1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 #include "statcommon.h"
27
28 #include <stdarg.h>
29 #include <signal.h>
30 #include <errno.h>
31 #include <string.h>
32 #include <stdlib.h>
33
34 extern char *cmdname;
35 extern int caught_cont;
36
37 /*PRINTFLIKE2*/
38 void
fail(int do_perror,char * message,...)39 fail(int do_perror, char *message, ...)
40 {
41 va_list args;
42 int save_errno = errno;
43
44 va_start(args, message);
45 (void) fprintf(stderr, "%s: ", cmdname);
46 (void) vfprintf(stderr, message, args);
47 va_end(args);
48 if (do_perror)
49 (void) fprintf(stderr, ": %s", strerror(save_errno));
50 (void) fprintf(stderr, "\n");
51 exit(2);
52 }
53
54 /*
55 * Sleep until *wakeup + interval, keeping cadence where desired
56 *
57 * *wakeup - The time we last wanted to wake up. Updated.
58 * interval - We want to sleep until *wakeup + interval
59 * forever - Running for infinite periods, so cadence not important
60 * *caught_cont - Global set by signal handler if we got a SIGCONT
61 */
62 void
sleep_until(hrtime_t * wakeup,hrtime_t interval,int forever,int * caught_cont)63 sleep_until(hrtime_t *wakeup, hrtime_t interval, int forever,
64 int *caught_cont)
65 {
66 hrtime_t now, pause, pause_left;
67 struct timespec pause_tv;
68 int status;
69
70 now = gethrtime();
71 pause = *wakeup + interval - now;
72
73 if (pause <= 0 || pause < (interval / 4))
74 if (forever || *caught_cont) {
75 /* Reset our cadence (see comment below) */
76 *wakeup = now + interval;
77 pause = interval;
78 } else {
79 /*
80 * If we got here, then the time between the
81 * output we just did, and the scheduled time
82 * for the next output is < 1/4 of our requested
83 * interval AND the number of intervals has been
84 * requested AND we have never caught a SIGCONT
85 * (so we have never been suspended). In this
86 * case, we'll try to stay to the desired
87 * cadence, and we will pause for 1/2 the normal
88 * interval this time.
89 */
90 pause = interval / 2;
91 *wakeup += interval;
92 }
93 else
94 *wakeup += interval;
95 if (pause < 1000)
96 /* Near enough */
97 return;
98
99 /* Now do the actual sleep */
100 pause_left = pause;
101 do {
102 pause_tv.tv_sec = pause_left / NANOSEC;
103 pause_tv.tv_nsec = pause_left % NANOSEC;
104 status = nanosleep(&pause_tv, (struct timespec *)NULL);
105 if (status < 0)
106 if (errno == EINTR) {
107 now = gethrtime();
108 pause_left = *wakeup - now;
109 if (pause_left < 1000)
110 /* Near enough */
111 return;
112 } else {
113 fail(1, "nanosleep failed");
114 }
115 } while (status != 0);
116 }
117
118 /*
119 * Signal handler - so we can be aware of SIGCONT
120 */
121 void
cont_handler(int sig_number)122 cont_handler(int sig_number)
123 {
124 /* Re-set the signal handler */
125 (void) signal(sig_number, cont_handler);
126 caught_cont = 1;
127 }
128