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ruanhaishen
redis
Commits
52970711
Commit
52970711
authored
Dec 26, 2010
by
antirez
Browse files
added diskstore.c, currently just a stub
parent
d3e5e288
Changes
1
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src/diskstore.c
0 → 100644
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52970711
/* diskstore.c implements a very simple disk backed key-value store used
* by Redis for the "disk" backend. This implementation uses the filesystem
* to store key/value pairs. Every file represents a given key.
*
* The key path is calculated using the SHA1 of the key name. For instance
* the key "foo" is stored as a file name called:
*
* /0b/ee/0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33
*
* The couples of characters from the hex output of SHA1 are also used
* to locate two two levels of directories to store the file (as most
* filesystems are not able to handle too many files in a single dir).
*
* In the end there are 65536 final directories (256 directories inside
* every 256 top level directories), so that with 1 billion of files every
* directory will contain in the average 15258 entires, that is ok with
* most filesystems implementation.
*
* The actaul implementation of this disk store is highly related to the
* filesystem implementation. This implementation may be replaced by
* a B+TREE implementation in future implementations.
*
* Data ok every key is serialized using the same format used for .rdb
* serialization. Everything is serialized on every entry: key name,
* ttl information in case of keys with an associated expire time, and the
* serialized value itself.
*
* Because the format is the same of the .rdb files it is trivial to create
* an .rdb file starting from this format just by mean of scanning the
* directories and concatenating entries, with the sole addition of an
* .rdb header at the start and the end-of-db opcode at the end.
*
* -------------------------------------------------------------------------
*
* Copyright (c) 2010-2011, Salvatore Sanfilippo <antirez at gmail dot com>
* 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.
* * Neither the name of Redis nor the names of its contributors may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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.
*/
#include "redis.h"
#include <fcntl.h>
#include <sys/stat.h>
int
dsOpen
(
void
)
{
struct
stat
sb
;
int
retval
;
char
*
path
=
server
.
diskstore_path
;
if
((
retval
=
stat
(
path
,
&
sb
)
==
-
1
)
&&
errno
!=
ENOENT
)
{
redisLog
(
REDIS_WARNING
,
"Error opening disk store at %s: %s"
,
path
,
strerror
(
errno
));
return
REDIS_ERR
;
}
/* Directory already in place. Assume everything is ok. */
if
(
retval
==
0
&&
S_ISDIR
(
sb
.
st_mode
))
return
REDIS_OK
;
/* File exists but it's not a directory */
if
(
retval
==
0
&&
!
S_ISDIR
(
sb
.
st_mode
))
{
redisLog
(
REDIS_WARNING
,
"Disk store at %s is not a directory"
,
path
);
return
REDIS_ERR
;
}
/* New disk store, create the directory structure now, as creating
* them in a lazy way is not a good idea, after very few insertions
* we'll need most of the 65536 directories anyway. */
if
(
mkdir
(
path
)
==
-
1
)
{
redisLog
(
REDIS_WARNING
,
"Disk store init failed creating dir %s: %s"
,
path
,
strerror
(
errno
));
return
REDIS_ERR
;
}
return
REDIS_OK
;
}
int
dsClose
(
void
)
{
return
REDIS_OK
;
}
int
dsSet
(
redisDb
*
db
,
robj
*
key
,
robj
*
val
)
{
}
robj
*
dsGet
(
redisDb
*
db
,
robj
*
key
)
{
}
int
dsExists
(
redisDb
*
db
,
robj
*
key
)
{
}
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