Make subscribe function async and make blockStore operational

1 files changed, 25 insertions, 4 deletions

diff --git a/src/stores/block_store.ts b/src/stores/block_store.ts
index d1b4d3c54..70798a999 100644
--- a/src/stores/block_store.ts
+++ b/src/stores/block_store.ts
@@ -1,8 +1,11 @@
 import * as _ from 'lodash';
 import * as Web3 from 'web3';
 import {BigNumber} from 'bignumber.js';
-import {BlockParamLiteral, InternalZeroExError} from '../types';
+import {BlockParamLiteral, InternalZeroExError, ZeroExError} from '../types';
 import {Web3Wrapper} from '../web3_wrapper';
+import {intervalUtils} from '../utils/interval_utils';
+
+const POLLING_INTERVAL_MS = 500;
 
 /**
  * Store for a current latest block number
@@ -10,9 +13,9 @@ import {Web3Wrapper} from '../web3_wrapper';
 export class BlockStore {
     private web3Wrapper?: Web3Wrapper;
     private latestBlockNumber?: number;
+    private intervalId?: NodeJS.Timer;
     constructor(web3Wrapper?: Web3Wrapper) {
         this.web3Wrapper = web3Wrapper;
-        // TODO start a subscription
     }
     public getBlockNumberWithNConfirmations(numConfirmations: number): Web3.BlockParam {
         let blockNumber;
@@ -32,7 +35,25 @@ export class BlockStore {
         }
         return blockNumber;
     }
-    public setLatestBlock(latestBlockNumber: number): void {
-        this.latestBlockNumber = latestBlockNumber;
+    public async startAsync(): Promise<void> {
+        await this.updateLatestBlockAsync();
+        this.intervalId = intervalUtils.setAsyncExcludingInterval(
+            this.updateLatestBlockAsync.bind(this), POLLING_INTERVAL_MS,
+        );
+    }
+    public stop(): void {
+        if (!_.isUndefined(this.intervalId)) {
+            intervalUtils.clearAsyncExcludingInterval(this.intervalId);
+        }
+    }
+    private async updateLatestBlockAsync(): Promise<void> {
+        if (_.isUndefined(this.web3Wrapper)) {
+            throw new Error(InternalZeroExError.Web3WrapperRequiredToStartBlockStore);
+        }
+        const block = await this.web3Wrapper.getBlockAsync(BlockParamLiteral.Latest);
+        if (_.isNull(block.number)) {
+            throw new Error(ZeroExError.FailedToFetchLatestBlock);
+        }
+        this.latestBlockNumber = block.number;
     }
 }