await zeroEx.exchange.subscribeAsync(
+                    ExchangeEvents.LogFill, indexFilterValues, callback,
+                );
                 await zeroEx.exchange.fillOrderAsync(
                     signedOrder, fillTakerAmountInBaseUnits, shouldThrowOnInsufficientBalanceOrAllowance, takerAddress,
                 );
@@ -670,75 +665,53 @@ describe('ExchangeWrapper', () => {
         });
         it('Should receive the LogCancel event when an order is cancelled', (done: DoneCallback) => {
             (async () => {
-                const zeroExEvent = await zeroEx.exchange.subscribeAsync(
-                    ExchangeEvents.LogCancel, subscriptionOpts, indexFilterValues, exchangeContractAddress,
+                const callback = (logEvent: LogEvent) => {
+                    expect(logEvent.event).to.be.equal(ExchangeEvents.LogCancel);
+                    done();
+                };
+                await zeroEx.exchange.subscribeAsync(
+                    ExchangeEvents.LogCancel, indexFilterValues, callback,
                 );
-                zeroExEvent.watch((err: Error, event: ContractEvent) => {
-                        expect(err).to.be.null();
-                        expect(event).to.not.be.undefined();
-                        expect(event.event).to.be.equal('LogCancel');
-                        done();
-                });
                 await zeroEx.exchange.cancelOrderAsync(signedOrder, cancelTakerAmountInBaseUnits);
             })().catch(done);
         });
         it('Outstanding subscriptions are cancelled when zeroEx.setProviderAsync called', (done: DoneCallback) => {
             (async () => {
-                const eventSubscriptionToBeCancelled = await zeroEx.exchange.subscribeAsync(
-                    ExchangeEvents.LogFill, subscriptionOpts, indexFilterValues, exchangeContractAddress,
-                );
-                eventSubscriptionToBeCancelled.watch((err: Error, event: ContractEvent) => {
+                const callbackNeverToBeCalled = (logEvent: LogEvent) => {
                     done(new Error('Expected this subscription to have been cancelled'));
-                });
+                };
+                await zeroEx.exchange.subscribeAsync(
+                    ExchangeEvents.LogFill, indexFilterValues, callbackNeverToBeCalled,
+                );
 
                 const newProvider = web3Factory.getRpcProvider();
                 await zeroEx.setProviderAsync(newProvider);
 
