feat: add getBlockTime method

web3.js/module.d.ts

@@ -198,6 +198,7 @@ declare module '@solana/web3.js' {
       commitment?: Commitment,
     ): Promise<RpcResponseAndContext<number>>;
     getBalance(publicKey: PublicKey, commitment?: Commitment): Promise<number>;
+    getBlockTime(slot: number): Promise<number | null>;
     getClusterNodes(): Promise<Array<ContactInfo>>;
     getConfirmedBlock(slot: number): Promise<ConfirmedBlock>;
     getConfirmedTransaction(

web3.js/module.flow.js

@@ -211,6 +211,7 @@ declare module '@solana/web3.js' {
       commitment: ?Commitment,
     ): Promise<RpcResponseAndContext<number>>;
     getBalance(publicKey: PublicKey, commitment: ?Commitment): Promise<number>;
+    getBlockTime(slot: number): Promise<number | null>;
     getClusterNodes(): Promise<Array<ContactInfo>>;
     getConfirmedBlock(slot: number): Promise<ConfirmedBlock>;
     getConfirmedTransaction(

web3.js/src/connection.js

@@ -356,6 +356,16 @@ const GetEpochScheduleRpcResult = struct({
  */
 const GetBalanceAndContextRpcResult = jsonRpcResultAndContext('number?');
 
+/**
+ * Expected JSON RPC response for the "getBlockTime" message
+ */
+const GetBlockTimeRpcResult = struct({
+  jsonrpc: struct.literal('2.0'),
+  id: 'string',
+  error: 'any?',
+  result: struct.union(['null', 'number']),
+});
+
 /**
  * Expected JSON RPC response for the "getVersion" message
  */
@@ -942,6 +952,21 @@ export class Connection {
       });
   }
 
+  /**
+   * Fetch the estimated production time of a block
+   */
+  async getBlockTime(slot: number): Promise<number | null> {
+    const unsafeRes = await this._rpcRequest('getBlockTime', [slot]);
+    const res = GetBlockTimeRpcResult(unsafeRes);
+    if (res.error) {
+      throw new Error(
+        'failed to get block time for slot ' + slot + ': ' + res.error.message,
+      );
+    }
+    assert(typeof res.result !== 'undefined');
+    return res.result;
+  }
+
   /**
    * Fetch all the account info for the specified public key, return with context
    */

web3.js/test/connection.test.js

@@ -1039,6 +1039,29 @@ test('get recent blockhash', async () => {
   expect(feeCalculator.lamportsPerSignature).toBeGreaterThanOrEqual(0);
 });
 
+test('get block time', async () => {
+  const connection = new Connection(url);
+
+  mockRpc.push([
+    url,
+    {
+      method: 'getBlockTime',
+      params: [1],
+    },
+    {
+      error: null,
+      result: 10000,
+    },
+  ]);
+
+  const blockTime = await connection.getBlockTime(1);
+  if (blockTime === null) {
+    expect(blockTime).not.toBeNull();
+  } else {
+    expect(blockTime).toBeGreaterThan(0);
+  }
+});
+
 test('getVersion', async () => {
   const connection = new Connection(url);