forked from KolibriOS/kolibrios
492 lines
16 KiB
C++
492 lines
16 KiB
C++
/*
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* Copyright (c) 1996
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* Silicon Graphics Computer Systems, Inc.
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Silicon Graphics makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*/
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#ifndef _CPP_BITS_PTHREAD_ALLOCIMPL_H
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#define _CPP_BITS_PTHREAD_ALLOCIMPL_H 1
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// Pthread-specific node allocator.
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// This is similar to the default allocator, except that free-list
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// information is kept separately for each thread, avoiding locking.
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// This should be reasonably fast even in the presence of threads.
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// The down side is that storage may not be well-utilized.
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// It is not an error to allocate memory in thread A and deallocate
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// it in thread B. But this effectively transfers ownership of the memory,
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// so that it can only be reallocated by thread B. Thus this can effectively
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// result in a storage leak if it's done on a regular basis.
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// It can also result in frequent sharing of
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// cache lines among processors, with potentially serious performance
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// consequences.
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#include <bits/c++config.h>
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#include <bits/std_cerrno.h>
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#include <bits/stl_alloc.h>
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#ifndef __RESTRICT
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# define __RESTRICT
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#endif
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#include <new>
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namespace std
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{
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#define __STL_DATA_ALIGNMENT 8
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union _Pthread_alloc_obj {
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union _Pthread_alloc_obj * __free_list_link;
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char __client_data[__STL_DATA_ALIGNMENT]; /* The client sees this. */
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};
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// Pthread allocators don't appear to the client to have meaningful
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// instances. We do in fact need to associate some state with each
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// thread. That state is represented by
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// _Pthread_alloc_per_thread_state<_Max_size>.
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template<size_t _Max_size>
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struct _Pthread_alloc_per_thread_state {
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typedef _Pthread_alloc_obj __obj;
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enum { _S_NFREELISTS = _Max_size/__STL_DATA_ALIGNMENT };
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_Pthread_alloc_obj* volatile __free_list[_S_NFREELISTS];
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_Pthread_alloc_per_thread_state<_Max_size> * __next;
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// Free list link for list of available per thread structures.
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// When one of these becomes available for reuse due to thread
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// termination, any objects in its free list remain associated
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// with it. The whole structure may then be used by a newly
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// created thread.
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_Pthread_alloc_per_thread_state() : __next(0)
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{
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memset((void *)__free_list, 0, (size_t) _S_NFREELISTS * sizeof(__obj *));
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}
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// Returns an object of size __n, and possibly adds to size n free list.
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void *_M_refill(size_t __n);
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};
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// Pthread-specific allocator.
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// The argument specifies the largest object size allocated from per-thread
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// free lists. Larger objects are allocated using malloc_alloc.
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// Max_size must be a power of 2.
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template <size_t _Max_size = 128>
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class _Pthread_alloc_template {
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public: // but only for internal use:
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typedef _Pthread_alloc_obj __obj;
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// Allocates a chunk for nobjs of size size. nobjs may be reduced
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// if it is inconvenient to allocate the requested number.
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static char *_S_chunk_alloc(size_t __size, int &__nobjs);
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enum {_S_ALIGN = __STL_DATA_ALIGNMENT};
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static size_t _S_round_up(size_t __bytes) {
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return (((__bytes) + (int) _S_ALIGN-1) & ~((int) _S_ALIGN - 1));
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}
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static size_t _S_freelist_index(size_t __bytes) {
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return (((__bytes) + (int) _S_ALIGN-1)/(int)_S_ALIGN - 1);
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}
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private:
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// Chunk allocation state. And other shared state.
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// Protected by _S_chunk_allocator_lock.
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static pthread_mutex_t _S_chunk_allocator_lock;
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static char *_S_start_free;
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static char *_S_end_free;
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static size_t _S_heap_size;
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static _Pthread_alloc_per_thread_state<_Max_size>* _S_free_per_thread_states;
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static pthread_key_t _S_key;
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static bool _S_key_initialized;
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// Pthread key under which per thread state is stored.
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// Allocator instances that are currently unclaimed by any thread.
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static void _S_destructor(void *instance);
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// Function to be called on thread exit to reclaim per thread
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// state.
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static _Pthread_alloc_per_thread_state<_Max_size> *_S_new_per_thread_state();
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// Return a recycled or new per thread state.
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static _Pthread_alloc_per_thread_state<_Max_size> *_S_get_per_thread_state();
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// ensure that the current thread has an associated
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// per thread state.
