summaryrefslogtreecommitdiffstats
path: root/src/sandglass.c
blob: 3399b7364b3c03a257e72275b1db8913a237f3cf (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
/*************************************************************************
 * Copyright (C) 2008 Tavian Barnes <tavianator@gmail.com>               *
 *                                                                       *
 * This file is part of The Sandglass Library.                           *
 *                                                                       *
 * The Sandglass Library is free software; you can redistribute it       *
 * and/or modify it under the terms of the GNU Lesser General Public     *
 * License as published by the Free Software Foundation; either version  *
 * 3 of the License, or (at your option) any later version.              *
 *                                                                       *
 * The Sandglass Library is distributed in the hope that it will be      *
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty   *
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  *
 * Lesser General Public License for more details.                       *
 *                                                                       *
 * You should have received a copy of the GNU Lesser General Public      *
 * License along with this program.  If not, see                         *
 * <http://www.gnu.org/licenses/>.                                       *
 *************************************************************************/

#include "sandglass_impl.h"
#include "sandglass.h"
#include <unistd.h>
#include <time.h>
#include <errno.h>

static int sandglass_real_create(sandglass_t *sandglass,
                                 const sandglass_attributes_t *attr);

/* Create a timer */
int
sandglass_create(sandglass_t *sandglass,
                 const sandglass_attributes_t *min,
                 const sandglass_attributes_t *max)
{
  sandglass_attributes_t realmin, realmax;

  /* Get our real min and max values */

  if (min)
    realmin = *min;
  else {
    /* min defaults to { SANDGLASS_INTROSPECTIVE, SANDGLASS_SYSTEM } */
    realmin.incrementation = SANDGLASS_INTROSPECTIVE;
    realmin.resolution     = SANDGLASS_SYSTEM;
  }

  if (max)
    realmax = *max;
  else {
    /* max defaults to the greater of min and { SANDGLASS_INTROSPECTIVE,
       SANDGLASS_CPUTIME } */
    if (realmin.incrementation > SANDGLASS_INTROSPECTIVE
        || (realmin.incrementation == SANDGLASS_INTROSPECTIVE
            && realmin.resolution > SANDGLASS_CPUTIME))
      realmax = realmin;
    else {
      realmax.incrementation = SANDGLASS_INTROSPECTIVE;
      realmax.resolution     = SANDGLASS_CPUTIME;
    }
  }

  /* Ensure max >= min */
  if (realmax.incrementation < realmin.incrementation
      || (realmax.incrementation == realmin.incrementation
          && realmax.resolution < realmin.resolution))
  {
    errno = EINVAL;
    return -1;
  }

  /* Now search for available timers, starting from max */

  while (sandglass_real_create(sandglass, &realmax) != 0) {
    /* Once we reach the minimum attributes, bail out */
    if (realmax.incrementation == realmin.incrementation
        && realmax.resolution == realmin.resolution)
    {
      errno = ENOTSUP;
      return -1;
    }

    /* Try the next lowest allowable settings */
    if (realmax.resolution)
      --realmax.resolution;
    else {
      if (realmax.incrementation) {
        --realmax.incrementation;
        realmax.resolution = SANDGLASS_CPUTIME;
      } else {
        errno = ENOTSUP;
        return -1;
      }
    }
  }

  return 0;
}

static int
sandglass_real_create(sandglass_t *sandglass,
                      const sandglass_attributes_t *attr)
{
  switch (attr->incrementation) {
    case SANDGLASS_MONOTONIC:
      switch (attr->resolution) {
        case SANDGLASS_REALTICKS:
#ifdef SANDGLASS_TSC
          sandglass->resolution = sandglass_tsc_resolution();
          sandglass->loops      = sandglass_tsc_loops();
          break;
#else
          return -1;
#endif

        case SANDGLASS_CPUTIME:
#ifdef SANDGLASS_TSC
          sandglass->resolution = sandglass_tsc_resolution();
          sandglass->loops      = 1;
          break;
#else
          return -1;
#endif

        case SANDGLASS_SYSTEM:
          sandglass->resolution = 1e9;
          sandglass->loops      = 1;
          break;

        default:
          return -1;
      }
      break;

    case SANDGLASS_INTROSPECTIVE:
      switch (attr->resolution) {
        case SANDGLASS_REALTICKS:
          /* No such thing as an introspective raw TSC */
          return -1;

        case SANDGLASS_CPUTIME:
          if (sysconf(_SC_THREAD_CPUTIME) > 0 || sysconf(_SC_CPUTIME) > 0) {
            sandglass->resolution = 1e9;
            sandglass->loops      = 1;
          } else
            return -1;
          break;

        case SANDGLASS_SYSTEM:
          sandglass->resolution = CLOCKS_PER_SEC;
          sandglass->loops      = 1;
          break;

        default:
          return -1;
      }
      break;

    default:
      return -1;
  }

  sandglass->attributes = *attr;
  return 0;
}

/* Store a timer value in sandglass->grains */
static int sandglass_real_gettime(sandglass_t *sandglass);

/* Start timing */
int
sandglass_begin(sandglass_t *sandglass)
{
  return sandglass_real_gettime(sandglass);
}

/* Finish timing */
int
sandglass_elapse(sandglass_t *sandglass)
{
  long oldgrains = sandglass->grains;

  if (sandglass_real_gettime(sandglass) != 0)
    return -1;

  sandglass->grains -= oldgrains;
  /* Magical correction for timespec-based grains */
  if (sandglass->grains < 0)
    sandglass->grains += 2000000000L;
  sandglass->grains /= sandglass->loops;

  return 0;
}

/* Store a timer value in sandglass->grains */
static int
sandglass_real_gettime(sandglass_t *sandglass)
{
  struct timespec ts;
  clock_t clock_ticks;

  switch (sandglass->attributes.incrementation) {
    case SANDGLASS_MONOTONIC:
      switch (sandglass->attributes.resolution) {
        case SANDGLASS_REALTICKS:
#ifdef SANDGLASS_TSC
          sandglass->grains = sandglass_get_tsc();
          break;
#else
          return -1;
#endif

        case SANDGLASS_CPUTIME:
#ifdef SANDGLASS_TSC
          sandglass->grains = sandglass_get_tsc();
          break;
#else
          return -1;
#endif

        case SANDGLASS_SYSTEM:
          if (sysconf(_SC_MONOTONIC_CLOCK) > 0) {
            if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
              return -1;
          } else {
            if (clock_gettime(CLOCK_REALTIME, &ts) != 0)
              return -1;
          }
          sandglass->grains = sandglass_timespec_grains(&ts);
          break;

        default:
          return -1;
      }
      break;

    case SANDGLASS_INTROSPECTIVE:
      switch (sandglass->attributes.resolution) {
        case SANDGLASS_REALTICKS:
          /* No such thing as an introspective raw TSC */
          return -1;

        case SANDGLASS_CPUTIME:
          if (sysconf(_SC_THREAD_CPUTIME) > 0) {
            if (clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts) != 0)
              return -1;
          } else if (sysconf(_SC_CPUTIME) > 0) {
            if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts) != 0)
              return -1;
          } else
            return -1;
          sandglass->grains = sandglass_timespec_grains(&ts);
          break;

        case SANDGLASS_SYSTEM:
          if ((clock_ticks = clock()) == -1)
            return -1;
          sandglass->grains = clock();
          break;

        default:
          return -1;
      }
      break;

    default:
      return -1;
  }

  return 0;
}