Fix for UIApplicationDidReceiveMemoryWarningNotification not being obeyed on iOS

[liamjones]

Summary:

Prior to 0.69, an RN app receiving the UIApplicationDidReceiveMemoryWarningNotification notification resulted in RN performing a GC on the JSC. Since 0.69 this has not worked, this PR fixes the issue.

Before 0.69 this was handled via a hardcoded memory pressure level:

react-native/React/CxxBridge/RCTCxxBridge.mm

Line 362 in c5c1798

reactInstance->handleMemoryPressure(15 /* TRIM_MEMORY_RUNNING_CRITICAL */);

(It seems like the levels are an Android concept - see https://developer.android.com/reference/android/content/ComponentCallbacks2#constants_1)

In commit 0916df9 it was changed to run from a constant which could be reconfigured but a mistake (return type of BOOL rather than int) was resulting in the intended default memory pressure level of 15 (same as the old hardcoded value) being changed to 1 when it was passed on to handleMemoryPressure.

Changelog:

[IOS] [FIXED] - UIApplicationDidReceiveMemoryWarningNotification has not been obeyed on iOS since RN 0.69

Test Plan:

Tested manually via the Simulator using Debug -> Simulate Memory Warning and monitoring the console output of the app.

Before fix:

WARNING: Logging before InitGoogleLogging() is written to STDERR
W0620 11:21:42.824463 257294336 JSIExecutor.cpp:377] Memory warning (pressure level: 1) received by JS VM, unrecognized pressure level

With fix (and also the same output for the latest 0.68 tag in the repo):

WARNING: Logging before InitGoogleLogging() is written to STDERR
I0620 11:25:47.479444 79212544 JSIExecutor.cpp:370] Memory warning (pressure level: TRIM_MEMORY_RUNNING_CRITICAL) received by JS VM, running a GC

[facebook-github-bot]

@sammy-SC has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[javache]

Thanks for the fix! I'm surprised this actually was causing issues, since BOOL (and bool) are actually defined as char and are perfectly capable of representing 15

[liamjones]

I'm surprised this actually was causing issues, since BOOL (and bool) are actually defined as char and are perfectly capable of representing 15

Yeah, I was confused by that too. I only picked up on it when trying to debug a memory usage issue and saw the "unrecognized pressure level" message in the console. 🤷

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	9,014,611	+1
android	hermes	armeabi-v7a	8,275,839	+1
android	hermes	x86	9,528,325	-1
android	hermes	x86_64	9,370,718	-1
android	jsc	arm64-v8a	9,575,959	-1
android	jsc	armeabi-v7a	8,714,501	+0
android	jsc	x86	9,660,535	-2
android	jsc	x86_64	9,907,034	+0

Base commit: 6e1210e
Branch: main

[facebook-github-bot]

@sammy-SC merged this pull request in 8f072b4.