98 lines
2.6 KiB
C++
98 lines
2.6 KiB
C++
#include <cstddef>
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#include <cstring>
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#include "bpt/buffer_pool_manager.h"
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#include "bpt/config.h"
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#include "bpt/disk_manager.h"
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#ifndef BPT_MEMORYRIVER_HPP
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#define BPT_MEMORYRIVER_HPP
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#include <fstream>
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using std::fstream;
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using std::ifstream;
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using std::ofstream;
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using std::string;
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template <class T, int info_len = 2>
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class MemoryRiver {
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private:
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union Page {
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T data;
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char filler[4096];
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};
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std::string file_name;
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DiskManager *disk_manager;
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BufferPoolManager *bpm;
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char *raw_mem;
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static_assert(info_len * sizeof(int) <= 4000, "info_len should be less than 4000");
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static_assert(sizeof(T) <= 4096, "T should be less than 4096");
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public:
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MemoryRiver() : disk_manager(nullptr), bpm(nullptr), file_name("") {}
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MemoryRiver(const string &file_name) : file_name(file_name) {
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disk_manager = new DiskManager(file_name);
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bpm = new BufferPoolManager(100, 5, disk_manager);
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raw_mem = bpm->RawDataMemory();
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}
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void CloseFile() {
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bpm->FlushAllPages();
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file_name = "";
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delete bpm;
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bpm = nullptr;
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delete disk_manager;
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disk_manager = nullptr;
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}
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~MemoryRiver() {
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if (file_name != "") CloseFile();
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}
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void initialise(string FN = "") {
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if (file_name != "") {
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std::string name_bak=file_name;
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CloseFile();
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file_name = name_bak;
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}
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if (FN != "") file_name = FN;
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if (file_name == "") return;
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disk_manager = new DiskManager(file_name);
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bpm = new BufferPoolManager(100, 5, disk_manager);
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raw_mem = bpm->RawDataMemory();
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memset(raw_mem, 0, bpm->RawDatMemorySize());
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}
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void get_info(int &tmp, int n) {
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if (n > info_len) return;
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n--;
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memcpy(&tmp, raw_mem + n * sizeof(int), sizeof(int));
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}
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void write_info(int tmp, int n) {
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if (n > info_len) return;
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n--;
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memcpy(raw_mem + n * sizeof(int), &tmp, sizeof(int));
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}
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int write(T &t) {
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frame_id_t frame_id;
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BasicPageGuard guard = bpm->NewPageGuarded(&frame_id);
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guard.AsMut<Page>()->data = t;
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return frame_id;
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}
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void update(T &t, const int index) {
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WritePageGuard guard = bpm->FetchPageWrite(index);
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guard.AsMut<Page>()->data = t;
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}
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//读出位置索引index对应的T对象的值并赋值给t，保证调用的index都是由write函数产生
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void read(T &t, const int index) {
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ReadPageGuard guard = bpm->FetchPageRead(index);
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t = guard.As<Page>()->data;
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}
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//删除位置索引index对应的对象(不涉及空间回收时，可忽略此函数)，保证调用的index都是由write函数产生
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void Delete(int index) { bpm->DeletePage(index); }
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};
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#endif // BPT_MEMORYRIVER_HPP
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