From a1f31d12fde29db43f5af5d23c0d403c0bd22003 Mon Sep 17 00:00:00 2001
From: Pieter De Baets <pieterdb@fb.com>
Date: Tue, 6 Sep 2016 03:58:00 -0700
Subject: [PATCH] Log timer identifiers in systrace

Reviewed By: davidaurelio

Differential Revision: D3819518

fbshipit-source-id: 98e9ed4af93c9c02f4bb8d9152b19556566b81f1
---
 .../JavaScriptAppEngine/System/JSTimers/JSTimers.js   |  9 +++++++++
 .../System/JSTimers/JSTimersExecution.js              | 11 +++++++++++
 2 files changed, 20 insertions(+)

diff --git a/Libraries/JavaScriptAppEngine/System/JSTimers/JSTimers.js b/Libraries/JavaScriptAppEngine/System/JSTimers/JSTimers.js
index ce83778ed..0ff75f23d 100644
--- a/Libraries/JavaScriptAppEngine/System/JSTimers/JSTimers.js
+++ b/Libraries/JavaScriptAppEngine/System/JSTimers/JSTimers.js
@@ -15,6 +15,7 @@
 // in dependencies. NativeModules > BatchedBridge > MessageQueue > JSTimersExecution
 const RCTTiming = require('NativeModules').Timing;
 const JSTimersExecution = require('JSTimersExecution');
+const parseErrorStack = require('parseErrorStack');
 
 // Returns a free index if one is available, and the next consecutive index otherwise.
 function _getFreeIndex(): number {
@@ -31,6 +32,14 @@ function _allocateCallback(func: Function, type: $Keys<typeof JSTimersExecution.
   JSTimersExecution.timerIDs[freeIndex] = id;
   JSTimersExecution.callbacks[freeIndex] = func;
   JSTimersExecution.types[freeIndex] = type;
+  if (__DEV__) {
+    const e = (new Error() : any);
+    e.framesToPop = 1;
+    const stack = parseErrorStack(e);
+    if (stack) {
+      JSTimersExecution.identifiers[freeIndex] = stack.shift();
+    }
+  }
   return id;
 }
 
diff --git a/Libraries/JavaScriptAppEngine/System/JSTimers/JSTimersExecution.js b/Libraries/JavaScriptAppEngine/System/JSTimers/JSTimersExecution.js
index e306cc033..175b0794b 100644
--- a/Libraries/JavaScriptAppEngine/System/JSTimers/JSTimersExecution.js
+++ b/Libraries/JavaScriptAppEngine/System/JSTimers/JSTimersExecution.js
@@ -46,6 +46,7 @@ const JSTimersExecution = {
   timerIDs: [],
   immediates: [],
   requestIdleCallbacks: [],
+  identifiers: ([] : [{methodName: string}]),
 
   errors: (null : ?[Error]),
 
@@ -78,6 +79,11 @@ const JSTimersExecution = {
       return;
     }
 
+    if (__DEV__) {
+      const identifier = JSTimersExecution.identifiers[timerIndex] || {};
+      Systrace.beginEvent('Systrace.callTimer: ' + identifier.methodName);
+    }
+
     // Clear the metadata
     if (type === JSTimersExecution.Type.setTimeout ||
         type === JSTimersExecution.Type.setImmediate ||
@@ -113,6 +119,10 @@ const JSTimersExecution = {
         JSTimersExecution.errors.push(e);
       }
     }
+
+    if (__DEV__) {
+      Systrace.endEvent();
+    }
   },
 
   /**
@@ -228,6 +238,7 @@ const JSTimersExecution = {
     JSTimersExecution.timerIDs[i] = null;
     JSTimersExecution.callbacks[i] = null;
     JSTimersExecution.types[i] = null;
+    JSTimersExecution.identifiers[i] = null;
   },
 };