85 lines
3.2 KiB
C++
85 lines
3.2 KiB
C++
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#include <unordered_map>
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#include <list>
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#include "2Q_cache.h"
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class TwoCache {
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private:
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//2 LRU caches
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size_t cpct_q1;
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std::unordered_map<int, std::list<int>::iterator> umap1;
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std::list <int> q1; //fast queue - the most popular pages
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size_t cpct_q2;
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std::unordered_map<int, std::list<int>::iterator> umap2;
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std::list <int> q2; //slow queue - if page asked at the first time put it to q2, if itasked from q2 it put it to q1,
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public:
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TwoCache(size_t q1sz, size_t q2sz): cpct_q1(q1sz), cpct_q2(q2sz) {} //ctor
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int get_page(int id) { //get_page(<int id>) - returns <int id> if page is found, and -1 if not
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if(umap1.find(id) != umap1.end()) {
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q1.splice(q1.begin(), q1, umap1[id]); //if page did not find in the end of fast(q1) queue - put it in the begin
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return id;
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}
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if (umap2.find(id) != umap2.end()) { //if page was not found in the end of slow queue - put is from slow(q2) to begin fast(q1)
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auto it = umap2[id];
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q2.splice(q2.begin(), q2, it); //put this page from queue to the slow
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umap2.erase(id); //delete it from slow queue
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if (q1.size() == cpct_q1) { //if q1 is overflowed delete oldest element from fast(q1)
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umap1.erase(q1.back());
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q1.pop_back();
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}
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q1.push_front(id); //if it is not overflowed put it at the begin
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umap2[id] = q1.begin();
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return id;
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} else return -1; //page was not found - return PAGE_DID_NOT_FOUND = -1
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}
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void put_page(int id) { //puts page in cache
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if (umap1.find(id) != umap1.end()) { //if page is q1
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return;
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}
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if (umap2.find(id) != umap2.end()) { //I know that in this case there will be 2 loops in get_page() i will think about it...
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get_page(id);
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return;
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}
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if (q1.size() == cpct_q1) { //if overflow
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umap1.erase(q1.back());
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q1.pop_back();
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}
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if (q2.size() == cpct_q2) {
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umap2.erase(q2.back());
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q2.pop_back();
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}
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q1.push_front(id); //in the end push page in cache
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umap1[id] = q1.begin();
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}
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void info() {
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std::cout << "q1 (the most usable): ";
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for (auto i = q1.begin(); i != q1.end(); i++) {
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std::cout << *i << " ";
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}
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std::cout << "\nq2(Less usable): ";
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for (auto i = q2.begin(); i != q2.end(); i++) {
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std::cout << *i << " ";
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}
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std::cout << "\ncapacity q1: " << cpct_q1
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<< "\ncapacity q2: " << cpct_q2 << std::endl;
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}
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}; |