The final issue was making sure we do the same thing on ctl-c/SIGINT
from the user. That is, if there's already a bg-thread in REPL, we
`log.pdb()` about SIGINT shielding and re-draw the prompt; the same UX
as normal actor-runtime-task behaviour.
Reasons this wasn't workin.. and the fix:
- `.pause_from_sync()` was overriding the local `repl` var with `None`
delivered by (transitive) calls to `_pause(debug_func=None)`.. so
remove all that and only assign it OAOO prior to thread-type case
branching.
- always call `DebugStatus.shield_sigint()` as needed from all requesting
threads/tasks:
- in `_pause_from_bg_root_thread()` BEFORE calling `._pause()` AND BEFORE
yielding back to the bg-thread via `.started(out)` to ensure we're
definitely overriding the handler in the `trio`-main-thread task
before unblocking the requesting bg-thread.
- from any requesting bg-thread in the root actor such that both its
main-`trio`-thread scheduled task (as per above bullet) AND it are
SIGINT shielded.
- always call `.shield_sigint()` BEFORE any `greenback._await()` case
don't entirely grok why yet, but it works)?
- for `greenback._await()` case always set `bg_task` to the current one..
- tweaks to the `SIGINT` handler, now renamed `sigint_shield()` so as
not to name-collide with the methods when editor-searching:
- always try to `repr()` the REPL thread/task "owner" as well as the
active `PdbREPL` instance.
- add `.devx()` notes around the prompt flushing deats and comments
for any root-actor-bg-thread edge cases.
Related/supporting refinements:
- add `get_lock()`/`get_debug_req()` factory funcs since the plan is to
eventually implement both as `@singleton` instances per actor.
- fix `acquire_debug_lock()`'s call-sig-bug for scheduling
`request_root_stdio_lock()`..
- in `._pause()` only call `mk_pdb()` when `debug_func != None`.
- add some todo/warning notes around the `cls.repl = None` in
`DebugStatus.release()`
`test_pause_from_sync()` tweaks:
- don't use a `attach_patts.copy()`, since we always `break` on match.
- do `pytest.fail()` on that ^ loop's fallthrough..
- pass `do_ctlc(child, patt=attach_key)` such that we always match the
the current thread's name with the ctl-c triggered `.pdb()` emission.
- oh yeah, return the last `before: str` from `do_ctlc()`.
- in the script, flip `abandon_on_cancel=True` since when `False` it
seems to cause `trio.run()` to hang on exit from the last bg-thread
case?!?
Originally discovered as while using `tractor.pause_from_sync()`
from the `i3ipc` client running in a bg-thread that uses `asyncio`
inside `modden`.
Turns out we definitely aren't correctly handling `.pause_from_sync()`
from the root actor when called from a `trio.to_thread.run_sync()`
bg thread:
- root-actor bg threads which can't `Lock._debug_lock.acquire()` since
they aren't in `trio.Task`s.
- even if scheduled via `.to_thread.run_sync(_debug._pause)` the
acquirer won't be the task/thread which calls `Lock.release()` from
`PdbREPL` hooks; this results in a RTE raised by `trio`..
- multiple threads will step on each other's stdio since cpython's GIL
seems to ctx switch threads on every input from the user to the REPL
loop..
Reproduce via reworking our example and test so that they catch and fail
for all edge cases:
- rework the `/examples/debugging/sync_bp.py` example to demonstrate the
above issues, namely the stdio clobbering in the REPL when multiple
threads and/or a subactor try to debug simultaneously.
|_ run one thread using a task nursery to ensure it runs conc with the
nursery's parent task.
|_ ensure the bg threads run conc a subactor usage of
`.pause_from_sync()`.
|_ gravely detail all the special cases inside a TODO comment.
|_ add some control flags to `sync_pause()` helper and don't use
`breakpoint()` by default.
- extend and adjust `test_debugger.test_pause_from_sync` to match (and
thus currently fail) by ensuring exclusive `PdbREPL` attachment when
the 2 bg root-actor threads are concurrently interacting alongside the
subactor:
|_ should only see one of the `_pause_msg` logs at a time for either
one of the threads or the subactor.
|_ ensure each attaches (in no particular order) before expecting the
script to exit.