-                const eventSubscriptionToStay = await zeroEx.exchange.subscribeAsync(
-                    ExchangeEvents.LogFill, subscriptionOpts, indexFilterValues, exchangeContractAddress,
-                );
-                eventSubscriptionToStay.watch((err: Error, event: ContractEvent) => {
-                    expect(err).to.be.null();
-                    expect(event).to.not.be.undefined();
-                    expect(event.event).to.be.equal('LogFill');
+                const callback = (logEvent: LogEvent) => {
+                    expect(logEvent.event).to.be.equal(ExchangeEvents.LogFill);
                     done();
-                });
-                await zeroEx.exchange.fillOrderAsync(
-                    signedOrder, fillTakerAmountInBaseUnits, shouldThrowOnInsufficientBalanceOrAllowance, takerAddress,
-                );
-            })().catch(done);
-        });
-        it('Should stop watch for events when stopWatchingAsync called on the eventEmitter', (done: DoneCallback) => {
-            (async () => {
-                const eventSubscriptionToBeStopped = await zeroEx.exchange.subscribeAsync(
-                    ExchangeEvents.LogFill, subscriptionOpts, indexFilterValues, exchangeContractAddress,
+                };
+                await zeroEx.exchange.subscribeAsync(
+                    ExchangeEvents.LogFill, indexFilterValues, callback,
                 );
-                eventSubscriptionToBeStopped.watch((err: Error, event: ContractEvent) => {
-                    done(new Error('Expected this subscription to have been stopped'));
-                });
-                await eventSubscriptionToBeStopped.stopWatchingAsync();
                 await zeroEx.exchange.fillOrderAsync(
                     signedOrder, fillTakerAmountInBaseUnits, shouldThrowOnInsufficientBalanceOrAllowance, takerAddress,
                 );
-                done();
             })().catch(done);
         });
-        it('Should wrap all event args BigNumber instances in a newer version of BigNumber', (done: DoneCallback) => {
+        it('Should cancel subscription when unsubscribe called', (done: DoneCallback) => {
             (async () => {
-                const zeroExEvent = await zeroEx.exchange.subscribeAsync(
-                    ExchangeEvents.LogFill, subscriptionOpts, indexFilterValues, exchangeContractAddress,
+                const callbackNeverToBeCalled = (logEvent: LogEvent) => {
+                    done(new Error('Expected this subscription to have been cancelled'));
+                };
+                const subscriptionToken = await zeroEx.exchange.subscribeAsync(
+                    ExchangeEvents.LogFill, indexFilterValues, callbackNeverToBeCalled,
                 );
-                zeroExEvent.watch((err: Error, event: ContractEvent) => {
-                    const args = event.args as LogFillContractEventArgs;
-                    expect(args.filledMakerTokenAmount.isBigNumber).to.be.true();
-                    expect(args.filledTakerTokenAmount.isBigNumber).to.be.true();
-                    expect(args.paidMakerFee.isBigNumber).to.be.true();
-                    expect(args.paidTakerFee.isBigNumber).to.be.true();
-                    done();
-                });
+                zeroEx.exchange.unsubscribe(subscriptionToken);
                 await zeroEx.exchange.fillOrderAsync(
                     signedOrder, fillTakerAmountInBaseUnits, shouldThrowOnInsufficientBalanceOrAllowance, takerAddress,
                 );
+                done();
             })().catch(done);
         });
     });
diff --git a/test/token_wrapper_test.ts b/test/token_wrapper_test.ts
index da020f714..be97496e0 100644
--- a/test/token_wrapper_test.ts
+++ b/test/token_wrapper_test.ts
@@ -15,6 +15,7 @@ import {
     TransferContractEventArgs,
     ApprovalContractEventArgs,
     LogWithDecodedArgs,
+    LogEvent,
 } from '../src';
 import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
 import {TokenUtils} from './utils/token_utils';
@@ -336,22 +337,18 @@ describe('TokenWrapper', () => {
             return expect(allowance).to.be.bignumber.equal(zeroEx.token.UNLIMITED_ALLOWANCE_IN_BASE_UNITS);
         });
     });
-    describe('#subscribeAsync', () => {
+    describe('#subscribe', () => {
         const indexFilterValues = {};
         const shouldThrowOnInsufficientBalanceOrAllowance = true;
         let tokenAddress: string;
-        const subscriptionOpts: SubscriptionOpts = {
-            fromBlock: 0,
-            toBlock: 'latest',
-        };
         const transferAmount = new BigNumber(42);
         const allowanceAmount = new BigNumber(42);
         before(() => {
             const token = tokens[0];
             tokenAddress = token.address;
         });
-        afterEach(async () => {
-            await zeroEx.token.stopWatchingAllEventsAsync();
+        afterEach(() => {
+            zeroEx.token.unsubscribeAll();
         });
         // Hack: Mocha does not allow a test to be both async and have a `done` callback
         // Since we need to await the receipt of the event in the `subscribeAsync` callback,
@@ -360,81 +357,66 @@ describe('TokenWrapper', () => {
         // Source: https://github.com/mochajs/mocha/issues/2407
         it('Should receive the Transfer event when tokens are transfered', (done: DoneCallback) => {
             (async () => {
-                const zeroExEvent = await zeroEx.token.subscribeAsync(
-                    tokenAddress, TokenEvents.Transfer, subscriptionOpts, indexFilterValues);
-                zeroExEvent.watch((err: Error, event: ContractEvent) => {
-                    expect(err).to.be.null();
-                    expect(event).to.not.be.undefined();
-                    const args = event.args as TransferContractEventArgs;
+                const callback = (logEvent: LogEvent) => {
+                    expect(logEvent).to.not.be.undefined();
+                    const args = logEvent.args as any as TransferContractEventArgs;
                     expect(args._from).to.be.equal(coinbase);
