90 lines
2.5 KiB
C++
90 lines
2.5 KiB
C++
#ifndef GREENLET_ALLOCATOR_HPP
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#define GREENLET_ALLOCATOR_HPP
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#define PY_SSIZE_T_CLEAN
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#include <Python.h>
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#include <memory>
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#include "greenlet_compiler_compat.hpp"
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#include "greenlet_cpython_compat.hpp"
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namespace greenlet
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{
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#if defined(Py_GIL_DISABLED)
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// Python on free threaded builds says this
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// (https://docs.python.org/3/howto/free-threading-extensions.html#memory-allocation-apis):
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//
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// For thread-safety, the free-threaded build requires that only
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// Python objects are allocated using the object domain, and that all
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// Python object are allocated using that domain.
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//
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// This turns out to be important because the GC implementation on
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// free threaded Python uses internal mimalloc APIs to find allocated
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// objects. If we allocate non-PyObject objects using that API, then
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// Bad Things could happen, including crashes and improper results.
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// So in that case, we revert to standard C++ allocation.
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template <class T>
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struct PythonAllocator : public std::allocator<T> {
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// This member is deprecated in C++17 and removed in C++20
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template< class U >
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struct rebind {
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typedef PythonAllocator<U> other;
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};
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};
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#else
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// This allocator is stateless; all instances are identical.
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// It can *ONLY* be used when we're sure we're holding the GIL
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// (Python's allocators require the GIL).
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template <class T>
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struct PythonAllocator : public std::allocator<T> {
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PythonAllocator(const PythonAllocator& UNUSED(other))
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: std::allocator<T>()
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{
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}
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PythonAllocator(const std::allocator<T> other)
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: std::allocator<T>(other)
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{}
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template <class U>
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PythonAllocator(const std::allocator<U>& other)
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: std::allocator<T>(other)
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{
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}
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PythonAllocator() : std::allocator<T>() {}
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T* allocate(size_t number_objects, const void* UNUSED(hint)=0)
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{
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void* p;
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if (number_objects == 1)
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p = PyObject_Malloc(sizeof(T));
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else
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p = PyMem_Malloc(sizeof(T) * number_objects);
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return static_cast<T*>(p);
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}
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void deallocate(T* t, size_t n)
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{
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void* p = t;
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if (n == 1) {
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PyObject_Free(p);
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}
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else
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PyMem_Free(p);
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}
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// This member is deprecated in C++17 and removed in C++20
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template< class U >
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struct rebind {
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typedef PythonAllocator<U> other;
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};
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};
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#endif // allocator type
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}
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#endif
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