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// -*- mode: c++; c-file-style: "k&r"; c-basic-offset: 4 -*-
// vim: set ts=4 sw=4:
/***********************************************************************
*
* common/versionedKVStore.h:
*
* Simple versioned key-value store that tracks the write timestamp
* and latest read timestamp for each version.
*
**********************************************************************/
#ifndef _VERSIONED_KV_STORE_H_
#define _VERSIONED_KV_STORE_H_
#include "lib/assert.h"
#include "lib/message.h"
#include "store/common/timestamp.h"
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#include <set>
#include <map>
#include <unordered_map>
#include <fstream>
#include <iostream>
class VersionedKVStore
{
public:
VersionedKVStore();
~VersionedKVStore();
bool get(const std::string &key, std::pair<Timestamp, std::string> &value);
bool get(const std::string &key, const Timestamp &t, std::pair<Timestamp, std::string> &value);
bool getRange(const std::string &key, const Timestamp &t, std::pair<Timestamp, Timestamp> &range);
bool getLastRead(const std::string &key, Timestamp &readTime);
bool getLastRead(const std::string &key, const Timestamp &t, Timestamp &readTime);
void put(const std::string &key, const std::string &value, const Timestamp &t);
void commitGet(const std::string &key, const Timestamp &readTime, const Timestamp &commit);
private:
struct VersionedValue {
Timestamp write;
std::string value;
VersionedValue(Timestamp commit) : write(commit), value("tmp") { };
VersionedValue(Timestamp commit, std::string val) : write(commit), value(val) { };
friend bool operator> (const VersionedValue &v1, const VersionedValue &v2) {
return v1.write > v2.write;
};
friend bool operator< (const VersionedValue &v1, const VersionedValue &v2) {
return v1.write < v2.write;
};
};
/* Global store which keeps key -> (timestamp, value) list. */
std::unordered_map< std::string, std::set<VersionedValue> > store;
std::unordered_map< std::string, std::map< Timestamp, Timestamp > > lastReads;
bool inStore(const std::string &key);
void getValue(const std::string &key, const Timestamp &t, std::set<VersionedValue>::iterator &it);
};
#endif /* _VERSIONED_KV_STORE_H_ */