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optimized the scheduler for performance by replacing the linked list with a heap.

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This commit is contained in:
Tobias Brunner
2008-11-25 19:56:05 +00:00
parent 6df2731e78
commit 999072ea02
1 changed files with 109 additions and 47 deletions
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src/charon/processing/scheduler.c
+109 -47
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@@ -1,4 +1,5 @@
/*
* Copyright (C) 2008 Tobias Brunner
* Copyright (C) 2005-2006 Martin Willi
* Copyright (C) 2005 Jan Hutter
* Hochschule fuer Technik Rapperswil
@@ -27,6 +28,9 @@
#include <processing/jobs/callback_job.h>
#include <utils/mutex.h>
/* the initial size of the heap */
#define HEAP_SIZE_DEFAULT 64
typedef struct event_t event_t;
/**
@@ -65,14 +69,24 @@ struct private_scheduler_t {
scheduler_t public;
/**
* Job wich schedules
* Job which queues scheduled jobs to the processor.
*/
callback_job_t *job;
/**
* The heap in which the events are stored.
*/
event_t **heap;
/**
* The jobs are scheduled in a list.
* The size of the heap.
*/
linked_list_t *list;
u_int heap_size;
/**
* The number of scheduled events.
*/
u_int event_count;
/**
* Exclusive access to list
@@ -98,6 +112,62 @@ static long time_difference(timeval_t *end, timeval_t *start)
return (s * 1000 + us/1000);
}
/**
* Returns the top event without removing it. Returns NULL if the heap is empty.
*/
static event_t *peek_event(private_scheduler_t *this)
{
return this->event_count > 0 ? this->heap[1] : NULL;
}
/**
* Removes the top event from the heap and returns it. Returns NULL if the heap
* is empty.
*/
static event_t *remove_event(private_scheduler_t *this)
{
event_t *event, *top;
if (!this->event_count)
{
return NULL;
}
/* store the value to return */
event = this->heap[1];
/* move the bottom event to the top */
top = this->heap[1] = this->heap[this->event_count];
if (--this->event_count > 1)
{
/* seep down the top event */
u_int position = 1;
while ((position << 1) <= this->event_count)
{
u_int child = position << 1;
if ((child + 1) <= this->event_count &&
time_difference(&this->heap[child + 1]->time,
&this->heap[child]->time) < 0)
{
/* the "right" child is smaller */
child++;
}
if (time_difference(&top->time, &this->heap[child]->time) <= 0)
{
/* the top event fires before the smaller of the two children, stop */
break;
}
/* exchange with the smaller child */
this->heap[position] = this->heap[child];
position = child;
}
this->heap[position] = top;
}
return event;
}
/**
* Get events from the queue and pass it to the processor
*/
@@ -114,15 +184,14 @@ static job_requeue_t schedule(private_scheduler_t * this)
gettimeofday(&now, NULL);
if (this->list->get_count(this->list) > 0)
if ((event = peek_event(this)) != NULL)
{
this->list->get_first(this->list, (void **)&event);
difference = time_difference(&now, &event->time);
if (difference > 0)
{
this->list->remove_first(this->list, (void **)&event);
remove_event(this);
this->mutex->unlock(this->mutex);
DBG2(DBG_JOB, "got event, queueing job for execution");
DBG2(DBG_JOB, "got event, queuing job for execution");
charon->processor->queue_job(charon->processor, event->job);
free(event);
return JOB_REQUEUE_DIRECT;
@@ -152,7 +221,7 @@ static u_int get_job_load(private_scheduler_t *this)
{
int count;
this->mutex->lock(this->mutex);
count = this->list->get_count(this->list);
count = this->event_count;
this->mutex->unlock(this->mutex);
return count;
}
@@ -163,8 +232,8 @@ static u_int get_job_load(private_scheduler_t *this)
static void schedule_job(private_scheduler_t *this, job_t *job, u_int32_t time)
{
timeval_t now;
event_t *event, *current;
iterator_t *iterator;
event_t *event;
u_int position;
time_t s;
suseconds_t us;
@@ -179,43 +248,27 @@ static void schedule_job(private_scheduler_t *this, job_t *job, u_int32_t time)
event->time.tv_sec = now.tv_sec + (now.tv_usec + us)/1000000 + s;
this->mutex->lock(this->mutex);
while(TRUE)
this->event_count++;
if (this->event_count > this->heap_size)
{
if (this->list->get_count(this->list) == 0)
{
this->list->insert_first(this->list,event);
break;
}
this->list->get_last(this->list, (void**)&current);
if (time_difference(&event->time, &current->time) >= 0)
{ /* new event has to be fired after the last event in list */
this->list->insert_last(this->list, event);
break;
}
this->list->get_first(this->list, (void**)&current);
if (time_difference(&event->time, &current->time) < 0)
{ /* new event has to be fired before the first event in list */
this->list->insert_first(this->list, event);
break;
}
iterator = this->list->create_iterator(this->list, TRUE);
/* first element has not to be checked (already done) */
iterator->iterate(iterator, (void**)&current);
while(iterator->iterate(iterator, (void**)&current))
{
if (time_difference(&event->time, &current->time) <= 0)
{
/* new event has to be fired before the current event in list */
iterator->insert_before(iterator, event);
break;
}
}
iterator->destroy(iterator);
break;
/* double the size of the heap */
this->heap_size <<= 1;
this->heap = (event_t**)realloc(this->heap, (this->heap_size + 1) * sizeof(event_t*));
}
/* "put" the event to the bottom */
position = this->event_count;
/* then bubble it up */
while (position > 1 && time_difference(&this->heap[position >> 1]->time,
&event->time) > 0)
{
/* parent has to be fired after the new event, move up */
this->heap[position] = this->heap[position >> 1];
position >>= 1;
}
this->heap[position] = event;
this->condvar->signal(this->condvar);
this->mutex->unlock(this->mutex);
}
@@ -225,10 +278,15 @@ static void schedule_job(private_scheduler_t *this, job_t *job, u_int32_t time)
*/
static void destroy(private_scheduler_t *this)
{
event_t *event;
this->job->cancel(this->job);
this->condvar->destroy(this->condvar);
this->mutex->destroy(this->mutex);
this->list->destroy_function(this->list, (void*)event_destroy);
while ((event = remove_event(this)) != NULL)
{
event_destroy(event);
}
free(this->heap);
free(this);
}
@@ -243,7 +301,11 @@ scheduler_t * scheduler_create()
this->public.schedule_job = (void (*) (scheduler_t *this, job_t *job, u_int32_t ms)) schedule_job;
this->public.destroy = (void(*)(scheduler_t*)) destroy;
this->list = linked_list_create();
/* Note: the root of the heap is at index 1 */
this->event_count = 0;
this->heap_size = HEAP_SIZE_DEFAULT;
this->heap = (event_t**)calloc(this->heap_size + 1, sizeof(event_t*));
this->mutex = mutex_create(MUTEX_DEFAULT);
this->condvar = condvar_create(CONDVAR_DEFAULT);