                     expect(args._to).to.be.equal(addressWithoutFunds);
                     expect(args._value).to.be.bignumber.equal(transferAmount);
                     done();
-                });
+                };
+                zeroEx.token.subscribe(
+                    tokenAddress, TokenEvents.Transfer, indexFilterValues, callback);
                 await zeroEx.token.transferAsync(tokenAddress, coinbase, addressWithoutFunds, transferAmount);
             })().catch(done);
         });
         it('Should receive the Approval event when allowance is being set', (done: DoneCallback) => {
             (async () => {
-                const zeroExEvent = await zeroEx.token.subscribeAsync(
-                    tokenAddress, TokenEvents.Approval, subscriptionOpts, indexFilterValues);
-                zeroExEvent.watch((err: Error, event: ContractEvent) => {
-                    expect(err).to.be.null();
-                    expect(event).to.not.be.undefined();
-                    const args = event.args as ApprovalContractEventArgs;
+                const callback = (logEvent: LogEvent) => {
+                    expect(logEvent).to.not.be.undefined();
+                    const args = logEvent.args as any as ApprovalContractEventArgs;
                     expect(args._owner).to.be.equal(coinbase);
                     expect(args._spender).to.be.equal(addressWithoutFunds);
                     expect(args._value).to.be.bignumber.equal(allowanceAmount);
                     done();
-                });
+                };
+                zeroEx.token.subscribe(
+                    tokenAddress, TokenEvents.Approval, indexFilterValues, callback);
                 await zeroEx.token.setAllowanceAsync(tokenAddress, coinbase, addressWithoutFunds, allowanceAmount);
             })().catch(done);
         });
         it('Outstanding subscriptions are cancelled when zeroEx.setProviderAsync called', (done: DoneCallback) => {
             (async () => {
-                const eventSubscriptionToBeCancelled = await zeroEx.token.subscribeAsync(
-                    tokenAddress, TokenEvents.Transfer, subscriptionOpts, indexFilterValues);
-                eventSubscriptionToBeCancelled.watch((err: Error, event: ContractEvent) => {
+                const callbackNeverToBeCalled = (logEvent: LogEvent) => {
                     done(new Error('Expected this subscription to have been cancelled'));
-                });
-
+                };
+                zeroEx.token.subscribe(
+                    tokenAddress, TokenEvents.Transfer, indexFilterValues, callbackNeverToBeCalled,
+                );
+                const callbackToBeCalled = (logEvent: LogEvent) => {
+                    done();
+                };
                 const newProvider = web3Factory.getRpcProvider();
                 await zeroEx.setProviderAsync(newProvider);
-
-                const eventSubscriptionToStay = await zeroEx.token.subscribeAsync(
-                    tokenAddress, TokenEvents.Transfer, subscriptionOpts, indexFilterValues);
-                eventSubscriptionToStay.watch((err: Error, event: ContractEvent) => {
-                    expect(err).to.be.null();
-                    expect(event).to.not.be.undefined();
-                    done();
-                });
+                zeroEx.token.subscribe(
+                    tokenAddress, TokenEvents.Transfer, indexFilterValues, callbackToBeCalled,
+                );
                 await zeroEx.token.transferAsync(tokenAddress, coinbase, addressWithoutFunds, transferAmount);
             })().catch(done);
         });
-        it('Should stop watch for events when stopWatchingAsync called on the eventEmitter', (done: DoneCallback) => {
+        it('Should cancel subscription when unsubscribe called', (done: DoneCallback) => {
             (async () => {
-                const eventSubscriptionToBeStopped = await zeroEx.token.subscribeAsync(
-                    tokenAddress, TokenEvents.Transfer, subscriptionOpts, indexFilterValues);
-                eventSubscriptionToBeStopped.watch((err: Error, event: ContractEvent) => {
-                    done(new Error('Expected this subscription to have been stopped'));
-                });
-                await eventSubscriptionToBeStopped.stopWatchingAsync();
+                const callbackNeverToBeCalled = (logEvent: LogEvent) => {
+                    done(new Error('Expected this subscription to have been cancelled'));
+                };
+                const subscriptionToken = zeroEx.token.subscribe(
+                    tokenAddress, TokenEvents.Transfer, indexFilterValues, callbackNeverToBeCalled);
+                zeroEx.token.unsubscribe(subscriptionToken);
                 await zeroEx.token.transferAsync(tokenAddress, coinbase, addressWithoutFunds, transferAmount);
                 done();
             })().catch(done);
         });
-        it('Should wrap all event args BigNumber instances in a newer version of BigNumber', (done: DoneCallback) => {
-            (async () => {
-                const zeroExEvent = await zeroEx.token.subscribeAsync(
-                    tokenAddress, TokenEvents.Transfer, subscriptionOpts, indexFilterValues);
-                zeroExEvent.watch((err: Error, event: ContractEvent) => {
-                    const args = event.args as TransferContractEventArgs;
-                    expect(args._value.isBigNumber).to.be.true();
-                    done();
-                });
-                await zeroEx.token.transferAsync(tokenAddress, coinbase, addressWithoutFunds, transferAmount);
-            })().catch(done);
-        });
+        // TODO test block reorgs
     });
     describe('#getLogsAsync', () => {
         let tokenAddress: string;
diff --git a/yarn.lock b/yarn.lock
index 4d27d246c..577aa03c1 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -62,6 +62,12 @@
   version "2.3.2"
   resolved "https://registry.yarnpkg.com/@types/sinon/-/sinon-2.3.2.tgz#1e1e99e67162d78e2db17816892bf93bf5209885"
 
