Allow high precision performance.now() (#1977)

5 files changed, 36 insertions, 19 deletions

diff --git a/js/performance.ts b/js/performance.ts
index 1af75809b..51e213f0f 100644
--- a/js/performance.ts
+++ b/js/performance.ts
@@ -5,13 +5,9 @@ import * as flatbuffers from "./flatbuffers";
 import { assert } from "./util";
 
 export class Performance {
-  timeOrigin = 0;
-
-  constructor() {
-    this.timeOrigin = new Date().getTime();
-  }
-
-  /** Returns a current time from Deno's start
+  /** Returns a current time from Deno's start.
+   *  In milliseconds. Flag --allow-high-precision give
+   *  a precise measure.
    *
    *       const t = performance.now();
    *       console.log(`${t} ms since start!`);
@@ -23,6 +19,6 @@ export class Performance {
     assert(msg.Any.NowRes === baseRes.innerType());
     const res = new msg.NowRes();
     assert(baseRes.inner(res) != null);
-    return res.time().toFloat64() - this.timeOrigin;
+    return res.seconds().toFloat64() * 1e3 + res.subsecNanos() / 1e6;
   }
 }
diff --git a/js/performance_test.ts b/js/performance_test.ts
index 154dadbbe..8f9dbc990 100644
--- a/js/performance_test.ts
+++ b/js/performance_test.ts
@@ -1,7 +1,7 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
-import { test, assert } from "./test_util.ts";
+import { testPerm, assert } from "./test_util.ts";
 
-test(function now() {
+testPerm({ highPrecision: false }, function now() {
   const start = performance.now();
   setTimeout(() => {
     const end = performance.now();
diff --git a/js/permissions.ts b/js/permissions.ts
index 46c809cf6..d0885ba6a 100644
--- a/js/permissions.ts
+++ b/js/permissions.ts
@@ -11,7 +11,7 @@ export interface Permissions {
   net: boolean;
   env: boolean;
   run: boolean;
-
+  highPrecision: boolean;
   // NOTE: Keep in sync with src/permissions.rs
 }
 
@@ -29,7 +29,8 @@ function createPermissions(inner: msg.PermissionsRes): Permissions {
     write: inner.write(),
     net: inner.net(),
     env: inner.env(),
-    run: inner.run()
+    run: inner.run(),
+    highPrecision: inner.highPrecision()
   };
 }
 
diff --git a/js/permissions_test.ts b/js/permissions_test.ts
index e44be79bb..c49696c01 100644
--- a/js/permissions_test.ts
+++ b/js/permissions_test.ts
@@ -6,7 +6,8 @@ const knownPermissions: Deno.Permission[] = [
   "read",
   "write",
   "net",
-  "env"
+  "env",
+  "highPrecision"
 ];
 
 for (let grant of knownPermissions) {
diff --git a/js/test_util.ts b/js/test_util.ts
index e683d32b1..15bbb521b 100644
--- a/js/test_util.ts
+++ b/js/test_util.ts
@@ -26,6 +26,7 @@ interface DenoPermissions {
   net?: boolean;
   env?: boolean;
   run?: boolean;
+  highPrecision?: boolean;
 }
 
 function permToString(perms: DenoPermissions): string {
@@ -34,11 +35,12 @@ function permToString(perms: DenoPermissions): string {
   const n = perms.net ? 1 : 0;
   const e = perms.env ? 1 : 0;
   const u = perms.run ? 1 : 0;
-  return `permR${r}W${w}N${n}E${e}U${u}`;
+  const h = perms.highPrecision ? 1 : 0;
+  return `permR${r}W${w}N${n}E${e}U${u}H${h}`;
 }
 
 function permFromString(s: string): DenoPermissions {
-  const re = /^permR([01])W([01])N([01])E([01])U([01])$/;
+  const re = /^permR([01])W([01])N([01])E([01])U([01])H([01])$/;
   const found = s.match(re);
   if (!found) {
     throw Error("Not a permission string");
@@ -48,7 +50,8 @@ function permFromString(s: string): DenoPermissions {
     write: Boolean(Number(found[2])),
     net: Boolean(Number(found[3])),
     env: Boolean(Number(found[4])),
-    run: Boolean(Number(found[5]))
+    run: Boolean(Number(found[5])),
+    highPrecision: Boolean(Number(found[6]))
   };
 }
 
@@ -62,7 +65,14 @@ export function testPerm(
 
 export function test(fn: testing.TestFunction): void {
   testPerm(
-    { read: false, write: false, net: false, env: false, run: false },
+    {
+      read: false,
+      write: false,
+      net: false,
+      env: false,
+      run: false,
+      highPrecision: false
+    },
     fn
   );
 }
@@ -73,8 +83,17 @@ test(function permSerialization() {
       for (const env of [true, false]) {
         for (const run of [true, false]) {
           for (const read of [true, false]) {
-            const perms: DenoPermissions = { write, net, env, run, read };
-            assertEquals(perms, permFromString(permToString(perms)));
+            for (const highPrecision of [true, false]) {
+              const perms: DenoPermissions = {
+                write,
+                net,
+                env,
+                run,
+                read,
+                highPrecision
+              };
+              assertEquals(perms, permFromString(permToString(perms)));
+            }
           }
         }
       }