/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/* camel-message-cache.c: Class for a Camel cache.
*
* Authors: Michael Zucchi <notzed@ximian.com>
*
* Copyright (C) 2001 Ximian, Inc. (www.ximian.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* 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
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <sys/types.h>
#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#ifdef HAVE_ALLOCA_H
#include <alloca.h>
#endif
#include "camel-data-cache.h"
#include "camel-exception.h"
#include "camel-stream-fs.h"
#include "camel-stream-mem.h"
#include "camel-file-utils.h"
extern int camel_verbose_debug;
#define dd(x) (camel_verbose_debug?(x):0)
#define d(x)
/* how many 'bits' of hash are used to key the toplevel directory */
#define CAMEL_DATA_CACHE_BITS (6)
#define CAMEL_DATA_CACHE_MASK ((1<<CAMEL_DATA_CACHE_BITS)-1)
/* timeout before a cache dir is checked again for expired entries,
once an hour should be enough */
#define CAMEL_DATA_CACHE_CYCLE_TIME (60*60)
struct _CamelDataCachePrivate {
CamelObjectBag *busy_bag;
int expire_inc;
time_t expire_last[1<<CAMEL_DATA_CACHE_BITS];
};
static CamelObject *camel_data_cache_parent;
static void data_cache_class_init(CamelDataCacheClass *klass)
{
camel_data_cache_parent = (CamelObject *)camel_object_get_type ();
#if 0
klass->add = data_cache_add;
klass->get = data_cache_get;
klass->close = data_cache_close;
klass->remove = data_cache_remove;
klass->clear = data_cache_clear;
#endif
}
static void data_cache_init(CamelDataCache *cdc, CamelDataCacheClass *klass)
{
struct _CamelDataCachePrivate *p;
p = cdc->priv = g_malloc0(sizeof(*cdc->priv));
p->busy_bag = camel_object_bag_new(g_str_hash, g_str_equal);
}
static void data_cache_finalise(CamelDataCache *cdc)
{
struct _CamelDataCachePrivate *p;
p = cdc->priv;
camel_object_bag_destroy(p->busy_bag);
g_free(p);
g_free (cdc->path);
}
CamelType
camel_data_cache_get_type(void)
{
static CamelType camel_data_cache_type = CAMEL_INVALID_TYPE;
if (camel_data_cache_type == CAMEL_INVALID_TYPE) {
camel_data_cache_type = camel_type_register(
CAMEL_OBJECT_TYPE, "CamelDataCache",
sizeof (CamelDataCache),
sizeof (CamelDataCacheClass),
(CamelObjectClassInitFunc) data_cache_class_init,
NULL,
(CamelObjectInitFunc) data_cache_init,
(CamelObjectFinalizeFunc) data_cache_finalise);
}
return camel_data_cache_type;
}
/**
* camel_data_cache_new:
* @path: Base path of cache, subdirectories will be created here.
* @flags: Open flags, none defined.
* @ex:
*
* Create a new data cache.
*
* Return value: A new cache object, or NULL if the base path cannot
* be written to.
**/
CamelDataCache *
camel_data_cache_new(const char *path, guint32 flags, CamelException *ex)
{
CamelDataCache *cdc;
if (camel_file_util_mkdir(path, 0700) == -1) {
camel_exception_setv(ex, CAMEL_EXCEPTION_SYSTEM,
_("Unable to create cache path"));
return NULL;
}
cdc = (CamelDataCache *)camel_object_new(CAMEL_DATA_CACHE_TYPE);
cdc->path = g_strdup(path);
cdc->flags = flags;
cdc->expire_age = -1;
cdc->expire_access = -1;
return cdc;
}
/**
* camel_data_cache_set_expire_age:
* @cdc:
* @when: Timeout for age expiry, or -1 to disable.
*
* Set the cache expiration policy for aged entries.
*
* Items in the cache older than @when seconds may be
* flushed at any time. Items are expired in a lazy
* manner, so it is indeterminate when the items will
* physically be removed.
*
* Note you can set both an age and an access limit. The
* age acts as a hard limit on cache entries.
**/
void
camel_data_cache_set_expire_age(CamelDataCache *cdc, time_t when)
{
cdc->expire_age = when;
}
/**
* camel_data_cache_set_expire_access:
* @cdc:
* @when: Timeout for access, or -1 to disable access expiry.
*
* Set the cache expiration policy for access times.
*
* Items in the cache which haven't been accessed for @when
* seconds may be expired at any time. Items are expired in a lazy
* manner, so it is indeterminate when the items will
* physically be removed.
*
* Note you can set both an age and an access limit. The
* age acts as a hard limit on cache entries.
**/
void
camel_data_cache_set_expire_access(CamelDataCache *cdc, time_t when)
{
cdc->expire_access = when;
}
static void
data_cache_expire(CamelDataCache *cdc, const char *path, const char *keep, time_t now)
{
DIR *dir;
struct dirent *d;
GString *s;
struct stat st;
CamelStream *stream;
dir = opendir(path);
if (dir == NULL)
return;
s = g_string_new("");
while ( (d = readdir(dir)) ) {
if (strcmp(d->d_name, keep) == 0)
continue;
g_string_printf (s, "%s/%s", path, d->d_name);
dd(printf("Checking '%s' for expiry\n", s->str));
if (stat(s->str, &st) == 0
&& S_ISREG(st.st_mode)
&& ((cdc->expire_age != -1 && st.st_mtime + cdc->expire_age < now)
|| (cdc->expire_access != -1 && st.st_atime + cdc->expire_access < now))) {
dd(printf("Has expired! Removing!\n"));
unlink(s->str);
stream = camel_object_bag_get(cdc->priv->busy_bag, s->str);
if (stream) {
camel_object_bag_remove(cdc->priv->busy_bag, stream);
camel_object_unref(stream);
}
}
}
g_string_free(s, TRUE);
closedir(dir);
}
/* Since we have to stat the directory anyway, we use this opportunity to
lazily expire old data.
