/* * Copyright (c) 1989 Jan-Simon Pendry * Copyright (c) 1989 Imperial College of Science, Technology & Medicine * Copyright (c) 1989, 1993 * 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. 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. * * from: @(#)clock.c 8.1 (Berkeley) 6/6/93 * $Id: clock.c,v 1.7 2014/10/26 03:08:21 guenther Exp $ */ /* * Callouts. * * Modelled 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. */ #include "am.h" typedef struct callout callout; struct callout { callout *c_next; /* List of callouts */ void (*c_fn)(void *); /* Function to call */ void *c_closure; /* Closure 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(callout); } static void free_callout(callout *cp) { if (nfree_callouts > CALLOUT_FREE_SLOP) { free(cp); } else { cp->c_next = free_callouts; free_callouts = cp; nfree_callouts++; } } /* * Schedule a callout. * * (*fn)(closure) will be called at clocktime() + secs */ int timeout(unsigned int secs, void (*fn)(void *), void *closure) { callout *cp, *cp2; time_t t = clocktime() + secs; /* * Allocate and fill in a new callout structure */ callout *cpnew = alloc_callout(); cpnew->c_closure = closure; 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); #ifdef DEBUG dlog("rescheduling job %d back %d seconds", cp->c_id, cp->c_time - now); #endif 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(); /* * While there are more callouts waiting... */ while ((cp = callouts.c_next) && cp->c_time <= now) { /* * Extract first from list, save fn & closure 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 */ void (*fn)(void *) = cp->c_fn; void *closure = cp->c_closure; callouts.c_next = cp->c_next; free_callout(cp); #ifdef DEBUG /*dlog("Calling %#x(%#x)", fn, closure);*/ #endif /* DEBUG */ (*fn)(closure); } } 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; }
