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

/**
 * @file rd_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_rd_paxos_log_INC
#define  cluster_rd_paxos_log_INC

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

namespace rocksdb
{
class DB;
}

namespace alisql
{

/**
 * @class RDPaxosLog
 *
 * @brief class for RocksDB Paxos Log
 *
 **/
class RDPaxosLog : public PaxosLog {
  public:
    RDPaxosLog(const std::string &dataDir, bool compress, size_t writeBufferSize, bool sync=true);
    virtual ~RDPaxosLog();

    virtual int getEntry(uint64_t logIndex, LogEntry &entry, bool fastfail= false);
    virtual int getEmptyEntry(LogEntry &entry);
    virtual uint64_t getLastLogIndex();
    virtual uint64_t append(const LogEntry &entry);
    virtual void truncateBackward(uint64_t firstIndex);
    virtual void truncateForward(uint64_t lastIndex);
    virtual int getMetaData(const std::string &key, std::string &value);
    virtual int setMetaData(const std::string &key, const std::string &value);
    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();

    uint64_t getFirstLogIndex();
    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;}

    void setPurgeLogFilter(std::function<bool(const LogEntry &le)> cb) {purgeLogFilter_ = cb;}
    void debugSetLastLogIndex(uint i) {std::lock_guard<std::mutex> lg(lock_);firstLogIndex_= lastLogIndex_= i;}

  private:
    void initLastLogTerm();
    rocksdb::DB* db_;
    uint64_t lastLogIndex_;
    uint64_t lastLogTerm_;
    /* log index we purge from */
    std::atomic<uint64_t> firstLogIndex_;
    bool async_;
    bool sync_;

    std::function<bool(const LogEntry &le)> purgeLogFilter_; /* act as a filter for purging log */
};/* end of class RDPaxosLog */

};/* end of namespace alisql */

#endif     //#ifndef cluster_rd_paxos_log_INC