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lmdb: rework key/data comparison to avoid alignment errors.

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Change-Id: I291b50ad6f7dd18f6cbdef34028d917e10166cf1
This commit is contained in:
Leo Yuriev 2015-08-05 00:30:45 +03:00
parent 41d38a1e4d
commit b60f510355
1 changed files with 77 additions and 42 deletions
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119
mdb.c
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@ -1194,7 +1194,7 @@ static void mdb_default_cmp(MDB_txn *txn, MDB_dbi dbi);
static int mdb_reader_check0(MDB_env *env, int rlocked, int *dead);
/** @cond */
static MDB_cmp_func mdb_cmp_memn, mdb_cmp_memnr, mdb_cmp_int_a, mdb_cmp_int_na;
static MDB_cmp_func mdb_cmp_memn, mdb_cmp_memnr, mdb_cmp_int_ai, mdb_cmp_int_a2, mdb_cmp_int_ua;
/** @endcond */
/** Return the library version info. */
@ -4649,7 +4649,7 @@ mdb_env_open(MDB_env *env, const char *path, unsigned flags, mode_t mode)
rc = ENOMEM;
goto leave;
}
env->me_dbxs[FREE_DBI].md_cmp = mdb_cmp_int_a; /* aligned MDB_INTEGERKEY */
env->me_dbxs[FREE_DBI].md_cmp = mdb_cmp_int_ai; /* aligned MDB_INTEGERKEY */
/* For RDONLY, get lockfile after we know datafile exists */
if (!(flags & MDB_RDONLY)) {
@ -4818,29 +4818,26 @@ mdb_env_close_ex(MDB_env *env, int dont_sync)
free(env);
}
/** Compare two items pointing at aligned unsigned int's.
*
* This is also set as #MDB_INTEGERDUP|#MDB_DUPFIXED's #MDB_dbx.%md_dcmp.
*/
/** Compare two items pointing at aligned unsigned int's. */
static int
mdb_cmp_int_a(const MDB_val *a, const MDB_val *b)
mdb_cmp_int_ai(const MDB_val *a, const MDB_val *b)
{
mdb_assert(NULL, a->mv_size == b->mv_size);
mdb_assert(NULL, 0 == (uintptr_t) a->mv_data % sizeof(int));
mdb_assert(NULL, 0 == (uintptr_t) a->mv_data % sizeof(int)
&& 0 == (uintptr_t) b->mv_data % sizeof(int));
if (sizeof(int) != sizeof(size_t) && likely(a->mv_size == sizeof(size_t)))
if (sizeof(int) != sizeof(size_t) && likely(a->mv_size == sizeof(size_t))) {
return (*(size_t *)a->mv_data < *(size_t *)b->mv_data) ? -1 :
*(size_t *)a->mv_data > *(size_t *)b->mv_data;
}
mdb_assert(NULL, a->mv_size == sizeof(int) );
return *(int *)a->mv_data - *(int *)b->mv_data;
}
/** Compare two items pointing at unsigneds of unknown alignment.
* Nodes and keys are guaranteed to be 2-byte aligned.
*/
/** Compare two items pointing at 2-byte aligned unsigned int's. */
static int
mdb_cmp_int_na(const MDB_val *a, const MDB_val *b)
mdb_cmp_int_a2(const MDB_val *a, const MDB_val *b)
{
mdb_assert(NULL, a->mv_size == b->mv_size);
mdb_assert(NULL, 0 == a->mv_size % sizeof(short));
@ -4854,29 +4851,68 @@ mdb_cmp_int_na(const MDB_val *a, const MDB_val *b)
mdb_assert(NULL, a->mv_size == sizeof(int) );
return *(int *)a->mv_data - *(int *)b->mv_data;
#elif BYTE_ORDER == LITTLE_ENDIAN
unsigned short *u, *c;
int x;
u = (unsigned short *) ((char *) a->mv_data + a->mv_size);
c = (unsigned short *) ((char *) b->mv_data + a->mv_size);
do {
x = *--u - *--c;
} while(!x && u > (unsigned short *)a->mv_data);
return x;
#else
unsigned short *u, *c, *end;
int x;
{
int x;
unsigned short *u, *c;
end = (unsigned short *) ((char *) a->mv_data + a->mv_size);
u = (unsigned short *)a->mv_data;
c = (unsigned short *)b->mv_data;
do {
x = *u++ - *c++;
} while(!x && u < end);
return x;
#endif /* BYTE_ORDER & MISALIGNED_OK */
#if BYTE_ORDER == LITTLE_ENDIAN
u = (unsigned short *) ((char *) a->mv_data + a->mv_size);
c = (unsigned short *) ((char *) b->mv_data + a->mv_size);
do {
x = *--u - *--c;
} while(!x && u > (unsigned short *)a->mv_data);
#else /* BYTE_ORDER */
unsigned short *end;
end = (unsigned short *) ((char *) a->mv_data + a->mv_size);
u = (unsigned short *)a->mv_data;
c = (unsigned short *)b->mv_data;
do {
x = *u++ - *c++;
} while(!x && u < end);
#endif /* BYTE_ORDER */
return x;
}
#endif /* MISALIGNED_OK */
}
/** Compare two items pointing at unsigneds of unknown alignment.
