ConnectionPool.h

/* Copyright (c) 2020 vesoft inc. All rights reserved.
 *
 * This source code is licensed under Apache 2.0 License.
 */
 
#pragma once
 
#include <list>
#include <memory>
#include <mutex>
#include <thread>
 
#include "nebula/client/Config.h"
#include "nebula/client/Connection.h"
#include "nebula/client/Session.h"
 
namespace nebula {
 
class ConnectionPool {
 public:
  ~ConnectionPool();
 
  void init(const std::vector<std::string> &addresses, const Config &config);
 
  void close();
 
  Session getSession(const std::string &username,
                     const std::string &password,
                     bool retryConnect = true);
 
  Connection getConnection();
 
  void giveBack(Connection &&conn);
 
  std::size_t size() const {
    std::lock_guard<std::mutex> l(lock_);
    return conns_.size();
  }
 
 private:
  // The count may can't perform if can't create enough valid connection
  void newConnection(std::size_t cursor, std::size_t count);
 
  std::size_t nextCursor() {
    return cursor_ >= address_.size() ? cursor_ = 0 : cursor_++;
  }
 
  std::size_t cursor_{0};
  // host, port
  std::vector<std::pair<std::string, int32_t>> address_;
  Config config_;
 
  mutable std::mutex lock_;
  std::list<Connection> conns_;
};
 
}  // namespace nebula