1 /*
2 * Copyright (c) 1997-2014 Erez Zadok
3 * Copyright (c) 1989 Jan-Simon Pendry
4 * Copyright (c) 1989 Imperial College of Science, Technology & Medicine
5 * Copyright (c) 1989 The Regents of the University of California.
6 * All rights reserved.
7 *
8 * This code is derived from software contributed to Berkeley by
9 * Jan-Simon Pendry at Imperial College, London.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 *
36 * File: am-utils/amd/clock.c
37 *
38 */
39
40 /*
41 * Callouts.
42 *
43 * Modeled on kernel object of the same name.
44 * See usual references.
45 *
46 * Use of a heap-based mechanism was rejected:
47 * 1. more complex implementation needed.
48 * 2. not obvious that a list is too slow for Amd.
49 */
50
51 #ifdef HAVE_CONFIG_H
52 # include <config.h>
53 #endif /* HAVE_CONFIG_H */
54 #include <am_defs.h>
55 #include <amd.h>
56
57 void reschedule_timeouts(time_t now, time_t then);
58
59 typedef struct callout callout;
60 struct callout {
61 callout *c_next; /* List of callouts */
62 callout_fun *c_fn; /* Function to call */
63 opaque_t c_arg; /* Argument to pass to call */
64 time_t c_time; /* Time of call */
65 int c_id; /* Unique identifier */
66 };
67
68 static callout callouts; /* List of pending callouts */
69 static callout *free_callouts; /* Cache of free callouts */
70 static int nfree_callouts; /* Number on free list */
71 static int callout_id; /* Next free callout identifier */
72
73 time_t next_softclock; /* Time of next call to softclock() */
74
75
76 /*
77 * Number of callout slots we keep on the free list
78 */
79 #define CALLOUT_FREE_SLOP 10
80
81 /*
82 * Global assumption: valid id's are non-zero.
83 */
84 #define CID_ALLOC() (++callout_id)
85 #define CID_UNDEF (0)
86
87
88 static callout *
alloc_callout(void)89 alloc_callout(void)
90 {
91 callout *cp = free_callouts;
92
93 if (cp) {
94 --nfree_callouts;
95 free_callouts = free_callouts->c_next;
96 return cp;
97 }
98 return ALLOC(struct callout);
99 }
100
101
102 static void
free_callout(callout * cp)103 free_callout(callout *cp)
104 {
105 if (nfree_callouts > CALLOUT_FREE_SLOP) {
106 XFREE(cp);
107 } else {
108 cp->c_next = free_callouts;
109 free_callouts = cp;
110 nfree_callouts++;
111 }
112 }
113
114
115 /*
116 * Schedule a callout.
117 *
118 * (*fn)(fn_arg) will be called at clocktime(NULL) + secs
119 */
120 int
timeout(u_int secs,callout_fun * fn,opaque_t fn_arg)121 timeout(u_int secs, callout_fun *fn, opaque_t fn_arg)
122 {
123 callout *cp, *cp2;
124 time_t t = clocktime(NULL) + secs;
125
126 /*
127 * Allocate and fill in a new callout structure
128 */
129 callout *cpnew = alloc_callout();
130 cpnew->c_arg = fn_arg;
131 cpnew->c_fn = fn;
132 cpnew->c_time = t;
133 cpnew->c_id = CID_ALLOC();
134
135 if (t < next_softclock)
136 next_softclock = t;
137
138 /*
139 * Find the correct place in the list
140 */
141 for (cp = &callouts; (cp2 = cp->c_next); cp = cp2)
142 if (cp2->c_time >= t)
143 break;
144
145 /*
146 * And link it in
147 */
148 cp->c_next = cpnew;
149 cpnew->c_next = cp2;
150
151 /*
152 * Return callout identifier
153 */
154 return cpnew->c_id;
155 }
156
157
158 /*
159 * De-schedule a callout
160 */
161 void
untimeout(int id)162 untimeout(int id)
163 {
164 callout *cp, *cp2;
165 for (cp = &callouts; (cp2 = cp->c_next); cp = cp2) {
166 if (cp2->c_id == id) {
167 cp->c_next = cp2->c_next;
168 free_callout(cp2);
169 break;
170 }
171 }
172 }
173
174
175 /*
176 * Reschedule after clock changed
177 */
178 void
reschedule_timeouts(time_t now,time_t then)179 reschedule_timeouts(time_t now, time_t then)
180 {
181 callout *cp;
182
183 for (cp = callouts.c_next; cp; cp = cp->c_next) {
184 if (cp->c_time >= now && cp->c_time <= then) {
185 plog(XLOG_WARNING, "job %d rescheduled to run immediately", cp->c_id);
186 dlog("rescheduling job %d back %ld seconds",
187 cp->c_id, (long) (cp->c_time - now));
188 next_softclock = cp->c_time = now;
189 }
190 }
191 }
192
193
194 /*
195 * Clock handler
196 */
197 int
softclock(void)198 softclock(void)
199 {
200 time_t now;
201 callout *cp;
202
203 do {
204 if (task_notify_todo)
205 do_task_notify();
206
207 now = clocktime(NULL);
208
209 /*
210 * While there are more callouts waiting...
211 */
212 while ((cp = callouts.c_next) && cp->c_time <= now) {
213 /*
214 * Extract first from list, save fn & fn_arg and
215 * unlink callout from list and free.
216 * Finally call function.
217 *
218 * The free is done first because
219 * it is quite common that the
220 * function will call timeout()
221 * and try to allocate a callout
222 */
223 callout_fun *fn = cp->c_fn;
224 opaque_t fn_arg = cp->c_arg;
225
226 callouts.c_next = cp->c_next;
227 free_callout(cp);
228 (*fn) (fn_arg);
229 }
230
231 } while (task_notify_todo);
232
233 /*
234 * Return number of seconds to next event,
235 * or 0 if there is no event.
236 */
237 if ((cp = callouts.c_next))
238 return cp->c_time - now;
239 return 0;
240 }
241