* BUG: ReactPartialRenderer / New Context polutes mutable global state
The new context API stores the provided values on the shared context instance. When used in a synchronous context, this is not an issue. However when used in an concurrent context this can cause a "push provider" from one react render to have an effect on an unrelated concurrent react render.
I've encountered this bug in production when using renderToNodeStream, which asks ReactPartialRenderer for bytes up to a high water mark before yielding. If two Node Streams are created and read from in parallel, the state of one can polute the other.
I wrote a failing test to illustrate the conditions under which this happens.
I'm also concerned that the experimental concurrent/async React rendering on the client could suffer from the same issue.
* Use unique thread ID for each partial render to access Context
This first adds an allocator that keeps track of a unique ThreadID index
for each currently executing partial renderer. IDs are not just growing
but are reused as streams are destroyed.
This ensures that IDs are kept nice and compact.
This lets us use an "array" for each Context object to store the current
values. The look up for these are fast because they're just looking up
an offset in a tightly packed "array".
I don't use an actual Array object to store the values. Instead, I rely
on that VMs (notably V8) treat storage of numeric index property access
as a separate "elements" allocation.
This lets us avoid an extra indirection.
However, we must ensure that these arrays are not holey to preserve this
feature.
To do that I store the _threadCount on each context (effectively it takes
the place of the .length property on an array).
This lets us first validate that the context has enough slots before we
access the slot. If not, we fill in the slots with the default value.
* Don't stop context traversal at matching consumers
Originally, the idea was to time slice the traversal. This worked when
there was only a single context type per consumer.
Now that each fiber may have a list of context dependencies, including
duplicate entries, that optimization no longer makes sense – we could
end up scanning the same subtree multiple times.
* Remove changedBits from context object and stack
Don't need it anymore, yay
* Store list of contexts on the fiber
Currently, context can only be read by a special type of component,
ContextConsumer. We want to add support to all fibers, including
classes and functional components.
Each fiber may read from one or more contexts. To enable quick, mono-
morphic access of this list, we'll store them on a fiber property.
* Context.unstable_read
unstable_read can be called anywhere within the render phase. That
includes the render method, getDerivedStateFromProps, constructors,
functional components, and context consumer render props.
If it's called outside the render phase, an error is thrown.
* Remove vestigial context cursor
Wasn't being used.
* Split fiber.expirationTime into two separate fields
Currently, the `expirationTime` field represents the pending work of
both the fiber itself — including new props, state, and context — and of
any updates in that fiber's subtree.
This commit adds a second field called `childExpirationTime`. Now
`expirationTime` only represents the pending work of the fiber itself.
The subtree's pending work is represented by `childExpirationTime`.
The biggest advantage is it requires fewer checks to bailout on already
finished work. For most types of work, if the `expirationTime` does not
match the render expiration time, we can bailout immediately without
any further checks. This won't work for fibers that have
`shouldComponentUpdate` semantics (class components), for which we still
need to check for props and state changes explicitly.
* Performance nits
Optimize `readContext` for most common case
* Support concurrent primary and secondary renderers.
As a workaround to support multiple concurrent renderers, we categorize
some renderers as primary and others as secondary. We only expect
there to be two concurrent renderers at most: React Native (primary) and
Fabric (secondary); React DOM (primary) and React ART (secondary).
Secondary renderers store their context values on separate fields.
* Add back concurrent renderer warning
Only warn for two concurrent primary or two concurrent secondary renderers.
* Change "_secondary" suffix to "2"
#EveryBitCounts
* Switch to JSX API for context
80% sure this will be the final API. Merging this now so we can get this
into the next www sync in preparation for 16.3.
* Promote context to a stable API
* New context API
Introduces a declarative context API that propagates updates even when
shouldComponentUpdate returns false.
* Fuzz tester for context
* Use ReactElement for provider and consumer children
* Unify more branches in createFiberFromElement
* Compare context values using Object.is
Same semantics as PureComponent/shallowEqual.
* Add support for Provider and Consumer to server-side renderer
* Store providers on global stack
Rather than using a linked list stored on the context type. The global
stack can be reset in case of an interruption or error, whereas with the
linked list implementation, you'd need to keep track of every
context type.
* Put new context API behind a feature flag
We'll enable this in www only for now.
* Store nearest provider on context object
* Handle reentrancy in server renderer
Context stack should be per server renderer instance.
* Bailout of consumer updates using bitmask
The context type defines an optional function that compares two context
values, returning a bitfield. A consumer may specify the bits it needs
for rendering. If a provider's context changes, and the consumer's bits
do not intersect with the changed bits, we can skip the consumer.
This is similar to how selectors are used in Redux but fast enough to do
while scanning the tree. The only user code involved is the function
that computes the changed bits. But that's only called once per provider
update, not for every consumer.
* Store current value and changed bits on context object
There are fewer providers than consumers, so better to do this work
at the provider.
* Use maximum of 31 bits for bitmask
This is the largest integer size in V8 on 32-bit systems. Warn in
development if too large a number is used.
* ProviderComponent -> ContextProvider, ConsumerComponent -> ContextConsumer
* Inline Object.is
* Warn if multiple renderers concurrently render the same context provider
Let's see if we can get away with not supporting this for now. If it
turns out that it's needed, we can fall back to backtracking the
fiber return path.
* Nits that came up during review
* Call and Return components should use ReactElement
ReactChildFiber contains lots of branches that do the same thing for
different child types. We can unify them by having more child types be
ReactElements. This requires that the `type` and `key` fields are
sufficient to determine the identity of the child.
The main benefit is decreased file size, especially as we add more
component types, like context providers and consumers.
This updates Call and Return components to use ReactElement. Portals are
left alone for now because their identity includes the host instance.
* Move server render invariant for call and return types
* Sort ReactElement type checks by most likely
* Performance timeline should skip over call components
Don't think these were intentionally omitted from the blacklist of
component types.
I went ahead and updated getComponentName to include special types, even
though I don't think they're used anywhere right now.
* Remove surrounding brackets from internal display names
* Use relative paths in packages/react
* Use relative paths in packages/react-art
* Use relative paths in packages/react-cs
* Use relative paths in other packages
* Fix as many issues as I can
This uncovered an interesting problem where ./b from package/src/a would resolve to a different instantiation of package/src/b in Jest.
Either this is a showstopper or we can solve it by completely fobbidding remaining /src/.
* Fix all tests
It seems we can't use relative requires in tests anymore. Otherwise Jest becomes confused between real file and symlink.
https://github.com/facebook/jest/issues/3830
This seems bad... Except that we already *don't* want people to create tests that import individual source files.
All existing cases of us doing so are actually TODOs waiting to be fixed.
So perhaps this requirement isn't too bad because it makes bad code looks bad.
Of course, if we go with this, we'll have to lint against relative requires in tests.
It also makes moving things more painful.
* Prettier
* Remove @providesModule
* Fix remaining Haste imports I missed earlier
* Fix up paths to reflect new flat structure
* Fix Flow
* Fix CJS and UMD builds
* Fix FB bundles
* Fix RN bundles
* Prettier
* Fix lint
* Fix warning printing and error codes
* Fix buggy return
* Fix lint and Flow
* Use Yarn on CI
* Unbreak Jest
* Fix lint
* Fix aliased originals getting included in DEV
Shouldn't affect correctness (they were ignored) but fixes DEV size regression.
* Record sizes
* Fix weird version in package.json
* Tweak bundle labels
* Get rid of output option by introducing react-dom/server.node
* Reconciler should depend on prop-types
* Update sizes last time
