From 2690e7363ce9b1a48eccb49bdae31a1c8ae27b89 Mon Sep 17 00:00:00 2001
From: Valentin Shergin <shergin@fb.com>
Date: Mon, 4 Nov 2019 18:19:05 -0800
Subject: [PATCH] Fabric: Cross-platform implementation of
 `monotonicTimeInMilliseconds`

Summary:
Now the function supports iOS.
We will use it soon.

Changelog: [Internal] Fabric-specific internal change.

Reviewed By: mdvacca

Differential Revision: D18285828

fbshipit-source-id: b9c16433e9c75ab4c071e4bd55074757372f6c0a
---
 .../com/facebook/react/fabric/jni/Binding.cpp |  4 +-
 .../fabric/mounting/MountingTelemetry.cpp     | 12 ++---
 ReactCommon/utils/TimeUtils.h                 | 51 ++++++++++++++++---
 3 files changed, 52 insertions(+), 15 deletions(-)

diff --git a/ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.cpp b/ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.cpp
index 5dfcd760eb3..b6638a439a8 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.cpp
+++ b/ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.cpp
@@ -555,7 +555,7 @@ void Binding::schedulerDidFinishTransaction(
   std::lock_guard<std::recursive_mutex> lock(commitMutex_);
 
   SystraceSection s("FabricUIManagerBinding::schedulerDidFinishTransaction");
-  long finishTransactionStartTime = getTime();
+  long finishTransactionStartTime = monotonicTimeInMilliseconds();
 
   jni::global_ref<jobject> localJavaUIManager = getJavaUIManager();
   if (!localJavaUIManager) {
@@ -784,7 +784,7 @@ void Binding::schedulerDidFinishTransaction(
           ->getMethod<void(JMountItem::javaobject, jint, jlong, jlong, jlong, jlong, jlong, jlong, jlong)>(
               "scheduleMountItem");
 
-  long finishTransactionEndTime = getTime();
+  long finishTransactionEndTime = monotonicTimeInMilliseconds();
 
   scheduleMountItem(
       localJavaUIManager,
diff --git a/ReactCommon/fabric/mounting/MountingTelemetry.cpp b/ReactCommon/fabric/mounting/MountingTelemetry.cpp
index 0910d685e16..f96e4b1d292 100644
--- a/ReactCommon/fabric/mounting/MountingTelemetry.cpp
+++ b/ReactCommon/fabric/mounting/MountingTelemetry.cpp
@@ -17,38 +17,38 @@ namespace react {
 void MountingTelemetry::willCommit() {
   assert(commitStartTime_ == kUndefinedTime);
   assert(commitEndTime_ == kUndefinedTime);
-  commitStartTime_ = getTime();
+  commitStartTime_ = monotonicTimeInMilliseconds();
   commitNumber_++;
 }
 
 void MountingTelemetry::didCommit() {
   assert(commitStartTime_ != kUndefinedTime);
   assert(commitEndTime_ == kUndefinedTime);
-  commitEndTime_ = getTime();
+  commitEndTime_ = monotonicTimeInMilliseconds();
 }
 
 void MountingTelemetry::willDiff() {
   assert(diffStartTime_ == kUndefinedTime);
   assert(diffEndTime_ == kUndefinedTime);
-  diffStartTime_ = getTime();
+  diffStartTime_ = monotonicTimeInMilliseconds();
 }
 
 void MountingTelemetry::didDiff() {
   assert(diffStartTime_ != kUndefinedTime);
   assert(diffEndTime_ == kUndefinedTime);
-  diffEndTime_ = getTime();
+  diffEndTime_ = monotonicTimeInMilliseconds();
 }
 
 void MountingTelemetry::willLayout() {
   assert(layoutStartTime_ == kUndefinedTime);
   assert(layoutEndTime_ == kUndefinedTime);
-  layoutStartTime_ = getTime();
+  layoutStartTime_ = monotonicTimeInMilliseconds();
 }
 
 void MountingTelemetry::didLayout() {
   assert(layoutStartTime_ != kUndefinedTime);
   assert(layoutEndTime_ == kUndefinedTime);
-  layoutEndTime_ = getTime();
+  layoutEndTime_ = monotonicTimeInMilliseconds();
 }
 
 int64_t MountingTelemetry::getDiffStartTime() const {
diff --git a/ReactCommon/utils/TimeUtils.h b/ReactCommon/utils/TimeUtils.h
index eaf295da95d..91e6e5ae151 100644
--- a/ReactCommon/utils/TimeUtils.h
+++ b/ReactCommon/utils/TimeUtils.h
@@ -7,15 +7,44 @@
 
 #pragma once
 
+#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
+
+// It's Unix
 #include <time.h>
+#include <unistd.h>
+
+#endif
+
+#if defined(__APPLE__) && defined(__MACH__)
+
+// It's iOS or macOS or one of derivatives.
+#include <dispatch/dispatch.h>
+#include <mach/mach.h>
+#include <mach/mach_time.h>
+
+#endif
 
 namespace facebook {
 namespace react {
 
-inline static int64_t getTime() {
-#ifdef ANDROID
-  static const int64_t NANOSECONDS_IN_SECOND = 1000000000LL;
-  static const int64_t NANOSECONDS_IN_MILLISECOND = 1000000LL;
+inline static int64_t monotonicTimeInMilliseconds() {
+#if defined(__APPLE__) && defined(__MACH__)
+
+  static struct mach_timebase_info tb_info = {0};
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    __unused int ret = mach_timebase_info(&tb_info);
+    assert(0 == ret);
+  });
+
+  return (mach_absolute_time() * tb_info.numer) / tb_info.denom / 1000000;
+
+#elif defined(_POSIX_MONOTONIC_CLOCK)
+
+  // It's Unix with MONOTONIC_CLOCK support (e.g. Android)
+
+  constexpr static int64_t NANOSECONDS_IN_SECOND = 1000000000LL;
+  constexpr static int64_t NANOSECONDS_IN_MILLISECOND = 1000000LL;
 
   // Since SystemClock.uptimeMillis() is commonly used for performance
   // measurement in Java and uptimeMillis() internally uses
@@ -25,11 +54,19 @@ inline static int64_t getTime() {
   // https://android.googlesource.com/platform/frameworks/native/+/jb-mr1-release/libs/utils/SystemClock.cpp
   // https://android.googlesource.com/platform/system/core/+/master/libutils/Timers.cpp
   struct timespec now;
+
   clock_gettime(CLOCK_MONOTONIC, &now);
-  int64_t nano = now.tv_sec * NANOSECONDS_IN_SECOND + now.tv_nsec;
-  return nano / NANOSECONDS_IN_MILLISECOND;
+
+  return (now.tv_sec * NANOSECONDS_IN_SECOND + now.tv_nsec) /
+      NANOSECONDS_IN_MILLISECOND;
+
 #else
-  return 0l;
+
+  It's Unix *without* MONOTONIC_CLOCK support or Microsoft Windows.
+  If you run this on Microsoft Windows, could you please implement the
+  function using some Windows-specific APIs, and submit a PR?
+  https://stackoverflow.com/questions/5404277/porting-clock-gettime-to-windows
+
 #endif
 }