/*
 * $Id: event.c,v 1.39 2008/06/04 20:09:15 hno Exp $
 *
 * DEBUG: section 41    Event Processing
 * AUTHOR: Henrik Nordstrom
 *
 * SQUID Web Proxy Cache          http://www.squid-cache.org/
 * ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from
 *  the Internet community; see the CONTRIBUTORS file for full
 *  details.   Many organizations have provided support for Squid's
 *  development; see the SPONSORS file for full details.  Squid is
 *  Copyrighted (C) 2001 by the Regents of the University of
 *  California; see the COPYRIGHT file for full details.  Squid
 *  incorporates software developed and/or copyrighted by other
 *  sources; see the CREDITS file for full details.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *  
 *  This program 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 General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 */

#include "squid.h"

/* The list of event processes */
struct ev_entry {
    EVH *func;
    void *arg;
    const char *name;
    double when;
    struct ev_entry *next;
    int weight;
    int id;
};

static struct ev_entry *tasks = NULL;
static OBJH eventMgr;
static OBJH eventDump;
static int run_id = 0;
static const char *last_event_ran = NULL;

void
eventAdd(const char *name, EVH * func, void *arg, double when, int weight)
{
    struct ev_entry *event = memAllocate(MEM_EVENT);
    struct ev_entry **E;
    event->func = func;
    event->arg = arg;
    event->name = name;
    event->when = current_dtime + when;
    event->weight = weight;
    event->id = run_id;
    if (NULL != arg)
	cbdataLock(arg);
    debug(41, 7) ("eventAdd: Adding '%s', in %f seconds\n", name, when);
    /* Insert after the last event with the same or earlier time */
    for (E = &tasks; *E; E = &(*E)->next) {
	if ((*E)->when > event->when)
	    break;
    }
    event->next = *E;
    *E = event;
}

/* same as eventAdd but adds a random offset within +-1/3 of delta_ish */
void
eventAddIsh(const char *name, EVH * func, void *arg, double delta_ish, int weight)
{
    if (delta_ish >= 3.0) {
	const double two_third = (2.0 * delta_ish) / 3.0;
	delta_ish = two_third + (drand48() * two_third);
	/*
	 * I'm sure drand48() isn't portable.  Tell me what function
	 * you have that returns a random double value in the range 0,1.
	 */
    }
    eventAdd(name, func, arg, delta_ish, weight);
}

void
eventDelete(EVH * func, void *arg)
{
    struct ev_entry **E;
    struct ev_entry *event;
    for (E = &tasks; (event = *E) != NULL; E = &(*E)->next) {
	if (event->func != func)
	    continue;
	if (arg && event->arg != arg)
	    continue;
	*E = event->next;
	if (NULL != event->arg)
	    cbdataUnlock(event->arg);
	memFree(event, MEM_EVENT);
	return;
    }
    if (arg)
	debug_trap("eventDelete: event not found");
}

void
eventRun(void)
{
    struct ev_entry *event = NULL;
    EVH *func;
    void *arg;
    int weight = 0;
    if (NULL == tasks)
	return;
    if (tasks->when > current_dtime)
	return;
    run_id++;
    debug(41, 5) ("eventRun: RUN ID %d\n", run_id);
    while ((event = tasks)) {
	int valid = 1;
	if (event->when > current_dtime)
	    break;
	if (event->id == run_id)	/* was added during this run */
	    break;
	if (weight)
	    break;
	func = event->func;
	arg = event->arg;
	event->func = NULL;
	event->arg = NULL;
	tasks = event->next;
	if (NULL != arg) {
	    valid = cbdataValid(arg);
	    cbdataUnlock(arg);
	}
	if (valid) {
	    weight += event->weight;
	    /* XXX assumes ->name is static memory! */
	    last_event_ran = event->name;
	    debug(41, 5) ("eventRun: Running '%s', id %d\n",
		event->name, event->id);
	    func(arg);
	}
	memFree(event, MEM_EVENT);
    }
}

void
eventCleanup(void)
{
    struct ev_entry **p = &tasks;

    debug(41, 2) ("eventCleanup\n");

    while (*p) {
	struct ev_entry *event = *p;
	if (!cbdataValid(event->arg)) {
	    debug(41, 2) ("eventCleanup: cleaning '%s'\n", event->name);
	    *p = event->next;
	    cbdataUnlock(event->arg);
	    memFree(event, MEM_EVENT);
	} else {
	    p = &event->next;
	}
    }
}

int
eventNextTime(void)
{
    if (!tasks)
	return 10000;
    return ceil((tasks->when - current_dtime) * 1000);
}

void
eventInit(void)
{
    memDataInit(MEM_EVENT, "event", sizeof(struct ev_entry), 0);
    cachemgrRegister("events",
	"Event Queue",
	eventMgr, 0, 1);
}

static void
eventDump(StoreEntry * sentry)
{
    struct ev_entry *e = tasks;
    if (last_event_ran)
	storeAppendPrintf(sentry, "Last event to run: %s\n\n", last_event_ran);
    storeAppendPrintf(sentry, "%s\t%s\t%s\t%s\n",
	"Operation",
	"Next Execution",
	"Weight",
	"Callback Valid?");
    while (e != NULL) {
	storeAppendPrintf(sentry, "%s\t%f seconds\t%d\t%s\n",
	    e->name, e->when - current_dtime, e->weight,
	    e->arg ? cbdataValid(e->arg) ? "yes" : "no" : "N/A");
	e = e->next;
    }
}

static void
eventMgrTrigger(StoreEntry * sentry, const char *name)
{
#if DEBUG_MEMPOOL		/* XXX: this abuses the existing mempool debug configure option.. too lazy to create a new one for this */
    struct ev_entry **E, *e;
    for (E = &tasks; (e = *E) != NULL; E = *E ? &(*E)->next : NULL) {
	if (strcmp(e->name, name) == 0) {
	    debug(50, 1) ("eventMgrTrigger: Scheduling '%s' to be run NOW\n", e->name);
	    e->when = 0;
	    *E = e->next;
	    e->next = tasks;
	    tasks = e;
	}
    }
#endif
}

static void
eventMgr(StoreEntry * e)
{
    char *arg = strchr(strBuf(e->mem_obj->request->urlpath) + 1, '/');
    if (arg) {
	char *name = xstrdup(arg + 1);
	rfc1738_unescape(name);
	eventMgrTrigger(e, name);
	safe_free(name);
    } else {
	eventDump(e);
    }
}

void
eventFreeMemory(void)
{
    struct ev_entry *event;
    while ((event = tasks)) {
	tasks = event->next;
	if (NULL != event->arg)
	    cbdataUnlock(event->arg);
	memFree(event, MEM_EVENT);
    }
    tasks = NULL;
}

int
eventFind(EVH * func, void *arg)
{
    struct ev_entry *event;
    for (event = tasks; event != NULL; event = event->next) {
	if (event->func == func && event->arg == arg)
	    return 1;
    }
    return 0;
}