Impl adjustments to `.devx._debug`:
- drop `Lock.repl`, no longer used.
- add `Lock._owned_by_root: bool` for the `.ctx_in_debug == None`
root-actor-task active case.
- always `log.exception()` for any `._debug_lock.release()` ownership
RTE emitted by `trio`, like we used to..
- add special `Lock.release()` log message for the stale lock but
`._owned_by_root == True` case; oh yeah and actually
`log.devx(message)`..
- rename `Lock.acquire()` -> `.acquire_for_ctx()` since it's only ever
used from subactor IPC usage; well that and for local root-task
usage we should prolly add a `.acquire_from_root_task()`?
- buncha `._pause()` impl improvements:
|_ type `._pause()`'s `debug_func` as a `partial` as well.
|_ offer `called_from_sync: bool` and `called_from_bg_thread: bool`
for the special case handling when called from `.pause_from_sync()`
|_ only set `DebugStatus.repl/repl_task` when `debug_func != None`
(OW ensure the `.repl_task` is not the current one).
|_ handle error logging even when `debug_func is None`..
|_ lotsa detailed commentary around root-actor-bg-thread special cases.
- when `._set_trace(hide_tb=False)` do `pdbp.set_trace(frame=currentframe())`
so the `._debug` internal frames are always included.
- by default always hide tracebacks for `.pause[_from_sync]()` internals.
- improve `.pause_from_sync()` to avoid root-bg-thread crashes:
|_ pass new `called_from_xxx_` flags and ensure `DebugStatus.repl_task`
is actually set to the `threading.current_thread()` when needed.
|_ manually call `Lock._debug_lock.acquire_nowait()` for the non-bg
thread case.
|_ TODO: still need to implement the bg-thread case using a bg
`trio.Task`-in-thread with an `trio.Event` set by thread REPL exit.
Now supports use from any `trio` task, any sync thread started with
`trio.to_thread.run_sync()` AND also via `breakpoint()` builtin API!
The only bit missing now is support for `asyncio` tasks when in infected
mode.. Bo
`greenback` setup/API adjustments:
- move `._rpc.maybe_import_gb()` to -> `devx._debug` and factor out the cached
import checking into a sync func whilst placing the async `.ensure_portal()`
bootstrapping into a new async `maybe_init_greenback()`.
- use the new init-er func inside `open_root_actor()` with the output
predicating whether we override the `breakpoint()` hook.
core `devx._debug` implementation deatz:
- make `mk_mpdb()` only return the `pdp.Pdb` subtype instance since
the sigint unshielding func is now accessible from the `Lock`
singleton from anywhere.
- add non-main thread support (at least for `trio.to_thread` use cases)
to our `Lock` with a new `.is_trio_thread()` predicate that delegates
directly to `trio`'s internal version.
- do `Lock.is_trio_thread()` checks inside any methods which require
special provisions when invoked from a non-main `trio` thread:
- `.[un]shield_sigint()` methods since `signal.signal` usage is only
allowed from cpython's main thread.
- `.release()` since `trio.StrictFIFOLock` can only be called from
a `trio` task.
- rework `.pause_from_sync()` itself to directly call `._set_trace()`
and don't bother with `greenback._await()` when we're already calling
it from a `.to_thread.run_sync()` thread, oh and try to use the
thread/task name when setting `Lock.local_task_in_debug`.
- make it an RTE for now if you try to use `.pause_from_sync()` from any
infected-`asyncio` task, but support is (hopefully) coming soon!
For testing we add a new `test_debugger.py::test_pause_from_sync()`
which includes a ctrl-c parametrization around the
`examples/debugging/sync_bp.py` script which includes all currently
supported/working usages:
- `tractor.pause_from_sync()`.
- via `breakpoint()` overload.
- from a `trio.to_thread.run_sync()` spawn.
Tyler Goodlet