Commit Graph
474 Commits
Author SHA1 Message Date
Janic Duplessis 0165489b8f Add DEFINES_MODULE=YES to the yoga podspec (#26276)
Summary:
This fixes an error when using RN's version of yoga with Flipper.

```
[!] The following Swift pods cannot yet be integrated as static libraries:

The Swift pod `YogaKit` depends upon `Yoga`, which does not define modules. To opt into those targets generating module maps (which is necessary to import them from Swift when building as static libraries), you may set `use_modular_headers!` globally in your Podfile, or specify `:modular_headers => true` for particular dependencies.
```

Taken from https://github.com/facebook/yoga/blob/master/Yoga.podspec#L25

## Changelog

[Internal] [Fixed] - Add `DEFINES_MODULE=YES` to the yoga podspec
Pull Request resolved: https://github.com/facebook/react-native/pull/26276

Reviewed By: priteshrnandgaonkar

Differential Revision: D17149819

Pulled By: axe-fb

fbshipit-source-id: 5060b8e7111ba411f6e26e3479ad4fb55a552b4e
2019-09-02 09:11:33 -07:00
Ram N a58dd9683d Update the version of yoga podspec to match the actual version of Yoga published
Summary: Yoga is currently published in cocoapods. While we don't use the Yoga from Cocoapods in React Native, we should atleast try to follow that version, so that other integrations with Yoga are possible

Reviewed By: shergin

Differential Revision: D17127625

fbshipit-source-id: bca2e1e33ad775e2a0d7a6f1e4177c3b480c023a
2019-08-30 07:12:34 -07:00
Ram N 82a8080f07 Change podspec name of yoga to Yoga
Summary:
Needed to capitalize the name, since this is the convention used elsewhere too

## Changelog:

[iOS] [Changed] - Renamed yoga podspec to Yoga

Reviewed By: shergin

Differential Revision: D17127104

fbshipit-source-id: 14047bf452edda000037701f4ba7f4a02a0e717b
2019-08-30 07:12:34 -07:00
Sidharth Guglani 8830698657 use array for passing measure callback reasons count
Summary:
Use an array for counting measure callbacks due to each reason.
and this is now added as qpl metadata in Layout Calculation qpl event

Reviewed By: davidaurelio

Differential Revision: D16666786

fbshipit-source-id: ff85fba835148f06b9c5d90c4604e552a813777a
2019-08-08 07:28:26 -07:00
Adlai Holler 4c11b55053 Don't copy children in YGNodeComputeFlexBasisForChildren (#919)
Summary:
No need for a copy here.
Pull Request resolved: https://github.com/facebook/yoga/pull/919

Differential Revision: D16701461

Pulled By: davidaurelio

fbshipit-source-id: 3a90adbb2b5c43d5aefe693a8525aa3a37e53b3d
2019-08-08 00:25:00 -07:00
David Aurelio c9b757f513 Back out "[Yoga] Experiment: double invocations of measure callbacks"
Summary:
Removes the double measure callbacks experiment
Original commit changesets: c6cf9c01a173,  b157d8137c72

Reviewed By: SidharthGuglani

Differential Revision: D16687367

fbshipit-source-id: 9649f8731bd1b27f4d291cee4fa30153165cea02
2019-08-07 18:27:40 -07:00
David Aurelio f94360a377 Use Bitfield in YGLayout
Summary: Replaces the usage of C++ bitfields with our portable `Bitfield` class.

Reviewed By: SidharthGuglani

Differential Revision: D16656361

fbshipit-source-id: 05f679e2e994e109b2bd1090c879d6850fabdc40
2019-08-07 16:22:01 -07:00
David Aurelio 2c73dbdc9b Use Bitfield in YGNode and YGStyle
Summary:
@public

Replaces the usage of C++ bitfields with our portable `Bitfield` class.

Reviewed By: SidharthGuglani

Differential Revision: D16649875

fbshipit-source-id: 539f016d5e1c9a8c48cc9bacbbf6ed985e385e69
2019-08-07 16:22:01 -07:00
David Aurelio f33a623c92 Remove style property bitmask
Summary:
@public

Removes the style properties bitmask. We have used this for experimentation, and it's no longer necessary.

This simplifyies the code, and allows us to cut over to `Bitfield.h` more easily.

