Lazily instantiate exchangeContract and store as instance variable instead of re-instantiating on every call

1 files changed, 14 insertions, 3 deletions

diff --git a/src/contract_wrappers/exchange_wrapper.ts b/src/contract_wrappers/exchange_wrapper.ts
index f0f153c2b..a7abbb078 100644
--- a/src/contract_wrappers/exchange_wrapper.ts
+++ b/src/contract_wrappers/exchange_wrapper.ts
@@ -1,4 +1,5 @@
 import * as _ from 'lodash';
+import * as Web3 from 'web3';
 import {Web3Wrapper} from '../web3_wrapper';
 import {ECSignature, ZeroExError, ExchangeContract} from '../types';
 import {assert} from '../utils/assert';
@@ -7,9 +8,13 @@ import * as ExchangeArtifacts from '../artifacts/Exchange.json';
 import {ecSignatureSchema} from '../schemas/ec_signature_schema';
 
 export class ExchangeWrapper extends ContractWrapper {
+    private exchangeContractIfExists: ExchangeContract;
     constructor(web3Wrapper: Web3Wrapper) {
         super(web3Wrapper);
     }
+    public invalidateExchangeContract() {
+        delete this.exchangeContractIfExists;
+    }
     public async isValidSignatureAsync(dataHex: string, ecSignature: ECSignature,
                                        signerAddressHex: string): Promise<boolean> {
         assert.isHexString('dataHex', dataHex);
@@ -19,10 +24,9 @@ export class ExchangeWrapper extends ContractWrapper {
         const senderAddressIfExists = await this.web3Wrapper.getSenderAddressIfExistsAsync();
         assert.assert(!_.isUndefined(senderAddressIfExists), ZeroExError.USER_HAS_NO_ASSOCIATED_ADDRESSES);
 
-        const contractInstance = await this.instantiateContractIfExistsAsync((ExchangeArtifacts as any));
-        const exchangeInstance = contractInstance as ExchangeContract;
+        await this.instantiateExchangeContractIfDoesntExistAsync();
 
-        const isValidSignature = await exchangeInstance.isValidSignature.call(
+        const isValidSignature = await this.exchangeContractIfExists.isValidSignature.call(
             signerAddressHex,
             dataHex,
             ecSignature.v,
@@ -34,4 +38,11 @@ export class ExchangeWrapper extends ContractWrapper {
         );
         return isValidSignature;
     }
+    private async instantiateExchangeContractIfDoesntExistAsync() {
+        if (!_.isUndefined(this.exchangeContractIfExists)) {
+            return;
+        }
+        const contractInstance = await this.instantiateContractIfExistsAsync((ExchangeArtifacts as any));
+        this.exchangeContractIfExists = contractInstance as ExchangeContract;
+    }
 }