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class _M_lock;
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friend class _M_lock;
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class _M_lock {
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public:
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_M_lock () { pthread_mutex_lock(&_S_chunk_allocator_lock); }
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~_M_lock () { pthread_mutex_unlock(&_S_chunk_allocator_lock); }
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};
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public:
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/* n must be > 0 */
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static void * allocate(size_t __n)
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{
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__obj * volatile * __my_free_list;
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__obj * __RESTRICT __result;
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_Pthread_alloc_per_thread_state<_Max_size>* __a;
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if (__n > _Max_size) {
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return(malloc_alloc::allocate(__n));
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}
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if (!_S_key_initialized ||
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!(__a = (_Pthread_alloc_per_thread_state<_Max_size>*)
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pthread_getspecific(_S_key))) {
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__a = _S_get_per_thread_state();
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}
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__my_free_list = __a -> __free_list + _S_freelist_index(__n);
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__result = *__my_free_list;
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if (__result == 0) {
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void *__r = __a -> _M_refill(_S_round_up(__n));
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return __r;
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}
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*__my_free_list = __result -> __free_list_link;
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return (__result);
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};
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/* p may not be 0 */
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static void deallocate(void *__p, size_t __n)
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{
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__obj *__q = (__obj *)__p;
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__obj * volatile * __my_free_list;
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_Pthread_alloc_per_thread_state<_Max_size>* __a;
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if (__n > _Max_size) {
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malloc_alloc::deallocate(__p, __n);
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return;
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}
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if (!_S_key_initialized ||
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!(__a = (_Pthread_alloc_per_thread_state<_Max_size> *)
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pthread_getspecific(_S_key))) {
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__a = _S_get_per_thread_state();
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}
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__my_free_list = __a->__free_list + _S_freelist_index(__n);
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__q -> __free_list_link = *__my_free_list;
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*__my_free_list = __q;
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}
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static void * reallocate(void *__p, size_t __old_sz, size_t __new_sz);
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} ;
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typedef _Pthread_alloc_template<> pthread_alloc;
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template <size_t _Max_size>
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void _Pthread_alloc_template<_Max_size>::_S_destructor(void * __instance)
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{
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_M_lock __lock_instance; // Need to acquire lock here.
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_Pthread_alloc_per_thread_state<_Max_size>* __s =
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(_Pthread_alloc_per_thread_state<_Max_size> *)__instance;
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__s -> __next = _S_free_per_thread_states;
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_S_free_per_thread_states = __s;
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}
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template <size_t _Max_size>
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_Pthread_alloc_per_thread_state<_Max_size> *
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_Pthread_alloc_template<_Max_size>::_S_new_per_thread_state()
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{
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/* lock already held here. */
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if (0 != _S_free_per_thread_states) {
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_Pthread_alloc_per_thread_state<_Max_size> *__result =
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_S_free_per_thread_states;
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_S_free_per_thread_states = _S_free_per_thread_states -> __next;
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return __result;
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} else {
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return new _Pthread_alloc_per_thread_state<_Max_size>;
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}
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}
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template <size_t _Max_size>
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_Pthread_alloc_per_thread_state<_Max_size> *
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_Pthread_alloc_template<_Max_size>::_S_get_per_thread_state()
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{
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/*REFERENCED*/
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_M_lock __lock_instance; // Need to acquire lock here.
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int __ret_code;
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_Pthread_alloc_per_thread_state<_Max_size> * __result;
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if (!_S_key_initialized) {
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if (pthread_key_create(&_S_key, _S_destructor)) {
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std::__throw_bad_alloc(); // defined in funcexcept.h
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}
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_S_key_initialized = true;
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}
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__result = _S_new_per_thread_state();
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__ret_code = pthread_setspecific(_S_key, __result);
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if (__ret_code) {
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if (__ret_code == ENOMEM) {
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std::__throw_bad_alloc();
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} else {
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// EINVAL
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abort();
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}
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}
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return __result;
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}
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/* We allocate memory in large chunks in order to avoid fragmenting */
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/* the malloc heap too much. */
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/* We assume that size is properly aligned. */
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template <size_t _Max_size>
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char *_Pthread_alloc_template<_Max_size>
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::_S_chunk_alloc(size_t __size, int &__nobjs)
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{
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{
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char * __result;
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size_t __total_bytes;
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size_t __bytes_left;
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/*REFERENCED*/
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_M_lock __lock_instance; // Acquire lock for this routine
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__total_bytes = __size * __nobjs;
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__bytes_left = _S_end_free - _S_start_free;
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if (__bytes_left >= __total_bytes) {
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__result = _S_start_free;
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_S_start_free += __total_bytes;
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return(__result);
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} else if (__bytes_left >= __size) {
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__nobjs = __bytes_left/__size;
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__total_bytes = __size * __nobjs;
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__result = _S_start_free;
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_S_start_free += __total_bytes;
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return(__result);
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} else {
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size_t __bytes_to_get =
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2 * __total_bytes + _S_round_up(_S_heap_size >> 4);
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// Try to make use of the left-over piece.
