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dfs.hh
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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: 2013-03-07 20:56:21 +0100 (Thu, 07 Mar 2013) $ by $Author: schulte $
11  * $Revision: 13463 $
12  *
13  * This file is part of Gecode, the generic constraint
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15  * http://www.gecode.org
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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  void reset(Space* s);
61  };
64  public:
66  Worker* worker(unsigned int i) const;
67 
69 
70 
71  void solution(Space* s);
73 
75 
76 
77  DFS(Space* s, size_t sz, const Options& o);
79  virtual Statistics statistics(void) const;
81  virtual void reset(Space* s);
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  */
128  forceinline void
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  } else {
139  cur = s;
141  }
142  }
143  /*
144  * Engine: search control
145  */
146  forceinline void
148  m_search.acquire();
149  bool bs = signal();
150  solutions.push(s);
151  if (bs)
152  e_search.signal();
153  m_search.release();
154  }
155 
156 
157 
158  /*
159  * Worker: finding and stealing working
160  */
161  forceinline void
163  // Try to find new work (even if there is none)
164  for (unsigned int i=0; i<engine().workers(); i++) {
165  unsigned long int r_d = 0ul;
166  if (Space* s = engine().worker(i)->steal(r_d)) {
167  // Reset this guy
168  m.acquire();
169  idle = false;
170  d = 0;
171  cur = s;
172  Search::Worker::reset(cur,r_d);
173  m.release();
174  return;
175  }
176  }
177  }
178 
179 }}}
180 
181 #endif
182 
183 // STATISTICS: search-parallel