Poll node in batch to get validator indices

packages/validator/src/services/indices.ts

@@ -3,6 +3,13 @@ import {ILogger} from "@chainsafe/lodestar-utils";
 import {toHexString} from "@chainsafe/ssz";
 import {Api} from "@chainsafe/lodestar-api";
 import {ValidatorStore} from "./validatorStore";
+import {batchItems} from "../util/batch";
+
+/**
+ * URLs have a limitation on size, adding an unbounded num of pubkeys will break the request.
+ * For reasoning on the specific number see: https://github.com/ChainSafe/lodestar/pull/2730#issuecomment-866749083
+ */
+const PUBKEYS_PER_REQUEST = 10;
 
 // To assist with readability
 type PubkeyHex = string;
@@ -58,9 +65,21 @@ export class IndicesService {
     }
 
     // Query the remote BN to resolve a pubkey to a validator index.
+    // support up to 1000 pubkeys per poll
     const pubkeysHex = pubkeysToPoll.map((pubkey) => toHexString(pubkey));
-    const validatorsState = await this.api.beacon.getStateValidators("head", {indices: pubkeysHex});
+    const pubkeysHexBatches = batchItems(pubkeysHex, {batchSize: PUBKEYS_PER_REQUEST});
+
+    const newIndices: number[] = [];
+    for (const pubkeysHexBatch of pubkeysHexBatches) {
+      const validatorIndicesArr = await this.fetchValidatorIndices(pubkeysHexBatch);
+      newIndices.push(...validatorIndicesArr);
+    }
+    this.logger.info("Discovered new validators", {count: newIndices.length});
+    return newIndices;
+  }
 
+  private async fetchValidatorIndices(pubkeysHex: string[]): Promise<ValidatorIndex[]> {
+    const validatorsState = await this.api.beacon.getStateValidators("head", {indices: pubkeysHex});
     const newIndices = [];
     for (const validatorState of validatorsState.data) {
       const pubkeyHex = toHexString(validatorState.validator.pubkey);
@@ -71,7 +90,6 @@ export class IndicesService {
         newIndices.push(validatorState.index);
       }
     }
-
     return newIndices;
   }
 }

packages/validator/src/util/batch.ts

@@ -0,0 +1,16 @@
+/**
+ * Divide pubkeys into batches, each batch contains at most 5 http requests,
+ * each request can work on at most 40 pubkeys.
+ */
+export function batchItems<T>(items: T[], opts: {batchSize: number; maxBatches?: number}): T[][] {
+  const batches: T[][] = [];
+  const maxBatches = opts.maxBatches ?? Math.ceil(items.length / opts.batchSize);
+
+  for (let i = 0; i < maxBatches; i++) {
+    const batch = items.slice(opts.batchSize * i, opts.batchSize * (i + 1));
+    if (batch.length === 0) break;
+    batches.push(batch);
+  }
+
+  return batches;
+}

packages/validator/test/unit/utils/batch.test.ts

@@ -0,0 +1,42 @@
+import {expect} from "chai";
+import {batchItems} from "../../../src/util/batch";
+
+describe("util / batch", function () {
+  const testCases: {items: string[]; expected: string[][]}[] = [
+    {items: [], expected: []},
+    {items: ["1"], expected: [["1"]]},
+    {items: ["1", "2"], expected: [["1", "2"]]},
+    {items: ["1", "2", "3"], expected: [["1", "2"], ["3"]]},
+    {
+      items: ["1", "2", "3", "4"],
+      expected: [
+        ["1", "2"],
+        ["3", "4"],
+      ],
+    },
+    {items: ["1", "2", "3", "4", "5"], expected: [["1", "2"], ["3", "4"], ["5"]]},
+    {
+      items: ["1", "2", "3", "4", "5", "6"],
+      expected: [
+        ["1", "2"],
+        ["3", "4"],
+        ["5", "6"],
+      ],
+    },
+    // Ignore item 7 since it's over the max
+    {
+      items: ["1", "2", "3", "4", "5", "6", "7"],
+      expected: [
+        ["1", "2"],
+        ["3", "4"],
+        ["5", "6"],
+      ],
+    },
+  ];
+
+  for (const {items: pubkeys, expected} of testCases) {
+    it(`Batch ${pubkeys.length} items`, () => {
+      expect(batchItems(pubkeys, {batchSize: 2, maxBatches: 3})).to.deep.equal(expected);
+    });
+  }
+});