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Diffstat (limited to '.venv/lib/python3.12/site-packages/greenlet/TThreadStateDestroy.cpp')
-rw-r--r-- | .venv/lib/python3.12/site-packages/greenlet/TThreadStateDestroy.cpp | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/greenlet/TThreadStateDestroy.cpp b/.venv/lib/python3.12/site-packages/greenlet/TThreadStateDestroy.cpp new file mode 100644 index 00000000..37fcc8c1 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/greenlet/TThreadStateDestroy.cpp @@ -0,0 +1,258 @@ +/* -*- 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 "TGreenlet.hpp" + +#include "greenlet_thread_support.hpp" +#include "greenlet_cpython_add_pending.hpp" +#include "greenlet_compiler_compat.hpp" +#include "TGreenletGlobals.cpp" +#include "TThreadState.hpp" +#include "TThreadStateCreator.hpp" + +namespace greenlet { + +extern "C" { + +struct ThreadState_DestroyNoGIL +{ + /** + This function uses the same lock that the PendingCallback does + */ + static void + MarkGreenletDeadAndQueueCleanup(ThreadState* const state) + { +#if GREENLET_BROKEN_THREAD_LOCAL_CLEANUP_JUST_LEAK + return; +#endif + // 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 (!MarkGreenletDeadIfNeeded(state)) { + // No state, or no greenlet + return; + } + + // XXX: 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; + } + + AddToCleanupQueue(state); + + } + +private: + + // If the state has an allocated main greenlet: + // - mark the greenlet as dead by disassociating it from the state; + // - return 1 + // Otherwise, return 0. + static bool + MarkGreenletDeadIfNeeded(ThreadState* const state) + { + 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().borrow()); + assert(p->pimpl->thread_state() == state || p->pimpl->thread_state() == nullptr); + dynamic_cast<MainGreenlet*>(p->pimpl)->thread_state(nullptr); + return true; + } + return false; + } + + static void + AddToCleanupQueue(ThreadState* const state) + { + assert(state && state->has_main_greenlet()); + + // 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 happened 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); + + 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. + + // A size greater than 1 means that we have already added the pending call, + // and in fact, it may be executing now. + // If it is executing, our lock makes sure that it will see the item we just added + // to the queue on its next iteration (after we release the lock) + // + // A size of 1 means there is no pending call, OR the pending call is + // currently executing, has dropped the lock, and is deleting the last item + // from the queue; its next iteration will go ahead and delete the item we just added. + // And the pending call we schedule here will have no work to do. + int result = AddPendingCall( + PendingCallback_DestroyQueueWithGIL, + nullptr); + 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 + PendingCallback_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(); + } + assert(to_destroy); + assert(to_destroy->has_main_greenlet()); + // Drop the lock while we do the actual deletion. + // This allows other calls to MarkGreenletDeadAndQueueCleanup + // to enter and add to our queue. + DestroyOneWithGIL(to_destroy); + } + return 0; + } + + static void + DestroyOneWithGIL(const ThreadState* const 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. + dynamic_cast<MainGreenlet*>(main->pimpl)->thread_state(nullptr); + + delete state; // Deleting this runs the destructor, DECREFs the main greenlet. + } + + // 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) + { + // If the interpreter is in the middle of finalizing, we can't add a + // pending call. Trying to do so will end up in a SIGSEGV, as + // Py_AddPendingCall will not be able to get the interpreter and will + // try to dereference a NULL pointer. It's possible this can still + // segfault if we happen to get context switched, and maybe we should + // just always implement our own AddPendingCall, but I'd like to see if + // this works first +#if GREENLET_PY313 + if (Py_IsFinalizing()) { +#else + if (_Py_IsFinalizing()) { +#endif +#ifdef GREENLET_DEBUG + // No need to log in the general case. Yes, we'll leak, + // but we're shutting down so it should be ok. + fprintf(stderr, + "greenlet: WARNING: Interpreter is finalizing. Ignoring " + "call to Py_AddPendingCall; \n"); +#endif + return 0; + } + return Py_AddPendingCall(func, arg); + } +#endif + + + + +}; +}; + +}; // 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::MarkGreenletDeadAndQueueCleanup> ThreadStateCreator; +static thread_local ThreadStateCreator g_thread_state_global; +#define GET_THREAD_STATE() g_thread_state_global + +#endif //T_THREADSTATE_DESTROY |