Reviewed By: astreet

Differential Revision: D16648862

fbshipit-source-id: 17c0899807af976f4ba34db54f8f0f6a3cd92519
2019-08-07 16:22:00 -07:00
David Aurelio d1d48ef915 Add portable bit field implementation
Summary:
@public
Our usage of C++ bit fields has lead to quite some problems with different compiler setups. Problems include sign bits, alignment, etc.

Here we introduce a portable implementation as a variadic template, allowing the user to store a number of booleans and enums (defined with `YG_ENUM_SEQ_DECL`) in an unsigned integer type of their choice.

This will replace all usages of bit fields across the Yoga code base.

Differential Revision: D16647801

fbshipit-source-id: 230ffab500885a3ad662ea8f19e35a5e9357a563
2019-08-07 16:22:00 -07:00
Sidharth Guglani c36737204e Added counts for measure callbacks reasons in an array inside qpl annotations
Summary:
Added an array to maintain the counts of each of the reason of measure callbacks
and this is now added as qpl metadata in Layout Calculation qpl event

Reviewed By: davidaurelio

Differential Revision: D16516379

fbshipit-source-id: 201c5d2463f0a921841a0bbfec8f4d5e007000c8
2019-07-31 14:38:38 -07:00
Sidharth Guglani 6ce985463b create two layout pass reason flexLayout and flexMeasure instead of flex
Summary:
We had flex as a reason for both layout and measure. Now creating separating reason flexLayout and flexMeasure in this diff.

Also changed ordering of items in Enum to group layout and measure reasons

Reviewed By: davidaurelio

Differential Revision: D16562350

fbshipit-source-id: 75501f9d4dde0974009193b3991a8acc97b02ad0
2019-07-31 14:38:38 -07:00
Min ho Kim 84f5ebe4f9 Fix typos (#25770)
Summary:
Fix typos mostly in comments and some string literals.

## Changelog

[General] [Fixed] - Fix typos
Pull Request resolved: https://github.com/facebook/react-native/pull/25770

Differential Revision: D16437857

Pulled By: cpojer

fbshipit-source-id: ffeb4d6b175e341381352091134f7c97d78c679f
2019-07-23 03:23:11 -07:00
David Aurelio 5ca10c7caa Implement double measure experiment
Reviewed By: SidharthGuglani

Differential Revision: D16340462

fbshipit-source-id: b157d8137c72f83a3bea46f30d0f46f65055f9ef
2019-07-19 10:42:51 -07:00
David Aurelio f68c16e388 Add internal experiments API
Summary: Adds internal API that we can use to conduct experiments.

Reviewed By: SidharthGuglani

Differential Revision: D16340463

fbshipit-source-id: 07a8bb7dbc4a02c5c95f1ad29b18845ab43752cf
2019-07-19 10:42:51 -07:00
Sidharth Guglani 86b671fdbc using enum struct for LayoutPassReason and LayoutType
Summary: Using enum struct for using enums in form ENUM_NAME::ENUM_VALUE for better code readablility

Reviewed By: davidaurelio

Differential Revision: D16356562

fbshipit-source-id: cbe7adadad78eb5d0756c44679c0e102b7d31ec6
2019-07-18 07:05:09 -07:00
Uladzislau Paulovich 45a4bec60c yoga | Fix error about implicit conversion to bit-field
Summary:
`YGStyle` puts Yoga enums (which are signed integers by default) into bitfields: https://fburl.com/7fowlunu

Mixing signed values and bit-fields can be error-prone and it also fails to build on Windows with `clang-cl` due to `-Wbitfield-constant-conversion` warning being treated as error:

```
stderr: In file included from xplat\yoga\yoga\YGLayout.cpp:8:
In file included from xplat\yoga\yoga/Utils.h:8:
In file included from xplat\yoga\yoga/YGNode.h:13:
xplat\yoga\yoga/YGStyle.h(110,9): error: implicit truncation from 'YGAlign' to bit-field changes value from 4 to -4 [-Werror,-Wbitfield-constant-conversion]
        alignItems_(YGAlignStretch),
```

This diff fixes the problem by making all enums unsigned integers. This change can be problematic only if values of the enums are serialized somewhere. CC: David Aurelio

