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sc_timer.c
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sc_timer.c
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/*
* BSD-3-Clause
*
* Copyright 2021 Ozan Tezcan
* All rights reserved.
*
* 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 copyright holder 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 COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
*/
#include "sc_timer.h"
#include <assert.h>
#include <memory.h>
#define TICK 16u
#define WHEEL_COUNT 16u
#ifndef SC_TIMER_MAX
#define SC_TIMER_MAX ((UINT32_MAX / sizeof(struct sc_timer_data)) / WHEEL_COUNT)
#endif
void sc_timer_init(struct sc_timer *t, uint64_t timestamp)
{
*t = (struct sc_timer){
.timestamp = timestamp,
};
}
void sc_timer_term(struct sc_timer *t)
{
sc_timer_free(t->list);
*t = (struct sc_timer){
.timestamp = t->timestamp,
};
}
void sc_timer_clear(struct sc_timer *t)
{
const uint32_t cap = t->wheel * WHEEL_COUNT;
t->head = 0;
for (uint32_t i = 0; i < cap; i++) {
t->list[i].timeout = SC_TIMER_INVALID;
t->list[i].data = NULL;
}
}
static bool expand(struct sc_timer *t)
{
uint32_t wheel = t->wheel != 0 ? t->wheel * 2 : 4;
uint32_t cap = wheel * WHEEL_COUNT * 2;
size_t size = cap * sizeof(struct sc_timer_data);
struct sc_timer_data *alloc;
assert(size != 0);
if (t->wheel >= SC_TIMER_MAX / 2) {
return false;
}
alloc = sc_timer_malloc(size);
if (alloc == NULL) {
return false;
}
for (uint32_t i = 0; i < cap; i++) {
alloc[i].timeout = SC_TIMER_INVALID;
alloc[i].data = NULL;
}
// Copy from old list to new list
if (t->wheel != 0) {
for (uint32_t i = 0; i < WHEEL_COUNT; i++) {
void *dest = &alloc[(i * t->wheel * 2)];
void *src = &t->list[(i * t->wheel)];
size_t copy = sizeof(struct sc_timer_data) * t->wheel;
memcpy(dest, src, copy);
}
}
sc_timer_free(t->list);
t->list = alloc;
t->wheel = wheel;
return true;
}
uint64_t sc_timer_add(struct sc_timer *t, uint64_t timeout, uint64_t type,
void *data)
{
const uint32_t offset = (uint32_t) (timeout / TICK + t->head);
const uint32_t pos = offset & (WHEEL_COUNT - 1);
uint64_t id;
uint32_t seq, index, wheel_pos;
wheel_pos = (pos * t->wheel);
for (seq = 0; seq < t->wheel; seq++) {
index = wheel_pos + seq;
if (t->list[index].timeout == SC_TIMER_INVALID) {
goto out;
}
}
if (!expand(t)) {
return SC_TIMER_INVALID;
}
index = (pos * t->wheel) + (seq);
assert(t->list[index].timeout == SC_TIMER_INVALID);
out:
t->list[index].timeout = timeout + t->timestamp;
t->list[index].type = type;
t->list[index].data = data;
id = (((uint64_t) seq) << 32u) | pos;
assert(id != SC_TIMER_INVALID);
return id;
}
void sc_timer_cancel(struct sc_timer *t, uint64_t *id)
{
uint64_t pos;
if (*id == SC_TIMER_INVALID) {
return;
}
pos = (uint64_t) (((uint32_t) *id) * t->wheel) + (*id >> 32u);
t->list[pos].timeout = SC_TIMER_INVALID;
*id = SC_TIMER_INVALID;
}
#define sc_timer_min(a, b) (a) < (b) ? (a) : (b)
uint64_t sc_timer_timeout(struct sc_timer *t, uint64_t timestamp, void *arg,
void (*callback)(void *, uint64_t, uint64_t, void *))
{
const uint64_t time = timestamp - t->timestamp;
uint64_t timeout;
uint32_t wheel, base;
uint32_t head = t->head;
uint32_t wheels = (uint32_t) (sc_timer_min(time / TICK, WHEEL_COUNT));
struct sc_timer_data *item;
if (wheels == 0) {
return sc_timer_min(TICK - time, TICK);
}
t->timestamp = timestamp;
t->head = (t->head + wheels) & (WHEEL_COUNT - 1);
while (wheels-- > 0) {
wheel = t->wheel;
base = wheel * head;
for (uint32_t i = 0; i < wheel; i++) {
item = &t->list[base + i];
if (item->timeout <= t->timestamp) {
timeout = item->timeout;
item->timeout = SC_TIMER_INVALID;
callback(arg, timeout, item->type, item->data);
// Recalculates position each time because there
// might be newly added timers in the callback,
// and it might require expansion of the list.
base = t->wheel * head;
}
}
head = (head + 1) & (WHEEL_COUNT - 1);
}
return sc_timer_min(TICK - time, TICK);
}