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Diffstat (limited to '.venv/lib/python3.12/site-packages/greenlet/TUserGreenlet.cpp')
| -rw-r--r-- | .venv/lib/python3.12/site-packages/greenlet/TUserGreenlet.cpp | 662 |
1 files changed, 662 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/greenlet/TUserGreenlet.cpp b/.venv/lib/python3.12/site-packages/greenlet/TUserGreenlet.cpp new file mode 100644 index 00000000..73a81330 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/greenlet/TUserGreenlet.cpp @@ -0,0 +1,662 @@ +/* -*- indent-tabs-mode: nil; tab-width: 4; -*- */ +/** + * Implementation of greenlet::UserGreenlet. + * + * 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_USER_GREENLET_CPP +#define T_USER_GREENLET_CPP + +#include "greenlet_internal.hpp" +#include "TGreenlet.hpp" + +#include "TThreadStateDestroy.cpp" + + +namespace greenlet { +using greenlet::refs::BorrowedMainGreenlet; +greenlet::PythonAllocator<UserGreenlet> UserGreenlet::allocator; + +void* UserGreenlet::operator new(size_t UNUSED(count)) +{ + return allocator.allocate(1); +} + + +void UserGreenlet::operator delete(void* ptr) +{ + return allocator.deallocate(static_cast<UserGreenlet*>(ptr), + 1); +} + + +UserGreenlet::UserGreenlet(PyGreenlet* p, BorrowedGreenlet the_parent) + : Greenlet(p), _parent(the_parent) +{ +} + +UserGreenlet::~UserGreenlet() +{ + // Python 3.11: If we don't clear out the raw frame datastack + // when deleting an unfinished greenlet, + // TestLeaks.test_untracked_memory_doesnt_increase_unfinished_thread_dealloc_in_main fails. + this->python_state.did_finish(nullptr); + this->tp_clear(); +} + + +const BorrowedMainGreenlet +UserGreenlet::main_greenlet() const +{ + return this->_main_greenlet; +} + + +BorrowedMainGreenlet +UserGreenlet::find_main_greenlet_in_lineage() const +{ + if (this->started()) { + assert(this->_main_greenlet); + return BorrowedMainGreenlet(this->_main_greenlet); + } + + if (!this->_parent) { + /* garbage collected greenlet in chain */ + // XXX: WHAT? + return BorrowedMainGreenlet(nullptr); + } + + return this->_parent->find_main_greenlet_in_lineage(); +} + + +/** + * CAUTION: This will allocate memory and may trigger garbage + * collection and arbitrary Python code. + */ +OwnedObject +UserGreenlet::throw_GreenletExit_during_dealloc(const ThreadState& current_thread_state) +{ + /* The dying greenlet cannot be a parent of ts_current + because the 'parent' field chain would hold a + reference */ + UserGreenlet::ParentIsCurrentGuard with_current_parent(this, current_thread_state); + + // We don't care about the return value, only whether an + // exception happened. Whether or not an exception happens, + // we need to restore the parent in case the greenlet gets + // resurrected. + return Greenlet::throw_GreenletExit_during_dealloc(current_thread_state); +} + +ThreadState* +UserGreenlet::thread_state() const noexcept +{ + // TODO: maybe make this throw, if the thread state isn't there? + // if (!this->main_greenlet) { + // throw std::runtime_error("No thread state"); // TODO: Better exception + // } + if (!this->_main_greenlet) { + return nullptr; + } + return this->_main_greenlet->thread_state(); +} + + +bool +UserGreenlet::was_running_in_dead_thread() const noexcept +{ + return this->_main_greenlet && !this->thread_state(); +} + +OwnedObject +UserGreenlet::g_switch() +{ + assert(this->args() || PyErr_Occurred()); + + try { + this->check_switch_allowed(); + } + catch (const PyErrOccurred&) { + this->release_args(); + throw; + } + + // Switching greenlets used to attempt to clean out ones that need + // deleted *if* we detected a thread switch. Should it still do + // that? + // An issue is that if we delete a greenlet from another thread, + // it gets queued to this thread, and ``kill_greenlet()`` switches + // back into the greenlet + + /* find the real target by ignoring dead greenlets, + and if necessary starting a greenlet. */ + switchstack_result_t err; + Greenlet* target = this; + // TODO: probably cleaner to handle the case where we do + // switch to ourself separately from the other cases. + // This can probably even further be simplified if we keep + // track of the switching_state we're going for and just call + // into g_switch() if it's not