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pbs.hpp
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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, 2015
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33
34#include <climits>
35
36namespace Gecode { namespace Search { namespace Seq {
37
38
41 : so(so0) {}
42 forceinline void
44 ssi = ssi0;
45 }
46
47
50 : slave(nullptr), stop(nullptr) {}
51 forceinline void
53 slave = e; stop = s;
54 }
57 return slave->next();
58 }
60 Slave::statistics(void) const {
61 return slave->statistics();
62 }
63 forceinline bool
64 Slave::stopped(void) const {
65 return slave->stopped();
66 }
67 forceinline void
69 slave->constrain(b);
70 }
73 delete slave;
74 delete stop;
75 }
76
77
78 template<bool best>
80 PBS<best>::PBS(Engine** e, Stop** s, unsigned int n,
81 const Statistics& stat0,
82 const Search::Options& opt)
83 : stat(stat0), slice(opt.slice),
84 slaves(heap.alloc<Slave>(n)), n_slaves(n), cur(0),
85 slave_stop(false) {
86 ssi.done = false;
87 ssi.l = opt.slice;
88
89 for (unsigned int i=0U; i<n; i++) {
90 slaves[i].init(e[i],static_cast<PortfolioStop*>(s[i]));
91 static_cast<PortfolioStop*>(s[i])->share(&ssi);
92 }
93 }
94
95 template<bool best>
96 Space*
98 slave_stop = false;
99 unsigned int n_exhausted = 0;
100 while (n_slaves > 0) {
101 if (Space* s = slaves[cur].next()) {
102 // Constrain other slaves
103 if (best) {
104 for (unsigned int i=0U; i<cur; i++)
105 slaves[i].constrain(*s);
106 for (unsigned int i=cur+1; i<n_slaves; i++)
107 slaves[i].constrain(*s);
108 }
109 return s;
110 }
111 if (slaves[cur].stopped()) {
112 if (ssi.done) {
113 cur++; n_exhausted++;
114 } else {
115 slave_stop = true;
116 return NULL;
117 }
118 } else {
119 // This slave is done, kill it after saving the statistics
120 stat += slaves[cur].statistics();
121 slaves[cur].~Slave();
123 if (n_slaves == 1)
124 // Disable stoping by seeting a high limit
125 ssi.l = ULONG_MAX;
126 }
127 if (n_exhausted == n_slaves) {
128 n_exhausted = 0;
129 // Increment by one slice
130 ssi.l += slice;
131 }
132 if (cur == n_slaves)
133 cur = 0;
134 }
135 return NULL;
136 }
137
138 template<bool best>
139 bool
140 PBS<best>::stopped(void) const {
141 return slave_stop;
142 }
143
144 template<bool best>
147 Statistics s(stat);
148 for (unsigned int i=0U; i<n_slaves; i++)
149 s += slaves[i].statistics();
150 return s;
151 }
152
153 template<bool best>
154 void
156 if (!best)
157 throw NoBest("PBS::constrain");
158 for (unsigned int i=0U; i<n_slaves; i++)
159 slaves[i].constrain(b);
160 }
161
162 template<bool best>
164 for (unsigned int i=0U; i<n_slaves; i++)
165 slaves[i].~Slave();
166 // Note that n_slaves might be different now!
167 heap.rfree(slaves);
168 }
169
170}}}
171
172// STATISTICS: search-seq
Search engine implementation interface
Definition search.hh:899
Exception: Best solution search is not supported
Definition exception.hpp:60
Search engine options
Definition search.hh:746
Slave * slaves
Slaves.
Definition pbs.hh:107
SharedStopInfo ssi
Shared slave information.
Definition pbs.hh:103
virtual ~PBS(void)
Destructor.
Definition pbs.hpp:163
unsigned int n_slaves
Number of slave engines.
Definition pbs.hh:109
bool slave_stop
Whether a slave has been stopped.
Definition pbs.hh:113
unsigned int slice
Size of a slice.
Definition pbs.hh:105
virtual Space * next(void)
Return next solution (NULL, if none exists or search has been stopped)
Definition pbs.hpp:97
Statistics stat
Master statistics.
Definition pbs.hh:101
virtual bool stopped(void) const
Check whether engine has been stopped.
Definition pbs.hpp:140
virtual Statistics statistics(void) const
Return statistics.
Definition pbs.hpp:146
unsigned int cur
Current slave to run.
Definition pbs.hh:111
virtual void constrain(const Space &b)
Constrain future solutions to be better than b.
Definition pbs.hpp:155
PBS(Engine **slaves, Stop **stops, unsigned int n, const Statistics &stat, const Search::Options &opt)
Initialize.
Definition pbs.hpp:80
Stop object used for controling slaves in a portfolio.
Definition pbs.hh:51
void share(SharedStopInfo *ssi)
Intialize shared stop information.
Definition pbs.hpp:43
PortfolioStop(Stop *so)
Initialize.
Definition pbs.hpp:40
Shared stop information.
Definition pbs.hh:42
Runnable slave of a portfolio master.
Definition pbs.hh:67
bool stopped(void) const
Check whether slave has been stopped.
Definition pbs.hpp:64
Space * next(void)
Return next solution.
Definition pbs.hpp:56
Engine * slave
The slave engine.
Definition pbs.hh:70
Slave(void)
Default constructor.
Definition pbs.hpp:49
void constrain(const Space &b)
Constrain with better solution b.
Definition pbs.hpp:68
Stop * stop
Stop object.
Definition pbs.hh:72
void init(Engine *s, Stop *so)
Initialize with slave s and its stop object so.
Definition pbs.hpp:52
Statistics statistics(void) const
Return statistics of slave.
Definition pbs.hpp:60
~Slave(void)
Delete slave.
Definition pbs.hpp:72
Search engine statistics
Definition search.hh:147
Base-class for Stop-object.
Definition search.hh:799
Stop(void)
Default constructor.
Definition stop.hpp:41
Computation spaces.
Definition core.hpp:1744
Heap heap
The single global heap.
Definition heap.cpp:44
Search engines
Gecode toplevel namespace
#define forceinline
Definition config.hpp:194