Reviewed By: davidaurelio

Differential Revision: D16336729

fbshipit-source-id: ee4dabd7bd1ee429e644bd322b375ec2694cc742
2019-07-18 06:20:35 -07:00
Sidharth Guglani 87aca7ed74 Pass reason for measure pass along with measurecallbackend event (#566)
Summary:
Pull Request resolved: https://github.com/facebook/litho/pull/566

Pull Request resolved: https://github.com/facebook/react-native/pull/25702

Pass reason for each measure callback to the flipper plugin

Reviewed By: davidaurelio

Differential Revision: D16221771

fbshipit-source-id: 2e72e1ebb3c7e633d189e7a7a81d655ac9531e51
2019-07-18 05:21:15 -07:00
Sidharth Guglani a43615a38a remove YGMarker code
Summary: Removes code for now unused marker based approach

Reviewed By: davidaurelio

Differential Revision: D16048800

fbshipit-source-id: 228e0e906252782ee0bed543728b666d1f9cc854
2019-07-17 08:12:00 -07:00
Sidharth Guglani fb855f60ba move YGMarkerMeasure and YGMarkerBaselineFn to event based system
Summary: Using yoga event listener for adding systrace sections for measure and baseline events

Reviewed By: davidaurelio

Differential Revision: D16048795

fbshipit-source-id: 3c2161328250184929ed1a3357b8c42ec8ca2e29
2019-07-17 08:12:00 -07:00
James Treanor 6ef91061e8 CocoaPods frameworks compatibility: Step 1 (#25496)
Summary:
This is the first step towards fixing https://github.com/facebook/react-native/issues/25349. These are the changes to the podspec to correctly update dependencies and build config that will cause any breaking change for users or libraries.

I am breaking these changes out from https://github.com/facebook/react-native/pull/25393 as suggested by fkgozali in https://github.com/facebook/react-native/pull/25393#issuecomment-508322884.

These are the changes:

- Made C++ headers in `React-Core` private by default so that ObjC files can import the module without failures.
- Reduced the number of `yoga` headers that are exposed for the same reason as above. As far as I can see this doesn't cause issues but we can find another solution if it does.
- Adding some missing dependencies to fix undefined symbols errors.
- Added `DoubleConversion` to `HEADER_SEARCH_PATHS` where it was missing.

## Changelog

[iOS] [Fixed] - Updated podspecs for improved compatibility with different install types.
Pull Request resolved: https://github.com/facebook/react-native/pull/25496

Test Plan:
Everything should work exactly as before. I have a branch on my [sample project](https://github.com/jtreanor/react-native-cocoapods-frameworks) here which points at this branch to show that it is still working `Podfile` to demonstrate this is fixed.

You can see that it works with these steps:

1. `git clone git@github.com:jtreanor/react-native-cocoapods-frameworks.git`
2. `git checkout podspec-updates`
3. `cd ios && pod install`
4. `cd .. && react-native run-ios`

The sample app will build and run successfully.

Reviewed By: mmmulani

Differential Revision: D16167346

Pulled By: fkgozali

fbshipit-source-id: 1917b2f8779cb172362a457fb3fce686c55056d3
2019-07-10 10:21:38 -07:00
Sidharth Guglani 12ca9830c8 add baseline start and baseline end events
Summary: Adds Baseline start and end events to be handled later for instrumentation

Reviewed By: davidaurelio

Differential Revision: D16048790

fbshipit-source-id: 8409dbb633168753a7bf8fab20bc6551d113ddd6
2019-07-10 08:48:37 -07:00
Sidharth Guglani fdf3873281 move YGMarkerLayout to event based system
Summary: Using layoutPassStart and LayoutPassEnd events instead of YGMarkerLayout for instrumentation

Reviewed By: davidaurelio

Differential Revision: D16048789

fbshipit-source-id: 041a35bc2cb1b7281ca83cf9d35041b4011cfeb9
2019-07-10 08:48:37 -07:00
Uladzislau Paulovich ce9c47f34b Remove incorrect constexpr specifier in YGLayout (#25430)
Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/25430

Pull Request resolved: https://github.com/facebook/litho/pull/561

Pull Request resolved: https://github.com/facebook/yoga/pull/910

* According to C++ standard values which produce undefined behavior cannot be declared as `constexpr`.
* Expressions which evaluate to `nan, infinity, etc` are undefined behavior.

