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Simplify mdb_hash_val() -> mdb_hash()

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Simpler usage since it's only called once, rename to match new usage,
and drop 3 loop pessimizations which were optimizations 20 years ago.
This commit is contained in:
Hallvard Furuseth 2017-03-12 16:58:51 +01:00
parent 68eda68f0b
commit 172d825155
1 changed files with 8 additions and 24 deletions
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32
libraries/liblmdb/mdb.c
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@ -4965,31 +4965,21 @@ mdb_env_excl_lock(MDB_env *env, int *excl)
* Share and Enjoy! :-)
*/
#define MDB_HASH_INIT ((mdb_hash_t)0xcbf29ce484222325ULL)
/** perform a 64 bit Fowler/Noll/Vo FNV-1a hash on a buffer
* @param[in] val value to hash
* @param[in] hval initial value for hash
* @param[in] len length of value
* @return 64 bit hash
*
* NOTE: To use the recommended 64 bit FNV-1a hash, use MDB_HASH_INIT as the
* hval arg on the first call.
*/
static mdb_hash_t
mdb_hash_val(MDB_val *val, mdb_hash_t hval)
mdb_hash(const void *val, size_t len)
{
unsigned char *s = (unsigned char *)val->mv_data; /* unsigned string */
unsigned char *end = s + val->mv_size;
const unsigned char *s = (const unsigned char *) val, *end = s + len;
mdb_hash_t hval = 0xcbf29ce484222325ULL;
/*
* FNV-1a hash each octet of the string
* FNV-1a hash each octet of the buffer
*/
while (s < end) {
/* xor the bottom with the current octet */
hval ^= (mdb_hash_t)*s++;
/* multiply by the 64 bit FNV magic prime mod 2^64 */
hval += (hval << 1) + (hval << 4) + (hval << 5) +
(hval << 7) + (hval << 8) + (hval << 40);
hval = (hval ^ *s++) * 0x100000001b3ULL;
}
/* return our new hash value */
return hval;
@ -5130,7 +5120,6 @@ mdb_env_setup_locks(MDB_env *env, MDB_name *fname, int mode, int *excl)
DWORD nhigh;
DWORD nlow;
} idbuf;
MDB_val val;
if (!mdb_sec_inited) {
InitializeSecurityDescriptor(&mdb_null_sd,
@ -5145,9 +5134,7 @@ mdb_env_setup_locks(MDB_env *env, MDB_name *fname, int mode, int *excl)
idbuf.volume = stbuf.dwVolumeSerialNumber;
idbuf.nhigh = stbuf.nFileIndexHigh;
idbuf.nlow = stbuf.nFileIndexLow;
val.mv_data = &idbuf;
val.mv_size = sizeof(idbuf);
env->me_txns->mti_mutexid = mdb_hash_val(&val, MDB_HASH_INIT);
env->me_txns->mti_mutexid = mdb_hash(&idbuf, sizeof(idbuf));
mdb_env_mname_init(env);
env->me_rmutex = CreateMutexA(&mdb_all_sa, FALSE, MUTEXNAME(env, 'r'));
if (!env->me_rmutex) goto fail_errno;
@ -5159,7 +5146,6 @@ mdb_env_setup_locks(MDB_env *env, MDB_name *fname, int mode, int *excl)
dev_t dev;
ino_t ino;
} idbuf;
MDB_val val;
#if defined(__NetBSD__)
#define MDB_SHORT_SEMNAMES 1 /* limited to 14 chars */
@ -5167,9 +5153,7 @@ mdb_env_setup_locks(MDB_env *env, MDB_name *fname, int mode, int *excl)
if (fstat(env->me_lfd, &stbuf)) goto fail_errno;
idbuf.dev = stbuf.st_dev;
idbuf.ino = stbuf.st_ino;
val.mv_data = &idbuf;
val.mv_size = sizeof(idbuf);
env->me_txns->mti_mutexid = mdb_hash_val(&val, MDB_HASH_INIT)
env->me_txns->mti_mutexid = mdb_hash(&idbuf, sizeof(idbuf))
#ifdef MDB_SHORT_SEMNAMES
/* Max 9 base85-digits. We truncate here instead of in
* mdb_env_mname_init() to keep the latter portable.