103 lines
2.5 KiB
C++
103 lines
2.5 KiB
C++
#ifndef GREENLET_THREAD_STATE_CREATOR_HPP
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#define GREENLET_THREAD_STATE_CREATOR_HPP
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#include <ctime>
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#include <stdexcept>
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#include "greenlet_internal.hpp"
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#include "greenlet_refs.hpp"
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#include "greenlet_thread_support.hpp"
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#include "TThreadState.hpp"
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namespace greenlet {
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typedef void (*ThreadStateDestructor)(ThreadState* const);
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template<ThreadStateDestructor Destructor>
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class ThreadStateCreator
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{
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private:
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// Initialized to 1, and, if still 1, created on access.
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// Set to 0 on destruction.
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ThreadState* _state;
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G_NO_COPIES_OF_CLS(ThreadStateCreator);
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inline bool has_initialized_state() const noexcept
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{
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return this->_state != (ThreadState*)1;
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}
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inline bool has_state() const noexcept
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{
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return this->has_initialized_state() && this->_state != nullptr;
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}
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public:
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// Only one of these, auto created per thread.
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// Constructing the state constructs the MainGreenlet.
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ThreadStateCreator() :
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_state((ThreadState*)1)
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{
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}
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~ThreadStateCreator()
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{
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if (this->has_state()) {
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Destructor(this->_state);
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}
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this->_state = nullptr;
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}
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inline ThreadState& state()
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{
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// The main greenlet will own this pointer when it is created,
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// which will be right after this. The plan is to give every
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// greenlet a pointer to the main greenlet for the thread it
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// runs in; if we are doing something cross-thread, we need to
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// access the pointer from the main greenlet. Deleting the
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// thread, and hence the thread-local storage, will delete the
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// state pointer in the main greenlet.
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if (!this->has_initialized_state()) {
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// XXX: Assuming allocation never fails
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this->_state = new ThreadState;
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// For non-standard threading, we need to store an object
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// in the Python thread state dictionary so that it can be
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// DECREF'd when the thread ends (ideally; the dict could
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// last longer) and clean this object up.
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}
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if (!this->_state) {
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throw std::runtime_error("Accessing state after destruction.");
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}
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return *this->_state;
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}
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operator ThreadState&()
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{
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return this->state();
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}
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operator ThreadState*()
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{
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return &this->state();
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}
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inline int tp_traverse(visitproc visit, void* arg)
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{
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if (this->has_state()) {
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return this->_state->tp_traverse(visit, arg);
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}
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return 0;
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}
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};
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}; // namespace greenlet
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#endif
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