Merge pull request #137 from 0xProject/unlimited-allowance

Add setUnlimitedProxyAllowanceAsync and setUnlimitedAllowanceAsync

4 files changed, 91 insertions, 1 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index df161b3a2..ad72b3d04 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # CHANGELOG
 
+v0.11.0 - _TBD_
+------------------------
+    * Added `zeroEx.token.setUnlimitedProxyAllowanceAsync` (#137)
+    * Added `zeroEx.token.setUnlimitedAllowanceAsync` (#137)
+    * Added `zeroEx.token.UNLIMITED_ALLOWANCE_IN_BASE_UNITS` (#137)
+
 v0.10.4 - _Aug 24, 2017_
 ------------------------
     * Fixed a bug where checksummed addresses were being pulled from artifacts and not lower-cased. (#135)
diff --git a/src/contract_wrappers/token_wrapper.ts b/src/contract_wrappers/token_wrapper.ts
index 8c1bf6b52..a2812ccdb 100644
--- a/src/contract_wrappers/token_wrapper.ts
+++ b/src/contract_wrappers/token_wrapper.ts
@@ -21,7 +21,7 @@ import {
     ContractEventObj,
 } from '../types';
 
-const ALLOWANCE_TO_ZERO_GAS_AMOUNT = 45730;
+const ALLOWANCE_TO_ZERO_GAS_AMOUNT = 47155;
 
 /**
  * This class includes all the functionality related to interacting with ERC20 token contracts.
@@ -29,6 +29,7 @@ const ALLOWANCE_TO_ZERO_GAS_AMOUNT = 45730;
  * to the 0x Proxy smart contract.
  */
 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[];
     constructor(web3Wrapper: Web3Wrapper) {
@@ -80,6 +81,22 @@ export class TokenWrapper extends ContractWrapper {
         });
     }
     /**
+     * Sets the spender's allowance to an unlimited number of baseUnits on behalf of the owner address.
+     * Equivalent to the ERC20 spec method `approve`.
+     * Setting an unlimited allowance will lower the gas cost for filling orders involving tokens that forego updating
+     * allowances set to the max amount (e.g ZRX, WETH)
+     * @param   tokenAddress        The hex encoded contract Ethereum address where the ERC20 token is deployed.
+     * @param   ownerAddress        The hex encoded user Ethereum address who would like to set an allowance
+     *                              for spenderAddress.
+     * @param   spenderAddress      The hex encoded user Ethereum address who will be able to spend the set allowance.
+     */
+    public async setUnlimitedAllowanceAsync(tokenAddress: string, ownerAddress: string,
+                                            spenderAddress: string): Promise<void> {
+        await this.setAllowanceAsync(
+            tokenAddress, ownerAddress, spenderAddress, this.UNLIMITED_ALLOWANCE_IN_BASE_UNITS,
+        );
+    }
+    /**
      * Retrieves the owners allowance in baseUnits set to the spender's address.
      * @param   tokenAddress    The hex encoded contract Ethereum address where the ERC20 token is deployed.
      * @param   ownerAddress    The hex encoded user Ethereum address whose allowance to spenderAddress
@@ -127,6 +144,18 @@ export class TokenWrapper extends ContractWrapper {
         await this.setAllowanceAsync(tokenAddress, ownerAddress, proxyAddress, amountInBaseUnits);
     }
     /**
+     * Sets the 0x proxy contract's allowance to a unlimited number of a tokens' baseUnits on behalf
+     * of an owner address.
+     * Setting an unlimited allowance will lower the gas cost for filling orders involving tokens that forego updating
+     * allowances set to the max amount (e.g ZRX, WETH)
+     * @param   tokenAddress        The hex encoded contract Ethereum address where the ERC20 token is deployed.
+     * @param   ownerAddress        The hex encoded user Ethereum address who is setting an allowance
+     *                              for the Proxy contract.
+     */
+    public async setUnlimitedProxyAllowanceAsync(tokenAddress: string, ownerAddress: string): Promise<void> {
+        await this.setProxyAllowanceAsync(tokenAddress, ownerAddress, this.UNLIMITED_ALLOWANCE_IN_BASE_UNITS);
+    }
+    /**
      * Transfers `amountInBaseUnits` ERC20 tokens from `fromAddress` to `toAddress`.
      * @param   tokenAddress        The hex encoded contract Ethereum address where the ERC20 token is deployed.
      * @param   fromAddress         The hex encoded user Ethereum address that will send the funds.
diff --git a/src/utils/constants.ts b/src/utils/constants.ts
index d56ee16c5..1b11d7055 100644
--- a/src/utils/constants.ts
+++ b/src/utils/constants.ts
@@ -1,7 +1,10 @@
+import * as BigNumber from 'bignumber.js';
+
 export const constants = {
     NULL_ADDRESS: '0x0000000000000000000000000000000000000000',
     TESTRPC_NETWORK_ID: 50,
     MAX_DIGITS_IN_UNSIGNED_256_INT: 78,
     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),
 };
diff --git a/test/token_wrapper_test.ts b/test/token_wrapper_test.ts
index 8adaa6351..f4653e432 100644
--- a/test/token_wrapper_test.ts
+++ b/test/token_wrapper_test.ts
@@ -16,6 +16,7 @@ import {
     ApprovalContractEventArgs,
 } from '../src';
 import {BlockchainLifecycle} from './utils/blockchain_lifecycle';
+import {TokenUtils} from './utils/token_utils';
 import {DoneCallback} from '../src/types';
 