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if (__bytes_left > 0) {
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_Pthread_alloc_per_thread_state<_Max_size>* __a =
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(_Pthread_alloc_per_thread_state<_Max_size>*)
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pthread_getspecific(_S_key);
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__obj * volatile * __my_free_list =
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__a->__free_list + _S_freelist_index(__bytes_left);
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((__obj *)_S_start_free) -> __free_list_link = *__my_free_list;
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*__my_free_list = (__obj *)_S_start_free;
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}
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# ifdef _SGI_SOURCE
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// Try to get memory that's aligned on something like a
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// cache line boundary, so as to avoid parceling out
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// parts of the same line to different threads and thus
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// possibly different processors.
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{
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const int __cache_line_size = 128; // probable upper bound
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__bytes_to_get &= ~(__cache_line_size-1);
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_S_start_free = (char *)memalign(__cache_line_size, __bytes_to_get);
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if (0 == _S_start_free) {
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_S_start_free = (char *)malloc_alloc::allocate(__bytes_to_get);
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}
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}
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# else /* !SGI_SOURCE */
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_S_start_free = (char *)malloc_alloc::allocate(__bytes_to_get);
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# endif
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_S_heap_size += __bytes_to_get;
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_S_end_free = _S_start_free + __bytes_to_get;
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}
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}
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// lock is released here
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return(_S_chunk_alloc(__size, __nobjs));
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}
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/* Returns an object of size n, and optionally adds to size n free list.*/
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/* We assume that n is properly aligned. */
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/* We hold the allocation lock. */
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template <size_t _Max_size>
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void *_Pthread_alloc_per_thread_state<_Max_size>
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::_M_refill(size_t __n)
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{
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int __nobjs = 128;
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char * __chunk =
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_Pthread_alloc_template<_Max_size>::_S_chunk_alloc(__n, __nobjs);
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__obj * volatile * __my_free_list;
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__obj * __result;
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__obj * __current_obj, * __next_obj;
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int __i;
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if (1 == __nobjs) {
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return(__chunk);
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}
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__my_free_list = __free_list
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+ _Pthread_alloc_template<_Max_size>::_S_freelist_index(__n);
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/* Build free list in chunk */
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__result = (__obj *)__chunk;
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*__my_free_list = __next_obj = (__obj *)(__chunk + __n);
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for (__i = 1; ; __i++) {
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__current_obj = __next_obj;
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__next_obj = (__obj *)((char *)__next_obj + __n);
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if (__nobjs - 1 == __i) {
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__current_obj -> __free_list_link = 0;
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break;
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} else {
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__current_obj -> __free_list_link = __next_obj;
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}
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}
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return(__result);
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}
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template <size_t _Max_size>
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void *_Pthread_alloc_template<_Max_size>
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::reallocate(void *__p, size_t __old_sz, size_t __new_sz)
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{
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void * __result;
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size_t __copy_sz;
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if (__old_sz > _Max_size
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&& __new_sz > _Max_size) {
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return(realloc(__p, __new_sz));
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}
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if (_S_round_up(__old_sz) == _S_round_up(__new_sz)) return(__p);
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__result = allocate(__new_sz);
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__copy_sz = __new_sz > __old_sz? __old_sz : __new_sz;
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memcpy(__result, __p, __copy_sz);
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deallocate(__p, __old_sz);
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return(__result);
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}
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template <size_t _Max_size>
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_Pthread_alloc_per_thread_state<_Max_size> *
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_Pthread_alloc_template<_Max_size>::_S_free_per_thread_states = 0;
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template <size_t _Max_size>
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pthread_key_t _Pthread_alloc_template<_Max_size>::_S_key;
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template <size_t _Max_size>
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bool _Pthread_alloc_template<_Max_size>::_S_key_initialized = false;
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template <size_t _Max_size>
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pthread_mutex_t _Pthread_alloc_template<_Max_size>::_S_chunk_allocator_lock
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= PTHREAD_MUTEX_INITIALIZER;
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template <size_t _Max_size>
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char *_Pthread_alloc_template<_Max_size>
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::_S_start_free = 0;
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template <size_t _Max_size>
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char *_Pthread_alloc_template<_Max_size>
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::_S_end_free = 0;
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template <size_t _Max_size>
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size_t _Pthread_alloc_template<_Max_size>
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::_S_heap_size = 0;
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template <class _Tp>
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class pthread_allocator {
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typedef pthread_alloc _S_Alloc; // The underlying allocator.
