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Moved scheduler_t to libhydra.

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This commit is contained in:
Tobias Brunner
2010-09-02 19:01:24 +02:00
parent 4e258e63c3
commit 8c387909eb
10 changed files with 24 additions and 22 deletions
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src/libcharon/processing/scheduler.c
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@@ -1,359 +0,0 @@
/*
* Copyright (C) 2008 Tobias Brunner
* Copyright (C) 2005-2006 Martin Willi
* Copyright (C) 2005 Jan Hutter
* Hochschule fuer Technik Rapperswil
*
* 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. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* 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.
*/
#include <stdlib.h>
#include "scheduler.h"
#include <hydra.h>
#include <daemon.h>
#include <processing/processor.h>
#include <processing/jobs/callback_job.h>
#include <threading/thread.h>
#include <threading/condvar.h>
#include <threading/mutex.h>
/* the initial size of the heap */
#define HEAP_SIZE_DEFAULT 64
typedef struct event_t event_t;
/**
* Event containing a job and a schedule time
*/
struct event_t {
/**
* Time to fire the event.
*/
timeval_t time;
/**
* Every event has its assigned job.
*/
job_t *job;
};
/**
* destroy an event and its job
*/
static void event_destroy(event_t *event)
{
event->job->destroy(event->job);
free(event);
}
typedef struct private_scheduler_t private_scheduler_t;
/**
* Private data of a scheduler_t object.
*/
struct private_scheduler_t {
/**
* Public part of a scheduler_t object.
*/
scheduler_t public;
/**
* Job which queues scheduled jobs to the processor.
*/
callback_job_t *job;
/**
* The heap in which the events are stored.
*/
event_t **heap;
/**
* The size of the heap.
*/
u_int heap_size;
/**
* The number of scheduled events.
*/
u_int event_count;
/**
* Exclusive access to list
*/
mutex_t *mutex;
/**
* Condvar to wait for next job.
*/
condvar_t *condvar;
};
/**
* Comparse two timevals, return >0 if a > b, <0 if a < b and =0 if equal
*/
static int timeval_cmp(timeval_t *a, timeval_t *b)
{
if (a->tv_sec > b->tv_sec)
{
return 1;
}
if (a->tv_sec < b->tv_sec)
{
return -1;
}
if (a->tv_usec > b->tv_usec)
{
return 1;
}
if (a->tv_usec < b->tv_usec)
{
return -1;
}
return 0;
}
/**
* 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 &&
timeval_cmp(&this->heap[child + 1]->time,
&this->heap[child]->time) < 0)
{
/* the "right" child is smaller */
child++;
}
if (timeval_cmp(&top->time, &this->heap[child]->time) <= 0)
{
/* the top event fires before the smaller of the two children,
* stop */
break;
}
/* swap 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
*/
static job_requeue_t schedule(private_scheduler_t * this)
{
timeval_t now;
event_t *event;
bool timed = FALSE, oldstate;
this->mutex->lock(this->mutex);
time_monotonic(&now);
if ((event = peek_event(this)) != NULL)
{
if (timeval_cmp(&now, &event->time) >= 0)
{
remove_event(this);
this->mutex->unlock(this->mutex);
DBG2(DBG_JOB, "got event, queuing job for execution");
hydra->processor->queue_job(hydra->processor, event->job);
free(event);
return JOB_REQUEUE_DIRECT;
}
timersub(&event->time, &now, &now);
if (now.tv_sec)
{
DBG2(DBG_JOB, "next event in %ds %dms, waiting",
now.tv_sec, now.tv_usec/1000);
}
else
{
DBG2(DBG_JOB, "next event in %dms, waiting", now.tv_usec/1000);
}
timed = TRUE;
}
thread_cleanup_push((thread_cleanup_t)this->mutex->unlock, this->mutex);
oldstate = thread_cancelability(TRUE);
if (timed)
{
this->condvar->timed_wait_abs(this->condvar, this->mutex, event->time);
}
else
{
DBG2(DBG_JOB, "no events, waiting");
this->condvar->wait(this->condvar, this->mutex);
}
thread_cancelability(oldstate);
thread_cleanup_pop(TRUE);
return JOB_REQUEUE_DIRECT;
}
/**
* Implements scheduler_t.get_job_load
*/
static u_int get_job_load(private_scheduler_t *this)
{
int count;
this->mutex->lock(this->mutex);
count = this->event_count;
this->mutex->unlock(this->mutex);
return count;
}
/**
* Implements scheduler_t.schedule_job_tv.
*/
static void schedule_job_tv(private_scheduler_t *this, job_t *job, timeval_t tv)
{
event_t *event;
u_int position;
event = malloc_thing(event_t);
event->job = job;
event->time = tv;
this->mutex->lock(this->mutex);
this->event_count++;
if (this->event_count > this->heap_size)
{
/* 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 && timeval_cmp(&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);
}
/**
* Implements scheduler_t.schedule_job.
*/
static void schedule_job(private_scheduler_t *this, job_t *job, u_int32_t s)
{
timeval_t tv;
time_monotonic(&tv);
tv.tv_sec += s;
schedule_job_tv(this, job, tv);
}
/**
* Implements scheduler_t.schedule_job_ms.
*/
static void schedule_job_ms(private_scheduler_t *this, job_t *job, u_int32_t ms)
{
timeval_t tv, add;
time_monotonic(&tv);
add.tv_sec = ms / 1000;
add.tv_usec = (ms % 1000) * 1000;
timeradd(&tv, &add, &tv);
schedule_job_tv(this, job, tv);
}
/**
* Implementation of scheduler_t.destroy.
