When possible, decode the DrainLock/ExecutionLock fields of tasks and actors in concurrency runtimes built with priority escalation, and show the corresponding thread info in swift-inspect output.
We weren't properly decoding actor flags previously, so fix that up as well and have Remote Mirror split them out into separate fields so clients don't have to. We were missing the Job Storage field from the definition of DefaultActorImpl in RuntimeInternals.h, fix that so we actually read the right data.
rdar://88598003
Have RemoteMirror internally decode these flags fields and return them as separate fields in the task/actor info. Handle the structures both with and without task escalation support.
Also show when a task is the current task on a thread in swift-inspect's task listing.
rdar://88598003
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.
Adjust the types of `ConcurrentHashMap` to match the implementation. This field is always a `uint32_t`, which would be misread previously. Thanks to @mikeash for helping identify this.
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
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
We were missing a Status field. The reflect_task test didn't catch this becasue it was reading LastAllocation as FirstSlab, which still worked well enough in that context.
rdar://81427584
Fix the declaration of AsyncTask and add a test for iterateAsyncTaskAllocations. Reflection's declaration of AsyncTask had fallen out of sync with the real thing. The test that was supposed to catch this was never actually committed, oops.
Add a swift_reflection_libraryVersion variable to Remote Mirror to indicate the presence of this fix. In the future, the value can be incremented to signal the presence of other changes that can't otherwise be detected.
rdar://80035307
to use it.
ConcurrentReadableHashMap is lock-free for readers, with writers using a lock to
ensure mutual exclusion amongst each other. The intent is to eventually replace
all uses ConcurrentMap with ConcurrentReadableHashMap.
ConcurrentReadableHashMap provides for relatively quick lookups by using a hash
table. Rearders perform an atomic increment/decrement in order to inform writers
that there are active readers. The design attempts to minimize wasted memory by
storing the actual elements out-of-line, and having the table store indices into
a separate array of elements.
The protocol conformance cache now uses ConcurrentReadableHashMap, which
provides faster lookups and less memory use than the previous ConcurrentMap
implementation. The previous implementation caches
ProtocolConformanceDescriptors and extracts the WitnessTable after the cache
lookup. The new implementation directly caches the WitnessTable, removing an
extra step (potentially a quite slow one) from the fast path.
The previous implementation used a generational scheme to detect when negative
cache entries became obsolete due to new dynamic libraries being loaded, and
update them in place. The new implementation just clears the entire cache when
libraries are loaded, greatly simplifying the code and saving the memory needed
to track the current generation in each negative cache entry. This means we need
to re-cache all requested conformances after loading a dynamic library, but
loading libraries at runtime is rare and slow anyway.
rdar://problem/67268325
