a terrible hack to make hrtime faster

just.cc

@@ -3,6 +3,7 @@
 std::map<std::string, just::builtin*> just::builtins;
 std::map<std::string, just::register_plugin> just::modules;
 uint32_t scriptId = 1;
+just::handle* handles[1024];
 
 ssize_t just::process_memory_usage() {
   char buf[1024];
@@ -558,8 +559,22 @@ void just::Modules(const FunctionCallbackInfo<Value> &args) {
 }
 
 void just::HRTime(const FunctionCallbackInfo<Value> &args) {
-  uint64_t* ptr = reinterpret_cast<uint64_t*>(Local<BigInt>::Cast(args[0])->Uint64Value());
+  int index = Local<Integer>::Cast(args[0])->Value();
+  // todo: check out of bounds etc.
+  just::handle* h = handles[index];
+  if (h) {
+    uint64_t* ptr = (uint64_t*)h->ptr;    
+    *ptr = just::hrtime();
+    return;
+  }
+  h = (just::handle*)calloc(1, sizeof(just::handle));
+  Local<ArrayBuffer> ab = args[1].As<ArrayBuffer>();
+  std::shared_ptr<BackingStore> backing = ab->GetBackingStore();
+  h->ptr = static_cast<char *>(backing->Data());
+  uint64_t* ptr = (uint64_t*)h->ptr;
   *ptr = just::hrtime();
+  h->ptr = ptr;
+  handles[index] = h;
 }
 
 void just::Init(Isolate* isolate, Local<ObjectTemplate> target) {

just.h

@@ -80,6 +80,9 @@ struct builtin {
   unsigned int size;
   const char* source;
 };
+struct handle {
+  void* ptr;
+};
 extern std::map<std::string, builtin*> builtins;
 extern std::map<std::string, register_plugin> modules;
 void builtins_add (const char* name, const char* source, 

just.js

@@ -1,11 +1,13 @@
 (function () {
+  let handles = 0
+
   function wrapHRTime (hrtime) {
     const buf = new ArrayBuffer(8)
-    const u64 = new BigUint64Array(buf)
-    const address = buf.getAddress()
+    const handle = handles++
+    hrtime(handle, buf)
     return () => {
-      hrtime(address)
-      return u64[0]
+      hrtime(handle)
+      return buf
     }
   }
 
@@ -299,6 +301,7 @@
     just.net.setNonBlocking = setNonBlocking
     just.require = global.require = require
     just.require.cache = cache
+    just._hrtime = just.hrtime
     just.hrtime = wrapHRTime(just.hrtime)
     just.memoryUsage = wrapMemoryUsage(just.memoryUsage)
     just.cpuUsage = wrapCpuUsage(just.sys.cpuUsage)