mc/lib/vfs/gc.c

/* Virtual File System garbage collection code
   Copyright (C) 2003, 2004, 2005, 2007 Free Software Foundation, Inc.

   Written by: 1995 Miguel de Icaza
   1995 Jakub Jelinek
   1998 Pavel Machek
   2003 Pavel Roskin

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library 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 Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

/**
 * \file
 * \brief Source: Virtual File System: garbage collection code
 * \author Miguel de Icaza
 * \author Jakub Jelinek
 * \author Pavel Machek
 * \author Pavel Roskin
 * \date 1995, 1998, 2003
 */


#include <config.h>

#include <stdlib.h>             /* For atol() */
#include <sys/types.h>
#include <sys/time.h>           /* gettimeofday() */

#include "lib/global.h"
#include "lib/event.h"

#include "vfs.h"
#include "utilvfs.h"

#include "gc.h"

/*** global variables ****************************************************************************/

int vfs_timeout = 60;           /* VFS timeout in seconds */

/*** file scope macro definitions ****************************************************************/

/*** file scope type declarations ****************************************************************/

/*** file scope variables ************************************************************************/

static struct vfs_stamping *stamps;

/*** file scope functions ************************************************************************/
/* --------------------------------------------------------------------------------------------- */

static void
vfs_addstamp (struct vfs_class *v, vfsid id)
{
    if (!(v->flags & VFSF_LOCAL) && id != NULL)
    {
        struct vfs_stamping *stamp;
        struct vfs_stamping *last_stamp = NULL;

        for (stamp = stamps; stamp != NULL; stamp = stamp->next)
        {
            if (stamp->v == v && stamp->id == id)
            {
                gettimeofday (&(stamp->time), NULL);
                return;
            }
            last_stamp = stamp;
        }
        stamp = g_new (struct vfs_stamping, 1);
        stamp->v = v;
        stamp->id = id;

        gettimeofday (&(stamp->time), NULL);
        stamp->next = 0;

        if (stamps)
        {
            /* Add to the end */
            last_stamp->next = stamp;
        }
        else
        {
            /* Add first element */
            stamps = stamp;
        }
    }
}

/* --------------------------------------------------------------------------------------------- */
/** Compare two timeval structures.  Return 0 is t1 is less than t2. */

static inline int
timeoutcmp (struct timeval *t1, struct timeval *t2)
{
    return ((t1->tv_sec < t2->tv_sec)
            || ((t1->tv_sec == t2->tv_sec) && (t1->tv_usec <= t2->tv_usec)));
}

/* --------------------------------------------------------------------------------------------- */
/*** public functions ****************************************************************************/
/* --------------------------------------------------------------------------------------------- */

void
vfs_stamp (struct vfs_class *v, vfsid id)
{
    struct vfs_stamping *stamp;

    for (stamp = stamps; stamp != NULL; stamp = stamp->next)
        if (stamp->v == v && stamp->id == id)
        {
            gettimeofday (&(stamp->time), NULL);
            return;
        }
}

/* --------------------------------------------------------------------------------------------- */

void
vfs_rmstamp (struct vfs_class *v, vfsid id)
{
    struct vfs_stamping *stamp, *st1;

    for (stamp = stamps, st1 = NULL; stamp != NULL; st1 = stamp, stamp = stamp->next)
        if (stamp->v == v && stamp->id == id)
        {
            if (st1 == NULL)
            {
                stamps = stamp->next;
            }
            else
            {
                st1->next = stamp->next;
            }
            g_free (stamp);

            return;
        }
}

/* --------------------------------------------------------------------------------------------- */

void
vfs_stamp_path (const char *path)
{
    vfsid id;
    vfs_path_t *vpath;
    vfs_path_element_t *path_element;

    vpath = vfs_path_from_str (path);
    path_element = vfs_path_get_by_index (vpath, vfs_path_length (vpath) - 1);

    id = vfs_getid (vpath);
    vfs_addstamp (path_element->class, id);
    vfs_path_free (vpath);
}

