From f8be78379858c5d78eaf81e8a00d5e276481b72f Mon Sep 17 00:00:00 2001
From: Tadeu Zagallo <tadeuzagallo@fb.com>
Date: Wed, 9 Dec 2015 04:37:40 -0800
Subject: [PATCH] Document intentional retain cycle on RCTJavaScriptContext

Summary:
public

More people wanted to understand the motivation behind the intentional retain
cycle in `RCTJavaScriptContext`, add a small comment with some context.

Reviewed By: jspahrsummers

Differential Revision: D2738930

fb-gh-sync-id: d8c950778eb6bf3eaca627aabb6c98335d25d1fc
---
 React/Executors/RCTContextExecutor.m | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/React/Executors/RCTContextExecutor.m b/React/Executors/RCTContextExecutor.m
index 42b0a37e14..3c22398d5d 100644
--- a/React/Executors/RCTContextExecutor.m
+++ b/React/Executors/RCTContextExecutor.m
@@ -51,14 +51,22 @@ static NSString *const RCTJSCProfilerEnabledDefaultsKey = @"RCTJSCProfilerEnable
 
 @implementation RCTJavaScriptContext
 {
-  RCTJavaScriptContext *_self;
+  RCTJavaScriptContext *_selfReference;
 }
 
 - (instancetype)initWithJSContext:(JSContext *)context
 {
   if ((self = [super init])) {
     _context = context;
-    _self = self;
+
+    /**
+     * Explicitly introduce a retain cycle here - The RCTContextExecutor might
+     * be deallocated while there's still work enqueued in the JS thread, so
+     * we wouldn't be able kill the JSContext. Instead we create this retain
+     * cycle, and enqueue the -invalidate message in this object, it then
+     * releases the JSContext, breaks the cycle and stops the runloop.
+     */
+    _selfReference = self;
   }
   return self;
 }
@@ -79,7 +87,7 @@ RCT_NOT_IMPLEMENTED(-(instancetype)init)
 {
   if (self.isValid) {
     _context = nil;
-    _self = nil;
+    _selfReference = nil;
   }
 }