forked from bartvdbraak/blender
aeee7118ae
- Made code a bit less cluttered to follow - Fixed possible deadlock when enforcing limit and highest priority element is still referenced.
286 lines
6.2 KiB
C++
286 lines
6.2 KiB
C++
/*
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* ***** BEGIN GPL LICENSE BLOCK *****
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* Contributor(s): Peter Schlaile <peter@schlaile.de> 2005
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*
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* ***** END GPL LICENSE BLOCK *****
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*/
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/** \file memutil/MEM_CacheLimiter.h
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* \ingroup memutil
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*/
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#ifndef __MEM_CACHELIMITER_H__
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#define __MEM_CACHELIMITER_H__
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/**
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* @section MEM_CacheLimiter
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* This class defines a generic memory cache management system
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* to limit memory usage to a fixed global maximum.
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*
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* Please use the C-API in MEM_CacheLimiterC-Api.h for code written in C.
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*
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* Usage example:
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*
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* class BigFatImage {
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* public:
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* ~BigFatImage() { tell_everyone_we_are_gone(this); }
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* };
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*
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* void doit() {
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* MEM_Cache<BigFatImage> BigFatImages;
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*
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* MEM_Cache_Handle<BigFatImage>* h = BigFatImages.insert(new BigFatImage);
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*
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* BigFatImages.enforce_limits();
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* h->ref();
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*
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* work with image...
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*
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* h->unref();
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*
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* leave image in cache.
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*/
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#include <list>
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#include <queue>
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#include <vector>
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#include "MEM_Allocator.h"
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template<class T>
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class MEM_CacheLimiter;
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#ifndef __MEM_CACHELIMITERC_API_H__
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extern "C" {
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void MEM_CacheLimiter_set_maximum(size_t m);
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size_t MEM_CacheLimiter_get_maximum();
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};
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#endif
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template<class T>
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class MEM_CacheLimiterHandle {
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public:
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explicit MEM_CacheLimiterHandle(T * data_,MEM_CacheLimiter<T> *parent_) :
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data(data_),
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refcount(0),
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parent(parent_)
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{ }
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void ref() {
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refcount++;
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}
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void unref() {
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refcount--;
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}
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T *get() {
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return data;
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}
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const T *get() const {
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return data;
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}
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int get_refcount() const {
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return refcount;
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}
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bool can_destroy() const {
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return !data || !refcount;
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}
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bool destroy_if_possible() {
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if (can_destroy()) {
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delete data;
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data = NULL;
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unmanage();
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return true;
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}
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return false;
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}
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void unmanage() {
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parent->unmanage(this);
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}
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void touch() {
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parent->touch(this);
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}
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private:
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friend class MEM_CacheLimiter<T>;
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T * data;
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int refcount;
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typename std::list<MEM_CacheLimiterHandle<T> *, MEM_Allocator<MEM_CacheLimiterHandle<T> *> >::iterator me;
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MEM_CacheLimiter<T> * parent;
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};
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template<class T>
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class MEM_CacheLimiter {
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public:
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typedef size_t (*MEM_CacheLimiter_DataSize_Func) (void *data);
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typedef int (*MEM_CacheLimiter_ItemPriority_Func) (void *item, int default_priority);
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MEM_CacheLimiter(MEM_CacheLimiter_DataSize_Func data_size_func)
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: data_size_func(data_size_func) {
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}
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~MEM_CacheLimiter() {
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for (iterator it = queue.begin(); it != queue.end(); it++) {
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delete *it;
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}
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}
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MEM_CacheLimiterHandle<T> *insert(T * elem) {
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queue.push_back(new MEM_CacheLimiterHandle<T>(elem, this));
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iterator it = queue.end();
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--it;
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queue.back()->me = it;
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return queue.back();
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}
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void unmanage(MEM_CacheLimiterHandle<T> *handle) {
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queue.erase(handle->me);
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delete handle;
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}
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size_t get_memory_in_use() {
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size_t size = 0;
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if (data_size_func) {
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for (iterator it = queue.begin(); it != queue.end(); it++) {
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size += data_size_func((*it)->get()->get_data());
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}
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}
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else {
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size = MEM_get_memory_in_use();
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}
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return size;
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}
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void enforce_limits() {
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size_t max = MEM_CacheLimiter_get_maximum();
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size_t mem_in_use, cur_size;
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if (max == 0) {
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return;
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}
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mem_in_use = get_memory_in_use();
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if (mem_in_use <= max) {
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return;
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}
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while (!queue.empty() && mem_in_use > max) {
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MEM_CacheElementPtr elem = get_least_priority_destroyable_element();
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if (!elem)
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break;
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if (data_size_func) {
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cur_size = data_size_func(elem->get()->get_data());
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}
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else {
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cur_size = mem_in_use;
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}
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if (elem->destroy_if_possible()) {
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if (data_size_func) {
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mem_in_use -= cur_size;
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}
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else {
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mem_in_use -= cur_size - MEM_get_memory_in_use();
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}
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}
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}
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}
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void touch(MEM_CacheLimiterHandle<T> * handle) {
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/* If we're using custom priority callback re-arranging the queue
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* doesn't make much sense because we'll iterate it all to get
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* least priority element anyway.
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*/
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if (item_priority_func == NULL) {
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queue.push_back(handle);
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queue.erase(handle->me);
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iterator it = queue.end();
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--it;
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handle->me = it;
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}
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}
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void set_item_priority_func(MEM_CacheLimiter_ItemPriority_Func item_priority_func) {
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this->item_priority_func = item_priority_func;
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}
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private:
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typedef MEM_CacheLimiterHandle<T> *MEM_CacheElementPtr;
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typedef std::list<MEM_CacheElementPtr, MEM_Allocator<MEM_CacheElementPtr> > MEM_CacheQueue;
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typedef typename MEM_CacheQueue::iterator iterator;
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MEM_CacheElementPtr get_least_priority_destroyable_element(void) {
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if (queue.empty())
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return NULL;
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MEM_CacheElementPtr best_match_elem = NULL;
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if (!item_priority_func) {
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for (iterator it = queue.begin(); it != queue.end(); it++) {
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MEM_CacheElementPtr elem = *it;
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if (!elem->can_destroy())
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continue;
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best_match_elem = elem;
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break;
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}
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}
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else {
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int best_match_priority = 0;
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iterator it;
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int i;
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for (it = queue.begin(), i = 0; it != queue.end(); it++, i++) {
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MEM_CacheElementPtr elem = *it;
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if (!elem->can_destroy())
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continue;
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/* by default 0 means highest priority element */
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/* casting a size type to int is questionable,
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but unlikely to cause problems */
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int priority = -((int)(queue.size()) - i - 1);
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priority = item_priority_func(elem->get()->get_data(), priority);
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if (priority < best_match_priority || best_match_elem == NULL) {
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best_match_priority = priority;
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best_match_elem = elem;
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}
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}
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}
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return best_match_elem;
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}
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MEM_CacheQueue queue;
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MEM_CacheLimiter_DataSize_Func data_size_func;
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MEM_CacheLimiter_ItemPriority_Func item_priority_func;
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};
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#endif // __MEM_CACHELIMITER_H__
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