Generated on Sat Feb 7 2015 02:01:29 for Gecode by doxygen 1.8.9.1
dfs.hh
Go to the documentation of this file.
1 /* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
2 /*
3  * Main authors:
4  * Christian Schulte <schulte@gecode.org>
5  *
6  * Copyright:
7  * Christian Schulte, 2009
8  *
9  * Last modified:
10  * $Date: 2013-07-11 12:30:18 +0200 (Thu, 11 Jul 2013) $ by $Author: schulte $
11  * $Revision: 13840 $
12  *
13  * This file is part of Gecode, the generic constraint
14  * development environment:
15  * http://www.gecode.org
16  *
17  * Permission is hereby granted, free of charge, to any person obtaining
18  * a copy of this software and associated documentation files (the
19  * "Software"), to deal in the Software without restriction, including
20  * without limitation the rights to use, copy, modify, merge, publish,
21  * distribute, sublicense, and/or sell copies of the Software, and to
22  * permit persons to whom the Software is furnished to do so, subject to
23  * the following conditions:
24  *
25  * The above copyright notice and this permission notice shall be
26  * included in all copies or substantial portions of the Software.
27  *
28  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
29  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
30  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
31  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
32  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
33  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
34  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
35  *
36  */
37 
38 #ifndef __GECODE_SEARCH_PARALLEL_DFS_HH__
39 #define __GECODE_SEARCH_PARALLEL_DFS_HH__
40 
42 
43 namespace Gecode { namespace Search { namespace Parallel {
44 
46  class DFS : public Engine {
47  protected:
49  class Worker : public Engine::Worker {
50  public:
52  Worker(Space* s, DFS& e);
54  DFS& engine(void) const;
56  virtual void run(void);
58  void find(void);
60  void reset(Space* s, int ngdl);
61  };
64  public:
66  Worker* worker(unsigned int i) const;
67 
69 
70  void solution(Space* s);
73 
75 
76  DFS(Space* s, const Options& o);
79  virtual Statistics statistics(void) const;
81  virtual void reset(Space* s);
83  virtual NoGoods& nogoods(void);
85  virtual ~DFS(void);
87  };
88 
89 
90  /*
91  * Basic access routines
92  */
94  DFS::Worker::engine(void) const {
95  return static_cast<DFS&>(_engine);
96  }
98  DFS::worker(unsigned int i) const {
99  return _worker[i];
100  }
101 
102 
103  /*
104  * Engine: initialization
105  */
108  : Engine::Worker(s,e) {}
110  DFS::DFS(Space* s, const Options& o)
111  : Engine(o) {
112  // Create workers
113  _worker = static_cast<Worker**>
114  (heap.ralloc(workers() * sizeof(Worker*)));
115  // The first worker gets the entire search tree
116  _worker[0] = new Worker(s,*this);
117  // All other workers start with no work
118  for (unsigned int i=1; i<workers(); i++)
119  _worker[i] = new Worker(NULL,*this);
120  // Block all workers
121  block();
122  // Create and start threads
123  for (unsigned int i=0; i<workers(); i++)
125  }
126 
127  /*
128  * Reset
129  */
130  forceinline void
131  DFS::Worker::reset(Space* s, int ngdl) {
132  delete cur;
133  path.reset((s != NULL) ? ngdl : 0);
134  d = 0;
135  idle = false;
136  if ((s == NULL) || (s->status(*this) == SS_FAILED)) {
137  delete s;
138  cur = NULL;
139  } else {
140  cur = s;
141  }
143  }
144 
145 
146  /*
147  * Engine: search control
148  */
149  forceinline void
151  m_search.acquire();
152  bool bs = signal();
153  solutions.push(s);
154  if (bs)
155  e_search.signal();
156  m_search.release();
157  }
158 
159 
160 
161  /*
162  * Worker: finding and stealing working
163  */
164  forceinline void
166  // Try to find new work (even if there is none)
167  for (unsigned int i=0; i<engine().workers(); i++) {
168  unsigned long int r_d = 0ul;
169  if (Space* s = engine().worker(i)->steal(r_d)) {
170  // Reset this guy
171  m.acquire();
172  idle = false;
173  // Not idle but also does not have the root of the tree
174  path.ngdl(0);
175  d = 0;
176  cur = s;
178  m.release();
179  return;
180  }
181  }
182  }
183 
184 }}}
185 
186 #endif
187 
188 // STATISTICS: search-parallel
Worker(void)
Initialize.