For more details you can checkout this Stackoverflow answer: https://stackoverflow.com/a/46373136

Reviewed By: davidaurelio

Differential Revision: D16055108

fbshipit-source-id: ee85ba63a714b18bfb8aa8c0770652e184454f74
2019-07-01 08:51:41 -07:00
David Aurelio 0d89653dd6 Move YG_ENABLE_EVENTS checks to event.h
Summary:
Instead of checking whether `YG_ENABLE_EVENTS` is defined for every publish, we simply wrap the body of the `publish` function macro that delegates to the method that actually publishes the event.

This way we get

1. easier to write code where we publish events
2. more type safety when editing, enabling editors/IDEs to show errors without knowing about `YG_ENABLE_EVENTS`

Reviewed By: SidharthGuglani

Differential Revision: D16049888

fbshipit-source-id: cbf362d6f7be5053c3f377125d303b7137d6a241
2019-06-28 09:59:06 -07:00
David Aurelio 792f715178 Stop recording measure callback duration
Summary: Removes time measurements for measure callbacks. This functionality should not be part of Yoga/core, and can now be done by event subscribers themselves, as we have two events per measure callback.

Reviewed By: SidharthGuglani

Differential Revision: D16049812

fbshipit-source-id: e16556f3854e42f4bada39a97a668e718719b22c
2019-06-28 09:59:05 -07:00
David Aurelio 2985ddbc33 Publish two events for measure callbacks
Summary: Publishing two events will allow us to replace marker functionality completely with events. This also allows us to remove measuring time spent from Yoga itself.

Reviewed By: SidharthGuglani

Differential Revision: D16049810

fbshipit-source-id: 98628a92ed3c94d479e9fbcd53fac90c5f524087
2019-06-28 09:59:05 -07:00
David Aurelio 18eba792dd Remove duplicate declaration of YGRoundValueToPixelGrid from Yoga-internal.h
Summary:
@public

Removes the declaration of `YGRoundValueToPixelGrid` from `Yoga-internal.h`, as it is already declared in `Yoga.h`. `Yoga.h` is included from `Yoga-internal.h`

Reviewed By: SidharthGuglani

Differential Revision: D16047832

fbshipit-source-id: 72d9d2510372c983eedacc5d7af406b9346f18e6
2019-06-28 05:17:51 -07:00
dattc2 1dbc38ad93 make yoga threadsafe (#852)
Summary:
Continuing https://github.com/facebook/yoga/pull/791
nokia6686 is a former member of our team, so we are trying to pick up what he left and carry out the pull request.
# Solution
Improved from previous solution with jpap's suggestions.
2. Passing ```gDepth``` and ```gCurrentGenerationCount``` (renamed to **_depth_** and **_generationCount_** respectively) between function calls that stem from ```YGNodeCalculateLayout```.
In ```YGNodeCalculateLayout```, pass ```depth``` as value 0, to indicate the root depth.
Pull Request resolved: https://github.com/facebook/yoga/pull/852

Reviewed By: SidharthGuglani

Differential Revision: D15537450

Pulled By: davidaurelio

fbshipit-source-id: 338f51383591ba27702ebe759f6c47c2dede3530
2019-06-26 10:05:32 -07:00
Sidharth Guglani 055b28b4f4 pass cachedLayout and cachedMeasure measures to plugin
Summary: Passing whether layout cache or measure cache was used or not

Reviewed By: davidaurelio

Differential Revision: D15920937

fbshipit-source-id: a6728e7af07ea228a285f824fbdfddc8130c5990
2019-06-24 08:35:34 -07:00
Sidharth Guglani 4332a28750 Move event NodeLayout to end of NodeLayout step
Summary:
Added event NodeLayoutEnd and this is being used now instead of NodeLayout
It will be used later to add more information about caches

Reviewed By: davidaurelio

Differential Revision: D15920935

fbshipit-source-id: c9f5e193bc8cc70d26ff5d84882d483c9b09f67d
2019-06-24 08:35:34 -07:00
David Aurelio 52e4c8df6c Replace relative include
Summary: Replaces the relative include to `YGEnums.h` in `yoga/event/event.h` with `#include <yoga/YGEnums.h>

Reviewed By: SidharthGuglani

Differential Revision: D15778634

fbshipit-source-id: 2bceeb58f26c0d9d0df6c0e7ea20b8ddf68a1ee5
2019-06-21 04:09:52 -07:00
Sidharth Guglani fc82c59be7 Send measure pass duration
Summary: Send measure callback duration time to yoga plugin

Reviewed By: davidaurelio

Differential Revision: D15917548

fbshipit-source-id: 2c947f14ddbc5932cedd0aab8622260478ec29a6
2019-06-21 02:33:02 -07:00
David Aurelio 853c667eb5 Allow to end markers early
Summary:
Adds the ability to `MarkerSection` to end the marker before it goes out of scope.