ourself. The main problem with that + // is that we would be using more stack space. + bool target_was_me = true; + bool was_initial_stub = false; + while (target) { + if (target->active()) { + if (!target_was_me) { + target->args() <<= this->args(); + assert(!this->args()); + } + err = target->g_switchstack(); + break; + } + if (!target->started()) { + // We never encounter a main greenlet that's not started. + assert(!target->main()); + UserGreenlet* real_target = static_cast<UserGreenlet*>(target); + assert(real_target); + void* dummymarker; + was_initial_stub = true; + if (!target_was_me) { + target->args() <<= this->args(); + assert(!this->args()); + } + try { + // This can only throw back to us while we're + // still in this greenlet. Once the new greenlet + // is bootstrapped, it has its own exception state. + err = real_target->g_initialstub(&dummymarker); + } + catch (const PyErrOccurred&) { + this->release_args(); + throw; + } + catch (const GreenletStartedWhileInPython&) { + // The greenlet was started sometime before this + // greenlet actually switched to it, i.e., + // "concurrent" calls to switch() or throw(). + // We need to retry the switch. + // Note that the current greenlet has been reset + // to this one (or we wouldn't be running!) + continue; + } + break; + } + + target = target->parent(); + target_was_me = false; + } + // The ``this`` pointer and all other stack or register based + // variables are invalid now, at least where things succeed + // above. + // But this one, probably not so much? It's not clear if it's + // safe to throw an exception at this point. + + if (err.status < 0) { + // If we get here, either g_initialstub() + // failed, or g_switchstack() failed. Either one of those + // cases SHOULD leave us in the original greenlet with a valid + // stack. + return this->on_switchstack_or_initialstub_failure(target, err, target_was_me, was_initial_stub); + } + + // err.the_new_current_greenlet would be the same as ``target``, + // if target wasn't probably corrupt. + return err.the_new_current_greenlet->g_switch_finish(err); +} + + + +Greenlet::switchstack_result_t +UserGreenlet::g_initialstub(void* mark) +{ + OwnedObject run; + + // We need to grab a reference to the current switch arguments + // in case we're entered concurrently during the call to + // GetAttr() and have to try again. + // We'll restore them when we return in that case. + // Scope them tightly to avoid ref leaks. + { + SwitchingArgs args(this->args()); + + /* save exception in case getattr clears it */ + PyErrPieces saved; + + /* + self.run is the object to call in the new greenlet. + This could run arbitrary python code and switch greenlets! + */ + run = this->self().PyRequireAttr(mod_globs->str_run); + /* restore saved exception */ + saved.PyErrRestore(); + + + /* recheck that it's safe to switch in case greenlet reparented anywhere above */ + this->check_switch_allowed(); + + /* by the time we got here another start could happen elsewhere, + * that means it should now be a regular switch. + * This can happen if the Python code is a subclass that implements + * __getattribute__ or __getattr__, or makes ``run`` a descriptor; + * all of those can run arbitrary code that switches back into + * this greenlet. + */ + if (this->stack_state.started()) { + // the successful switch cleared these out, we need to + // restore our version. They will be copied on up to the + // next target. + assert(!this->args()); + this->args() <<= args; + throw GreenletStartedWhileInPython(); + } + } + + // Sweet, if we got here, we have the go-ahead and will switch + // greenlets. + // Nothing we do from here on out should allow for a thread or + // greenlet switch: No arbitrary calls to Python, including + // decref'ing + +#if GREENLET_USE_CFRAME + /* OK, we need it, we're about to switch greenlets, save the state. */ + /* + See green_new(). This is a stack-allocated variable used + while *self* is in PyObject_Call(). + We want to defer copying the state info until we're sure + we need it and are in a stable place to do so. + */ + _PyCFrame trace_info; + + this->python_state.set_new_cframe(trace_info); +#endif + /* start the greenlet */ + ThreadState& thread_state = GET_THREAD_STATE().state(); + this->stack_state = StackState(mark, + thread_state.borrow_current()->stack_state); + this->python_state.set_initial_state(PyThreadState_GET()); + this->exception_state.clear(); + this->_main_greenlet = thread_state.get_main_greenlet(); + + /* perform the initial switch */ + switchstack_result_t err = this->g_switchstack(); + /* returns twice! + The 1st time with ``err == 1``: we are in the new greenlet. + This one owns a greenlet that used to be current. + The 2nd time with ``err <= 0``: back in the caller's + greenlet; this happens if the child finishes or switches + explicitly to us. Either way, the ``err`` variable is + created twice at the same memory location, but possibly + having different ``origin`` values. Note that it's not + constructed for the second time until the switch actually happens. + */ + if (err.status == 1) { + // In the new greenlet. + + // This never returns! Calling inner_bootstrap steals + // the contents of our run object within this stack frame, so + // it is not valid to do anything with it. + try { + this->inner_bootstrap(err.origin_greenlet.relinquish_ownership(), + run.relinquish_ownership()); + } + // Getting a C++ exception here isn't good. It's probably a + // bug in the underlying greenlet, meaning it's probably a + // C++ extension. We're going to abort anyway, but try to + // display some nice information *if* possible. Some obscure + // platforms don't properly support this (old 32-bit Arm, see see + // https://github.com/python-greenlet/greenlet/issues/385); that's not + // great, but should usually be OK because, as mentioned above, we're + // terminating anyway. + // + // The catching is tested by + // ``test_cpp.CPPTests.test_unhandled_exception_in_greenlet_aborts``. + // + // PyErrOccurred can theoretically be thrown by + // inner_bootstrap() -> g_switch_finish(), but that should + // never make it back to here. It is a std::exception and + // would be caught if it is. + catch (const std::exception& e) { + std::string base = "greenlet: Unhandled C++ exception: "; + base += e.what(); + Py_FatalError(base.c_str()); + } + catch (...) { + // Some compilers/runtimes use exceptions internally. + // It appears that GCC on Linux with libstdc++ throws an + // exception internally at process shutdown time to unwind + // stacks and clean up resources. Depending on exactly + // where we are when the process exits, that could result + // in an unknown exception getting here. If we + // Py_FatalError() or abort() here, we interfere with + // orderly process shutdown. Throwing the exception on up + // is the right thing to do. + // + // gevent's ``examples/dns_mass_resolve.py`` demonstrates this. +#ifndef NDEBUG + fprintf(stderr, + "greenlet: inner_bootstrap threw unknown exception; " + "is the process terminating?\n"); +#endif + throw; + } + Py_FatalError("greenlet: inner_bootstrap returned with no exception.\n"); + } + + + // In contrast, notice that we're keeping the origin greenlet + // around as an owned reference; we need it to call the trace + // function for the switch back into the parent. It was only + // captured at the time the switch actually happened, though, + // so we haven't been keeping an extra reference around this + // whole time. + + /* back in the parent */ + if (err.status < 0) { + /* start failed badly, restore greenlet state */ + this->stack_state = StackState(); + this->_main_greenlet.CLEAR(); + // CAUTION: This may run arbitrary Python code. + run.CLEAR(); // inner_bootstrap didn't run, we own the reference. + } + + // In the success case, the spawned code (inner_bootstrap) will + // take care of decrefing this, so we relinquish ownership so as + // to not double-decref. + + run.relinquish_ownership(); + + return err; +} + + +void +UserGreenlet::inner_bootstrap(PyGreenlet* origin_greenlet, PyObject* run) +{ + // The arguments here would be another great place for move. + // As it is, we take them as a reference so that when we clear + // them we clear what's on the stack above us. Do that NOW, and + // without using a C++ RAII object, + // so there's no way that exiting the parent frame can clear it, + // or we clear it unexpectedly. This arises in the context of the + // interpreter shutting down. See