*
* This is also set as #MDB_INTEGERDUP|#MDB_DUPFIXED's #MDB_dbx.%md_dcmp.
*/
static int
mdb_cmp_int_ua(const MDB_val *a, const MDB_val *b)
{
mdb_assert(NULL, a->mv_size == b->mv_size);
#if MISALIGNED_OK
if (sizeof(int) != sizeof(size_t) && likely(a->mv_size == sizeof(size_t)))
return (*(size_t *)a->mv_data < *(size_t *)b->mv_data) ? -1 :
*(size_t *)a->mv_data > *(size_t *)b->mv_data;
mdb_assert(NULL, a->mv_size == sizeof(int) );
return *(int *)a->mv_data - *(int *)b->mv_data;
#else
mdb_assert(NULL, a->mv_size == sizeof(int) || a->mv_size == sizeof(size_t));
{
#if BYTE_ORDER == LITTLE_ENDIAN
const unsigned char *p1, *p2;
int diff;
p1 = (const unsigned char *)a->mv_data + a->mv_size;
p2 = (const unsigned char *)b->mv_data + a->mv_size;
do {
diff = *--p1 - *--p2;
if (diff)
return diff;
} while(p1 != a->mv_data);
return 0;
}
#else /* BYTE_ORDER */
return memcmp(a->mv_data, b->mv_data, a->mv_size);
#endif /* BYTE_ORDER */
#endif /* MISALIGNED_OK */
}
/** Compare two items lexically */
@ -4954,10 +4990,10 @@ mdb_node_search(MDB_cursor *mc, MDB_val *key, int *exactp)
cmp = mc->mc_dbx->md_cmp;
/* Branch pages have no data, so if using integer keys,
* alignment is guaranteed. Use faster mdb_cmp_int_a.
* alignment is guaranteed. Use faster mdb_cmp_int_ai.
*/
if (cmp == mdb_cmp_int_na && IS_BRANCH(mp))
cmp = mdb_cmp_int_a;
if (cmp == mdb_cmp_int_a2 && IS_BRANCH(mp))
cmp = mdb_cmp_int_ai;
if (IS_LEAF2(mp)) {
nodekey.mv_size = mc->mc_db->md_xsize;
@ -9124,17 +9160,16 @@ mdb_env_info(MDB_env *env, MDB_envinfo *arg)
static void
mdb_default_cmp(MDB_txn *txn, MDB_dbi dbi)
{
uint16_t f = txn->mt_dbs[dbi].md_flags;
unsigned f = txn->mt_dbs[dbi].md_flags;
txn->mt_dbxs[dbi].md_cmp =
(f & MDB_REVERSEKEY) ? mdb_cmp_memnr :
(f & MDB_INTEGERKEY) ? mdb_cmp_int_na : mdb_cmp_memn;
(f & MDB_INTEGERKEY) ? mdb_cmp_int_a2 : mdb_cmp_memn;
txn->mt_dbxs[dbi].md_dcmp =
!(f & MDB_DUPSORT) ? 0 :
((f & MDB_INTEGERDUP)
? ((f & MDB_DUPFIXED) ? mdb_cmp_int_a : mdb_cmp_int_na)
: ((f & MDB_REVERSEDUP) ? mdb_cmp_memnr : mdb_cmp_memn));
((f & MDB_INTEGERDUP) ? mdb_cmp_int_ua :
((f & MDB_REVERSEDUP) ? mdb_cmp_memnr : mdb_cmp_memn));
}
int mdb_dbi_open(MDB_txn *txn, const char *name, unsigned flags, MDB_dbi *dbi)