crypto: improve randomUUID performance

lib/internal/crypto/random.js

@@ -1,12 +1,15 @@
 'use strict';
 
 const {
+  Array,
   BigInt,
   FunctionPrototypeBind,
   FunctionPrototypeCall,
   MathMin,
   NumberIsNaN,
   NumberIsSafeInteger,
+  NumberPrototypeToString,
+  StringPrototypePadStart,
 } = primordials;
 
 const {
@@ -291,104 +294,79 @@ function getRandomValues(data) {
 // Implements an RFC 4122 version 4 random UUID.
 // To improve performance, random data is generated in batches
 // large enough to cover kBatchSize UUID's at a time. The uuidData
-// and uuid buffers are reused. Each call to randomUUID() consumes
-// 16 bytes from the buffer.
-
-const kHexDigits = [
-  48, 49, 50, 51, 52, 53, 54, 55,
-  56, 57, 97, 98, 99, 100, 101, 102,
-];
+// buffer is reused. Each call to randomUUID() consumes 16 bytes
+// from the buffer.
 
 const kBatchSize = 128;
 let uuidData;
 let uuidNotBuffered;
-let uuid;
 let uuidBatch = 0;
 
-function getBufferedUUID() {
-  if (uuidData === undefined) {
-    uuidData = secureBuffer(16 * kBatchSize);
-    if (uuidData === undefined)
-      throw new ERR_OPERATION_FAILED('Out of memory');
+let hexBytesCache;
+function getHexBytes() {
+  if (hexBytesCache === undefined) {
+    hexBytesCache = new Array(256);
+    for (let i = 0; i < hexBytesCache.length; i++) {
+      const hex = NumberPrototypeToString(i, 16);
+      hexBytesCache[i] = StringPrototypePadStart(hex, 2, '0');
+    }
   }
+  return hexBytesCache;
+}
+
+function serializeUUID(buf, offset = 0) {
+  const kHexBytes = getHexBytes();
+  // xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
+  return kHexBytes[buf[offset]] +
+    kHexBytes[buf[offset + 1]] +
+    kHexBytes[buf[offset + 2]] +
+    kHexBytes[buf[offset + 3]] +
+    '-' +
+    kHexBytes[buf[offset + 4]] +
+    kHexBytes[buf[offset + 5]] +
+    '-' +
+    kHexBytes[(buf[offset + 6] & 0x0f) | 0x40] +
+    kHexBytes[buf[offset + 7]] +
+    '-' +
+    kHexBytes[(buf[offset + 8] & 0x3f) | 0x80] +
+    kHexBytes[buf[offset + 9]] +
+    '-' +
+    kHexBytes[buf[offset + 10]] +
+    kHexBytes[buf[offset + 11]] +
+    kHexBytes[buf[offset + 12]] +
+    kHexBytes[buf[offset + 13]] +
+    kHexBytes[buf[offset + 14]] +
+    kHexBytes[buf[offset + 15]];
+}
+
+function getBufferedUUID() {
+  uuidData ??= secureBuffer(16 * kBatchSize);
+  if (uuidData === undefined)
+    throw new ERR_OPERATION_FAILED('Out of memory');
 
   if (uuidBatch === 0) randomFillSync(uuidData);
   uuidBatch = (uuidBatch + 1) % kBatchSize;
-  return uuidData.slice(uuidBatch * 16, (uuidBatch * 16) + 16);
+  return serializeUUID(uuidData, uuidBatch * 16);
+}
+
+function getUnbufferedUUID() {
+  uuidNotBuffered ??= secureBuffer(16);
+  if (uuidNotBuffered === undefined)
+    throw new ERR_OPERATION_FAILED('Out of memory');
+  randomFillSync(uuidNotBuffered);
+  return serializeUUID(uuidNotBuffered);
 }
 
 function randomUUID(options) {
   if (options !== undefined)
     validateObject(options, 'options');
   const {
     disableEntropyCache = false,
-  } = { ...options };
+  } = options || {};
 
   validateBoolean(disableEntropyCache, 'options.disableEntropyCache');
 
-  if (uuid === undefined) {
-    uuid = Buffer.alloc(36, '-');
-    uuid[14] = 52; // '4', identifies the UUID version
-  }
-
-  let uuidBuf;
-  if (!disableEntropyCache) {
-    uuidBuf = getBufferedUUID();
-  } else {
-    uuidBuf = uuidNotBuffered;
-    if (uuidBuf === undefined)
-      uuidBuf = uuidNotBuffered = secureBuffer(16);
-    if (uuidBuf === undefined)
-      throw new ERR_OPERATION_FAILED('Out of memory');
-    randomFillSync(uuidBuf);
-  }
-
-  // Variant byte: 10xxxxxx (variant 1)
-  uuidBuf[8] = (uuidBuf[8] & 0x3f) | 0x80;
-
-  // This function is structured the way it is for performance.
-  // The uuid buffer stores the serialization of the random
-  // bytes from uuidData.
-  // xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
-  let n = 0;
-  uuid[0] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[1] = kHexDigits[uuidBuf[n++] & 0xf];
-  uuid[2] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[3] = kHexDigits[uuidBuf[n++] & 0xf];
-  uuid[4] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[5] = kHexDigits[uuidBuf[n++] & 0xf];
-  uuid[6] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[7] = kHexDigits[uuidBuf[n++] & 0xf];
-  // -
-  uuid[9] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[10] = kHexDigits[uuidBuf[n++] & 0xf];
-  uuid[11] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[12] = kHexDigits[uuidBuf[n++] & 0xf];
-  // -
-  // 4, uuid[14] is set already...
-  uuid[15] = kHexDigits[uuidBuf[n++] & 0xf];
-  uuid[16] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[17] = kHexDigits[uuidBuf[n++] & 0xf];
-  // -
-  uuid[19] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[20] = kHexDigits[uuidBuf[n++] & 0xf];
-  uuid[21] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[22] = kHexDigits[uuidBuf[n++] & 0xf];
-  // -
-  uuid[24] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[25] = kHexDigits[uuidBuf[n++] & 0xf];
-  uuid[26] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[27] = kHexDigits[uuidBuf[n++] & 0xf];
-  uuid[28] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[29] = kHexDigits[uuidBuf[n++] & 0xf];
-  uuid[30] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[31] = kHexDigits[uuidBuf[n++] & 0xf];
-  uuid[32] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[33] = kHexDigits[uuidBuf[n++] & 0xf];
-  uuid[34] = kHexDigits[uuidBuf[n] >> 4];
-  uuid[35] = kHexDigits[uuidBuf[n] & 0xf];
-
-  return uuid.latin1Slice(0, 36);
+  return disableEntropyCache ? getUnbufferedUUID() : getBufferedUUID();
 }
 
 function createRandomPrimeJob(type, size, options) {