Definition: worker.hh:74
Parallel depth-first search worker
Definition: dfs.hh:49
Path path
Current path ins search tree.
Definition: engine.hh:59
Search engine statistics
Definition: search.hh:136
void idle(void)
Report that worker is idle.
Definition: engine.hh:293
Search engine options
Definition: search.hh:204
Worker * worker(unsigned int i) const
Provide access to worker i.
Definition: dfs.hh:98
static void run(Runnable *r)
Construct a new thread and run r.
Definition: thread.hpp:109
void acquire(void)
Acquire the mutex and possibly block.
Definition: none.hpp:46
void * ralloc(size_t s)
Allocate s bytes from heap.
Definition: heap.hpp:341
virtual void run(void)
Start execution of worker.
Definition: dfs.cpp:62
void path(Home home, int offset, const IntVarArgs &x, IntVar s, IntVar e, IntConLevel icl)
Post propagator such that x forms a Hamiltonian path.
Definition: circuit.cpp:128
void block(void)
Block all workers.
Definition: engine.hh:222
void signal(void)
Signal the event.
Definition: none.hpp:63
Computation spaces.
Definition: core.hpp:1362
void find(void)
Try to find some work.
Definition: dfs.hh:165
Heap heap
The single global heap.
Definition: heap.cpp:49
Gecode::IntSet d(v, 7)
void release(void)
Release the mutex.
Definition: none.hpp:52
virtual NoGoods & nogoods(void)
Return no-goods.
Definition: dfs.cpp:208
Gecode::IntArgs i(4, 1, 2, 3, 4)
unsigned int d
Distance until next clone.
Definition: engine.hh:63
bool idle
Whether the worker is idle.
Definition: engine.hh:65
virtual void reset(Space *s)
Reset engine to restart at space s.
Definition: dfs.cpp:181
Space * cur
Current space being explored.
Definition: engine.hh:61
unsigned int workers(void) const
Return number of workers.
Definition: engine.hh:209
DFS(Space *s, const Options &o)
Initialize for space s with options o.
Definition: dfs.hh:110
Support::Event e_search
Event for search (solution found, no more solutions, search stopped)
Definition: engine.hh:167
Parallel depth-first search engine
Definition: engine.hh:49
virtual Statistics statistics(void) const
Return statistics.
Definition: dfs.cpp:50
void solution(Space *s)
Report solution s.
Definition: dfs.hh:150
No-goods recorded from restarts.
Definition: core.hpp:1240
#define forceinline
Definition: config.hpp:132
Parallel depth-first search worker
Definition: engine.hh:52
Parallel depth-first search engine
Definition: dfs.hh:46
SpaceStatus status(StatusStatistics &stat=unused_status)
Query space status.
Definition: core.cpp:252
Support::DynamicQueue< Space *, Heap > solutions
Queue of solutions.
Definition: engine.hh:169
Engine & _engine
Reference to engine.
Definition: engine.hh:55
Gecode toplevel namespace
DFS & engine(void) const
Provide access to engine.
Definition: dfs.hh:94
Worker ** _worker
Array of worker references.
Definition: dfs.hh:63
Space is failed
Definition: core.hpp:1301
void reset(int l)
Reset stack and set no-good depth limit to l.
Definition: path.hh:309
virtual ~DFS(void)
Destructor.
Definition: dfs.cpp:230
bool signal(void) const
Whether search state changed such that signal is needed.
Definition: engine.hh:289
void reset(void)
Reset.
Definition: statistics.hpp:43
Support::Mutex m_search
Mutex for search.
Definition: engine.hh:165