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/*
* Copyright 2006 Serge van den Boom <svdb@stack.nl>
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "port.h"
#include "types.h"
#include <assert.h>
#include <stdlib.h>
#include <sys/types.h>
#include "libs/threadlib.h"
typedef struct CallbackLink CallbackLink;
#define CALLBACK_INTERNAL
#include "callback.h"
struct CallbackLink {
CallbackLink *next;
CallbackFunction callback;
CallbackArg arg;
};
static CallbackLink *callbacks;
static CallbackLink **callbacksEnd;
static CallbackLink *const *callbacksProcessEnd;
static Mutex callbackListLock;
static inline void
CallbackList_lock(void) {
LockMutex(callbackListLock);
}
static inline void
CallbackList_unlock(void) {
UnlockMutex(callbackListLock);
}
#if 0
static inline bool
CallbackList_isLocked(void) {
// TODO
}
#endif
void
Callback_init(void) {
callbacks = NULL;
callbacksEnd = &callbacks;
callbacksProcessEnd = &callbacks;
callbackListLock = CreateMutex("Callback List Lock", SYNC_CLASS_TOPLEVEL);
}
void
Callback_uninit(void) {
// TODO: cleanup the queue?
DestroyMutex (callbackListLock);
callbackListLock = 0;
}
// Callbacks are guaranteed to be called in the order that they are queued.
CallbackID
Callback_add(CallbackFunction callback, CallbackArg arg) {
CallbackLink *link = malloc(sizeof (CallbackLink));
link->callback = callback;
link->arg = arg;
link->next = NULL;
CallbackList_lock();
*callbacksEnd = link;
callbacksEnd = &link->next;
CallbackList_unlock();
return (CallbackID) link;
}
static void
CallbackLink_delete(CallbackLink *link) {
free(link);
}
// Pre: CallbackList is locked.
static CallbackLink **
CallbackLink_find(CallbackLink *link) {
CallbackLink **ptr;
//assert(CallbackList_isLocked());
for (ptr = &callbacks; *ptr != NULL; ptr = &(*ptr)->next) {
if (*ptr == link)
return ptr;
}
return NULL;
}
bool
Callback_remove(CallbackID id) {
CallbackLink *link = (CallbackLink *) id;
CallbackLink **linkPtr;
CallbackList_lock();
linkPtr = CallbackLink_find(link);
if (linkPtr == NULL) {
CallbackList_unlock();
return false;
}
if (callbacksEnd == &(*linkPtr)->next)
callbacksEnd = linkPtr;
if (callbacksProcessEnd == &(*linkPtr)->next)
callbacksProcessEnd = linkPtr;
*linkPtr = (*linkPtr)->next;
CallbackList_unlock();
CallbackLink_delete(link);
return true;
}
static inline void
CallbackLink_doCallback(CallbackLink *link) {
(link->callback)(link->arg);
}
// Call all queued callbacks currently in the queue. Callbacks queued
// from inside the called functions will not be processed until the next
// call of Callback_process().
// It is allowed to remove callbacks from inside the called functions.
// NB: Callback_process() must never be called from more than one thread
// at the same time. It's the only sensible way to ensure that the
// callbacks are called in the order in which they were queued.
// It is however allowed to call Callback_process() from inside the
// callback function called by Callback_process() itself.
void
Callback_process(void) {
CallbackLink *link;
// We set 'callbacksProcessEnd' to callbacksEnd. Callbacks added
// from inside a callback function will be placed after
// callbacksProcessEnd, and will hence not be processed this
// call of Callback_process().
CallbackList_lock();
callbacksProcessEnd = callbacksEnd;
CallbackList_unlock();
for (;;) {
CallbackList_lock();
if (callbacksProcessEnd == &callbacks) {
CallbackList_unlock();
break;
}
assert(callbacks != NULL);
// If callbacks == NULL, then callbacksProcessEnd == &callbacks
link = callbacks;
callbacks = link->next;
if (callbacksEnd == &link->next)
callbacksEnd = &callbacks;
if (callbacksProcessEnd == &link->next)
callbacksProcessEnd = &callbacks;
CallbackList_unlock();
CallbackLink_doCallback(link);
CallbackLink_delete(link);
}
}
bool
Callback_haveMore(void) {
bool result;
CallbackList_lock();
result = (callbacks != NULL);
CallbackList_unlock();
return result;
}
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