+"@types/uuid@^3.4.2":
+  version "3.4.2"
+  resolved "https://registry.yarnpkg.com/@types/uuid/-/uuid-3.4.2.tgz#b8cde3c32c273d3fc658b96f810e8ff091e1b723"
+  dependencies:
+    "@types/node" "*"
+
 abbrev@1:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/abbrev/-/abbrev-1.1.0.tgz#d0554c2256636e2f56e7c2e5ad183f859428d81f"
@@ -1155,11 +1161,9 @@ combined-stream@^1.0.5, combined-stream@~1.0.5:
   dependencies:
     delayed-stream "~1.0.0"
 
-commander@2.9.0, commander@^2.9.0:
-  version "2.9.0"
-  resolved "https://registry.yarnpkg.com/commander/-/commander-2.9.0.tgz#9c99094176e12240cb22d6c5146098400fe0f7d4"
-  dependencies:
-    graceful-readlink ">= 1.0.0"
+commander@2.11.0, commander@^2.9.0:
+  version "2.11.0"
+  resolved "https://registry.yarnpkg.com/commander/-/commander-2.11.0.tgz#157152fd1e7a6c8d98a5b715cf376df928004563"
 
 commondir@^1.0.1:
   version "1.0.1"
@@ -1321,11 +1325,11 @@ debug-log@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/debug-log/-/debug-log-1.0.1.tgz#2307632d4c04382b8df8a32f70b895046d52745f"
 
-debug@2.6.0:
-  version "2.6.0"
-  resolved "https://registry.yarnpkg.com/debug/-/debug-2.6.0.tgz#bc596bcabe7617f11d9fa15361eded5608b8499b"
+debug@3.1.0:
+  version "3.1.0"
+  resolved "https://registry.yarnpkg.com/debug/-/debug-3.1.0.tgz#5bb5a0672628b64149566ba16819e61518c67261"
   dependencies:
-    ms "0.7.2"
+    ms "2.0.0"
 
 debug@^2.1.1, debug@^2.2.0, debug@^2.3.3, debug@^2.6.3:
   version "2.6.8"
@@ -1407,9 +1411,9 @@ detect-indent@^4.0.0:
   dependencies:
     repeating "^2.0.0"
 
