/*
* iSCSI timeout & deferred work handling
*
* Copyright (C) 2004 Dmitry Yusupov, Alex Aizman
* Copyright (C) 2014 Red Hat Inc.
* maintained by open-iscsi@googlegroups.com
*
* 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.
*
* See the file COPYING included with this distribution for more details.
*/
#include <inttypes.h>
#include <time.h>
#include <sys/signalfd.h>
#include <assert.h>
#include <unistd.h>
#include "actor.h"
#include "log.h"
#include "list.h"
static LIST_HEAD(pend_list);
static LIST_HEAD(ready_list);
static volatile int poll_in_progress;
static uint64_t
actor_time_left(actor_t *thread, uint64_t current_time)
{
if (current_time > thread->ttschedule)
return 0;
else
return (thread->ttschedule - current_time);
}
#define time_after(a,b) \
((int64_t)(b) - (int64_t)(a) < 0)
void
actor_init(actor_t *thread, void (*callback)(void *), void *data)
{
INIT_LIST_HEAD(&thread->list);
thread->state = ACTOR_NOTSCHEDULED;
thread->callback = callback;
thread->data = data;
}
void
actor_delete(actor_t *thread)
{
log_debug(7, "thread %08lx delete: state %d", (long)thread,
thread->state);
switch(thread->state) {
case ACTOR_WAITING:
/* TODO: remove/reset alarm if we were 1st entry in pend_list */
/* priority: low */
/* fallthrough */
case ACTOR_SCHEDULED:
log_debug(1, "deleting a scheduled/waiting thread!");
list_del_init(&thread->list);
if (list_empty(&pend_list)) {
log_debug(7, "nothing left on pend_list, deactivating alarm");
alarm(0);
}
break;
default:
break;
}
thread->state = ACTOR_NOTSCHEDULED;
}
/*
* Inserts actor on pend list and sets alarm if new item is
* sooner than previous entries.
*/
static void
actor_insert_on_pend_list(actor_t *thread, uint32_t delay_secs)
{
struct actor *orig_head;
struct actor *new_head;
struct actor *next_thread;
orig_head = list_first_entry_or_null(&pend_list,
struct actor, list);
/* insert new entry in sort order */
list_for_each_entry(next_thread, &pend_list, list) {
if (time_after(next_thread->ttschedule, thread->ttschedule)) {
log_debug(7, "next thread %p due %lld", next_thread,
(long long)next_thread->ttschedule);
log_debug(7, "new thread %p is before (%lld), inserting", thread,
(long long)thread->ttschedule);
/* insert new thread before the next thread */
__list_add(&thread->list, next_thread->list.prev, &next_thread->list);
goto inserted;
}
}
if (orig_head) {
log_debug(7, "last thread %p due %lld", next_thread,
(long long)next_thread->ttschedule);
log_debug(7, "new thread %p is after (%lld), inserting at tail", thread,
(long long)thread->ttschedule);
}
else
log_debug(7, "new thread %p due %lld is first item on pend_list", thread,
(long long)thread->ttschedule);
/* Not before any existing entries */
list_add_tail(&thread->list, &pend_list);
inserted:
new_head = list_first_entry(&pend_list, struct actor, list);
if (orig_head != new_head) {
int result = alarm(delay_secs);
log_debug(7, "new alarm set for %d seconds, old alarm %d",
delay_secs, result);
}
}
static void
actor_schedule_private(actor_t *thread, uint32_t delay_secs, int head)
{
time_t current_time;
struct timespec tv;
if (clock_gettime(CLOCK_MONOTONIC_COARSE, &tv)) {
log_error("clock_getime failed, can't schedule!");
return;
}
current_time = tv.tv_sec;
log_debug(7, "thread %p schedule: delay %u state %d",
thread, delay_secs, thread->state);
switch(thread->state) {
case ACTOR_WAITING:
log_error("rescheduling a waiting thread!");
list_del(&thread->list);
/* fall-through */
case ACTOR_NOTSCHEDULED:
INIT_LIST_HEAD(&thread->list);
if (delay_secs == 0) {
thread->state = ACTOR_SCHEDULED;
if (head)
list_add(&thread->list, &ready_list);
else
list_add_tail(&thread->list, &ready_list);
} else {
thread->state = ACTOR_WAITING;
thread->ttschedule = current_time + delay_secs;
actor_insert_on_pend_list(thread, delay_secs);
}
break;
case ACTOR_SCHEDULED:
// don't do anything
break;
case ACTOR_INVALID:
log_error("BUG: Trying to schedule a thread that has not been "
"setup. Ignoring sched.");
break;
}
}
void
actor_schedule_head(actor_t *thread)
{
actor_schedule_private(thread, 0, 1);
}
void
actor_schedule(actor_t *thread)
{
actor_schedule_private(thread, 0, 0);
}
void
actor_timer(actor_t *thread, uint32_t timeout_secs, void (*callback)(void *),
void *data)
{
actor_init(thread, callback, data);
actor_schedule_private(thread, timeout_secs, 0);
}
void
actor_timer_mod(actor_t *thread, uint32_t new_timeout_secs, void *data)
{
actor_delete(thread);
thread->data = data;
actor_schedule_private(thread, new_timeout_secs, 0);
}
/*
* Execute all items that have expired.
*
* Set an alarm if items remain. Caller must catch SIGALRM and
* then re-invoke this function.
*/
void
actor_poll(void)
{
struct actor *thread, *tmp;
uint64_t current_time;
struct timespec tv;
if (poll_in_progress) {
log_error("recursive actor_poll() is not allowed");
return;
}
if (clock_gettime(CLOCK_MONOTONIC_COARSE, &tv)) {
log_error("clock_gettime failed, can't schedule!");
return;
}
current_time = tv.tv_sec;
/*
* Move items that are ripe from pend_list to ready_list.
* Actors are in sorted order of ascending run time, so
* stop at the first unripe entry.
*/
log_debug(7, "current time %" PRIu64, current_time);
list_for_each_entry_safe(thread, tmp, &pend_list, list) {
uint64_t time_left = actor_time_left(thread, current_time);
if (time_left) {
log_debug(7, "thread %08lx due %" PRIu64 ", wait %" PRIu64 " more",
(long)thread, thread->ttschedule, time_left);
alarm(time_left);
break;
}
/* This entry can be run now */
list_del_init(&thread->list);
log_debug(2, "thread %08lx was scheduled for "
"%" PRIu64 ", curtime %" PRIu64 " q_forw %p "
"&pend_list %p",
(long)thread, thread->ttschedule,
current_time, pend_list.next, &pend_list);
list_add_tail(&thread->list, &ready_list);
assert(thread->state == ACTOR_WAITING);
thread->state = ACTOR_SCHEDULED;
log_debug(7, "thread %08lx now in ready_list",
(long)thread);
}
/* Disable alarm if nothing else pending */
if (list_empty(&pend_list)) {
log_debug(7, "nothing on pend_list, deactivating alarm");
alarm(0);
}
poll_in_progress = 1;
while (!list_empty(&ready_list)) {
thread = list_first_entry(&ready_list, struct actor, list);
list_del_init(&thread->list);
if (thread->state != ACTOR_SCHEDULED)
log_error("ready_list: thread state corrupted! "
"Thread with state %d in actor list.",
thread->state);
thread->state = ACTOR_NOTSCHEDULED;
log_debug(7, "exec thread %08lx callback", (long)thread);
thread->callback(thread->data);
log_debug(7, "thread %08lx done", (long)thread);
}
poll_in_progress = 0;
}