*/
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);
while ((event = remove_event(this)) != NULL)
{
event_destroy(event);
}
free(this->heap);
free(this);
}
/*
* Described in header.
*/
scheduler_t * scheduler_create()
{
private_scheduler_t *this = malloc_thing(private_scheduler_t);
this->public.get_job_load = (u_int (*) (scheduler_t *this)) get_job_load;
this->public.schedule_job = (void (*) (scheduler_t *this, job_t *job, u_int32_t s)) schedule_job;
this->public.schedule_job_ms = (void (*) (scheduler_t *this, job_t *job, u_int32_t ms)) schedule_job_ms;
this->public.schedule_job_tv = (void (*) (scheduler_t *this, job_t *job, timeval_t tv)) schedule_job_tv;
this->public.destroy = (void(*)(scheduler_t*)) destroy;
/* 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_TYPE_DEFAULT);
this->condvar = condvar_create(CONDVAR_TYPE_DEFAULT);
this->job = callback_job_create((callback_job_cb_t)schedule, this, NULL, NULL);
hydra->processor->queue_job(hydra->processor, (job_t*)this->job);
return &this->public;
}
src/libcharon/processing/scheduler.h
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/*
* Copyright (C) 2009 Tobias Brunner
* Copyright (C) 2005-2007 Martin Willi
* Copyright (C) 2005 Jan Hutter
* Hochschule fuer Technik Rapperswil
*
* 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. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* 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.
*/
/**
* @defgroup scheduler scheduler
* @{ @ingroup cprocessing
*/
#ifndef SCHEDULER_H_
#define SCHEDULER_H_
typedef struct scheduler_t scheduler_t;
#include <library.h>
#include <processing/jobs/job.h>
/**
* The scheduler queues timed events which are then passed to the processor.
*
* The scheduler is implemented as a heap. A heap is a special kind of tree-
* based data structure that satisfies the following property: if B is a child
* node of A, then key(A) >= (or <=) key(B). So either the element with the
* greatest (max-heap) or the smallest (min-heap) key is the root of the heap.
* We use a min-heap whith the key being the absolute unix time at which an
* event is scheduled. So the root is always the event that will fire next.
*
* An earlier implementation of the scheduler used a sorted linked list to store
* the events. That had the advantage that removing the next event was extremely
* fast, also, adding an event scheduled before or after all other events was
* equally fast (all in O(1)). The problem was, though, that adding an event
* in-between got slower, as the number of events grew larger (O(n)).
* For each connection there could be several events: IKE-rekey, NAT-keepalive,
* retransmissions, expire (half-open), and others. So a gateway that probably
* has to handle thousands of concurrent connnections has to be able to queue a
* large number of events as fast as possible. Locking makes this even worse, to
* provide thread-safety, no events can be processed, while an event is queued,
* so making the insertion fast is even more important.
*
* That's the advantage of the heap. Adding an element to the heap can be
* achieved in O(log n) - on the other hand, removing the root node also
* requires O(log n) operations. Consider 10000 queued events. Inserting a new
* event in the list implementation required up to 10000 comparisons. In the
* heap implementation, the worst case is about 13.3 comparisons. That's a
* drastic improvement.
*
* The implementation itself uses a binary tree mapped to a one-based array to
* store the elements. This reduces storage overhead and simplifies navigation:
* the children of the node at position n are at position 2n and 2n+1 (likewise
* the parent node of the node at position n is at position [n/2]). Thus,
* navigating up and down the tree is reduced to simple index computations.
*
* Adding an element to the heap works as follows: The heap is always filled
* from left to right, until a row is full, then the next row is filled. Mapped
* to an array this gets as simple as putting the new element to the first free
* position. In a one-based array that position equals the number of elements
* currently stored in the heap. Then the heap property has to be restored, i.e.
* the new element has to be "bubbled up" the tree until the parent node's key
* is smaller or the element got the new root of the tree.
*
* Removing the next event from the heap works similarly. The event itself is
* the root node and stored at position 1 of the array. After removing it, the
* root has to be replaced and the heap property has to be restored. This is
* done by moving the bottom element (last row, rightmost element) to the root
* and then "seep it down" by swapping it with child nodes until none of the
* children has a smaller key or it is again a leaf node.
*/
struct scheduler_t {
/**
* Adds a event to the queue, using a relative time offset in s.
*
* @param job job to schedule
* @param time relative time to schedule job, in s
*/
void (*schedule_job) (scheduler_t *this, job_t *job, u_int32_t s);
/**
* Adds a event to the queue, using a relative time offset in ms.
*
* @param job job to schedule
* @param time relative time to schedule job, in ms
*/
void (*schedule_job_ms) (scheduler_t *this, job_t *job, u_int32_t ms);
/**
* Adds a event to the queue, using an absolut time.
*
* The passed timeval should be calculated based on the time_monotonic()
* function.
*
* @param job job to schedule
* @param time absolut time to schedule job
*/
void (*schedule_job_tv) (scheduler_t *this, job_t *job, timeval_t tv);
/**
* Returns number of jobs scheduled.
*
* @return number of scheduled jobs
*/
u_int (*get_job_load) (scheduler_t *this);
/**
* Destroys a scheduler object.
*/
void (*destroy) (scheduler_t *this);
};
/**
* Create a scheduler.
*
* @return scheduler_t object
*/
scheduler_t *scheduler_create(void);
#endif /** SCHEDULER_H_ @}*/