This is the first of a series of PRs, that let you pass functions, by
reference, to the client and back. E.g. through Server Context. It's
like client references but they're opaque on the client and resolved on
the server.
To do this, for security, you must opt-in to exposing these functions to
the client using the `"use server"` directive. The `"use client"`
directive lets you enter the client from the server. The `"use server"`
directive lets you enter the server from the client.
This works by tagging those functions as Server References. We could
potentially expand this to other non-serializable or stateful objects
too like classes.
This only implements server->server CJS imports and server->server ESM
imports. We really should add a loader to the webpack plug-in for
client->server imports too. I'll leave closures as an exercise for
integrators.
You can't "call" a client reference on the server, however, you can
"call" a server reference on the client. This invokes a callback on the
Flight client options called `callServer`. This lets a router implement
calling back to the server. Effectively creating an RPC. This is using
JSON for serializing those arguments but more utils coming from
client->server serialization.
This renames Module References to Client References, since they are in
the server->client direction.
I also changed the Proxies exposed from the `node-register` loader to
provide better error messages. Ideally, some of this should be
replicated in the ESM loader too but neither are the source of truth.
We'll replicate this in the static form in the Next.js loaders. cc
@huozhi @shuding
- All references are now functions so that when you call them on the
server, we can yield a better error message.
- References that are themselves already referring to an export name are
now proxies that error when you dot into them.
- `use(...)` can now be used on a client reference to unwrap it server
side and then pass a reference to the awaited value.
* Facebook -> Meta in copyright
rg --files | xargs sed -i 's#Copyright (c) Facebook, Inc. and its affiliates.#Copyright (c) Meta Platforms, Inc. and affiliates.#g'
* Manual tweaks
* [Flight] Align Chunks with Thenable used with experimental_use
Use the field names used by the Thenable data structure passed to use().
These are considered public in this model.
This adds another field since we use a separate field name for "reason".
* Implement Thenable Protocol on Chunks
This doesn't just ping but resolves/rejects with the value.
* Subclass Promises
* Pass key through JSON parsing
* Wait for preloadModules before resolving module chunks
* Initialize lazy resolved values before reading the result
* Block a model from initializing if its direct dependencies are pending
If a module is blocked, then we can't complete initializing a model.
However, we can still let it parse, and then fill in the missing pieces
later.
We need to block it from resolving until all dependencies have filled in
which we can do with a ref count.
* Treat blocked modules or models as a special status
We currently loop over all chunks at the end to error them if they're
still pending. We shouldn't do this if they're pending because they're
blocked on an external resource like a module because the module might not
resolve before the Flight connection closes and that's not an error.
In an alternative solution I had a set that tracked pending chunks and
removed one at a time. While the loop at the end is faster it's more
work as we go.
I figured the extra status might also help debugging.
For modules we can probably assume no forward references, and the first
async module we can just use the promise as the chunk.
So we could probably get away with this only on models that are blocked by
modules.
* Simplify Relay protocol integration
* Encode Relay rows as tuples instead of objects
This is slightly more compact and more ressembles more closely the encoding
we use for the raw stream protocol.
This adds a new dimension similar to dom-relay. It's different from
"native" which would be Flight for RN without Relay.
This has some copy-pasta that's the same between the two Relay builds but
the key difference will be Metro and we're not quite sure what other
differences there will be yet.
* Refactor Flight to require a module reference to be brand checked
This exposes a host environment (bundler) specific hook to check if an
object is a module reference. This will be used so that they can be passed
directly into Flight without needing additional wrapper objects.
* Emit module references as a special type of value
We already have JSON and errors as special types of "rows". This encodes
module references as a special type of row value. This was always the
intention because it allows those values to be emitted first in the stream
so that as a large models stream down, we can start preloading as early
as possible.
We preload the module when they resolve but we lazily require them as they
are referenced.
* Emit module references where ever they occur
This emits module references where ever they occur. In blocks or even
directly in elements.
* Don't special case the root row
I originally did this so that a simple stream is also just plain JSON.
However, since we might want to emit things like modules before the root
module in the stream, this gets unnecessarily complicated. We could add
this back as a special case if it's the first byte written but meh.
* Update the protocol
* Add test for using a module reference as a client component
* Relax element type check
Since Flight now accepts a module reference as returned by any bundler
system, depending on the renderer running. We need to drastically relax
the check to include all of them. We can add more as we discover them.
* Move flow annotation
Seems like our compiler is not happy with stripping this.
* Some bookkeeping bug
* Can't use the private field to check
This is equivalent to the jsx-runtime in that this is what the compiled
output on the server is supposed to target.
It's really just the same code for all the different Flights, but they
have different types in their arguments so each one gets their own entry
point. We might use this to add runtime warnings per entry point.
Unlike the client-side React.block call this doesn't provide the factory
function that curries the load function. The compiler is expected to wrap
this call in the currying factory.
* Resolve Server-side Blocks instead of Components
React elements should no longer be used to extract arbitrary data but only
for prerendering trees.
Blocks are used to create asynchronous behavior.
* Resolve Blocks in the Client
* Tests
* Bug fix relay JSON traversal
It's supposed to pass the original object and not the new one.
* Lint
* Move Noop Module Test Helpers to top level entry points
This module has shared state. It needs to be external from builds.
This lets us test the built versions of the Noop renderer.
Follow ups from https://github.com/facebook/react/pull/18334
I also introduced the concept of a module reference on the client too.
We don't need this for webpack so that gets compiled out but we need it
for www. Similarly I also need a difference between preload and load.
* Add ReactFlightServerConfig intermediate
This just forwards to the stream version of Flight which is itself forked
between Node and W3C streams.
The dom-relay goes directly to the Relay config though which allows it to
avoid the stream part of Flight.
* Separate streaming protocol into the Stream config
* Split streaming parts into the ReactFlightServerConfigStream
This decouples it so that the Relay implementation doesn't have to encode
the JSON to strings. Instead it can be fed the values as JSON objects and
do its own encoding.
* Split FlightClient into a basic part and a stream part
Same split as the server.
* Expose lower level async hooks to Relay
This requires an external helper file that we'll wire up internally.