If it is this directories 'turn', and we haven't done it for CYCLE_TIME seconds,
then we perform an expiry run */
static char *
data_cache_path(CamelDataCache *cdc, int create, const char *path, const char *key)
{
char *dir, *real, *tmp;
guint32 hash;
hash = g_str_hash(key);
hash = (hash>>5)&CAMEL_DATA_CACHE_MASK;
dir = alloca(strlen(cdc->path) + strlen(path) + 8);
sprintf(dir, "%s/%s/%02x", cdc->path, path, hash);
if (access(dir, F_OK) == -1) {
if (create)
camel_file_util_mkdir(dir, 0700);
} else if (cdc->priv->expire_inc == hash
&& (cdc->expire_age != -1 || cdc->expire_access != -1)) {
time_t now;
dd(printf("Checking expire cycle time on dir '%s'\n", dir));
/* This has a race, but at worst we re-run an expire cycle which is safe */
now = time(0);
if (cdc->priv->expire_last[hash] + CAMEL_DATA_CACHE_CYCLE_TIME < now) {
cdc->priv->expire_last[hash] = now;
data_cache_expire(cdc, dir, key, now);
}
cdc->priv->expire_inc = (cdc->priv->expire_inc + 1) & CAMEL_DATA_CACHE_MASK;
}
tmp = camel_file_util_safe_filename(key);
real = g_strdup_printf("%s/%s", dir, tmp);
g_free(tmp);
return real;
}
/**
* camel_data_cache_add:
* @cdc:
* @path: Relative path of item to add.
* @key: Key of item to add.
* @ex:
*
* Add a new item to the cache.
*
* The key and the path combine to form a unique key used to store
* the item.
*
* Potentially, expiry processing will be performed while this call
* is executing.
*
* Return value: A CamelStream (file) opened in read-write mode.
* The caller must unref this when finished.
**/
CamelStream *
camel_data_cache_add(CamelDataCache *cdc, const char *path, const char *key, CamelException *ex)
{
char *real;
CamelStream *stream;
real = data_cache_path(cdc, TRUE, path, key);
stream = camel_object_bag_reserve(cdc->priv->busy_bag, real);
if (stream) {
unlink(real);
camel_object_bag_remove(cdc->priv->busy_bag, stream);
camel_object_unref(stream);
}
stream = camel_stream_fs_new_with_name(real, O_RDWR|O_CREAT|O_TRUNC, 0600);
if (stream)
camel_object_bag_add(cdc->priv->busy_bag, real, stream);
else
camel_object_bag_abort(cdc->priv->busy_bag, real);
g_free(real);
return stream;
}
/**
* camel_data_cache_get:
* @cdc:
* @path: Path to the (sub) cache the item exists in.
* @key: Key for the cache item.
* @ex:
*
* Lookup an item in the cache. If the item exists, a stream
* is returned for the item. The stream may be shared by
* multiple callers, so ensure the stream is in a valid state
* through external locking.
*
* Return value: A cache item, or NULL if the cache item does not exist.
**/
CamelStream *
camel_data_cache_get(CamelDataCache *cdc, const char *path, const char *key, CamelException *ex)
{
char *real;
CamelStream *stream;
real = data_cache_path(cdc, FALSE, path, key);
stream = camel_object_bag_reserve(cdc->priv->busy_bag, real);
if (!stream) {
stream = camel_stream_fs_new_with_name(real, O_RDWR, 0600);
if (stream)
camel_object_bag_add(cdc->priv->busy_bag, real, stream);
else
camel_object_bag_abort(cdc->priv->busy_bag, real);
}
g_free(real);
return stream;
}
/**
* camel_data_cache_remove:
* @cdc:
* @path:
* @key:
* @ex:
*
* Remove/expire a cache item.
*
* Return value:
**/
int
camel_data_cache_remove(CamelDataCache *cdc, const char *path, const char *key, CamelException *ex)
{
CamelStream *stream;
char *real;
int ret;
real = data_cache_path(cdc, FALSE, path, key);
stream = camel_object_bag_get(cdc->priv->busy_bag, real);
if (stream) {
camel_object_bag_remove(cdc->priv->busy_bag, stream);
camel_object_unref(stream);
}
/* maybe we were a mem stream */
if (unlink (real) == -1 && errno != ENOENT) {
camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM,
_("Could not remove cache entry: %s: %s"),
real, g_strerror (errno));
ret = -1;
} else {
ret = 0;
}
g_free(real);
return ret;
}
/**
* camel_data_cache_rename:
* @cache:
* @old:
* @new:
* @ex:
*
* Rename a cache path. All cache items accessed from the old path
* are accessible using the new path.
*
* CURRENTLY UNIMPLEMENTED
*
* Return value: -1 on error.
**/
int camel_data_cache_rename(CamelDataCache *cache,
const char *old, const char *new, CamelException *ex)
{
/* blah dont care yet */
return -1;
}
/**
* camel_data_cache_clear:
* @cache:
* @path: Path to clear, or NULL to clear all items in
* all paths.
* @ex:
*
* Clear all items in a given cache path or all items in the cache.
*
* CURRENTLY_UNIMPLEMENTED
*
* Return value: -1 on error.
**/
int
camel_data_cache_clear(CamelDataCache *cache, const char *path, CamelException *ex)
{
/* nor for this? */
return -1;
}
