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/*------------------------------------------------------------------------------
*
* This file is part of rendermq
*
* Author: matt.amos@mapquest.com
*
* Copyright 2010-1 Mapquest, Inc. All Rights reserved.
*
*
* 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
*
*-----------------------------------------------------------------------------*/
#ifndef STORAGE_WORKER_HPP
#define STORAGE_WORKER_HPP
#include "zstream.hpp"
#include "tile_protocol.hpp"
#include <boost/property_tree/ptree.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/thread.hpp>
#include <string>
#include <list>
namespace rendermq {
/* threaded storage worker. accepts requests for tiles to be looked up
* in the storage on an inproc set of sockets and spawns threads to
* handle the blocking storage requests.
*
* it would have been better to use non-blocking I/O or AIO for this,
* but that's not something that's supported by NFS.
*
* TODO: add queue so that large number of requests doesn't fork-bomb
* the machine the handler is on.
*/
class storage_worker {
public:
/* constructs a storage worker which listens on 0MQ sockets
* inproc://storage_request_${handler_id} and puts results onto
* inproc://storage_results_${handler_id}.
*
* @param ctx the 0MQ context to use for creating sockets.
* @param c the config for creating storage drivers.
* @param handler_id a string used to namespace the inproc
* sockets.
* @param max_concur the maximum number of threads to create to
* process storage requests.
* @param dirty_list a map of styles into a list of dependent
* styles to expire in addition to any specified in a dirty
* request.
*/
storage_worker(zmq::context_t &ctx,
const boost::property_tree::ptree &c,
const std::string &handler_id,
size_t max_concur,
const std::map<std::string, std::list<std::string> > &dirty_list);
~storage_worker();
// main loop
void operator()();
private:
static void thread_func(const boost::property_tree::ptree &conf,
zmq::context_t &ctx,
const std::map<std::string, std::list<std::string> > &dirty_list,
volatile bool &shutdown_requested,
std::string resp_ep, std::string reqs_ep);
// context for zeromq operations
zmq::context_t &m_context;
// streams for requests and responses
zstream::socket::pull requests_in;
zstream::socket::push results_out;
// stream for responses from sub-threads
zstream::socket::pull threads_in;
zstream::socket::push threads_out;
// maximum number of i/o threads to run. everything else gets queued.
size_t max_concurrency;
// the current number of i/o threads busy with work.
size_t cur_concurrency;
// storage configuration
const boost::property_tree::ptree &conf;
// map of style names into a list of style names which are dependent
// and should be dirtied whenever the keyed style is dirtied.
std::map<std::string, std::list<std::string> > m_dirty_list;
// signal to threads when they must shut down
volatile bool m_shutdown_requested;
// threads which are currently running i/o actions.
typedef std::list<boost::shared_ptr<boost::thread> > thread_list_t;
thread_list_t threads;
// queue of requests which didn't get processed because of the limit
// on i/o threads.
std::list<boost::shared_ptr<tile_protocol> > queued_requests;
};
} // namespace rendermq
#endif /* STORAGE_WORKER_HPP */
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