Patch to instrument JavaScriptCore startup time in React Native 0.56.0

react-native-instrument-startup.patch

From 76ad8283e5de2a0733cbac375c0c16d1d03de891 Mon Sep 17 00:00:00 2001
From: James Reggio <james.reggio@gmail.com>
Date: Wed, 14 Feb 2018 18:57:24 -0500
Subject: [PATCH] add trace statements to JSCLoadApp fn

---
 ReactCommon/cxxreact/JSCExecutor.cpp | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/ReactCommon/cxxreact/JSCExecutor.cpp b/ReactCommon/cxxreact/JSCExecutor.cpp
index 65ee3bd..b12f175 100644
--- a/ReactCommon/cxxreact/JSCExecutor.cpp
+++ b/ReactCommon/cxxreact/JSCExecutor.cpp
@@ -42,6 +42,25 @@
 #include "RecoverableError.h"
 #include "SystraceSection.h"
 
+#include <time.h>
+#if defined(__APPLE__)
+#include <os/log.h>
+#define LOGF(...) os_log(OS_LOG_DEFAULT, __VA_ARGS__)
+#else
+#include <android/log.h>
+#define LOGF(...) __android_log_print(ANDROID_LOG_INFO, "lifecycle", __VA_ARGS__)
+#endif
+
+int64_t getTimeNsec() {
+  struct timespec now;
+  clock_gettime(CLOCK_MONOTONIC, &now);
+  return (int64_t) now.tv_sec * 1000000000LL + now.tv_nsec;
+}
+
+#if defined(WITH_JSC_MEMORY_PRESSURE)
+#include <jsc_memory.h>
+#endif
+
 #if defined(WITH_FB_JSC_TUNING) && defined(__ANDROID__)
 #include <jsc_config_android.h>
 #endif
@@ -419,6 +438,7 @@ void JSCExecutor::loadApplicationScript(
   SystraceSection s(
       "JSCExecutor::loadApplicationScript", "sourceURL", sourceURL);
 
+  auto startLoad = getTimeNsec();
   std::string scriptName = simpleBasename(sourceURL);
   ReactMarker::logTaggedMarker(
       ReactMarker::RUN_JS_BUNDLE_START, scriptName.c_str());
@@ -476,6 +496,7 @@ void JSCExecutor::loadApplicationScript(
 #endif
   {
     String jsScript;
+    auto startAdopt = getTimeNsec();
     JSContextLock lock(m_context);
     {
       SystraceSection s_(
@@ -484,11 +505,22 @@ void JSCExecutor::loadApplicationScript(
       jsScript = adoptString(std::move(script));
       ReactMarker::logMarker(ReactMarker::JS_BUNDLE_STRING_CONVERT_STOP);
     }
+    auto endAdopt = getTimeNsec();
+    double durationAdopt = ((double) (endAdopt - startAdopt)) / 1000000;
+    LOGF("JSC_EXEC_ADOPT_TIME: %lf", durationAdopt);
 
     SystraceSection s_("JSCExecutor::loadApplicationScript-evaluateScript");
+    auto startEval = getTimeNsec();
     evaluateScript(m_context, jsScript, jsSourceURL);
+    auto endEval = getTimeNsec();
+    double durationEval = ((double) (endEval - startEval)) / 1000000;
+    LOGF("JSC_EXEC_EVAL_TIME: %lf", durationEval);
   }
 
+  auto endLoad = getTimeNsec();
+  double durationLoad = ((double) (endLoad - startLoad)) / 1000000;
+  LOGF("JSC_EXEC_TOTAL_LOAD_TIME: %lf", durationLoad);
+
   flush();
 
   ReactMarker::logMarker(ReactMarker::CREATE_REACT_CONTEXT_STOP);
-- 
2.7.4