-diff@3.2.0, diff@^3.1.0, diff@^3.2.0:
-  version "3.2.0"
-  resolved "https://registry.yarnpkg.com/diff/-/diff-3.2.0.tgz#c9ce393a4b7cbd0b058a725c93df299027868ff9"
+diff@3.3.1, diff@^3.1.0, diff@^3.2.0:
+  version "3.3.1"
+  resolved "https://registry.yarnpkg.com/diff/-/diff-3.3.1.tgz#aa8567a6eed03c531fc89d3f711cd0e5259dec75"
 
 diffie-hellman@^5.0.0:
   version "5.0.2"
@@ -1604,6 +1608,15 @@ escope@^3.6.0:
     esrecurse "^4.1.0"
     estraverse "^4.1.1"
 
+eslint-plugin-node@^5.1.0:
+  version "5.2.0"
+  resolved "https://registry.yarnpkg.com/eslint-plugin-node/-/eslint-plugin-node-5.2.0.tgz#e1efca04a385516cff3f2f04027ce8c5ae6db749"
+  dependencies:
+    ignore "^3.3.3"
+    minimatch "^3.0.4"
+    resolve "^1.3.3"
+    semver "5.3.0"
+
 esprima@^4.0.0:
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/esprima/-/esprima-4.0.0.tgz#4499eddcd1110e0b218bacf2fa7f7f59f55ca804"
@@ -2120,18 +2133,7 @@ glob-parent@^2.0.0:
   dependencies:
     is-glob "^2.0.0"
 
-glob@7.1.1:
-  version "7.1.1"
-  resolved "https://registry.yarnpkg.com/glob/-/glob-7.1.1.tgz#805211df04faaf1c63a3600306cdf5ade50b2ec8"
-  dependencies:
-    fs.realpath "^1.0.0"
-    inflight "^1.0.4"
-    inherits "2"
-    minimatch "^3.0.2"
-    once "^1.3.0"
-    path-is-absolute "^1.0.0"
-
-glob@^7.0.0, glob@^7.0.5, glob@^7.0.6, glob@^7.1.1, glob@~7.1.2:
+glob@7.1.2, glob@^7.0.0, glob@^7.0.5, glob@^7.0.6, glob@^7.1.1, glob@~7.1.2:
   version "7.1.2"
   resolved "https://registry.yarnpkg.com/glob/-/glob-7.1.2.tgz#c19c9df9a028702d678612384a6552404c636d15"
   dependencies:
@@ -2157,13 +2159,11 @@ graceful-fs@^4.1.11, graceful-fs@^4.1.2, graceful-fs@^4.1.6, graceful-fs@^4.1.9:
   version "4.1.11"
   resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-4.1.11.tgz#0e8bdfe4d1ddb8854d64e04ea7c00e2a026e5658"
 
-"graceful-readlink@>= 1.0.0":
-  version "1.0.1"
-  resolved "https://registry.yarnpkg.com/graceful-readlink/-/graceful-readlink-1.0.1.tgz#4cafad76bc62f02fa039b2f94e9a3dd3a391a725"
-
-growl@1.9.2:
-  version "1.9.2"
-  resolved "https://registry.yarnpkg.com/growl/-/growl-1.9.2.tgz#0ea7743715db8d8de2c5ede1775e1b45ac85c02f"
+growl@1.10.2:
+  version "1.10.2"
+  resolved "https://registry.yarnpkg.com/growl/-/growl-1.10.2.tgz#8f16dfcd8fb7c04cfc1f4e0012e0ea858726979a"
+  dependencies:
+    eslint-plugin-node "^5.1.0"
 
 handlebars@^4.0.3, handlebars@^4.0.6:
   version "4.0.10"
@@ -2196,6 +2196,10 @@ has-flag@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/has-flag/-/has-flag-1.0.0.tgz#9d9e793165ce017a00f00418c43f942a7b1d11fa"
 
+has-flag@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/has-flag/-/has-flag-2.0.0.tgz#e8207af1cc7b30d446cc70b734b5e8be18f88d51"
+
 has-unicode@^2.0.0:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/has-unicode/-/has-unicode-2.0.1.tgz#e0e6fe6a28cf51138855e086d1691e771de2a8b9"
@@ -2247,6 +2251,10 @@ hdkey@^0.7.0:
     coinstring "^2.0.0"
     secp256k1 "^3.0.1"
 
