This is done using a condition variable upon which the awaiting thread
will block if the continuation has not be resumed by the point of await.
The resuming thread will signal this condition variable, thereby
unblocking the awaiting thread.
Rdar://99977665
The new intrinsic, exposed via static functions on Task<T, Never> and
Task<T, Error> (rethrowing), begins an asynchronous context within a
synchronous caller's context. This is only available for use under the
task-to-thread concurrency model, and even then only under SPI.
Previously getAsyncClosureEntryPointAndContextSize took both a pointer
for a function and a closure context. That was a relic of a temporary
ABI where async function pointers were not used in all cases. Now that
that ABI is long gone, async function pointers are always used.
Consequently, the closure context argument was unused. Here, the
closure context argument is removed.
As soon as the waiting task is successfully enqueued on the blocking
task, both tasks have to be considered invalidated because the
blocking task can concurrently complete and resume its waiters:
- The waiting task ensures that the blocking task is valid while
it's waiting. However, that's measured from the perspective of
the waiting task, not from the perspective of the thread that was
previously executing it. As soon as the waiting task is resumed,
the wait call completes and the validity guarantee on the blocking
task disappears, so the blocking task must be treated as
invalidated.
- The waiting task ensures that it is valid as long as it isn't
complete. Since it's trying to wait, it must not be complete.
However, as soon we resume it, it can complete, so the waiting
task must also be treated as invalidated.
This is one of those things that's not really easy to test, and the
need for a fix is pretty urgent, so I'm submitting this patch without
a test. I'll try to land a race test that demonstrates the bug in
the next few days.
@kavon deserves all the credit here for some truly heroic debugging
and finally recognizing the flaw in the code; I'm just popping in
at the last minute to sheepishly patch the bug.
Fixes rdar://92666987
Moved all the threading code to one place. Added explicit support for
Darwin, Linux, Pthreads, C11 threads and Win32 threads, including new
implementations of Once for Linux, Pthreads, C11 and Win32.
rdar://90776105
Moved all the threading code to one place. Added explicit support for
Darwin, Linux, Pthreads, C11 threads and Win32 threads, including new
implementations of Once for Linux, Pthreads, C11 and Win32.
rdar://90776105
Change continuation signposts to emit an interval for init/resume.
Fix task_create to take the decoded flags as separate parameters, matching other calls.
Move job_run trace calls into runJobInEstablishedExecutorContext. swift_job_runImpl didn't catch everything.
rdar://92149411
Apply a blanket pass of including `new` for the placement new allocation
and namespacing the call to the global placement new allocator. This
should repair the Android ARMv7 builds.
Decode all fields from the various flags values, pass each field as a separate argument to the various signposts. We were just passing the raw value of the flags and requiring the signpost client to decode them, which was ugly and required the client to know details they shouldn't need to know.
Strip ptrauth bits from the task resume function when signposting, when ptrauth is supported.
Add signpost events for continuation init/await/resume events.
We also make task_wait into an interval, rather than a single event. The interval ends when the task resumes. As part of this change, we also skip emitting the interval when the wait completed immediately and the task didn't have to suspend.
While we're in there, clean up a few SWIFT_TASK_DEBUG_LOG lines that emitted warnings when built with the logging enabled.
rdar://88658803
Generated code has never actually initialized this field, so we
might as well remove it. Doing so mostly doesn't impact the ABI
since we don't store anything for arguments or results in the
context as part of the normal call sequence. We do need to adjust
some of the hard-coded contexts, however, such as continuation
contexts and the statically-sized context for special runtime
async functions.
A task can be in one of 4 states over its lifetime:
(a) suspended
(b) enqueued
(c) running
(d) completed
This change provides priority inversion avoidance support if a task gets
escalated when it is in state (a), (c), (d).
Radar-Id: rdar://problem/76127624
Most of the new inspection logic is in Remote Mirror. New code in swift-inspect calls the new Remote Mirror functions and formats the resulting information for display.
Specific Remote Mirror changes:
* Add a call to check if a given metadata is an actor.
