source: mainline/uspace/lib/c/include/fibril_synch.h@ c124c985

/*
 * Copyright (c) 2009 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup libc
 * @{
 */
/** @file
 */

#ifndef LIBC_FIBRIL_SYNCH_H_
#define LIBC_FIBRIL_SYNCH_H_

#include <fibril.h>
#include <adt/list.h>
#include <libarch/tls.h>
#include <sys/time.h>
#include <stdbool.h>
#include <futex.h>

/**
 * "Restricted" fibril mutex.
 *
 * Similar to `fibril_mutex_t`, but has a set of restrictions placed on its
 * use. Within a rmutex critical section, you
 *         - may not use any other synchronization primitive,
 *           save for another `fibril_rmutex_t`. This includes nonblocking
 *           operations like cvar signal and mutex unlock.
 *         - may not read IPC messages
 *         - may not start a new thread/fibril
 *           (creating fibril without starting is fine)
 *
 * Additionally, locking with a timeout is not possible on this mutex,
 * and there is no associated condition variable type.
 * This is a design constraint, not a lack of implementation effort.
 */
typedef struct {
        // TODO: At this point, this is just silly handwaving to hide current
        //       futex use behind a fibril based abstraction. Later, the imple-
        //       mentation will change, but the restrictions placed on this type
        //       will allow it to be simpler and faster than a regular mutex.
        //       There might also be optional debug checking of the assumptions.
        //
        //       Note that a consequence of the restrictions is that if we are
        //       running on a single thread, no other fibril can ever get to run
        //       while a fibril has a rmutex locked. That means that for
        //       single-threaded programs, we can reduce all rmutex locks and
        //       unlocks to simple branches on a global bool variable.

        futex_t futex;
} fibril_rmutex_t;

#define FIBRIL_RMUTEX_INITIALIZER(name) \
        { .futex = FUTEX_INITIALIZE(1) }

#define FIBRIL_RMUTEX_INITIALIZE(name) \
        fibril_rmutex_t name = FIBRIL_RMUTEX_INITIALIZER(name)

static inline void fibril_rmutex_initialize(fibril_rmutex_t *m)
{
        futex_initialize(&m->futex, 1);
}

static inline void fibril_rmutex_lock(fibril_rmutex_t *m)
{
        futex_lock(&m->futex);
}

static inline bool fibril_rmutex_trylock(fibril_rmutex_t *m)
{
        return futex_trylock(&m->futex);
}

static inline void fibril_rmutex_unlock(fibril_rmutex_t *m)
{
        futex_unlock(&m->futex);
}

typedef struct {
        fibril_owner_info_t oi;  /**< Keep this the first thing. */
        int counter;
        list_t waiters;
} fibril_mutex_t;

#define FIBRIL_MUTEX_INITIALIZER(name) \
        { \
                .oi = { \
                        .owned_by = NULL \
                }, \
                .counter = 1, \
                .waiters = { \
                        .head = { \
                                .prev = &(name).waiters.head, \
                                .next = &(name).waiters.head, \
                        } \
                } \
        }

#define FIBRIL_MUTEX_INITIALIZE(name) \
        fibril_mutex_t name = FIBRIL_MUTEX_INITIALIZER(name)

typedef struct {
        fibril_owner_info_t oi;  /**< Keep this the first thing. */
        unsigned int writers;
        unsigned int readers;
        list_t waiters;
} fibril_rwlock_t;

#define FIBRIL_RWLOCK_INITIALIZER(name) \
        { \
                .oi = { \
                        .owned_by = NULL \
                }, \
                .readers = 0, \
                .writers = 0, \
                .waiters = { \
                        .head = { \
                                .prev = &(name).waiters.head, \
                                .next = &(name).waiters.head, \
                        } \
                } \
        }

#define FIBRIL_RWLOCK_INITIALIZE(name) \
        fibril_rwlock_t name = FIBRIL_RWLOCK_INITIALIZER(name)

typedef struct {
        list_t waiters;
} fibril_condvar_t;

#define FIBRIL_CONDVAR_INITIALIZER(name) \
        { \
                .waiters = { \
                        .head = { \
                                .next = &(name).waiters.head, \
                                .prev = &(name).waiters.head, \
                        } \
                } \
        }

