perf(ext/crypto): optimize getRandomValues (#16212)

cli/bench/getrandom.js

@@ -0,0 +1,21 @@
+// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
+let [total, count] = typeof Deno !== "undefined"
+  ? Deno.args
+  : [process.argv[2], process.argv[3]];
+
+total = total ? parseInt(total, 0) : 50;
+count = count ? parseInt(count, 10) : 100000;
+
+async function bench(fun) {
+  const start = Date.now();
+  for (let i = 0; i < count; i++) await fun();
+  const elapsed = Date.now() - start;
+  const rate = Math.floor(count / (elapsed / 1000));
+  console.log(`time ${elapsed} ms rate ${rate}`);
+  if (--total) await bench(fun);
+}
+
+const c = typeof crypto !== "undefined" ? crypto : require("crypto").webcrypto;
+
+const ui8 = new Uint8Array(1024);
+bench(() => c.getRandomValues(ui8));

ext/crypto/00_crypto.js

@@ -4652,6 +4652,11 @@
       webidl.assertBranded(this, CryptoPrototype);
       const prefix = "Failed to execute 'getRandomValues' on 'Crypto'";
       webidl.requiredArguments(arguments.length, 1, { prefix });
+      // Fast path for Uint8Array
+      if (ObjectPrototypeIsPrototypeOf(Uint8ArrayPrototype, arrayBufferView)) {
+        ops.op_crypto_get_random_values(arrayBufferView);
+        return arrayBufferView;
+      }
       arrayBufferView = webidl.converters.ArrayBufferView(arrayBufferView, {
         prefix,
         context: "Argument 1",

ext/crypto/lib.rs

@@ -132,24 +132,24 @@ pub fn op_crypto_base64url_encode(data: ZeroCopyBuf) -> String {
   data
 }
 
-#[op]
+#[op(fast)]
 pub fn op_crypto_get_random_values(
   state: &mut OpState,
-  mut zero_copy: ZeroCopyBuf,
+  out: &mut [u8],
 ) -> Result<(), AnyError> {
-  if zero_copy.len() > 65536 {
+  if out.len() > 65536 {
     return Err(
-      deno_web::DomExceptionQuotaExceededError::new(&format!("The ArrayBufferView's byte length ({}) exceeds the number of bytes of entropy available via this API (65536)", zero_copy.len()))
+      deno_web::DomExceptionQuotaExceededError::new(&format!("The ArrayBufferView's byte length ({}) exceeds the number of bytes of entropy available via this API (65536)", out.len()))
         .into(),
     );
   }
 
   let maybe_seeded_rng = state.try_borrow_mut::<StdRng>();
   if let Some(seeded_rng) = maybe_seeded_rng {
-    seeded_rng.fill(&mut *zero_copy);
+    seeded_rng.fill(out);
   } else {
     let mut rng = thread_rng();
-    rng.fill(&mut *zero_copy);
+    rng.fill(out);
   }
 
   Ok(())