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author | antirez <antirez@gmail.com> | 2012-06-14 15:59:25 +0200 |
---|---|---|
committer | antirez <antirez@gmail.com> | 2012-06-14 16:01:27 +0200 |
commit | ba779119b8b08294cdb776302638ee5b7b9b5b84 (patch) | |
tree | 3e10799a2a00da986c14348d1ab61d9217cb5303 /src/ziplist.c | |
parent | 96b8ff3760b18d2962410322a56308d8410917c8 (diff) | |
download | redis-ba779119b8b08294cdb776302638ee5b7b9b5b84.tar.gz |
ziplistFind(): don't assume that entries are comparable by encoding.
Because Redis 2.6 introduced new integer encodings it is no longer true
that if two entries have a different encoding they are not equal.
An old ziplist can be loaded from an RDB file generated with Redis 2.4,
in this case for instance a small unsigned integers is encoded with a
16 bit encoding, while in Redis 2.6 a more specific 8 bit encoding
format is used.
Because of this bug hashes ended with duplicated values or fields lookup
failed, causing many bad behaviors.
This in turn caused a crash while converting the ziplist encoded hash into
a real hash table because an assertion was raised on duplicated elements.
This commit fixes issue #547.
Many thanks to Pinterest's Marty Weiner and colleagues for discovering
the problem and helping us in the debugging process.
Diffstat (limited to 'src/ziplist.c')
-rw-r--r-- | src/ziplist.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/src/ziplist.c b/src/ziplist.c index 31e61633e..50167651b 100644 --- a/src/ziplist.c +++ b/src/ziplist.c @@ -805,19 +805,24 @@ unsigned char *ziplistFind(unsigned char *p, unsigned char *vstr, unsigned int v return p; } } else { - /* Find out if the specified entry can be encoded */ + /* Find out if the searched field can be encoded. Note that + * we do it only the first time, once done vencoding is set + * to non-zero and vll is set to the integer value. */ if (vencoding == 0) { - /* UINT_MAX when the entry CANNOT be encoded */ if (!zipTryEncoding(vstr, vlen, &vll, &vencoding)) { + /* If the entry can't be encoded we set it to + * UCHAR_MAX so that we don't retry again the next + * time. */ vencoding = UCHAR_MAX; } - /* Must be non-zero by now */ assert(vencoding); } - /* Compare current entry with specified entry */ - if (encoding == vencoding) { + /* Compare current entry with specified entry, do it only + * if vencoding != UCHAR_MAX because if there is no encoding + * possible for the field it can't be a valid integer. */ + if (vencoding != UCHAR_MAX) { long long ll = zipLoadInteger(q, encoding); if (ll == vll) { return p; |