When a scripted frame provider calls back into the thread's frame
machinery (e.g. via HandleCommand or EvaluateExpression), two problems
arise:
1. GetStackFrameList() re-enters the SyntheticStackFrameList
construction, causing infinite recursion.
2. ClearStackFrames() tries to read-lock the StackFrameList's
shared_mutex that is already write-locked by GetFramesUpTo,
causing a deadlock.
This patch fixes those issues by tracking when a provider is actively
fetching frames via a per-host-thread map (m_provider_frames_by_thread)
keyed by HostThread. The map is pushed/popped in
SyntheticStackFrameList::FetchFramesUpTo before calling into the
provider. GetStackFrameList() checks it to route re-entrant calls:
- The provider's own host thread gets the parent frame list, preventing
circular dependency when get_frame_at_index calls back into
GetFrameAtIndex.
- The private state thread also gets the parent frame list, preventing
deadlock when a provider calls EvaluateExpression (which needs the
private state thread to process events).
- Other host threads proceed normally and block on the frame list mutex
until the provider finishes, getting the correct synthetic result.
ClearStackFrames() returns early if any provider is active, since the
frame state is shared and tearing it down while a provider is
mid-construction is both unnecessary and unsafe.
rdar://171558394
Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>
* Provide a minimal, working example
* Document the instance variables
* Remove mention of `thread.SetScriptedFrameProvider` (which doesn't exist)
* add missing `@staticmethod` annotation
* fix rendering of bullet-pointed lists
This patch adds `get_priority()` support to synthetic frame providers to
enable priority-based selection when multiple providers match a thread.
This is the first step toward supporting frame provider chaining for
visualizing coroutines, Swift async tasks, and et al.
Priority ordering follows Unix nice convention where lower numbers
indicate higher priority (0 = highest). Providers without explicit
priority return `std::nullopt`, which maps to UINT32_MAX (lowest
priority), ensuring backward compatibility with existing providers.
The implementation adds `GetPriority()` as a virtual method to
`SyntheticFrameProvider` base class, implements it through the scripting
interface hierarchy (`ScriptedFrameProviderInterface` and
`ScriptedFrameProviderPythonInterface`), and updates
`Thread::GetStackFrameList()` to sort applicable providers by priority
before attempting to load them.
Python frame providers can now specify priority:
```python
@staticmethod
def get_priority():
return 10 # Or return None for default priority.
```
Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>
This patch extends ScriptedFrame to work with real (non-scripted)
threads,
enabling frame providers to synthesize frames for native processes.
Previously, ScriptedFrame only worked within
ScriptedProcess/ScriptedThread
contexts. This patch decouples ScriptedFrame from ScriptedThread,
allowing
users to augment or replace stack frames in real debugging sessions for
use
cases like custom calling conventions, reconstructing corrupted frames
from
core files, or adding diagnostic frames.
Key changes:
- ScriptedFrame::Create() now accepts ThreadSP instead of requiring
ScriptedThread, extracting architecture from the target triple rather
than ScriptedProcess.arch
- Added SBTarget::RegisterScriptedFrameProvider() and
ClearScriptedFrameProvider() APIs, with Target storing a
SyntheticFrameProviderDescriptor template for new threads
- Added "target frame-provider register/clear" commands for CLI access
- Thread class gains LoadScriptedFrameProvider(),
ClearScriptedFrameProvider(),
and GetFrameProvider() methods for per-thread frame provider management
- New SyntheticStackFrameList overrides FetchFramesUpTo() to lazily
provide
frames from either the frame provider or the real stack
This enables practical use of the SyntheticFrameProvider infrastructure
in
real debugging workflows.
rdar://161834688
Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>
Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>
This patch implements the base and python interface for the
ScriptedFrameProvider class.
This is necessary to call python APIs from the ScriptedFrameProvider
that will come in a follow-up.
Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>
Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>