This unlocks two scenarios:
- reuse the data associated with a marker after ending it.
- end markers in the middle of a function without adding arbitrary blocks.

Reviewed By: SidharthGuglani

Differential Revision: D15837840

fbshipit-source-id: c0afaeeabd169c65189b5028be54ea7dac3e3b84
2019-06-15 10:19:33 -07:00
David Aurelio 3ce9ac6eed Count the number measure callback invocations
Summary: Counts how many times measure callbacks have been invoked during a layout pass. This is made available via the marker and event APIs.

Reviewed By: SidharthGuglani

Differential Revision: D15836983

fbshipit-source-id: 3835bef94e497375821c9f2ad8209447b4f11518
2019-06-15 10:19:33 -07:00
Sidharth Guglani 38adb8ecd2 pass measure callback data from c++ to java
Summary:
Passing Measure callback data - width, widthMeasureMode, height, heightMeasureMode, measuredWidth and measuredHeight along with NodeMeasure event
This data is then propagated to java layer in this diff

Reviewed By: davidaurelio

Differential Revision: D15697523

fbshipit-source-id: 615463da237175ff88abef3f6528b55333ccd915
2019-06-12 00:30:13 -07:00
David Aurelio 9d13af53ce Pass layout context for Event::LayoutPassStart
Summary: Adds the layout context pointer when publishing `Event::LayoutPassStart`.

Reviewed By: SidharthGuglani

Differential Revision: D15754425

fbshipit-source-id: 6295ae1ebec9eab72a79c43bc1cb0e05a6d7ae68
2019-06-11 01:41:22 -07:00
Sidharth Guglani b6dc9587e6 add node layout event and pass it java layer
Summary: Listen to NodeLayout event and passes this event callback to java layer along with the information whether layout or measure was done in this pass

Reviewed By: davidaurelio

Differential Revision: D15696021

fbshipit-source-id: 8c5ca69330a9baca26b77052d4965cc67fe97c75
2019-06-10 01:48:59 -07:00
Sidharth Guglani 348c3ebefa add node measure event and passing the callback to java layer
Summary: Adds measure event and its listener initial code structure

Reviewed By: davidaurelio

Differential Revision: D15600738

fbshipit-source-id: d15764e0b64edb170fcb15e0912ecce5f7e53595
2019-06-06 21:03:04 -07:00
Sidharth Guglani c44b221e13 moved PtrJNode map to YGJtypes.h and passing layout context as data in LayoutPassEnd Event
Summary: Move PtrJNodeMap to header file so that it can be accessed in events subscribers outside yoga

Reviewed By: davidaurelio

Differential Revision: D15619629

fbshipit-source-id: 1bf213efd38ec7bcac6a38070f21fa837c5f17da
2019-06-06 21:03:04 -07:00
Rain ⁣ 14f249178e standardize C-like MIT copyright headers throughout fbsource
Summary:
`/*` is the standard throughout open source code. For example, Firefox uses single /*: https://hg.mozilla.org/mozilla-central/file/21d22b2f541258d3d1cf96c7ba5ad73e96e616b5/gfx/ipc/CompositorWidgetVsyncObserver.cpp#l3

In addition, Rust considers `/**` to be a doc comment (similar to Javadoc) and having such a comment at the beginning of the file causes `rustc` to barf.

Note that some JavaScript tooling requires `/**`. This is OK since JavaScript files were not covered by the linter in the first place, but it would be good to have that tooling fixed too.

