fix: wait for the next lastId before sending a new transaction

web3.js/src/connection.js

@@ -7,6 +7,7 @@ import {struct} from 'superstruct';
 
 import {Transaction} from './transaction';
 import {PublicKey} from './publickey';
+import {sleep} from './util/sleep';
 import type {Account} from './account';
 import type {TransactionSignature, TransactionId} from './transaction';
 
@@ -158,6 +159,7 @@ export type SignatureStatus = 'Confirmed' | 'SignatureNotFound' | 'ProgramRuntim
  */
 export class Connection {
   _rpcRequest: RpcRequest;
+  _lastId: null | TransactionId;
 
   /**
    * Establish a JSON RPC connection
@@ -169,6 +171,7 @@ export class Connection {
       throw new Error('Connection endpoint not specified');
     }
     this._rpcRequest = createRpcRequest(endpoint);
+    this._lastId = null;
   }
 
   /**
@@ -298,7 +301,26 @@ export class Connection {
    * Sign and send a transaction
    */
   async sendTransaction(from: Account, transaction: Transaction): Promise<TransactionSignature> {
-    transaction.lastId = await this.getLastId();
+
+    let attempts = 0;
+    for (;;) {
+      transaction.lastId = await this.getLastId();
+
+      // TODO: Waiting for the next lastId is really only necessary if a second
+      //       transaction with the raw input bytes as an in-flight transaction
+      //       is issued.
+      if (this._lastId != transaction.lastId) {
+        this._lastId = transaction.lastId;
+        break;
+      }
+      if (attempts === 20) {
+        throw new Error('Unable to obtain new last id');
+      }
+      // TODO: Add a pubsub notification for obtaining the next last id instead
+      //       of polling?
+      await sleep(100);
+      ++attempts;
+    }
     transaction.sign(from);
 
     const wireTransaction = transaction.serialize();

web3.js/test/connection.test.js

@@ -6,6 +6,7 @@ import {
   SystemProgram,
 } from '../src';
 import {mockRpc, mockRpcEnabled} from './__mocks__/node-fetch';
+import {mockGetLastId} from './mockrpc/getlastid';
 import {url} from './url';
 
 if (!mockRpcEnabled) {
@@ -117,18 +118,7 @@ test('get transaction count', async () => {
 test('get last Id', async () => {
   const connection = new Connection(url);
 
-  mockRpc.push([
-    url,
-    {
-      method: 'getLastId',
-      params: [],
-    },
-    {
-      error: null,
-      result: '2BjEqiiT43J6XskiHdz7aoocjPeWkCPiKD72SiFQsrA2',
-    }
-  ]
-  );
+  mockGetLastId();
 
   const lastId = await connection.getLastId();
   expect(lastId.length).toBeGreaterThanOrEqual(43);
@@ -283,18 +273,7 @@ test('transaction', async () => {
   await connection.requestAirdrop(accountTo.publicKey, 21);
   expect(await connection.getBalance(accountTo.publicKey)).toBe(21);
 
-  mockRpc.push([
-    url,
-    {
-      method: 'getLastId',
-      params: [],
-    },
-    {
-      error: null,
-      result: '2BjEqiiT43J6XskiHdz7aoocjPeWkCPiKD72SiFQsrA2',
-    }
-  ]
-  );
+  mockGetLastId();
   mockRpc.push([
     url,
     {

web3.js/test/mockrpc/getlastid.js

@@ -0,0 +1,23 @@
+// @flow
+
+import {
+  Account,
+} from '../../src';
+import {url} from '../url';
+import {mockRpc} from '../__mocks__/node-fetch';
+
+export function mockGetLastId() {
+  const lastId = new Account();
+
+  mockRpc.push([
+    url,
+    {
+      method: 'getLastId',
+      params: [],
+    },
+    {
+      error: null,
+      result: lastId.publicKey.toBase58(),
+    }
+  ]);
+}

web3.js/test/token-program.test.js

@@ -10,26 +10,13 @@ import {SYSTEM_TOKEN_PROGRAM_ID} from '../src/token-program';
 import {mockRpc, mockRpcEnabled} from './__mocks__/node-fetch';
 import {url} from './url';
 import {newAccountWithTokens} from './new-account-with-tokens';
+import {mockGetLastId} from './mockrpc/getlastid';
 
 if (!mockRpcEnabled) {
   // The default of 5 seconds is too slow for live testing sometimes
   jest.setTimeout(10000);
 }
 
-function mockGetLastId() {
-  mockRpc.push([
-    url,
-    {
-      method: 'getLastId',
-      params: [],
-    },
-    {
-      error: null,
-      result: '2BjEqiiT43J6XskiHdz7aoocjPeWkCPiKD72SiFQsrA2',
-    }
-  ]);
-}
-
 function mockGetSignatureStatus(result: string = 'Confirmed') {
   mockRpc.push([
     url,