1 // ******************************************************************************
2 //
3 // Title: Force Field X.
4 // Description: Force Field X - Software for Molecular Biophysics.
5 // Copyright: Copyright (c) Michael J. Schnieders 2001-2025.
6 //
7 // This file is part of Force Field X.
8 //
9 // Force Field X is free software; you can redistribute it and/or modify it
10 // under the terms of the GNU General Public License version 3 as published by
11 // the Free Software Foundation.
12 //
13 // Force Field X is distributed in the hope that it will be useful, but WITHOUT
14 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
15 // FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
16 // details.
17 //
18 // You should have received a copy of the GNU General Public License along with
19 // Force Field X; if not, write to the Free Software Foundation, Inc., 59 Temple
20 // Place, Suite 330, Boston, MA 02111-1307 USA
21 //
22 // Linking this library statically or dynamically with other modules is making a
23 // combined work based on this library. Thus, the terms and conditions of the
24 // GNU General Public License cover the whole combination.
25 //
26 // As a special exception, the copyright holders of this library give you
27 // permission to link this library with independent modules to produce an
28 // executable, regardless of the license terms of these independent modules, and
29 // to copy and distribute the resulting executable under terms of your choice,
30 // provided that you also meet, for each linked independent module, the terms
31 // and conditions of the license of that module. An independent module is a
32 // module which is not derived from or based on this library. If you modify this
33 // library, you may extend this exception to your version of the library, but
34 // you are not obligated to do so. If you do not wish to do so, delete this
35 // exception statement from your version.
36 //
37 // ******************************************************************************
38 package ffx.potential.nonbonded;
39
40 import edu.rit.pj.IntegerSchedule;
41 import edu.rit.util.Range;
42 import java.util.logging.Logger;
43
44 /**
45 * A fixed schedule that balances pairwise work across threads.
46 *
47 * @author Michael J. Schnieders
48 * @since 1.0
49 */
50 public class PairwiseSchedule extends IntegerSchedule {
51
52 private static final Logger logger = Logger.getLogger(PairwiseSchedule.class.getName());
53 private final int nThreads;
54 private final Range[] ranges;
55 private final boolean[] threadDone;
56 private int nAtoms;
57 private int threadOffset;
58
59 /**
60 * Constructor for PairwiseSchedule.
61 *
62 * @param nThreads a int.
63 * @param nAtoms a int.
64 * @param ranges an array of {@link edu.rit.util.Range} objects.
65 */
66 public PairwiseSchedule(int nThreads, int nAtoms, Range[] ranges) {
67 this.nAtoms = nAtoms;
68 this.nThreads = nThreads;
69 threadOffset = 0;
70 this.ranges = ranges;
71 threadDone = new boolean[nThreads];
72 }
73
74 /**
75 * {@inheritDoc}
76 *
77 * <p>This is a fixed schedule.
78 */
79 @Override
80 public boolean isFixedSchedule() {
81 return true;
82 }
83
84 /** {@inheritDoc} */
85 @Override
86 public Range next(int threadID) {
87 if (!threadDone[threadID]) {
88 threadDone[threadID] = true;
89 return ranges[threadID];
90 }
91 return null;
92 }
93
94 /**
95 * setAtoms.
96 *
97 * @param nAtoms a int.
98 */
99 public void setAtoms(int nAtoms) {
100 this.nAtoms = nAtoms;
101 }
102
103 /** {@inheritDoc} */
104 @Override
105 public void start(int nThreads, Range chunkRange) {
106 assert (nThreads == this.nThreads);
107 assert (chunkRange.lb() == 0);
108 assert (chunkRange.ub() == nAtoms - 1);
109
110 for (int i = 0; i < nThreads; i++) {
111 threadDone[i] = false;
112 }
113 }
114
115 /**
116 * updateRanges
117 *
118 * @param totalInteractions a int.
119 * @param atomsWithInteractions the number of chunks of interactions.
120 * @param listCount an array of int.
121 */
122 void updateRanges(int totalInteractions, int atomsWithInteractions, int[] listCount) {
123 int id = 0;
124 int goal = totalInteractions / (nThreads + threadOffset);
125 int num = 0;
126 int start = 0;
127 for (int i = 0; i < nAtoms; i++) {
128 num += listCount[i];
129 if (num >= goal) {
130
131 // Last thread gets the remaining atoms.
132 if (id == nThreads - 1) {
133 ranges[id] = new Range(start, nAtoms - 1);
134 break;
135 }
136
137 ranges[id] = new Range(start, i);
138
139 // Zero out the interaction counter.
140 num = 0;
141 // Next thread.
142 id++;
143 // Next range starts at i+1.
144 start = i + 1;
145
146 // Out of atoms. Threads remaining get a null range.
147 if (start == nAtoms) {
148 if (atomsWithInteractions > nThreads + threadOffset + 1) {
149 threadOffset++;
150 updateRanges(totalInteractions, atomsWithInteractions, listCount);
151 break;
152 }
153 for (int j = id; j < nThreads; j++) {
154 ranges[j] = null;
155 }
156 break;
157 }
158 } else if (i == nAtoms - 1) {
159
160 // Last atom without reaching goal for current thread.
161 if (id < nThreads - 1 && atomsWithInteractions > nThreads + threadOffset + 1) {
162 threadOffset++;
163 updateRanges(totalInteractions, atomsWithInteractions, listCount);
164 break;
165 }
166 ranges[id] = new Range(start, nAtoms - 1);
167 for (int j = id + 1; j < nThreads; j++) {
168 ranges[j] = null;
169 }
170 }
171 }
172 threadOffset = 0;
173 }
174 }