perf(NODE-4194): improve objectId constructor performance

.gitignore

@@ -24,3 +24,5 @@ coverage/
 *.d.ts
 *.tgz
 docs/public
+
+*.0x

etc/benchmarks/main.mjs

@@ -0,0 +1,83 @@
+/* eslint-disable @typescript-eslint/no-var-requires */
+import { performance } from 'perf_hooks';
+import { readFile } from 'fs/promises';
+
+const readJSONFile = async path =>
+  JSON.parse(await readFile(new URL(path, import.meta.url), { encoding: 'utf8' }));
+
+const ITERATIONS = 10_000;
+
+function average(array) {
+  let sum = 0;
+  for (const value of array) sum += value;
+  return sum / array.length;
+}
+
+function testPerformance(fn, iterations = ITERATIONS) {
+  let measurements = [];
+  for (let i = 0; i < iterations; i++) {
+    const start = performance.now();
+    fn(i);
+    const end = performance.now();
+    measurements.push(end - start);
+  }
+  return average(measurements).toFixed(8);
+}
+
+async function main() {
+  const [currentBSON, currentReleaseBSON, legacyBSONLib] = await Promise.all([
+    (async () => ({
+      lib: await import('../../lib/bson.js'),
+      version: 'current local'
+    }))(),
+    (async () => ({
+      lib: await import('../../node_modules/bson_latest/lib/bson.js'),
+      version: (await readJSONFile('../../node_modules/bson_latest/package.json')).version
+    }))(),
+    (async () => {
+      const legacyBSON = (await import('../../node_modules/bson_legacy/index.js')).default;
+      return {
+        lib: { ...legacyBSON, ...legacyBSON.prototype },
+        version: (await readJSONFile('../../node_modules/bson_legacy/package.json')).version
+      };
+    })()
+  ]).catch(error => {
+    console.error(error);
+    console.error(
+      `Please run:\n${[
+        'npm run build',
+        'npm install --no-save bson_legacy@npm:bson@1 bson_latest@npm:bson@latest'
+      ].join('\n')}`
+    );
+    process.exit(1);
+  });
+
+  const documents = Array.from({ length: ITERATIONS }, () =>
+    currentReleaseBSON.lib.serialize({
+      _id: new currentReleaseBSON.lib.ObjectId(),
+      field1: 'value1'
+    })
+  );
+
+  console.log(`\nIterations: ${ITERATIONS}`);
+
+  for (const bson of [currentBSON, currentReleaseBSON, legacyBSONLib]) {
+    console.log(`\nBSON@${bson.version}`);
+    console.log(
+      `deserialize({ oid, string }, { validation: { utf8: false } }) takes ${testPerformance(i =>
+        bson.lib.deserialize(documents[i], { validation: { utf8: false } })
+      )}ms on average`
+    );
+
+    const oidBuffer = Buffer.from('00'.repeat(12), 'hex');
+    console.log(
+      `new Oid(buf) take ${testPerformance(() => new bson.lib.ObjectId(oidBuffer))}ms on average`
+    );
+  }
+
+  console.log();
+}
+
+main()
+  .then(() => null)
+  .catch(error => console.error(error));

src/objectid.ts

@@ -72,7 +72,8 @@ export class ObjectId {
       // Generate a new id
       this[kId] = ObjectId.generate(typeof workingId === 'number' ? workingId : undefined);
     } else if (ArrayBuffer.isView(workingId) && workingId.byteLength === 12) {
-      this[kId] = ensureBuffer(workingId);
+      // If intstanceof matches we can escape calling ensure buffer in Node.js environments
+      this[kId] = workingId instanceof Buffer ? workingId : ensureBuffer(workingId);
     } else if (typeof workingId === 'string') {
       if (workingId.length === 12) {
         const bytes = Buffer.from(workingId);

test/node/object_id_tests.js

@@ -383,4 +383,17 @@ describe('ObjectId', function () {
       expect(propAccessRecord).to.deep.equal([oidKId, oidKId]);
     });
   });
+
+  it('should return the same instance if a buffer is passed in', function () {
+    const inBuffer = Buffer.from('00'.repeat(12), 'hex');
+
+    const outBuffer = new ObjectId(inBuffer);
+
+    // instance equality
+    expect(inBuffer).to.equal(outBuffer.id);
+    // deep equality
+    expect(inBuffer).to.deep.equal(outBuffer.id);
+    // class method equality
+    expect(Buffer.prototype.equals.call(inBuffer, outBuffer.id)).to.be.true;
+  });
 });

test/node/tools/utils.js

@@ -1,3 +1,4 @@
+/* globals window */
 'use strict';
 
 exports.assertArrayEqual = function (array1, array2) {