Generated on Thu Mar 13 2014 04:39:35 for Gecode by doxygen 1.8.1.2
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: 2011-04-11 19:28:27 +1000 (Mon, 11 Apr 2011) $ by $Author: tack $
11  * $Revision: 11929 $
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, size_t sz, DFS& e);
54  DFS& engine(void) const;
56  virtual void run(void);
58  void find(void);
60  Space* reset(Space* s);
61  };
64  public:
66  Worker* worker(unsigned int i) const;
67 
69 
70 
71  void solution(Space* s);
73  Space* reset(Space* s);
75 
77 
78 
79  DFS(Space* s, size_t sz, const Options& o);
81  virtual Statistics statistics(void) const;
83  virtual ~DFS(void);
85  };
86 
87 
88  /*
89  * Basic access routines
90  */
92  DFS::Worker::engine(void) const {
93  return static_cast<DFS&>(_engine);
94  }
96  DFS::worker(unsigned int i) const {
97  return _worker[i];
98  }
99 
100 
101  /*
102  * Engine: initialization
103  */
105  DFS::Worker::Worker(Space* s, size_t sz, DFS& e)
106  : Engine::Worker(s,sz,e) {}
108  DFS::DFS(Space* s, size_t sz, const Options& o)
109  : Engine(o) {
110  // Create workers
111  _worker = static_cast<Worker**>
112  (heap.ralloc(workers() * sizeof(Worker*)));
113  // The first worker gets the entire search tree
114  _worker[0] = new Worker(s,sz,*this);
115  // All other workers start with no work
116  for (unsigned int i=1; i<workers(); i++)
117  _worker[i] = new Worker(NULL,sz,*this);
118  // Block all workers
119  block();
120  // Create and start threads
121  for (unsigned int i=0; i<workers(); i++)
123  }
124 
125  /*
126  * Statistics
127  */
130  delete cur;
131  path.reset();
132  d = 0;
133  idle = false;
134  if ((s == NULL) || (s->status(*this) == SS_FAILED)) {
135  delete s;
136  cur = NULL;
138  return NULL;
139  } else {
140  cur = s;
142  return s->clone(false);
143  }
144  }
147  // All workers are marked as busy again
148  n_busy = workers();
149  for (unsigned int i=1; i<workers(); i++)
150  (void) worker(i)->reset(NULL);
151  return worker(0)->reset(s);
152  }
153 
154  /*
155  * Engine: search control
156  */
157  forceinline void
159  m_search.acquire();
160  bool bs = signal();
161  solutions.push(s);
162  if (bs)
163  e_search.signal();
164  m_search.release();
165  }
166 
167 
168 
169 
170  /*
171  * Worker: finding and stealing working
172  */
173  forceinline void
175  // Try to find new work (even if there is none)
176  for (unsigned int i=0; i<engine().workers(); i++) {
177  unsigned long int r_d = 0ul;
178  if (Space* s = engine().worker(i)->steal(r_d)) {
179  // Reset this guy
180  m.acquire();
181  idle = false;
182  d = 0;
183  cur = s;
184  Search::Worker::reset(cur,r_d);
185  m.release();
186  return;
187  }
188  }
189  }
190 
191 }}}
192 
193 #endif
194 
195 // STATISTICS: search-parallel