#pragma once
#include "Pool.h"
#define MYSQLXX_POOL_WITH_FAILOVER_DEFAULT_START_CONNECTIONS 1
#define MYSQLXX_POOL_WITH_FAILOVER_DEFAULT_MAX_CONNECTIONS 16
#define MYSQLXX_POOL_WITH_FAILOVER_DEFAULT_MAX_TRIES 3
namespace mysqlxx
{
/** MySQL connection pool with support of failover.
* Have information about replicas and their priorities.
* Tries to connect to replica in an order of priority. When equal priority, choose replica with maximum time without connections.
*
* It could be configured without replicas, exactly as ordinary Pool:
*
*
* mtstat01c*
* 3306
* metrica
*
* Metrica
*
*
* Or like this:
*
*
*
* mtstat01c
* 3306
* metrica
*
* Metrica
* 0
*
*
* mtstat01d
* 3306
* metrica
*
* Metrica
* 1
*
*
*
* Or like this:
*
*
* 3306
* metrica
*
* Metrica
*
* mtstat01c
* 0
*
*
* mtstat01d
* 1
*
*
*/
class PoolWithFailover final
{
private:
using PoolPtr = std::shared_ptr;
using Replicas = std::vector;
/// [priority][index] -> replica.
using ReplicasByPriority = std::map;
ReplicasByPriority replicas_by_priority;
/// Number of connection tries.
size_t max_tries;
/// Mutex for set of replicas.
std::mutex mutex;
std::string config_name;
/// Can the Pool be shared
bool shareable;
public:
using Entry = Pool::Entry;
/**
* config_name Name of parameter in configuration file.
* default_connections Number of connection in pool to each replica at start.
* max_connections Maximum number of connections in pool to each replica.
* max_tries_ Max number of connection tries.
*/
PoolWithFailover(const std::string & config_name,
unsigned default_connections = MYSQLXX_POOL_WITH_FAILOVER_DEFAULT_START_CONNECTIONS,
unsigned max_connections = MYSQLXX_POOL_WITH_FAILOVER_DEFAULT_MAX_CONNECTIONS,
size_t max_tries = MYSQLXX_POOL_WITH_FAILOVER_DEFAULT_MAX_TRIES);
PoolWithFailover(const Poco::Util::AbstractConfiguration & config,
const std::string & config_name,
unsigned default_connections = MYSQLXX_POOL_WITH_FAILOVER_DEFAULT_START_CONNECTIONS,
unsigned max_connections = MYSQLXX_POOL_WITH_FAILOVER_DEFAULT_MAX_CONNECTIONS,
size_t max_tries = MYSQLXX_POOL_WITH_FAILOVER_DEFAULT_MAX_TRIES);
PoolWithFailover(const PoolWithFailover & other);
/** Allocates a connection to use. */
Entry get();
};
}