mapnik/include/mapnik/pool.hpp
2011-09-01 19:21:03 +00:00

168 lines
4.3 KiB
C++

/*****************************************************************************
*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2006 Artem Pavlenko
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*****************************************************************************/
//$Id: pool.hpp 39 2005-04-10 20:39:53Z pavlenko $
#ifndef POOL_HPP
#define POOL_HPP
// mapnik
#include <mapnik/utils.hpp>
// boost
#include <boost/shared_ptr.hpp>
#include <boost/utility.hpp>
#ifdef MAPNIK_THREADSAFE
#include <boost/thread/mutex.hpp>
#endif
// stl
#include <iostream>
#include <map>
#include <deque>
#include <ctime>
namespace mapnik
{
template <typename T, typename PoolT>
class PoolGuard
{
private:
const T& obj_;
PoolT& pool_;
public:
explicit PoolGuard(const T& ptr,PoolT& pool)
: obj_(ptr),
pool_(pool) {}
~PoolGuard()
{
pool_->returnObject(obj_);
}
private:
PoolGuard();
PoolGuard(const PoolGuard&);
PoolGuard& operator=(const PoolGuard&);
};
template <typename T,template <typename> class Creator>
class Pool : private boost::noncopyable
{
typedef boost::shared_ptr<T> HolderType;
typedef std::deque<HolderType> ContType;
Creator<T> creator_;
const unsigned initialSize_;
const unsigned maxSize_;
ContType usedPool_;
ContType unusedPool_;
#ifdef MAPNIK_THREADSAFE
mutable boost::mutex mutex_;
#endif
public:
Pool(const Creator<T>& creator,unsigned initialSize=1, unsigned maxSize=10)
:creator_(creator),
initialSize_(initialSize),
maxSize_(maxSize)
{
for (unsigned i=0; i < initialSize_; ++i)
{
HolderType conn(creator_());
if (conn->isOK())
unusedPool_.push_back(conn);
}
}
HolderType borrowObject()
{
#ifdef MAPNIK_THREADSAFE
mutex::scoped_lock lock(mutex_);
#endif
typename ContType::iterator itr=unusedPool_.begin();
while ( itr!=unusedPool_.end())
{
#ifdef MAPNIK_DEBUG
std::clog<<"borrow "<<(*itr).get()<<"\n";
#endif
if ((*itr)->isOK())
{
usedPool_.push_back(*itr);
unusedPool_.erase(itr);
return usedPool_[usedPool_.size()-1];
}
else
{
#ifdef MAPNIK_DEBUG
std::clog<<"bad connection (erase)" << (*itr).get()<<"\n";
#endif
itr=unusedPool_.erase(itr);
}
}
if (usedPool_.size() < maxSize_)
{
HolderType conn(creator_());
if (conn->isOK())
{
usedPool_.push_back(conn);
#ifdef MAPNIK_DEBUG
std::clog << "create << " << conn.get() << "\n";
#endif
return conn;
}
}
return HolderType();
}
void returnObject(HolderType obj)
{
#ifdef MAPNIK_THREADSAFE
mutex::scoped_lock lock(mutex_);
#endif
typename ContType::iterator itr=usedPool_.begin();
while (itr != usedPool_.end())
{
if (obj.get()==(*itr).get())
{
#ifdef MAPNIK_DEBUG
std::clog<<"return "<<(*itr).get()<<"\n";
#endif
unusedPool_.push_back(*itr);
usedPool_.erase(itr);
return;
}
++itr;
}
}
std::pair<unsigned,unsigned> size() const
{
#ifdef MAPNIK_THREADSAFE
mutex::scoped_lock lock(mutex_);
#endif
std::pair<unsigned,unsigned> size(unusedPool_.size(),usedPool_.size());
return size;
}
};
}
#endif //POOL_HPP