src/balancing.hpp

/*
  Copyright 2014 DataStax

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
*/

#ifndef __CASS_BALANCING_HPP_INCLUDED__
#define __CASS_BALANCING_HPP_INCLUDED__

#include <list>
#include <set>
#include <string>

#include "host.hpp"
#include "constants.hpp"
#include "cassandra.h"

extern "C" {

typedef struct CassBalancing_ CassBalancing;

typedef struct CassHost_ {
  CassInet address;
  CassString rack;
  CassString datacenter;
  CassString version;
} CassHost;

typedef enum CassBalancingState_ {
  CASS_BALANCING_INIT,
  CASS_BALANCING_CLEANUP,
  CASS_BALANCING_ON_UP,
  CASS_BALANCING_ON_DOWN,
  CASS_BALANCING_ON_ADD,
  CASS_BALANCING_ON_REMOVE,
  CASS_BALANCING_DISTANCE,
  CASS_BALANCING_NEW_QUERY_PLAN
} CassBalancingState;

typedef enum CassHostDistance_ {
  CASS_HOST_DISTANCE_LOCAL,
  CASS_HOST_DISTANCE_REMOTE,
  CASS_HOST_DISTANCE_IGNORE
} CassHostDistance;

/***********************************************************************************
 *
 * Balancing
 *
 ***********************************************************************************/

typedef void (*CassBalancingCallback)(void* data,
                                      CassBalancingState state,
                                      CassBalancing* balancing);

void
cass_balancing_set_session_data(CassBalancing* balancing,
                                void* session_data);

void*
cass_balancing_session_data(CassBalancing* balancing);

cass_size_t
cass_balancing_hosts_count(CassBalancing* balancing);

CassHost
cass_balancing_host(CassBalancing* balancing,
                    cass_size_t index);

void
cass_balancing_set_host_distance(CassBalancing* balancing,
                                 cass_size_t index,
                                 CassHostDistance distance);

void
cass_balancing_add_host_to_query(CassBalancing* balancing,
                                 CassInet host);

} // extern "C"

namespace cass {

class LoadBalancingPolicy {
public:
  virtual ~LoadBalancingPolicy() {}

  virtual void init(const std::set<Host>& hosts) = 0;

  virtual CassHostDistance distance(const Host& host) = 0;

  // TODO(mpenick): Figure out what parameters to pass, keyspace, consistency,
  // etc.
  virtual void new_query_plan(std::list<Host>* output) = 0;
};


class Balancing {
public:
  void* session_data() { return session_data_; }

  void set_session_data(void* session_data) {
    session_data_ = session_data;
  }

private:
  void* session_data_;
};

} // namespace cass

#endif