perf: use a random pool

Author: ronag

lib/random-util.js

@@ -0,0 +1,36 @@
+'use strict';
+
+const RANDOM_POOL_SIZE = 8192;
+const RANDOM_POOL_REFRESH = 1024;
+
+let randomPool = Buffer.alloc(RANDOM_POOL_SIZE);
+let randomPoolIdx = RANDOM_POOL_SIZE;
+let randomPending = true;
+
+function onRandomBytes (err, buf) {
+  randomPending = false;
+  if (!err) {
+    randomPool = buf;
+    randomPoolIdx = 0;
+  }
+}
+
+crypto.randomBytes(RANDOM_POOL_SIZE, onRandomBytes);
+
+function randomFillSync (buffer, offset, size) {
+  if (RANDOM_POOL_SIZE - randomPoolIdx < size) {
+    return crypto.randomFillSync(buffer, offset, size);
+  }
+
+  randomPool.copy(buffer, offset, randomPoolIdx, randomPoolIdx + size);
+  randomPoolIdx += size;
+
+  if (!randomPending && RANDOM_POOL_SIZE - randomPoolIdx < RANDOM_POOL_REFRESH) {
+    randomPending = true;
+    crypto.randomBytes(RANDOM_POOL_SIZE, onRandomBytes);
+  }
+
+  return buffer;
+}
+
+module.exports = { randomFillSync };

lib/sender.js

@@ -4,7 +4,7 @@
 
 const net = require('net');
 const tls = require('tls');
-const { randomFillSync } = require('crypto');
+const { randomFillSync } = require('./random-util');
 
 const PerMessageDeflate = require('./permessage-deflate');
 const { EMPTY_BUFFER } = require('./constants');