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/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
* Main authors:
* Christian Schulte <schulte@gecode.org>
*
* Copyright:
* Christian Schulte, 2009
*
* This file is part of Gecode, the generic constraint
* development environment:
* http://www.gecode.org
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
#ifndef GECODE_SEARCH_PAR_ENGINE_HH
#define GECODE_SEARCH_PAR_ENGINE_HH
#include <gecode/search.hh>
#include <gecode/search/support.hh>
#include <gecode/search/worker.hh>
#include <gecode/search/par/path.hh>
namespace Gecode { namespace Search { namespace Par {
/// %Parallel depth-first search engine
template<class Tracer>
class Engine : public Search::Engine, public Support::Terminator {
protected:
/// %Parallel depth-first search worker
class Worker : public Search::Worker, public Support::Runnable {
public:
/// Search tracer
Tracer tracer;
protected:
/// Reference to engine
Engine& _engine;
/// Mutex for access to worker
Support::Mutex m;
/// Current path ins search tree
Path<Tracer> path;
/// Current space being explored
Space* cur;
/// Distance until next clone
unsigned int d;
/// Whether the worker is idle
bool idle;
public:
/// Initialize for space \a s with engine \a e
Worker(Space* s, Engine& e);
/// Hand over some work (nullptr if no work available)
Space* steal(unsigned long int& d, Tracer& myt, Tracer& ot);
/// Return statistics
Statistics statistics(void);
/// Provide access to engine
Engine& engine(void) const;
/// Return no-goods
NoGoods& nogoods(void);
/// Destructor
virtual ~Worker(void);
/// Terminator (engine)
virtual Support::Terminator* terminator(void) const;
};
/// Search options
Options _opt;
public:
/// Provide access to search options
const Options& opt(void) const;
/// Return number of workers
unsigned int workers(void) const;
/// \name Commands from engine to workers and wait management
//@{
/// Commands from engine to workers
enum Cmd {
C_WORK, ///< Perform work
C_WAIT, ///< Run into wait lock
C_RESET, ///< Perform reset operation
C_TERMINATE ///< Terminate
};
protected:
/// The current command
volatile Cmd _cmd;
/// Mutex for forcing workers to wait
Support::Mutex _m_wait;
public:
/// Return current command
Cmd cmd(void) const;
/// Block all workers
void block(void);
/// Release all workers
void release(Cmd c);
/// Ensure that worker waits
void wait(void);
//@}
/// \name Termination control
//@{
protected:
/// Mutex for access to termination information
Support::Mutex _m_term;
/// Number of workers that have not yet acknowledged termination
volatile unsigned int _n_term_not_ack;
/// Event for termination acknowledgment
Support::Event _e_term_ack;
/// Mutex for waiting for termination
Support::Mutex _m_wait_terminate;
/// Number of not yet terminated workers
volatile unsigned int _n_not_terminated;
/// Event for termination (all threads have terminated)
Support::Event _e_terminate;
public:
/// For worker to acknowledge termination command
void ack_terminate(void);
/// For worker to register termination
virtual void terminated(void);
/// For worker to wait until termination is legal
void wait_terminate(void);
/// For engine to perform thread termination
void terminate(void);
//@}
/// \name Reset control
//@{
protected:
/// Mutex for access to reset information
Support::Mutex _m_reset;
/// Number of workers that have not yet acknowledged reset
volatile unsigned int _n_reset_not_ack;
/// Event for reset acknowledgment started
Support::Event e_reset_ack_start;
/// Event for reset acknowledgment stopped
Support::Event e_reset_ack_stop;
/// Mutex for waiting for reset
Support::Mutex m_wait_reset;
public:
/// For worker to acknowledge start of reset cycle
void ack_reset_start(void);
/// For worker to acknowledge stop of reset cycle
void ack_reset_stop(void);
/// For worker to wait for all workers to reset
void wait_reset(void);
//@}
/// \name Search control
//@{
protected:
/// Mutex for search
Support::Mutex m_search;
/// Event for search (solution found, no more solutions, search stopped)
Support::Event e_search;
/// Queue of solutions
Support::DynamicQueue<Space*,Heap> solutions;
/// Number of busy workers
volatile unsigned int n_busy;
/// Whether a worker had been stopped
volatile bool has_stopped;
/// Whether search state changed such that signal is needed
bool signal(void) const;
public:
/// Report that worker is idle
void idle(void);
/// Report that worker is busy
void busy(void);
/// Report that worker has been stopped
void stop(void);
//@}
/// \name Engine interface
//@{
/// Initialize with options \a o
Engine(const Options& o);
/// Return next solution (nullptr, if none exists or search has been stopped)
virtual Space* next(void);
/// Check whether engine has been stopped
virtual bool stopped(void) const;
//@}
/// Destructor
virtual ~Engine(void);
};
}}}
#include <gecode/search/par/engine.hpp>
#endif
// STATISTICS: search-par
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