Viewing github.com/facebook/react/scripts/perf-counters/src/jsc-perf.cpp

```
/**
```

 * Copyright (c) Meta Platforms, Inc. and affiliates.

```
 *
```

 * This source code is licensed under the MIT license found in the

 * LICENSE file in the root directory of this source tree.

```
 */
```
```
#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <fstream>
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#include <iostream>
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#include <string>
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#include <JavaScriptCore/JavaScript.h>
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#include "hardware-counter.h"
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```
using HPHP::HardwareCounter;
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```
void add_native_hook(
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  JSContextRef ctx,
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  JSObjectRef obj,
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  const char *name,
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  JSObjectCallAsFunctionCallback hook
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```
) {
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  JSStringRef jsName = JSStringCreateWithUTF8CString(name);

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  JSObjectSetProperty(
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    ctx,
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    obj,
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    jsName,
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    JSObjectMakeFunctionWithCallback(ctx, jsName, hook),

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    kJSPropertyAttributeNone,
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    NULL
```
```
  );
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  JSStringRelease(jsName);
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```
}
```
```
static void fprint_value(
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  FILE *file,
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  JSContextRef context,
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  JSValueRef obj
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```
) {
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  JSStringRef jsStr = JSValueToStringCopy(context, obj, NULL);

  size_t size = JSStringGetMaximumUTF8CStringSize(jsStr);

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  char *str = (char *) calloc(
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    size,
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    1
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```
  );
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  JSStringGetUTF8CString(
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    jsStr,
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    str,
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    size
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  );
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  JSStringRelease(jsStr);
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  fprintf(file, "%s", str);
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  free(str);
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```
}
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static JSValueRef js_print(
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  JSContextRef context,
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  JSObjectRef object,
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  JSObjectRef thisObject,
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```
  size_t argumentCount,
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  const JSValueRef arguments[],
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  JSValueRef *exception
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```
) {
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  for (int i = 0; i < argumentCount; i++) {

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    if (i != 0) {
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      printf(" ");
```
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    }
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    fprint_value(stdout, context, arguments[i]);

```
  }
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  printf("\n");
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  return JSValueMakeUndefined(context);

```
}
```

static JSValueRef js_perf_counters_init(

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  JSContextRef context,
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```
  JSObjectRef object,
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```
  JSObjectRef thisObject,
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```
  size_t argumentCount,
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```
  const JSValueRef arguments[],
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```
  JSValueRef *exception
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```
) {
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  // TODO: Allow customizing recorded events

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  bool enable = true;
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  std::string events = "";
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  bool recordSubprocesses = false;
```

  HardwareCounter::Init(enable, events, recordSubprocesses);

  HardwareCounter::s_counter.getCheck();

  return JSValueMakeUndefined(context);

```
}
```

static JSValueRef js_perf_counters_get_counters(

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  JSContextRef context,
```
```
  JSObjectRef object,
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  JSObjectRef thisObject,
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```
  size_t argumentCount,
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  const JSValueRef arguments[],
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  JSValueRef *exception
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) {
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  JSObjectRef result = JSObjectMake(context, NULL, NULL);

  std::pair<JSContextRef, JSObjectRef> pair(context, result);

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  HardwareCounter::GetPerfEvents(
```

    [](const std::string& key, int64_t value, void* data) {

      std::pair<JSContextRef, JSObjectRef>& pair =

        *reinterpret_cast<std::pair<JSContextRef, JSObjectRef>*>(data);

      JSContextRef context = pair.first;

      JSObjectRef result = pair.second;

```
      JSObjectSetProperty(
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        context,
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        result,
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        JSStringCreateWithUTF8CString(key.c_str()),

        JSValueMakeNumber(context, value),

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        kJSPropertyAttributeNone,
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        NULL
```
```
      );
```
```
    },
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    &pair);
```
```
  return result;
```
```
}
```
```
int main(int argc, char **argv) {
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  if (argc != 2) {
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    fprintf(stderr, "usage: jsc-runner file\n");

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    exit(1);
```
```
  }
```
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  char *filename = argv[1];
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  std::ifstream ifs(filename);
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```
  if (ifs.fail()) {
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    std::cerr << "Error opening \"" << filename << "\": " << strerror(errno) << "\n";

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    exit(1);
```
```
  }
```
```
  std::string script(
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    (std::istreambuf_iterator<char>(ifs)),

```
    (std::istreambuf_iterator<char>())
```
```
  );
```

  JSStringRef jsScript = JSStringCreateWithUTF8CString(script.c_str());

  JSStringRef jsURL = JSStringCreateWithUTF8CString(argv[1]);

  JSGlobalContextRef ctx = JSGlobalContextCreate(NULL);

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  add_native_hook(
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    ctx,
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```
    JSContextGetGlobalObject(ctx),
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```
    "print",
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    js_print
```
```
  );
```

  JSObjectRef jsPerfCounters = JSObjectMake(ctx, NULL, NULL);

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  add_native_hook(
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    ctx,
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    jsPerfCounters,
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    "init",
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    js_perf_counters_init
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```
  );
```
```
  add_native_hook(
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    ctx,
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    jsPerfCounters,
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    "getCounters",
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    js_perf_counters_get_counters
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```
  );
```
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  JSObjectSetProperty(
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    ctx,
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    JSContextGetGlobalObject(ctx),
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    JSStringCreateWithUTF8CString("PerfCounters"),

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    jsPerfCounters,
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    kJSPropertyAttributeNone,
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```
    NULL
```
```
  );
```
```
  JSValueRef jsError = NULL;
```

  JSValueRef result = JSEvaluateScript(

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    ctx,
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    jsScript,
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    NULL,
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    jsURL,
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    0,
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```
    &jsError
```
```
  );
```
```
  if (!result) {
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    fprintf(stderr, "Exception: ");
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    fprint_value(stderr, ctx, jsError);

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    fprintf(stderr, "\n");
```

    JSStringRef jsStackStr = JSStringCreateWithUTF8CString("stack");

    if (JSValueIsObject(ctx, jsError)) {

      JSValueRef jsStack = JSObjectGetProperty(ctx, (JSObjectRef)jsError, jsStackStr, NULL);

```
      JSStringRelease(jsStackStr);
```

      fprint_value(stderr, ctx, jsStack);

```
      fprintf(stderr, "\n");
```
```
    }
```
```
    exit(1);
```
```
  }
```
```
  JSGlobalContextRelease(ctx);
```
```
}
```

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