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/*
* Thread queue with water mark
*
* COPYRIGHT (C) 2014-2015, Shanghai Real-Thread Technology Co., Ltd
* http://www.rt-thread.com
*
* This file is part of RT-Thread (http://www.rt-thread.org)
*
* All rights reserved.
*
* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Change Logs:
* Date Author Notes
* 2014-04-16 Grissiom first version
*/
struct rt_watermark_queue
{
/* Current water level. */
unsigned int level;
unsigned int high_mark;
unsigned int low_mark;
rt_list_t suspended_threads;
};
/** Init the struct rt_watermark_queue.
*/
void rt_wm_que_init(struct rt_watermark_queue *wg,
unsigned int low, unsigned int high);
void rt_wm_que_set_mark(struct rt_watermark_queue *wg,
unsigned int low, unsigned int high);
void rt_wm_que_dump(struct rt_watermark_queue *wg);
/* Water marks are often used in performance critical places. Benchmark shows
* inlining functions will have 10% performance gain in some situation(for
* example, VBus). So keep the inc/dec compact and inline. */
/** Increase the water level.
*
* It should be called in the thread that want to raise the water level. If the
* current level is above the high mark, the thread will be suspended up to
* @timeout ticks.
*
* @return RT_EOK if water level increased successfully. -RT_EFULL on @timeout
* is zero and the level is above water mark. -RT_ETIMEOUT if timeout occurred.
*/
rt_inline rt_err_t rt_wm_que_inc(struct rt_watermark_queue *wg,
int timeout)
{
rt_base_t ilvl;
/* Assert as early as possible. */
if (timeout != 0)
{
RT_DEBUG_IN_THREAD_CONTEXT;
}
ilvl = rt_hw_interrupt_disable();
while (wg->level > wg->high_mark)
{
rt_thread_t thread;
if (timeout == 0)
{
rt_hw_interrupt_enable(ilvl);
return -RT_EFULL;
}
thread = rt_thread_self();
thread->error = RT_EOK;
rt_thread_suspend(thread);
rt_list_insert_after(&wg->suspended_threads, &thread->tlist);
if (timeout > 0)
{
rt_timer_control(&(thread->thread_timer),
RT_TIMER_CTRL_SET_TIME,
&timeout);
rt_timer_start(&(thread->thread_timer));
}
rt_hw_interrupt_enable(ilvl);
rt_schedule();
if (thread->error != RT_EOK)
return thread->error;
ilvl = rt_hw_interrupt_disable();
}
wg->level++;
if (wg->level == 0)
{
wg->level = ~0;
}
rt_hw_interrupt_enable(ilvl);
return RT_EOK;
}
/** Decrease the water level.
*
* It should be called by the consumer that drain the water out. If the water
* level reached low mark, all the thread suspended in this queue will be waken
* up. It's safe to call this function in interrupt context.
*/
rt_inline void rt_wm_que_dec(struct rt_watermark_queue *wg)
{
int need_sched = 0;
rt_base_t ilvl;
if (wg->level == 0)
return;
ilvl = rt_hw_interrupt_disable();
wg->level--;
if (wg->level == wg->low_mark)
{
/* There should be spaces between the low mark and high mark, so it's
* safe to resume all the threads. */
while (!rt_list_isempty(&wg->suspended_threads))
{
rt_thread_t thread;
thread = rt_list_entry(wg->suspended_threads.next,
struct rt_thread,
tlist);
rt_thread_resume(thread);
need_sched = 1;
}
}
rt_hw_interrupt_enable(ilvl);
if (need_sched)
rt_schedule();
}
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