LocationCache.h

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/* -*- c++ -*-
 * Copyright (C) 2007-2015 Hypertable, Inc.
 *
 * This file is part of Hypertable.
 *
 * Hypertable is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; version 3 of the
 * License, or any later version.
 *
 * Hypertable is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

#ifndef Hypertable_Lib_LocationCache_h
#define Hypertable_Lib_LocationCache_h

#include "RangeLocationInfo.h"

#include <Common/FlyweightString.h>
#include <Common/InetAddr.h>
#include <Common/StringExt.h>

#include <cstring>
#include <ostream>
#include <map>
#include <mutex>
#include <set>

namespace Hypertable {

  struct LocationCacheKey {
    const char *table_name;
    const char *end_row;
  };

  inline bool operator<(const LocationCacheKey &x, const LocationCacheKey &y) {
    int cmp = strcmp(x.table_name, y.table_name);
    if (cmp)
      return cmp < 0;
    if (y.end_row == 0)
      return (x.end_row == 0) ? false : true;
    else if (x.end_row == 0)
      return false;
    return strcmp(x.end_row, y.end_row) < 0;
  }

  inline bool operator==(const LocationCacheKey &x, const LocationCacheKey &y) {
    if (strcmp(x.table_name, y.table_name))
      return false;
    if (x.end_row == 0)
      return (y.end_row == 0) ? true : false;
    else if (y.end_row == 0)
      return false;
    return !strcmp(x.end_row, y.end_row);
  }

  inline bool operator!=(const LocationCacheKey &x, const LocationCacheKey &y) {
    return !(x == y);
  }


  class LocationCache {
  public:
    struct Value {
      struct Value *prev, *next;
      std::map<LocationCacheKey, Value *>::iterator map_iter;
      std::string start_row;
      std::string end_row;
      const CommAddress *addrp;
      bool pegged;
    };

    LocationCache(uint32_t max_entries) : m_mutex(), m_location_map(),
        m_head(0), m_tail(0), m_max_entries(max_entries) { return; }
    ~LocationCache();

    void insert(const char * table_name, RangeLocationInfo &range_loc_info,
                bool pegged=false);
    bool lookup(const char *table_name, const char *rowkey,
                RangeLocationInfo *range_loc_infop, bool inclusive=false);
    bool lookup(const char *table_name, const char *rowkey,
                RangeAddrInfo *range_addr_infop, bool inclusive=false);
    bool invalidate(const char *table_name, const char *rowkey);

    void invalidate_host(const std::string &hostname);

    void display(std::ostream &);

  private:
    bool lookup(const char *table_name, const char *rowkey,
                Value*& cacheval, bool inclusive);
    void move_to_head(Value *cacheval);
    void remove(Value *cacheval);

    const CommAddress *get_constant_address(const CommAddress &addr);

    struct CommAddressPointerLt {
      bool operator()(const CommAddress *addr1, const CommAddress *addr2) const {
        return *addr1 < *addr2;
      }
    };

    typedef std::map<LocationCacheKey, Value *> LocationMap;
    typedef std::set<const CommAddress *, CommAddressPointerLt> AddressSet;

    std::mutex m_mutex;
    LocationMap    m_location_map;
    AddressSet     m_addresses;
    Value         *m_head;
    Value         *m_tail;
    uint32_t       m_max_entries;
    FlyweightString m_strings;
  };

  typedef std::shared_ptr<LocationCache> LocationCachePtr;

}


#endif // Hypertable_Lib_LocationCache_h