 chaiSetup.configure();
@@ -27,6 +28,7 @@ describe('TokenWrapper', () => {
     let zeroEx: ZeroEx;
     let userAddresses: string[];
     let tokens: Token[];
+    let tokenUtils: TokenUtils;
     let coinbase: string;
     let addressWithoutFunds: string;
     before(async () => {
@@ -34,6 +36,7 @@ describe('TokenWrapper', () => {
         zeroEx = new ZeroEx(web3.currentProvider);
         userAddresses = await promisify(web3.eth.getAccounts)();
         tokens = await zeroEx.tokenRegistry.getTokensAsync();
+        tokenUtils = new TokenUtils(tokens);
         coinbase = userAddresses[0];
         addressWithoutFunds = userAddresses[1];
     });
@@ -206,6 +209,45 @@ describe('TokenWrapper', () => {
             return expect(allowanceAfterSet).to.be.bignumber.equal(expectedAllowanceAfterAllowanceSet);
         });
     });
+    describe('#setUnlimitedAllowanceAsync', () => {
+        it('should set the unlimited spender\'s allowance', async () => {
+            const token = tokens[0];
+            const ownerAddress = coinbase;
+            const spenderAddress = addressWithoutFunds;
+
+            await zeroEx.token.setUnlimitedAllowanceAsync(token.address, ownerAddress, spenderAddress);
+            const allowance = await zeroEx.token.getAllowanceAsync(token.address, ownerAddress, spenderAddress);
+            return expect(allowance).to.be.bignumber.equal(zeroEx.token.UNLIMITED_ALLOWANCE_IN_BASE_UNITS);
+        });
+        it('should reduce the gas cost for transfers including tokens with unlimited allowance support', async () => {
+            const transferAmount = new BigNumber(5);
+            const zrx = tokenUtils.getProtocolTokenOrThrow();
+            const [, userWithNormalAllowance, userWithUnlimitedAllowance] = userAddresses;
+            await zeroEx.token.setAllowanceAsync(zrx.address, coinbase, userWithNormalAllowance, transferAmount);
+            await zeroEx.token.setUnlimitedAllowanceAsync(zrx.address, coinbase, userWithUnlimitedAllowance);
+
+            const initBalanceWithNormalAllowance = await promisify(web3.eth.getBalance)(userWithNormalAllowance);
+            const initBalanceWithUnlimitedAllowance = await promisify(web3.eth.getBalance)(userWithUnlimitedAllowance);
+
+            await zeroEx.token.transferFromAsync(
+                zrx.address, coinbase, userWithNormalAllowance, userWithNormalAllowance, transferAmount,
+            );
+            await zeroEx.token.transferFromAsync(
+                zrx.address, coinbase, userWithUnlimitedAllowance, userWithUnlimitedAllowance, transferAmount,
+            );
+
+            const finalBalanceWithNormalAllowance = await promisify(web3.eth.getBalance)(userWithNormalAllowance);
+            const finalBalanceWithUnlimitedAllowance = await promisify(web3.eth.getBalance)(userWithUnlimitedAllowance);
+
+            const normalGasCost = initBalanceWithNormalAllowance.minus(finalBalanceWithNormalAllowance);
+            const unlimitedGasCost = initBalanceWithUnlimitedAllowance.minus(finalBalanceWithUnlimitedAllowance);
+
+            // In theory the gas cost with unlimited allowance should be smaller, but with testrpc it's actually bigger.
+            // This needs to be investigated in ethereumjs-vm. This test is essentially a repro.
+            // TODO: Make this test pass with inverted assertion.
+            expect(unlimitedGasCost.toNumber()).to.be.gt(normalGasCost.toNumber());
+        });
+    });
     describe('#getAllowanceAsync', () => {
         describe('With web3 provider with accounts', () => {
             it('should get the proxy allowance', async () => {
@@ -282,6 +324,16 @@ describe('TokenWrapper', () => {
             return expect(allowanceAfterSet).to.be.bignumber.equal(expectedAllowanceAfterAllowanceSet);
         });
     });
+    describe('#setUnlimitedProxyAllowanceAsync', () => {
+        it('should set the unlimited proxy allowance', async () => {
+            const token = tokens[0];
+            const ownerAddress = coinbase;
+
+            await zeroEx.token.setUnlimitedProxyAllowanceAsync(token.address, ownerAddress);
+            const allowance = await zeroEx.token.getProxyAllowanceAsync(token.address, ownerAddress);
+            return expect(allowance).to.be.bignumber.equal(zeroEx.token.UNLIMITED_ALLOWANCE_IN_BASE_UNITS);
+        });
+    });
     describe('#subscribeAsync', () => {
         const indexFilterValues = {};
         const shouldThrowOnInsufficientBalanceOrAllowance = true;