+he@1.1.1:
+  version "1.1.1"
+  resolved "https://registry.yarnpkg.com/he/-/he-1.1.1.tgz#93410fd21b009735151f8868c2f271f3427e23fd"
+
 highlight.js@^9.0.0:
   version "9.12.0"
   resolved "https://registry.yarnpkg.com/highlight.js/-/highlight.js-9.12.0.tgz#e6d9dbe57cbefe60751f02af336195870c90c01e"
@@ -2301,6 +2309,10 @@ ieee754@^1.1.4:
   version "1.1.8"
   resolved "https://registry.yarnpkg.com/ieee754/-/ieee754-1.1.8.tgz#be33d40ac10ef1926701f6f08a2d86fbfd1ad3e4"
 
+ignore@^3.3.3:
+  version "3.3.5"
+  resolved "https://registry.yarnpkg.com/ignore/-/ignore-3.3.5.tgz#c4e715455f6073a8d7e5dae72d2fc9d71663dba6"
+
 immediate@^3.2.3:
   version "3.2.3"
   resolved "https://registry.yarnpkg.com/immediate/-/immediate-3.2.3.tgz#d140fa8f614659bd6541233097ddaac25cdd991c"
@@ -2680,10 +2692,6 @@ json-stringify-safe@~5.0.1:
   version "5.0.1"
   resolved "https://registry.yarnpkg.com/json-stringify-safe/-/json-stringify-safe-5.0.1.tgz#1296a2d58fd45f19a0f6ce01d65701e2c735b6eb"
 
-json3@3.3.2:
-  version "3.3.2"
-  resolved "https://registry.yarnpkg.com/json3/-/json3-3.3.2.tgz#3c0434743df93e2f5c42aee7b19bcb483575f4e1"
-
 json5@^0.5.0, json5@^0.5.1:
   version "0.5.1"
   resolved "https://registry.yarnpkg.com/json5/-/json5-0.5.1.tgz#1eade7acc012034ad84e2396767ead9fa5495821"
@@ -2852,61 +2860,14 @@ locate-path@^2.0.0:
     p-locate "^2.0.0"
     path-exists "^3.0.0"
 
-lodash._baseassign@^3.0.0:
-  version "3.2.0"
-  resolved "https://registry.yarnpkg.com/lodash._baseassign/-/lodash._baseassign-3.2.0.tgz#8c38a099500f215ad09e59f1722fd0c52bfe0a4e"
-  dependencies:
-    lodash._basecopy "^3.0.0"
-    lodash.keys "^3.0.0"
-
-lodash._basecopy@^3.0.0:
-  version "3.0.1"
-  resolved "https://registry.yarnpkg.com/lodash._basecopy/-/lodash._basecopy-3.0.1.tgz#8da0e6a876cf344c0ad8a54882111dd3c5c7ca36"
-
-lodash._basecreate@^3.0.0:
-  version "3.0.3"
-  resolved "https://registry.yarnpkg.com/lodash._basecreate/-/lodash._basecreate-3.0.3.tgz#1bc661614daa7fc311b7d03bf16806a0213cf821"
-
-lodash._getnative@^3.0.0:
-  version "3.9.1"
-  resolved "https://registry.yarnpkg.com/lodash._getnative/-/lodash._getnative-3.9.1.tgz#570bc7dede46d61cdcde687d65d3eecbaa3aaff5"
-
-lodash._isiterateecall@^3.0.0:
-  version "3.0.9"
-  resolved "https://registry.yarnpkg.com/lodash._isiterateecall/-/lodash._isiterateecall-3.0.9.tgz#5203ad7ba425fae842460e696db9cf3e6aac057c"
-
 lodash.assign@^4.0.3, lodash.assign@^4.0.6:
   version "4.2.0"
   resolved "https://registry.yarnpkg.com/lodash.assign/-/lodash.assign-4.2.0.tgz#0d99f3ccd7a6d261d19bdaeb9245005d285808e7"
 
