Start time performance improvements to build tools (#3797)

* Make os.cpus() faster on Linux

* Fix crash

See https://github.com/ziglang/zig/issues/16540

* Handle watcher_count == 0

* Add assertion

* Clean up lifetimes of fs watcher a little

* :scissors:

* Use `errdefer`

* Make the error better

* Make os.cpus() more lazy

* Please don't translate-c on the entire C standard library

* immediately closing works correctly is still bug

* ops

* fmt+fixeup

* add back verbose

* free instead of destroy

* remove destroy option for watcher tasks

* flush verbose and add debug log

* fixup files

* use log for debug

---------

Co-authored-by: Jarred Sumner <709451+Jarred-Sumner@users.noreply.github.com>
Co-authored-by: cirospaciari <ciro.spaciari@gmail.com>

2 files changed, 116 insertions, 3 deletions

diff --git a/src/js/node/os.js b/src/js/node/os.js
index 2ff98beea..40250ef9a 100644
--- a/src/js/node/os.js
+++ b/src/js/node/os.js
@@ -14,10 +14,72 @@ export var tmpdir = function () {
   return tmpdir();
 };
 
+// os.cpus() is super expensive
+// Specifically: getting the CPU speed on Linux is very expensive
+// Some packages like FastGlob only bother to read the length of the array
+// so instead of actually populating the entire object
+// we turn them into getters
+function lazyCpus({ cpus }) {
+  return () => {
+    const array = new Array(navigator.hardwareConcurrency);
+    function populate() {
+      const results = cpus();
+      const length = results.length;
+      array.length = length;
+      for (let i = 0; i < length; i++) {
+        array[i] = results[i];
+      }
+    }
+
+    for (let i = 0; i < array.length; i++) {
+      // This is technically still observable via
+      // Object.getOwnPropertyDescriptors(), but it should be okay.
+      const instance = {
+        get model() {
+          if (array[i] === instance) populate();
+          return array[i].model;
+        },
+        set model(value) {
+          if (array[i] === instance) populate();
+          array[i].model = value;
+        },
+
+        get speed() {
+          if (array[i] === instance) populate();
+          return array[i].speed;
+        },
+
+        set speed(value) {
+          if (array[i] === instance) populate();
+          array[i].speed = value;
+        },
+
+        get times() {
+          if (array[i] === instance) populate();
+          return array[i].times;
+        },
+        set times(value) {
+          if (array[i] === instance) populate();
+          array[i].times = value;
+        },
+
+        toJSON() {
+          if (array[i] === instance) populate();
+          return array[i];
+        },
+      };
+
+      array[i] = instance;
+    }
+
+    return array;
+  };
+}
+
 function bound(obj) {
   return {
     arch: obj.arch.bind(obj),
-    cpus: obj.cpus.bind(obj),
+    cpus: lazyCpus(obj),
     endianness: obj.endianness.bind(obj),
     freemem: obj.freemem.bind(obj),
     getPriority: obj.getPriority.bind(obj),
diff --git a/src/js/out/modules/node/os.js b/src/js/out/modules/node/os.js
index cc457e06d..005e4df66 100644
--- a/src/js/out/modules/node/os.js
+++ b/src/js/out/modules/node/os.js
@@ -1,7 +1,58 @@
-var bound = function(obj) {
+var lazyCpus = function({ cpus }) {
+  return () => {
+    const array = new Array(navigator.hardwareConcurrency);
+    function populate() {
+      const results = cpus(), length = results.length;
+      array.length = length;
+      for (let i = 0;i < length; i++)
+        array[i] = results[i];
+    }
+    for (let i = 0;i < array.length; i++) {
+      const instance = {
+        get model() {
+          if (array[i] === instance)
+            populate();
+          return array[i].model;
+        },
+        set model(value) {
+          if (array[i] === instance)
+            populate();
+          array[i].model = value;
+        },
+        get speed() {
+          if (array[i] === instance)
+            populate();
+          return array[i].speed;
+        },
+        set speed(value) {
+          if (array[i] === instance)
+            populate();
+          array[i].speed = value;
+        },
+        get times() {
+          if (array[i] === instance)
+            populate();
+          return array[i].times;
+        },
+        set times(value) {
+          if (array[i] === instance)
+            populate();
+          array[i].times = value;
+        },
+        toJSON() {
+          if (array[i] === instance)
+            populate();
+          return array[i];
+        }
+      };
+      array[i] = instance;
+    }
+    return array;
+  };
+}, bound = function(obj) {
   return {
     arch: obj.arch.bind(obj),
-    cpus: obj.cpus.bind(obj),
+    cpus: lazyCpus(obj),
     endianness: obj.endianness.bind(obj),
     freemem: obj.freemem.bind(obj),
     getPriority: obj.getPriority.bind(obj),