* Add calls to get information about actors and tasks.
* Add a `readObj` call to MemoryReader that combines the read and the cast, greatly simplifying code chasing pointers in the remote process.
* Add a generalized facility to the C shims that can allocate a temporary object that remains valid until at least the next call, which is used to return various temporary arrays from the new calls. Remove the existing `lastString` and `lastChunks` member variables in favor of this new facility.
Swift-inspect changes:
* Add a new dump-concurrency command.
* Add a new `ConcurrencyDumper.swift` file with the implementation. The dumper needs to do some additional work with the results from Remote Mirror to build up the task tree and this keeps it all organized.
* Extend `Inspector` to query the target's threads and fetch each thread's current task.
Concurrency runtime changes:
* Add `_swift_concurrency_debug` variables pointing to the various future adapters. Remote Mirror uses these to provide a better view of a tasks's resume pointer.
rdar://85231338
This change adds support for WASI in stdlib tests. Some tests that expect a crash to happen had to be disabled, since there's currently no way to observe such crash from a WASI host.
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
This change has two parts to it:
1. Add in a new interface (addStatusRecordWithChecks) for adding task
status records that also takes in a function ref. This function ref will
be used to evaluate if current state of the parent task has any changes
that need to be propagated to the child task that has been created.
This is necessary to prevent the following race between task creation
and concurrent cancellation and escalation:
a. Parent task create child task. It does lazy relaxed loads on its own
state while doing so and propagates this state to the child.
b. Child task is created but has not been attached to the parent
task/task group.
c. Parent task gets cancelled by another thread.
d. Child task gets linked into the parent’s task status records but no
reevaluation has happened to account for changes that might have happened to
the parent after (a).
2. Move status record management functions from the
Runtime/Concurrency.h to TaskPrivate.h. Remove any corresponding
overrides that are no longer needed. Remove unused tryAddStatusRecord
method whose functionality is provided by addStatusRecordWithChecks.
Radar-Id: rdar://problem/86347801
`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.
The usage of libdispatch in Concurrency is dynamic - it does not
explicitly link against libdispatch and thus cannot directly invoke
`dispatch_main`. While linking against dispatch would be ideal, this
should improve the current path.
The 32-bit identifier in Job is locked down at this point, so we expand the ID by storing the top 32 bits separately inside AsyncTask::PrivateStorage.
rdar://85167409
We remove the existing `swift_reflection_iterateAsyncTaskAllocations` API that attempts to provide all necessary information about a tasks's allocations starting from the task. Instead, we split it into two pieces: `swift_reflection_asyncTaskSlabPointer` to get the first slab for a task, and `+swift_reflection_asyncTaskSlabAllocations` to get the allocations in a slab, and a pointer to the next slab.
We also add a dummy metadata pointer to the beginning of each slab. This allows tools to identify slab allocations on the heap without needing to locate every single async task object. They can then use `swift_reflection_asyncTaskSlabAllocations` on such allocations to find out about the contents.
rdar://82549631
We remove the existing `swift_reflection_iterateAsyncTaskAllocations` API that attempts to provide all necessary information about a tasks's allocations starting from the task. Instead, we split it into two pieces: `swift_reflection_asyncTaskSlabPointer` to get the first slab for a task, and `+swift_reflection_asyncTaskSlabAllocations` to get the allocations in a slab, and a pointer to the next slab.
We also add a dummy metadata pointer to the beginning of each slab. This allows tools to identify slab allocations on the heap without needing to locate every single async task object. They can then use `swift_reflection_asyncTaskSlabAllocations` on such allocations to find out about the contents.
rdar://82549631
The asm definition of `swift_async_extendedFramePointerFlags` prevents
the use of bitcode with the back-deployment libraries, so remove the
definition and use of this symbol from watchOS binaries entirely.
Instead, always force the async frame bit to be set. This trades off
backtraces on older OS's for debuggability of newer ones. If it causes
problems, it can be disabled via the option
`-swift-async-frame-pointer=never`.
Fixes rdar://84687579.