-lodash.create@3.1.1:
-  version "3.1.1"
-  resolved "https://registry.yarnpkg.com/lodash.create/-/lodash.create-3.1.1.tgz#d7f2849f0dbda7e04682bb8cd72ab022461debe7"
-  dependencies:
-    lodash._baseassign "^3.0.0"
-    lodash._basecreate "^3.0.0"
-    lodash._isiterateecall "^3.0.0"
-
 lodash.get@^4.4.2:
   version "4.4.2"
   resolved "https://registry.yarnpkg.com/lodash.get/-/lodash.get-4.4.2.tgz#2d177f652fa31e939b4438d5341499dfa3825e99"
 
-lodash.isarguments@^3.0.0:
-  version "3.1.0"
-  resolved "https://registry.yarnpkg.com/lodash.isarguments/-/lodash.isarguments-3.1.0.tgz#2f573d85c6a24289ff00663b491c1d338ff3458a"
-
-lodash.isarray@^3.0.0:
-  version "3.0.4"
-  resolved "https://registry.yarnpkg.com/lodash.isarray/-/lodash.isarray-3.0.4.tgz#79e4eb88c36a8122af86f844aa9bcd851b5fbb55"
-
-lodash.keys@^3.0.0:
-  version "3.1.2"
-  resolved "https://registry.yarnpkg.com/lodash.keys/-/lodash.keys-3.1.2.tgz#4dbc0472b156be50a0b286855d1bd0b0c656098a"
-  dependencies:
-    lodash._getnative "^3.0.0"
-    lodash.isarguments "^3.0.0"
-    lodash.isarray "^3.0.0"
-
 lodash@^3.3.1, lodash@^3.6.0:
   version "3.10.1"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-3.10.1.tgz#5bf45e8e49ba4189e17d482789dfd15bd140b7b6"
@@ -3155,25 +3116,20 @@ mkdirp@0.5.1, "mkdirp@>=0.5 0", mkdirp@^0.5.0, mkdirp@^0.5.1, mkdirp@~0.5.0:
   dependencies:
     minimist "0.0.8"
 
-mocha@^3.4.1:
-  version "3.4.2"
-  resolved "https://registry.yarnpkg.com/mocha/-/mocha-3.4.2.tgz#d0ef4d332126dbf18d0d640c9b382dd48be97594"
+mocha@^4.0.0:
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/mocha/-/mocha-4.0.0.tgz#3da718ccd76e93b9d82afb065e17086bdbe352bf"
   dependencies:
     browser-stdout "1.3.0"
-    commander "2.9.0"
-    debug "2.6.0"
-    diff "3.2.0"
+    commander "2.11.0"
+    debug "3.1.0"
+    diff "3.3.1"
     escape-string-regexp "1.0.5"
-    glob "7.1.1"
-    growl "1.9.2"
-    json3 "3.3.2"
-    lodash.create "3.1.1"
+    glob "7.1.2"
+    growl "1.10.2"
+    he "1.1.1"
     mkdirp "0.5.1"
-    supports-color "3.1.2"
-
-ms@0.7.2:
-  version "0.7.2"
-  resolved "https://registry.yarnpkg.com/ms/-/ms-0.7.2.tgz#ae25cf2512b3885a1d95d7f037868d8431124765"
+    supports-color "4.4.0"
 
 ms@2.0.0:
   version "2.0.0"
@@ -4017,7 +3973,7 @@ resolve-url@^0.2.1:
   version "0.2.1"
   resolved "https://registry.yarnpkg.com/resolve-url/-/resolve-url-0.2.1.tgz#2c637fe77c893afd2a663fe21aa9080068e2052a"
 
-resolve@^1.1.6, resolve@^1.3.2, resolve@~1.3.3:
+resolve@^1.1.6, resolve@^1.3.2, resolve@^1.3.3, resolve@~1.3.3:
   version "1.3.3"
   resolved "https://registry.yarnpkg.com/resolve/-/resolve-1.3.3.tgz#655907c3469a8680dc2de3a275a8fdd69691f0e5"
   dependencies:
@@ -4105,7 +4061,7 @@ semver-regex@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/semver-regex/-/semver-regex-1.0.0.tgz#92a4969065f9c70c694753d55248fc68f8f652c9"
 
