From a33ee087ce77b8eb15ae23858c6743ce12eea563 Mon Sep 17 00:00:00 2001
From: Aaron O'Mullan <aaron.omullan@gmail.com>
Date: Thu, 23 Sep 2021 00:45:58 +0200
Subject: perf(ops): optimize permission check (#11800)

* perf(ops): optimize permission check

Removes the overhead of permission check on access granted (should be common case):

Delta measured on `perf_now` from `deno_common` bench:
- before: `528ns/op
- after: `166ns/op`

So ~3x faster
---
 runtime/permissions.rs | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/runtime/permissions.rs b/runtime/permissions.rs
index c6fcfc58c..4b92f7835 100644
--- a/runtime/permissions.rs
+++ b/runtime/permissions.rs
@@ -12,7 +12,7 @@ use deno_core::serde::Serialize;
 use deno_core::url;
 use deno_core::ModuleSpecifier;
 use deno_core::OpState;
-use log::debug;
+use log;
 use std::collections::HashSet;
 use std::fmt;
 use std::hash::Hash;
@@ -24,6 +24,10 @@ use std::sync::atomic::Ordering;
 
 const PERMISSION_EMOJI: &str = "⚠️";
 
+lazy_static::lazy_static! {
+  static ref DEBUG_LOG_ENABLED: bool = log::log_enabled!(log::Level::Debug);
+}
+
 /// Tri-state value for storing permission state
 #[derive(PartialEq, Debug, Clone, Copy, Deserialize, PartialOrd)]
 pub enum PermissionState {
@@ -35,14 +39,19 @@ pub enum PermissionState {
 impl PermissionState {
   #[inline(always)]
   fn log_perm_access(name: &str, info: Option<&str>) {
-    debug!(
-      "{}",
-      colors::bold(&format!(
-        "{}️  Granted {}",
-        PERMISSION_EMOJI,
-        Self::fmt_access(name, info)
-      ))
-    );
+    // Eliminates log overhead (when logging is disabled),
+    // log_enabled!(Debug) check in a hot path still has overhead
+    // TODO(AaronO): generalize or upstream this optimization
+    if *DEBUG_LOG_ENABLED {
+      log::debug!(
+        "{}",
+        colors::bold(&format!(
+          "{}️  Granted {}",
+          PERMISSION_EMOJI,
+          Self::fmt_access(name, info)
+        ))
+      );
+    }
   }
 
   fn fmt_access(name: &str, info: Option<&str>) -> String {
-- 
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