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public:
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typedef size_t size_type;
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typedef ptrdiff_t difference_type;
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typedef _Tp* pointer;
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typedef const _Tp* const_pointer;
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typedef _Tp& reference;
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typedef const _Tp& const_reference;
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typedef _Tp value_type;
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template <class _NewType> struct rebind {
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typedef pthread_allocator<_NewType> other;
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};
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pthread_allocator() __STL_NOTHROW {}
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pthread_allocator(const pthread_allocator& a) __STL_NOTHROW {}
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template <class _OtherType>
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pthread_allocator(const pthread_allocator<_OtherType>&)
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__STL_NOTHROW {}
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~pthread_allocator() __STL_NOTHROW {}
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pointer address(reference __x) const { return &__x; }
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const_pointer address(const_reference __x) const { return &__x; }
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// __n is permitted to be 0. The C++ standard says nothing about what
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// the return value is when __n == 0.
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_Tp* allocate(size_type __n, const void* = 0) {
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return __n != 0 ? static_cast<_Tp*>(_S_Alloc::allocate(__n * sizeof(_Tp)))
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: 0;
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}
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// p is not permitted to be a null pointer.
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void deallocate(pointer __p, size_type __n)
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{ _S_Alloc::deallocate(__p, __n * sizeof(_Tp)); }
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size_type max_size() const __STL_NOTHROW
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{ return size_t(-1) / sizeof(_Tp); }
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void construct(pointer __p, const _Tp& __val) { new(__p) _Tp(__val); }
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void destroy(pointer _p) { _p->~_Tp(); }
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};
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template<>
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class pthread_allocator<void> {
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public:
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typedef size_t size_type;
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typedef ptrdiff_t difference_type;
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typedef void* pointer;
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typedef const void* const_pointer;
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typedef void value_type;
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template <class _NewType> struct rebind {
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typedef pthread_allocator<_NewType> other;
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};
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};
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template <size_t _Max_size>
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inline bool operator==(const _Pthread_alloc_template<_Max_size>&,
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const _Pthread_alloc_template<_Max_size>&)
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{
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return true;
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}
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template <class _T1, class _T2>
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inline bool operator==(const pthread_allocator<_T1>&,
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const pthread_allocator<_T2>& a2)
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{
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return true;
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}
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template <class _T1, class _T2>
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inline bool operator!=(const pthread_allocator<_T1>&,
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const pthread_allocator<_T2>&)
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{
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return false;
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}
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template <class _Tp, size_t _Max_size>
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struct _Alloc_traits<_Tp, _Pthread_alloc_template<_Max_size> >
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{
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static const bool _S_instanceless = true;
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typedef simple_alloc<_Tp, _Pthread_alloc_template<_Max_size> > _Alloc_type;
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typedef __allocator<_Tp, _Pthread_alloc_template<_Max_size> >
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allocator_type;
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};
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template <class _Tp, class _Atype, size_t _Max>
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struct _Alloc_traits<_Tp, __allocator<_Atype, _Pthread_alloc_template<_Max> > >
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{
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static const bool _S_instanceless = true;
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typedef simple_alloc<_Tp, _Pthread_alloc_template<_Max> > _Alloc_type;
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typedef __allocator<_Tp, _Pthread_alloc_template<_Max> > allocator_type;
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};
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template <class _Tp, class _Atype>
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struct _Alloc_traits<_Tp, pthread_allocator<_Atype> >
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{
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static const bool _S_instanceless = true;
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typedef simple_alloc<_Tp, _Pthread_alloc_template<> > _Alloc_type;
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typedef pthread_allocator<_Tp> allocator_type;
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};
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} // namespace std
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#endif /* _CPP_BITS_PTHREAD_ALLOCIMPL_H */
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// Local Variables:
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// mode:C++
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// End:
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