feat: add getRecentPrioritizationFees API (#1233)

* feat: add getRecentPrioritizationFees API

Fixes #1095

* test: make the recent prioritization fee tests run in live mode

* fix: when no keys are supplied to getRecentPrioritizationFees, don't forward an empty array to the RPC

* chore: more description for arguments of getRecentPrioritizationFees

* chore: express getRecentPrioritizationFees config as an object

---------

Co-authored-by: steveluscher <[email protected]>

Author: jeivardan

packages/library-legacy/src/connection.ts

@@ -788,6 +788,34 @@ const GetInflationRewardResult = jsonRpcResult(
   ),
 );
 
+export type RecentPrioritizationFees = {
+  /** slot in which the fee was observed */
+  slot: number;
+  /** the per-compute-unit fee paid by at least one successfully landed transaction, specified in increments of 0.000001 lamports*/
+  prioritizationFee: number;
+};
+
+/**
+ * Configuration object for changing `getRecentPrioritizationFees` query behavior
+ */
+export type GetRecentPrioritizationFeesConfig = {
+  /**
+   * If this parameter is provided, the response will reflect a fee to land a transaction locking
+   * all of the provided accounts as writable.
+   */
+  lockedWritableAccounts?: PublicKey[];
+};
+
+/**
+ * Expected JSON RPC response for the "getRecentPrioritizationFees" message
+ */
+const GetRecentPrioritizationFeesResult = array(
+  pick({
+    slot: number(),
+    prioritizationFee: number(),
+  }),
+);
+
 export type InflationRate = {
   /** total inflation */
   total: number;
@@ -1662,6 +1690,13 @@ const GetInflationGovernorRpcResult = jsonRpcResult(GetInflationGovernorResult);
  */
 const GetInflationRateRpcResult = jsonRpcResult(GetInflationRateResult);
 
+/**
+ * Expected JSON RPC response for the "getRecentPrioritizationFees" message
+ */
+const GetRecentPrioritizationFeesRpcResult = jsonRpcResult(
+  GetRecentPrioritizationFeesResult,
+);
+
 /**
  * Expected JSON RPC response for the "getEpochInfo" message
  */
@@ -4468,6 +4503,27 @@ export class Connection {
     return res.result;
   }
 
+  /**
+   * Fetch a list of prioritization fees from recent blocks.
+   */
+  async getRecentPrioritizationFees(
+    config?: GetRecentPrioritizationFeesConfig,
+  ): Promise<RecentPrioritizationFees[]> {
+    const accounts = config?.lockedWritableAccounts?.map(key => key.toBase58());
+    const args = this._buildArgs(accounts?.length ? [accounts] : []);
+    const unsafeRes = await this._rpcRequest(
+      'getRecentPrioritizationFees',
+      args,
+    );
+    const res = create(unsafeRes, GetRecentPrioritizationFeesRpcResult);
+    if ('error' in res) {
+      throw new SolanaJSONRPCError(
+        res.error,
+        'failed to get recent prioritization fees',
+      );
+    }
+    return res.result;
+  }
   /**
    * Fetch a recent blockhash from the cluster
    * @return {Promise<{blockhash: Blockhash, feeCalculator: FeeCalculator}>}

packages/library-legacy/test/connection.test.ts

@@ -4436,6 +4436,34 @@ describe('Connection', function () {
     expect(fee).to.eq(5000);
   });
 
+  it('get recent prioritization fee', async () => {
+    const pubkey = Keypair.generate().publicKey;
+    await mockRpcResponse({
+      method: 'getRecentPrioritizationFees',
+      params: [[pubkey.toBase58()]],
+      value: [
+        {
+          slot: 348127,
+          prioritizationFee: 500,
+        },
+        {
+          slot: 348128,
+          prioritizationFee: 0,
+        },
+      ],
+    });
+
+    const recentPrioritizationFees =
+      await connection.getRecentPrioritizationFees({
+        lockedWritableAccounts: [pubkey],
+      });
+    expect(recentPrioritizationFees).to.be.an('array');
+    for (const prioritizationFee of recentPrioritizationFees) {
+      expect(prioritizationFee.prioritizationFee).to.be.a('number');
+      expect(prioritizationFee.slot).to.be.a('number');
+    }
+  });
+
   it('get block time', async () => {
     await mockRpcResponse({
       method: 'getBlockTime',