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/*
* libusb synchronization on Microsoft Windows
*
* Copyright © 2010 Michael Plante <michael.plante@gmail.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <config.h>
#include <errno.h>
#include "libusbi.h"
struct usbi_cond_perthread {
struct list_head list;
HANDLE event;
};
void usbi_cond_init(usbi_cond_t *cond)
{
list_init(&cond->waiters);
list_init(&cond->not_waiting);
}
static int usbi_cond_intwait(usbi_cond_t *cond,
usbi_mutex_t *mutex, DWORD timeout_ms)
{
struct usbi_cond_perthread *pos;
DWORD r;
// Same assumption as usbi_cond_broadcast() holds
if (list_empty(&cond->not_waiting)) {
pos = malloc(sizeof(*pos));
if (pos == NULL)
return ENOMEM; // This errno is not POSIX-allowed.
pos->event = CreateEvent(NULL, FALSE, FALSE, NULL); // auto-reset.
if (pos->event == NULL) {
free(pos);
return ENOMEM;
}
} else {
pos = list_first_entry(&cond->not_waiting, struct usbi_cond_perthread, list);
list_del(&pos->list); // remove from not_waiting list.
// Ensure the event is clear before waiting
WaitForSingleObject(pos->event, 0);
}
list_add(&pos->list, &cond->waiters);
LeaveCriticalSection(mutex);
r = WaitForSingleObject(pos->event, timeout_ms);
EnterCriticalSection(mutex);
list_del(&pos->list);
list_add(&pos->list, &cond->not_waiting);
if (r == WAIT_OBJECT_0)
return 0;
else if (r == WAIT_TIMEOUT)
return ETIMEDOUT;
else
return EINVAL;
}
// N.B.: usbi_cond_*wait() can also return ENOMEM, even though pthread_cond_*wait cannot!
int usbi_cond_wait(usbi_cond_t *cond, usbi_mutex_t *mutex)
{
return usbi_cond_intwait(cond, mutex, INFINITE);
}
int usbi_cond_timedwait(usbi_cond_t *cond,
usbi_mutex_t *mutex, const struct timeval *tv)
{
DWORD millis;
millis = (DWORD)(tv->tv_sec * 1000) + (tv->tv_usec / 1000);
/* round up to next millisecond */
if (tv->tv_usec % 1000)
millis++;
return usbi_cond_intwait(cond, mutex, millis);
}
void usbi_cond_broadcast(usbi_cond_t *cond)
{
// Assumes mutex is locked; this is not in keeping with POSIX spec, but
// libusb does this anyway, so we simplify by not adding more sync
// primitives to the CV definition!
struct usbi_cond_perthread *pos;
list_for_each_entry(pos, &cond->waiters, list, struct usbi_cond_perthread)
SetEvent(pos->event);
// The wait function will remove its respective item from the list.
}
void usbi_cond_destroy(usbi_cond_t *cond)
{
// This assumes no one is using this anymore. The check MAY NOT BE safe.
struct usbi_cond_perthread *pos, *next;
if (!list_empty(&cond->waiters))
return; // (!see above!)
list_for_each_entry_safe(pos, next, &cond->not_waiting, list, struct usbi_cond_perthread) {
CloseHandle(pos->event);
list_del(&pos->list);
free(pos);
}
}
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