/************************************************************************
 *
 * Copyright (c) 2016 Alibaba.com, Inc. All Rights Reserved
 * $Id:  file_paxos_log.h,v 1.0 08/15/2016 02:46:50 PM hangfeng.fj(hangfeng.fj@alibaba-inc.com) $
 *
 ************************************************************************/

/**
 * @file file_paxos_log.h
 * @author hangfeng.fj(hangfeng.fj@alibaba-inc.com)
 * @date 08/15/2016 02:15:50 PM
 * @version 1.0
 * @brief 
 *
 **/

#ifndef  cluster_file_paxos_log_INC
#define  cluster_file_paxos_log_INC

#include <mutex>
#include <atomic>
#include <map>
#include <string>
#include <fstream>
#include <utility>
#include "paxos_log.h"
#include "paxos.h"

namespace alisql
{

/**
 * @class FilePaxosLog
 *
 * @brief class for File and Map based Paxos Log
 *
 **/
class FilePaxosLog : public PaxosLog {
  public:
    typedef enum LogType {
      LTMem= 0,
      LTFile,
      LTSync,
    } LogTypeT;

    FilePaxosLog(const std::string &dataDir, LogTypeT type= LTMem);
    virtual ~FilePaxosLog();

    virtual int getEntry(uint64_t logIndex, LogEntry &entry, bool fastfail= false);
    virtual const LogEntry *getEntry(uint64_t logIndex, bool fastfail= false);
    virtual int getEmptyEntry(LogEntry &entry);
    virtual uint64_t getLastLogIndex();
    virtual uint64_t append(const LogEntry &entry);
    virtual uint64_t appendWithCheck(const LogEntry &entry);
    virtual void truncateBackward(uint64_t firstIndex);
    virtual void truncateForward(uint64_t lastIndex);
    virtual int getMetaData(const std::string &key, uint64_t *value);
    virtual int setMetaData(const std::string &key, const uint64_t value);
    virtual uint64_t append(const ::google::protobuf::RepeatedPtrField<LogEntry> &entries);
    virtual uint64_t getLastLogTerm();

    void appendEmptyEntry();
    virtual uint64_t getLength();
    bool readEntry(uint64_t index, LogEntry *logEntry);
    uint64_t appendEntry(const LogEntry &logEntry);
    static uint64_t stringToInt(const std::string &s);
    static std::string intToString(uint64_t num);
    static void intToString(uint64_t num, std::string &key);
    void encodeLogEntry(const LogEntry &logEntry, std::string *buf);
    void decodeLogEntry(const std::string &buf, LogEntry *logEntry);

    void set_debug_async() {async_= true;}
    
  private:
    void initLastLogTerm();
    //std::atomic<uint64_t> length_;
    uint64_t length_;
    uint64_t lastLogTerm_;
    bool async_;
    LogTypeT type_;
    std::fstream fs_;
    int fd_;
    std::vector<LogEntry *> log_;

  public:
    static bool debugDisableWriteFile;
};/* end of class FilePaxosLog */

};/* end of namespace alisql */

#endif     //#ifndef cluster_file_paxos_log_INC