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Diffstat (limited to 'venv/lib/python3.11/site-packages/greenlet/TThreadStateDestroy.cpp')
-rw-r--r-- | venv/lib/python3.11/site-packages/greenlet/TThreadStateDestroy.cpp | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/venv/lib/python3.11/site-packages/greenlet/TThreadStateDestroy.cpp b/venv/lib/python3.11/site-packages/greenlet/TThreadStateDestroy.cpp new file mode 100644 index 0000000..a149a1a --- /dev/null +++ b/venv/lib/python3.11/site-packages/greenlet/TThreadStateDestroy.cpp @@ -0,0 +1,195 @@ +/* -*- indent-tabs-mode: nil; tab-width: 4; -*- */ +/** + * Implementation of the ThreadState destructors. + * + * Format with: + * clang-format -i --style=file src/greenlet/greenlet.c + * + * + * Fix missing braces with: + * clang-tidy src/greenlet/greenlet.c -fix -checks="readability-braces-around-statements" +*/ +#ifndef T_THREADSTATE_DESTROY +#define T_THREADSTATE_DESTROY + +#include "greenlet_greenlet.hpp" +#include "greenlet_thread_state.hpp" +#include "greenlet_thread_support.hpp" +#include "greenlet_cpython_add_pending.hpp" +#include "TGreenletGlobals.cpp" + +namespace greenlet { + +struct ThreadState_DestroyWithGIL +{ + ThreadState_DestroyWithGIL(ThreadState* state) + { + if (state && state->has_main_greenlet()) { + DestroyWithGIL(state); + } + } + + static int + DestroyWithGIL(ThreadState* state) + { + // Holding the GIL. + // Passed a non-shared pointer to the actual thread state. + // state -> main greenlet + assert(state->has_main_greenlet()); + PyGreenlet* main(state->borrow_main_greenlet()); + // When we need to do cross-thread operations, we check this. + // A NULL value means the thread died some time ago. + // We do this here, rather than in a Python dealloc function + // for the greenlet, in case there's still a reference out + // there. + static_cast<MainGreenlet*>(main->pimpl)->thread_state(nullptr); + + delete state; // Deleting this runs the destructor, DECREFs the main greenlet. + return 0; + } +}; + + + +struct ThreadState_DestroyNoGIL +{ + // ensure this is actually defined. + static_assert(GREENLET_BROKEN_PY_ADD_PENDING == 1 || GREENLET_BROKEN_PY_ADD_PENDING == 0, + "GREENLET_BROKEN_PY_ADD_PENDING not defined correctly."); + +#if GREENLET_BROKEN_PY_ADD_PENDING + static int _push_pending_call(struct _pending_calls *pending, + int (*func)(void *), void *arg) + { + int i = pending->last; + int j = (i + 1) % NPENDINGCALLS; + if (j == pending->first) { + return -1; /* Queue full */ + } + pending->calls[i].func = func; + pending->calls[i].arg = arg; + pending->last = j; + return 0; + } + + static int AddPendingCall(int (*func)(void *), void *arg) + { + _PyRuntimeState *runtime = &_PyRuntime; + if (!runtime) { + // obviously impossible + return 0; + } + struct _pending_calls *pending = &runtime->ceval.pending; + if (!pending->lock) { + return 0; + } + int result = 0; + PyThread_acquire_lock(pending->lock, WAIT_LOCK); + if (!pending->finishing) { + result = _push_pending_call(pending, func, arg); + } + PyThread_release_lock(pending->lock); + SIGNAL_PENDING_CALLS(&runtime->ceval); + return result; + } +#else + // Python < 3.8 or >= 3.9 + static int AddPendingCall(int (*func)(void*), void* arg) + { + return Py_AddPendingCall(func, arg); + } +#endif + + ThreadState_DestroyNoGIL(ThreadState* state) + { + // We are *NOT* holding the GIL. Our thread is in the middle + // of its death throes and the Python thread state is already + // gone so we can't use most Python APIs. One that is safe is + // ``Py_AddPendingCall``, unless the interpreter itself has + // been torn down. There is a limited number of calls that can + // be queued: 32 (NPENDINGCALLS) in CPython 3.10, so we + // coalesce these calls using our own queue. + if (state && state->has_main_greenlet()) { + // mark the thread as dead ASAP. + // this is racy! If we try to throw or switch to a + // greenlet from this thread from some other thread before + // we clear the state pointer, it won't realize the state + // is dead which can crash the process. + PyGreenlet* p = state->borrow_main_greenlet(); + assert(p->pimpl->thread_state() == state || p->pimpl->thread_state() == nullptr); + static_cast<MainGreenlet*>(p->pimpl)->thread_state(nullptr); + } + + // NOTE: Because we're not holding the GIL here, some other + // Python thread could run and call ``os.fork()``, which would + // be bad if that happenend while we are holding the cleanup + // lock (it wouldn't function in the child process). + // Make a best effort to try to keep the duration we hold the + // lock short. + // TODO: On platforms that support it, use ``pthread_atfork`` to + // drop this lock. + LockGuard cleanup_lock(*mod_globs->thread_states_to_destroy_lock); + + if (state && state->has_main_greenlet()) { + // Because we don't have the GIL, this is a race condition. + if (!PyInterpreterState_Head()) { + // We have to leak the thread state, if the + // interpreter has shut down when we're getting + // deallocated, we can't run the cleanup code that + // deleting it would imply. + return; + } + + mod_globs->queue_to_destroy(state); + if (mod_globs->thread_states_to_destroy.size() == 1) { + // We added the first item to the queue. We need to schedule + // the cleanup. + int result = ThreadState_DestroyNoGIL::AddPendingCall( + ThreadState_DestroyNoGIL::DestroyQueueWithGIL, + NULL); + if (result < 0) { + // Hmm, what can we do here? + fprintf(stderr, + "greenlet: WARNING: failed in call to Py_AddPendingCall; " + "expect a memory leak.\n"); + } + } + } + } + + static int + DestroyQueueWithGIL(void* UNUSED(arg)) + { + // We're holding the GIL here, so no Python code should be able to + // run to call ``os.fork()``. + while (1) { + ThreadState* to_destroy; + { + LockGuard cleanup_lock(*mod_globs->thread_states_to_destroy_lock); + if (mod_globs->thread_states_to_destroy.empty()) { + break; + } + to_destroy = mod_globs->take_next_to_destroy(); + } + // Drop the lock while we do the actual deletion. + ThreadState_DestroyWithGIL::DestroyWithGIL(to_destroy); + } + return 0; + } + +}; + +}; // namespace greenlet + +// The intent when GET_THREAD_STATE() is needed multiple times in a +// function is to take a reference to its return value in a local +// variable, to avoid the thread-local indirection. On some platforms +// (macOS), accessing a thread-local involves a function call (plus an +// initial function call in each function that uses a thread local); +// in contrast, static volatile variables are at some pre-computed +// offset. +typedef greenlet::ThreadStateCreator<greenlet::ThreadState_DestroyNoGIL> ThreadStateCreator; +static thread_local ThreadStateCreator g_thread_state_global; +#define GET_THREAD_STATE() g_thread_state_global + +#endif //T_THREADSTATE_DESTROY |