#define FIBRIL_CONDVAR_INITIALIZE(name) \
        fibril_condvar_t name = FIBRIL_CONDVAR_INITIALIZER(name)

typedef void (*fibril_timer_fun_t)(void *);

typedef enum {
        /** Timer has not been set or has been cleared */
        fts_not_set,
        /** Timer was set but did not fire yet */
        fts_active,
        /** Timer has fired and has not been cleared since */
        fts_fired,
        /** Timer fibril is requested to terminate */
        fts_cleanup,
        /** Timer fibril acknowledged termination */
        fts_clean
} fibril_timer_state_t;

/** Fibril timer.
 *
 * When a timer is set it executes a callback function (in a separate
 * fibril) after a specified time interval. The timer can be cleared
 * (canceled) before that. From the return value of fibril_timer_clear()
 * one can tell whether the timer fired or not.
 */
typedef struct {
        fibril_mutex_t lock;
        fibril_mutex_t *lockp;
        fibril_condvar_t cv;
        fid_t fibril;
        fibril_timer_state_t state;
        /** FID of fibril executing handler or 0 if handler is not running */
        fid_t handler_fid;

        suseconds_t delay;
        fibril_timer_fun_t fun;
        void *arg;
} fibril_timer_t;

/** A counting semaphore for fibrils. */
typedef struct {
        long int count;
        list_t waiters;
} fibril_semaphore_t;

#define FIBRIL_SEMAPHORE_INITIALIZER(name, cnt) \
        { \
                .count = (cnt), \
                .waiters = { \
                        .head = { \
                                .next = &(name).waiters.head, \
                                .prev = &(name).waiters.head, \
                        } \
                } \
        }

#define FIBRIL_SEMAPHORE_INITIALIZE(name, cnt) \
        fibril_semaphore_t name = FIBRIL_SEMAPHORE_INITIALIZER(name, cnt)

extern void fibril_mutex_initialize(fibril_mutex_t *);
extern void fibril_mutex_lock(fibril_mutex_t *);
extern bool fibril_mutex_trylock(fibril_mutex_t *);
extern void fibril_mutex_unlock(fibril_mutex_t *);
extern bool fibril_mutex_is_locked(fibril_mutex_t *);

extern void fibril_rwlock_initialize(fibril_rwlock_t *);
extern void fibril_rwlock_read_lock(fibril_rwlock_t *);
extern void fibril_rwlock_write_lock(fibril_rwlock_t *);
extern void fibril_rwlock_read_unlock(fibril_rwlock_t *);
extern void fibril_rwlock_write_unlock(fibril_rwlock_t *);
extern bool fibril_rwlock_is_read_locked(fibril_rwlock_t *);
extern bool fibril_rwlock_is_write_locked(fibril_rwlock_t *);
extern bool fibril_rwlock_is_locked(fibril_rwlock_t *);

extern void fibril_condvar_initialize(fibril_condvar_t *);
extern errno_t fibril_condvar_wait_timeout(fibril_condvar_t *, fibril_mutex_t *,
    suseconds_t);
extern void fibril_condvar_wait(fibril_condvar_t *, fibril_mutex_t *);
extern void fibril_condvar_signal(fibril_condvar_t *);
extern void fibril_condvar_broadcast(fibril_condvar_t *);

extern fibril_timer_t *fibril_timer_create(fibril_mutex_t *);
extern void fibril_timer_destroy(fibril_timer_t *);
extern void fibril_timer_set(fibril_timer_t *, suseconds_t, fibril_timer_fun_t,
    void *);
extern void fibril_timer_set_locked(fibril_timer_t *, suseconds_t,
    fibril_timer_fun_t, void *);
extern fibril_timer_state_t fibril_timer_clear(fibril_timer_t *);
extern fibril_timer_state_t fibril_timer_clear_locked(fibril_timer_t *);

extern void fibril_semaphore_initialize(fibril_semaphore_t *, long);
extern void fibril_semaphore_up(fibril_semaphore_t *);
extern void fibril_semaphore_down(fibril_semaphore_t *);

#endif

/** @}
 */