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/*
* ZeroTier One - Network Virtualization Everywhere
* Copyright (C) 2011-2016 ZeroTier, Inc. https://www.zerotier.com/
*
* This program 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, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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, see <http://www.gnu.org/licenses/>.
*/
#ifndef ZT_BACKGROUNDRESOLVER_HPP
#define ZT_BACKGROUNDRESOLVER_HPP
#include <vector>
#include <string>
#include "../node/Constants.hpp"
#include "../node/Mutex.hpp"
#include "../node/InetAddress.hpp"
#include "../node/NonCopyable.hpp"
#include "Thread.hpp"
namespace ZeroTier {
class BackgroundResolverJob;
/**
* A simple background resolver
*/
class BackgroundResolver : NonCopyable
{
friend class BackgroundResolverJob;
public:
/**
* Construct a new resolver
*
* resolveNow() must be called to actually initiate background resolution.
*
* @param name Name to resolve
*/
BackgroundResolver(const char *name);
~BackgroundResolver();
/**
* @return Most recent resolver results or empty vector if none
*/
std::vector<InetAddress> get() const;
/**
* Launch a background resolve job now
*
* If a resolve job is currently in progress, it is aborted and another
* job is started.
*
* Note that jobs can't actually be aborted due to the limitations of the
* ancient synchronous OS resolver APIs. As a result, in progress jobs
* that are aborted are simply abandoned. Don't call this too frequently
* or background threads might pile up.
*
* @param callback Callback function to receive notification or NULL if none
* @praam arg Second argument to callback function
*/
void resolveNow(void (*callback)(BackgroundResolver *,void *) = 0,void *arg = 0);
/**
* Abort (abandon) any current resolve jobs
*/
void abort();
/**
* @return True if a background job is in progress
*/
inline bool running() const
{
Mutex::Lock _l(_lock);
return (_job != (BackgroundResolverJob *)0);
}
/**
* Wait for pending job to complete (if any)
*/
inline void wait() const
{
Thread t;
{
Mutex::Lock _l(_lock);
if (!_job)
return;
t = _jobThread;
}
Thread::join(t);
}
private:
void _postResult(const std::vector<InetAddress> &ips);
std::string _name;
BackgroundResolverJob *_job;
Thread _jobThread;
void (*_callback)(BackgroundResolver *,void *);
void *_arg;
std::vector<InetAddress> _ips;
Mutex _lock;
};
} // namespace ZeroTier
#endif
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