buffer: improve equals() performance

PR-URL: #29199
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Yongsheng Zhang <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Trivikram Kamat <[email protected]>
Reviewed-By: Rich Trott <[email protected]>

Author: mscdex

benchmark/buffers/buffer-equals.js

@@ -0,0 +1,22 @@
+'use strict';
+const common = require('../common.js');
+
+const bench = common.createBenchmark(main, {
+  size: [0, 512, 16386],
+  difflen: ['true', 'false'],
+  n: [1e6]
+});
+
+function main({ n, size, difflen }) {
+  const b0 = Buffer.alloc(size, 'a');
+  const b1 = Buffer.alloc(size + (difflen === 'true' ? 1 : 0), 'a');
+
+  if (b1.length > 0)
+    b1[b1.length - 1] = 'b'.charCodeAt(0);
+
+  bench.start();
+  for (let i = 0; i < n; i++) {
+    b0.equals(b1);
+  }
+  bench.end(n);
+}

lib/buffer.js

@@ -716,10 +716,14 @@ Buffer.prototype.equals = function equals(otherBuffer) {
     throw new ERR_INVALID_ARG_TYPE(
       'otherBuffer', ['Buffer', 'Uint8Array'], otherBuffer);
   }
+
   if (this === otherBuffer)
     return true;
 
-  return _compare(this, otherBuffer) === 0;
+  if (this.byteLength !== otherBuffer.byteLength)
+    return false;
+
+  return this.byteLength === 0 || _compare(this, otherBuffer) === 0;
 };
 
 let INSPECT_MAX_BYTES = 50;

test/benchmark/test-benchmark-buffer.js

@@ -12,6 +12,7 @@ runBenchmark('buffers',
                'bytes=0',
                'byteLength=1',
                'charsPerLine=6',
+               'difflen=false',
                'encoding=utf8',
                'endian=BE',
                'len=256',