/* --------------------------------------------------------------------------------------------- */
/**
 * Create a new timestamp item by VFS class and VFS id.
 */

void
vfs_stamp_create (struct vfs_class *vclass, vfsid id)
{
    vfsid nvfsid;

    ev_vfs_stamp_create_t event_data = { vclass, id, FALSE };
    vfs_path_t *vpath;
    vfs_path_element_t *path_element;

    /* There are three directories we have to take care of: current_dir,
       current_panel->cwd and other_panel->cwd. Athough most of the time either
       current_dir and current_panel->cwd or current_dir and other_panel->cwd are the
       same, it's possible that all three are different -- Norbert */

    if (!mc_event_present (MCEVENT_GROUP_CORE, "vfs_timestamp"))
        return;

    vpath = vfs_path_from_str (vfs_get_current_dir ());
    path_element = vfs_path_get_by_index (vpath, vfs_path_length (vpath) - 1);

    nvfsid = vfs_getid (vpath);
    vfs_rmstamp (path_element->class, nvfsid);

    if (!(id == NULL || (path_element->class == vclass && nvfsid == id)))
    {
        mc_event_raise (MCEVENT_GROUP_CORE, "vfs_timestamp", (gpointer) & event_data);

        if (!event_data.ret && vclass != NULL && vclass->nothingisopen != NULL
            && vclass->nothingisopen (id) != 0)
            vfs_addstamp (vclass, id);
    }
    vfs_path_free (vpath);
}

/* --------------------------------------------------------------------------------------------- */
/** This is called from timeout handler with now = 0, or can be called
   with now = 1 to force freeing all filesystems that are not in use */

void
vfs_expire (int now)
{
    static int locked = 0;
    struct timeval lc_time;
    struct vfs_stamping *stamp, *st;

    /* Avoid recursive invocation, e.g. when one of the free functions
       calls message */
    if (locked)
        return;
    locked = 1;

    gettimeofday (&lc_time, NULL);
    lc_time.tv_sec -= vfs_timeout;

    for (stamp = stamps; stamp != NULL;)
    {
        if (now || (timeoutcmp (&stamp->time, &lc_time)))
        {
            st = stamp->next;
            if (stamp->v->free)
                (*stamp->v->free) (stamp->id);
            vfs_rmstamp (stamp->v, stamp->id);
            stamp = st;
        }
        else
            stamp = stamp->next;
    }
    locked = 0;
}

/* --------------------------------------------------------------------------------------------- */
/*
 * Return the number of seconds remaining to the vfs timeout.
 * FIXME: The code should be improved to actually return the number of
 * seconds until the next item times out.
 */

int
vfs_timeouts ()
{
    return stamps ? 10 : 0;
}

/* --------------------------------------------------------------------------------------------- */

void
vfs_timeout_handler (void)
{
    vfs_expire (0);
}

/* --------------------------------------------------------------------------------------------- */

void
vfs_release_path (const char *dir)
{
    vfs_path_t *vpath;
    vfs_path_element_t *path_element;

    vpath = vfs_path_from_str (dir);
    path_element = vfs_path_get_by_index (vpath, vfs_path_length (vpath) - 1);

    vfs_stamp_create (path_element->class, vfs_getid (vpath));
}

/* --------------------------------------------------------------------------------------------- */
/* Free all data */

void
vfs_gc_done (void)
{
    struct vfs_stamping *stamp, *st;

    for (stamp = stamps, stamps = 0; stamp != NULL;)
    {
        if (stamp->v->free)
            (*stamp->v->free) (stamp->id);
        st = stamp->next;
        g_free (stamp);
        stamp = st;
    }

    if (stamps)
        vfs_rmstamp (stamps->v, stamps->id);
}

/* --------------------------------------------------------------------------------------------- */