ClickHouse/libs/libzkutil/include/zkutil/Increment.h

#pragma once

#include <zkutil/ZooKeeperHolder.h>

namespace zkutil
{
	
class Increment
{
public:
	Increment(ZooKeeperHolderPtr zk_holder_, const std::string & path_)
	: zookeeper_holder(zk_holder_), path(path_)
	{
		zookeeper_holder->getZooKeeper()->createAncestors(path);
	}
	
	size_t get()
	{
		LOG_TRACE(log, "Get increment");
		
		size_t result = 0;
		std::string result_str;
		zkutil::Stat stat;
		
		bool success = false;
		auto zookeeper = zookeeper_holder->getZooKeeper();
		do
		{
			if (zookeeper->tryGet(path, result_str, &stat))
			{
				result = std::stol(result_str) + 1;
				success = zookeeper->trySet(path, std::to_string(result), stat.version) == ZOK;
			}
			else
			{
				success = zookeeper->tryCreate(path, std::to_string(result), zkutil::CreateMode::Persistent) == ZOK;
			}
		}
		while (!success);
		
		return result;
	}
private:
	zkutil::ZooKeeperHolderPtr zookeeper_holder;
	std::string path;
	Logger * log = &Logger::get("zkutil::Increment");
};

}