Reviewed By: zertosh

Differential Revision: D15640366

fbshipit-source-id: b4ed4599071516364d6109720750d6a43304c089
2019-06-06 19:40:32 -07:00
Joshua Gross 43d7664308 Revert D15602627: [yoga] moved PtrJNode map to YGJtypes.h and passing layout context as data in LayoutPassEnd Event
Differential Revision:
D15602627

Original commit changeset: bb5bd5bbf8dc

fbshipit-source-id: 5ae08826eb706c3794c36738cb9625f82b58641e
2019-06-03 19:58:08 -07:00
Sidharth Guglani d3cf756613 moved PtrJNode map to YGJtypes.h and passing layout context as data in LayoutPassEnd Event
Summary: Move PtrJNodeMap to header file so that it can be accessed in events subscribers outside yoga

Reviewed By: davidaurelio

Differential Revision: D15602627

fbshipit-source-id: bb5bd5bbf8dcb279f5f87a4fd7287909d4e895d8
2019-06-03 16:02:47 -07:00
David Aurelio fd607b1304 Back out "[Yoga] Remove comparison to YGUndefined *and* 0.0f"
Summary: Original commit changeset: 13c8f24e1bc8

Reviewed By: fabiomassimo

Differential Revision: D15583502

fbshipit-source-id: efc6175f6c4925a383fea723195c073f49e2eff1
2019-05-31 15:56:28 -07:00
David Aurelio a1bfb284ee Use atomic list for event subscribers
Summary:
Replace the *copy on write* vector with an atomic pointer to a linked list.

This allows to publish without locking a mutex, at the cost of the slower traversal of a linked list (a vector has better locality).

At the moment, the typical use case is to have one subscriber, meaning that the afforementioned slower traversal is not a problem.

Adding subscribers is implemented as atomic *compare and swap.*

Reviewed By: SidharthGuglani

Differential Revision: D15546964

fbshipit-source-id: 41bfa41f1ac6be5c9b6bf4288ea3271ee995877e
2019-05-31 01:24:44 -07:00
David Aurelio 6677f405a2 Deprecate YGNode::setConfig
Summary:
We want to phase out usage of config pointers on nodes. Setting configs is no longer needed, as a config is unly used during construction.

Here we deprecate the setter, as it is no longer working as it used to (e.g. changing `useWebDefaults` after a node is constructed).

Reviewed By: SidharthGuglani

Differential Revision: D15416474

fbshipit-source-id: a2cc06cad0c5148cecce056ece5f141b3defe9a9
2019-05-29 07:44:04 -07:00
David Aurelio 07398592f2 Remove comparison to YGUndefined *and* 0.0f
Summary: Removes a check introduced in D6969537, comparing `totalFlexGrowFactors` and `resolveFlexGrow` to both `0.0` *and* undefined.

Reviewed By: SidharthGuglani

Differential Revision: D15431425

fbshipit-source-id: 13c8f24e1bc8c49496097a6aa78e20ee5d3964a7
2019-05-22 09:43:02 -07:00
David Aurelio 80258b530d Remove YGNode::setAndPropogateUseLegacyFlag
Summary:
`YGNode::setAndPropogateUseLegacyFlag` was only used for debugging purposes.
Here, we replace it with a free function in `Yoga.cpp`.

Now that we have events, the diffing functionality should go into a separate debugging package and be implemented in terms of an event listener. Let's do that as soon as we can support multiple listeners.

Reviewed By: SidharthGuglani

Differential Revision: D15316863

fbshipit-source-id: db929eba7c2de8aa1550e362dd2c175929c0070e
2019-05-21 06:08:07 -07:00
David Aurelio 19a88d7f4a YGNode: Field for web defaults
Summary:
In order to remove the config pointer from nodes, we have to keep track of whether the node is using web defaults.
This information fits into one bit that we can place in padding (i.e. no extra memory needed).

This allows us to get rid of config usage withing `YGNode` with some exceptions:

- `iterChildrenAfterCloningIfNeeded` -- this function will simply receive the configuration, or the cloning callback.
- `setAndPropogateUseLegacyFlag` -- will be removed in D15316863
- in `YGNode::reset` -- will go away utomatically once we remove the config pointer

Reviewed By: SidharthGuglani

Differential Revision: D15391536

fbshipit-source-id: 0fa0d0805c6862bd741fe4a7d9b637ed534f56a4
2019-05-20 10:52:28 -07:00
Sidharth Guglani fb8a7c3cc5 mutex lock while accessing event subscribers vector for thread safety
Summary: Using Mutex lock_guard mechanism when writing to subscribers and when accessing them in publish to make a copy

Reviewed By: davidaurelio

Differential Revision: D15391679

fbshipit-source-id: 16713ff28ce1762a5ca4c48c152897a92417e80b
2019-05-19 23:32:38 -07:00