https://github.com/python-greenlet/greenlet/issues/325 + //PyObject* run = _run.relinquish_ownership(); + + /* in the new greenlet */ + assert(this->thread_state()->borrow_current() == BorrowedGreenlet(this->_self)); + // C++ exceptions cannot propagate to the parent greenlet from + // here. (TODO: Do we need a catch(...) clause, perhaps on the + // function itself? ALl we could do is terminate the program.) + // NOTE: On 32-bit Windows, the call chain is extremely + // important here in ways that are subtle, having to do with + // the depth of the SEH list. The call to restore it MUST NOT + // add a new SEH handler to the list, or we'll restore it to + // the wrong thing. + this->thread_state()->restore_exception_state(); + /* stack variables from above are no good and also will not unwind! */ + // EXCEPT: That can't be true, we access run, among others, here. + + this->stack_state.set_active(); /* running */ + + // We're about to possibly run Python code again, which + // could switch back/away to/from us, so we need to grab the + // arguments locally. + SwitchingArgs args; + args <<= this->args(); + assert(!this->args()); + + // XXX: We could clear this much earlier, right? + // Or would that introduce the possibility of running Python + // code when we don't want to? + // CAUTION: This may run arbitrary Python code. + this->_run_callable.CLEAR(); + + + // The first switch we need to manually call the trace + // function here instead of in g_switch_finish, because we + // never return there. + if (OwnedObject tracefunc = this->thread_state()->get_tracefunc()) { + OwnedGreenlet trace_origin; + trace_origin = origin_greenlet; + try { + g_calltrace(tracefunc, + args ? mod_globs->event_switch : mod_globs->event_throw, + trace_origin, + this->_self); + } + catch (const PyErrOccurred&) { + /* Turn trace errors into switch throws */ + args.CLEAR(); + } + } + + // We no longer need the origin, it was only here for + // tracing. + // We may never actually exit this stack frame so we need + // to explicitly clear it. + // This could run Python code and switch. + Py_CLEAR(origin_greenlet); + + OwnedObject result; + if (!args) { + /* pending exception */ + result = NULL; + } + else { + /* call g.run(*args, **kwargs) */ + // This could result in further switches + try { + //result = run.PyCall(args.args(), args.kwargs()); + // CAUTION: Just invoking this, before the function even + // runs, may cause memory allocations, which may trigger + // GC, which may run arbitrary Python code. + result = OwnedObject::consuming(PyObject_Call(run, args.args().borrow(), args.kwargs().borrow())); + } + catch (...) { + // Unhandled C++ exception! + + // If we declare ourselves as noexcept, if we don't catch + // this here, most platforms will just abort() the + // process. But on 64-bit Windows with older versions of + // the C runtime, this can actually corrupt memory and + // just return. We see this when compiling with the + // Windows 7.0 SDK targeting Windows Server 2008, but not + // when using the Appveyor Visual Studio 2019 image. So + // this currently only affects Python 2.7 on Windows 64. + // That is, the tests pass and the runtime aborts + // everywhere else. + // + // However, if we catch it and try to continue with a + // Python error, then all Windows 64 bit platforms corrupt + // memory. So all we can do is manually abort, hopefully + // with a good error message. (Note that the above was + // tested WITHOUT the `/EHr` switch being used at compile + // time, so MSVC may have "optimized" out important + // checking. Using that switch, we may be in a better + // place in terms of memory corruption.) But sometimes it + // can't be caught here at all, which is confusing but not + // terribly surprising; so again, the G_NOEXCEPT_WIN32 + // plus "/EHr". + // + // Hopefully the basic C stdlib is still functional enough + // for us to at least print an error. + // + // It gets more complicated than that, though, on some + // platforms, specifically at least Linux/gcc/libstdc++. They use + // an exception to unwind the stack when a background + // thread exits. (See comments about noexcept.) So this + // may not actually represent anything untoward. On those + // platforms we allow throws of this to propagate, or + // attempt to anyway. +# if defined(WIN32) || defined(_WIN32) + Py_FatalError( + "greenlet: Unhandled C++ exception from a greenlet run function. " + "Because memory is likely corrupted, terminating process."); + std::abort(); +#else + throw; +#endif + } + } + // These lines may run arbitrary code + args.CLEAR(); + Py_CLEAR(run); + + if (!result + && mod_globs->PyExc_GreenletExit.PyExceptionMatches() + && (this->args())) { + // This can happen, for example, if our only reference + // goes away after we switch back to the parent. + // See test_dealloc_switch_args_not_lost + PyErrPieces clear_error; + result <<= this->args(); + result = single_result(result); + } + this->release_args(); + this->python_state.did_finish(PyThreadState_GET()); + + result = g_handle_exit(result); + assert(this->thread_state()->borrow_current() == this->_self); + + /* jump back to parent */ + this->stack_state.set_inactive(); /* dead */ + + + // TODO: Can we decref some things here? Release our main greenlet + // and maybe parent? + for (Greenlet* parent = this->_parent; + parent; + parent = parent->parent()) { + // We need to somewhere consume a reference to + // the result; in most cases we'll never have control + // back in this stack frame again. Calling + // green_switch actually adds another reference! + // This would probably be clearer with a specific API + // to hand results to the parent. + parent->args() <<= result; + assert(!result); + // The parent greenlet now owns the result; in the + // typical case we'll never get back here to assign to + // result and thus release the reference. + try { + result = parent->g_switch(); + } + catch (const PyErrOccurred&) { + // Ignore, keep passing the error on up. + } + + /* Return here means switch to parent failed, + * in which case we throw *current* exception + * to the next parent in chain. + */ + assert(!result); + } + /* We ran out of parents, cannot continue */ + PyErr_WriteUnraisable(this->self().borrow_o()); + Py_FatalError("greenlet: ran out of parent greenlets while propagating exception; " + "cannot continue"); + std::abort(); +} + +void +UserGreenlet::run(const BorrowedObject nrun) +{ + if (this->started()) { + throw AttributeError( + "run cannot be set " + "after the start of the greenlet"); + } + this->_run_callable = nrun; +} + +const OwnedGreenlet +UserGreenlet::parent() const +{ + return this->_parent; +} + +void +UserGreenlet::parent(const BorrowedObject raw_new_parent) +{ + if (!raw_new_parent) { + throw AttributeError("can't delete attribute"); + } + + BorrowedMainGreenlet main_greenlet_of_new_parent; + BorrowedGreenlet new_parent(raw_new_parent.borrow()); // could + // throw + // TypeError! + for (BorrowedGreenlet p = new_parent; p; p = p->parent()) { + if (p == this->self()) { + throw ValueError("cyclic parent chain"); + } + main_greenlet_of_new_parent = p->main_greenlet(); + } + + if (!main_greenlet_of_new_parent) { + throw ValueError("parent must not be garbage collected"); + } + + if (this->started() + && this->_main_greenlet != main_greenlet_of_new_parent) { + throw ValueError("parent cannot be on a different thread"); + } + + this->_parent = new_parent; +} + +void +UserGreenlet::murder_in_place() +{ + this->_main_greenlet.CLEAR(); + Greenlet::murder_in_place(); +} + +bool +UserGreenlet::belongs_to_thread(const ThreadState* thread_state) const +{ + return Greenlet::belongs_to_thread(thread_state) && this->_main_greenlet == thread_state->borrow_main_greenlet(); +} + + +int +UserGreenlet::tp_traverse(visitproc visit, void* arg) +{ + Py_VISIT(this->_parent.borrow_o()); + Py_VISIT(this->_main_greenlet.borrow_o()); + Py_VISIT(this->_run_callable.borrow_o()); + + return Greenlet::tp_traverse(visit, arg); +} + +int +UserGreenlet::tp_clear() +{ + Greenlet::tp_clear(); + this->_parent.CLEAR(); + this->_main_greenlet.CLEAR(); + this->_run_callable.CLEAR(); + return 0; +} + +UserGreenlet::ParentIsCurrentGuard::ParentIsCurrentGuard(UserGreenlet* p, + const ThreadState& thread_state) + : oldparent(p->_parent), + greenlet(p) +{ + p->_parent = thread_state.get_current(); +} + +UserGreenlet::ParentIsCurrentGuard::~ParentIsCurrentGuard() +{ + this->greenlet->_parent = oldparent; + oldparent.CLEAR(); +} + +}; //namespace greenlet +#endif |