This changes the isIsolatingCurrentContext function to return `Bool?`
and removes all the witness table trickery we did previously to detect
if it was implemented or not. This comes at a cost of trying to invoke
it always, before `checkIsolated`, but it makes for an simpler
implementation and more checkable even by third party Swift code which
may want to ask this question.
Along with the `withSerialExecutor` function, this now enables us to
check the isolation at runtime when we have an `any Actor` e.g. from
`#isolation`.
Updates SE-0471 according to
https://forums.swift.org/t/se-0471-improved-custom-serialexecutor-isolation-checking-for-concurrency-runtime/78834/
review discussions
* [Concurrency] Initial steps for startSynchronously for Task
* [Concurrency] Rename to _startSynchronously while in development
* [Concurrency] StartSynchronously special executor to avoid switching
* startSynchronously bring back more info output
* [Concurrency] startSynchronously with more custom executor tests
* add missing ABI additions to test for x86
* [Concurrency] gyb generate _startSynchronously
* [Concurrency] %import dispatch for Linux startSynchronously test
* [Concurrency] Add TaskGroup.startTaskSynchronously funcs
* [Concurrency] DispatchSerialQueue does not exist on linux still
It cannot be used for executing general-purpose work, because such function would need to have a different signature to pass isolated actor instance.
And being explicit about using this method only for deinit allows to use object pointer for comparison with executor identity.
* [Concurrency] Fix task excutor handling of default actor isolation
The task executor API did not properly account for taking the default
actor locking into account when running code on it, we just took the job
and ran it without checking with the serial executor at all, which
resulted in potential concurrent executions inside the actor --
violating actor isolation.
Here we change the TaskExecutor enqueue API to accept the "target"
serial executor, which in practice will be either generic or a specific
default actor, and coordinate with it when we perform a
runSynchronously.
The SE proposal needs to be amended to showcase this new API, however
without this change we are introducing races so we must do this before
the API is stable.
* Remove _swift_task_enqueueOnTaskExecutor as we don't use it anymore
* no need for the new protocol requirement
* remove the enqueue(_ job: UnownedJob, isolatedTo unownedSerialExecutor: UnownedSerialExecutor)
Thankfully we dont need it after all
* Don't add swift_defaultActor_enqueue_withTaskExecutor and centralize the task executor getting to enqueue()
* move around extern definitions
When SWIFT_COMPACT_ABSOLUTE_FUNCTION_POINTER is enabled, relative direct
pointers whose pointees are functions will be turned into absolute
pointer at compile-time.
Each trace point is declared as a function in the new `Tracing.h` header. These functions are called from the appropriate places in the concurrency runtime.
On Darwin, an implementation of these functions is provided which uses the `os/signpost.h` API to emit signpost events/intervals.
When the signpost API is not available, no-op stub implementations are provided. Implementations for other OSes can be provided by providing implementations of the trace functions for that OS.
rdar://81858487
`AsyncFunctionTypeImpl` has its `type` defaulted to `TaskContinuationFunction`
which is incorrect because it has to append arguments, result type and account
for throws bit.
These changes expand `AsyncSignature` with `ContinuationType` and expand `FunctionType`
to include all of the appropriate information.
I added Builtin.buildMainActorExecutor before, but because I never
implemented it correctly in IRGen, it's not okay to use it on old
versions, so I had to introduce a new feature only for it.
The shim dispatch queue class in the Concurrency runtime is rather
awful, but I couldn't think of a reasonable alternative without
just entirely hard-coding the witness table in the runtime.
It's not ABI, at least.
Changes the task, taskGroup, asyncLet wait funtion call ABIs.
To reduce code size pass the context parameters and resumption function
as arguments to the wait function.
This means that the suspend point does not need to store parent context
and resumption to the suspend point's context.
```
void swift_task_future_wait_throwing(
OpaqueValue * result,
SWIFT_ASYNC_CONTEXT AsyncContext *callerContext,
AsyncTask *task,
ThrowingTaskFutureWaitContinuationFunction *resume,
AsyncContext *callContext);
```
The runtime passes the caller context to the resume entry point saving
the load of the parent context in the resumption function.
This patch adds a `Metadata *` field to `GroupImpl`. The await entry
pointer no longer pass the metadata pointer and there is a path through
the runtime where the task future is no longer available.
Previously, they were storing a low-bit flag that indicated that they
were a default actor. Using an extra inhabitant frees up the low bit
for future use without being conspicuously more expensive to check.
- Introduce an UnownedSerialExecutor type into the concurrency library.
- Create a SerialExecutor protocol which allows an executor type to
change how it executes jobs.
- Add an unownedExecutor requirement to the Actor protocol.
- Change the ABI for ExecutorRef so that it stores a SerialExecutor
witness table pointer in the implementation field. This effectively
makes ExecutorRef an `unowned(unsafe) SerialExecutor`, except that
default actors are represented without a witness table pointer (just
a bit-pattern).
- Synthesize the unownedExecutor method for default actors (i.e. actors
that don't provide an unownedExecutor property).
- Make synthesized unownedExecutor properties `final`, and give them
a semantics attribute specifying that they're for default actors.
- Split `Builtin.buildSerialExecutorRef` into a few more precise
builtins. We're not using the main-actor one yet, though.
Pitch thread:
https://forums.swift.org/t/support-custom-executors-in-swift-concurrency/44425
Most of the async runtime functions have been changed to not
expect the task and executor to be passed in. When knowing the
task and executor is necessary, there are runtime functions
available to recover them.
The biggest change I had to make to a runtime function signature
was to swift_task_switch, which has been altered to expect to be
passed the context and resumption function instead of requiring
the caller to park the task. This has the pleasant consequence
of allowing the implementation to very quickly turn around when
it recognizes that the current executor is satisfactory. It does
mean that on arm64e we have to sign the continuation function
pointer as an argument and then potentially resign it when
assigning into the task's resume slot.
rdar://70546948
* Adds support for generating code that uses swiftasync parameter lowering.
* Currently only arm64's llvm lowering supports the swift_async_context_addr intrinsic.
* Add arm64e pointer signing of updated swift_async_context_addr.
This commit needs the PR llvm-project#2291.
* [runtime] unittests should use just-built compiler if the runtime did
This will start to matter with the introduction of usage of swiftasync parameters which only very recent compilers support.
rdar://71499498
We expect to iterate on this quite a bit, both publicly
and internally, but this is a fine starting-point.
I've renamed runAsync to runAsyncAndBlock to underline
very clearly what it does and why it's not long for this
world. I've also had to give it a radically different
implementation in an effort to make it continue to work
given an actor implementation that is no longer just
running all work synchronously.
The major remaining bit of actor-scheduling work is to
make swift_task_enqueue actually do something sensible
based on the executor it's been given; currently it's
expecting a flag that IRGen simply doesn't know to set.
