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Diffstat (limited to 'amd/clock.c')
| -rw-r--r-- | amd/clock.c | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/amd/clock.c b/amd/clock.c new file mode 100644 index 000000000000..0caa7dff2c73 --- /dev/null +++ b/amd/clock.c @@ -0,0 +1,244 @@ +/* + * Copyright (c) 1997-2006 Erez Zadok + * Copyright (c) 1989 Jan-Simon Pendry + * Copyright (c) 1989 Imperial College of Science, Technology & Medicine + * Copyright (c) 1989 The Regents of the University of California. + * All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Jan-Simon Pendry at Imperial College, London. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgment: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * + * File: am-utils/amd/clock.c + * + */ + +/* + * Callouts. + * + * Modeled on kernel object of the same name. + * See usual references. + * + * Use of a heap-based mechanism was rejected: + * 1. more complex implementation needed. + * 2. not obvious that a list is too slow for Amd. + */ + +#ifdef HAVE_CONFIG_H +# include <config.h> +#endif /* HAVE_CONFIG_H */ +#include <am_defs.h> +#include <amd.h> + +void reschedule_timeouts(time_t now, time_t then); + +typedef struct callout callout; +struct callout { + callout *c_next; /* List of callouts */ + callout_fun *c_fn; /* Function to call */ + opaque_t c_arg; /* Argument to pass to call */ + time_t c_time; /* Time of call */ + int c_id; /* Unique identifier */ +}; + +static callout callouts; /* List of pending callouts */ +static callout *free_callouts; /* Cache of free callouts */ +static int nfree_callouts; /* Number on free list */ +static int callout_id; /* Next free callout identifier */ + +time_t next_softclock; /* Time of next call to softclock() */ + + +/* + * Number of callout slots we keep on the free list + */ +#define CALLOUT_FREE_SLOP 10 + +/* + * Global assumption: valid id's are non-zero. + */ +#define CID_ALLOC() (++callout_id) +#define CID_UNDEF (0) + + +static callout * +alloc_callout(void) +{ + callout *cp = free_callouts; + + if (cp) { + --nfree_callouts; + free_callouts = free_callouts->c_next; + return cp; + } + return ALLOC(struct callout); +} + + +static void +free_callout(callout *cp) +{ + if (nfree_callouts > CALLOUT_FREE_SLOP) { + XFREE(cp); + } else { + cp->c_next = free_callouts; + free_callouts = cp; + nfree_callouts++; + } +} + + +/* + * Schedule a callout. + * + * (*fn)(fn_arg) will be called at clocktime(NULL) + secs + */ +int +timeout(u_int secs, callout_fun *fn, opaque_t fn_arg) +{ + callout *cp, *cp2; + time_t t = clocktime(NULL) + secs; + + /* + * Allocate and fill in a new callout structure + */ + callout *cpnew = alloc_callout(); + cpnew->c_arg = fn_arg; + cpnew->c_fn = fn; + cpnew->c_time = t; + cpnew->c_id = CID_ALLOC(); + + if (t < next_softclock) + next_softclock = t; + + /* + * Find the correct place in the list + */ + for (cp = &callouts; (cp2 = cp->c_next); cp = cp2) + if (cp2->c_time >= t) + break; + + /* + * And link it in + */ + cp->c_next = cpnew; + cpnew->c_next = cp2; + + /* + * Return callout identifier + */ + return cpnew->c_id; +} + + +/* + * De-schedule a callout + */ +void +untimeout(int id) +{ + callout *cp, *cp2; + for (cp = &callouts; (cp2 = cp->c_next); cp = cp2) { + if (cp2->c_id == id) { + cp->c_next = cp2->c_next; + free_callout(cp2); + break; + } + } +} + + +/* + * Reschedule after clock changed + */ +void +reschedule_timeouts(time_t now, time_t then) +{ + callout *cp; + + for (cp = callouts.c_next; cp; cp = cp->c_next) { + if (cp->c_time >= now && cp->c_time <= then) { + plog(XLOG_WARNING, "job %d rescheduled to run immediately", cp->c_id); + dlog("rescheduling job %d back %ld seconds", + cp->c_id, (long) (cp->c_time - now)); + next_softclock = cp->c_time = now; + } + } +} + + +/* + * Clock handler + */ +int +softclock(void) +{ + time_t now; + callout *cp; + + do { + if (task_notify_todo) + do_task_notify(); + + now = clocktime(NULL); + + /* + * While there are more callouts waiting... + */ + while ((cp = callouts.c_next) && cp->c_time <= now) { + /* + * Extract first from list, save fn & fn_arg and + * unlink callout from list and free. + * Finally call function. + * + * The free is done first because + * it is quite common that the + * function will call timeout() + * and try to allocate a callout + */ + callout_fun *fn = cp->c_fn; + opaque_t fn_arg = cp->c_arg; + + callouts.c_next = cp->c_next; + free_callout(cp); + (*fn) (fn_arg); + } + + } while (task_notify_todo); + + /* + * Return number of seconds to next event, + * or 0 if there is no event. + */ + if ((cp = callouts.c_next)) + return cp->c_time - now; + return 0; +} |