-"semver@2 || 3 || 4 || 5", semver@^5.3.0:
+"semver@2 || 3 || 4 || 5", semver@5.3.0, semver@^5.3.0:
   version "5.3.0"
   resolved "https://registry.yarnpkg.com/semver/-/semver-5.3.0.tgz#9b2ce5d3de02d17c6012ad326aa6b4d0cf54f94f"
 
@@ -4294,6 +4250,12 @@ source-map-support@^0.4.15, source-map-support@^0.4.2:
   dependencies:
     source-map "^0.5.6"
 
+source-map-support@^0.5.0:
+  version "0.5.0"
+  resolved "https://registry.yarnpkg.com/source-map-support/-/source-map-support-0.5.0.tgz#2018a7ad2bdf8faf2691e5fddab26bed5a2bacab"
+  dependencies:
+    source-map "^0.6.0"
+
 source-map-url@^0.4.0:
   version "0.4.0"
   resolved "https://registry.yarnpkg.com/source-map-url/-/source-map-url-0.4.0.tgz#3e935d7ddd73631b97659956d55128e87b5084a3"
@@ -4308,6 +4270,10 @@ source-map@^0.5.0, source-map@^0.5.3, source-map@^0.5.6, source-map@~0.5.1, sour
   version "0.5.6"
   resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.5.6.tgz#75ce38f52bf0733c5a7f0c118d81334a2bb5f412"
 
+source-map@^0.6.0:
+  version "0.6.1"
+  resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.6.1.tgz#74722af32e9614e9c287a8d0bbde48b5e2f1a263"
+
 spawn-wrap@^1.3.7:
   version "1.3.8"
   resolved "https://registry.yarnpkg.com/spawn-wrap/-/spawn-wrap-1.3.8.tgz#fa2a79b990cbb0bb0018dca6748d88367b19ec31"
@@ -4500,16 +4466,22 @@ strip-json-comments@~2.0.1:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/strip-json-comments/-/strip-json-comments-2.0.1.tgz#3c531942e908c2697c0ec344858c286c7ca0a60a"
 
-supports-color@3.1.2, supports-color@^3.1.0, supports-color@^3.1.2:
-  version "3.1.2"
-  resolved "https://registry.yarnpkg.com/supports-color/-/supports-color-3.1.2.tgz#72a262894d9d408b956ca05ff37b2ed8a6e2a2d5"
+supports-color@4.4.0:
+  version "4.4.0"
+  resolved "https://registry.yarnpkg.com/supports-color/-/supports-color-4.4.0.tgz#883f7ddabc165142b2a61427f3352ded195d1a3e"
   dependencies:
-    has-flag "^1.0.0"
+    has-flag "^2.0.0"
 
 supports-color@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/supports-color/-/supports-color-2.0.0.tgz#535d045ce6b6363fa40117084629995e9df324c7"
 
+supports-color@^3.1.0, supports-color@^3.1.2:
+  version "3.1.2"
+  resolved "https://registry.yarnpkg.com/supports-color/-/supports-color-3.1.2.tgz#72a262894d9d408b956ca05ff37b2ed8a6e2a2d5"
+  dependencies:
+    has-flag "^1.0.0"
+
 tapable@^0.2.5, tapable@~0.2.5:
   version "0.2.6"
   resolved "https://registry.yarnpkg.com/tapable/-/tapable-0.2.6.tgz#206be8e188860b514425375e6f1ae89bfb01fd8d"
@@ -4886,7 +4858,7 @@ uuid@^2.0.1:
   version "2.0.3"
   resolved "https://registry.yarnpkg.com/uuid/-/uuid-2.0.3.tgz#67e2e863797215530dff318e5bf9dcebfd47b21a"
 
-uuid@^3.0.0:
+uuid@^3.0.0, uuid@^3.1.0:
   version "3.1.0"
   resolved "https://registry.yarnpkg.com/uuid/-/uuid-3.1.0.tgz#3dd3d3e790abc24d7b0d3a034ffababe28ebbc04"