path: root/lib/base/hash.c

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * hash.c
 *
 * This is merely a couple wrappers around NSPR's PLHashTable, using
 * the identity hash and arena-aware allocators.
 * This is a copy of ckfw/hash.c, with modifications to use NSS types
 * (not Cryptoki types).  Would like for this to be a single implementation,
 * but doesn't seem like it will work.
 */

#ifndef BASE_H
#include "base.h"
#endif /* BASE_H */

#include "prbit.h"

/*
 * nssHash
 *
 *  nssHash_Create
 *  nssHash_Destroy
 *  nssHash_Add
 *  nssHash_Remove
 *  nssHash_Count
 *  nssHash_Exists
 *  nssHash_Lookup
 *  nssHash_Iterate
 */

struct nssHashStr {
    NSSArena *arena;
    PRBool i_alloced_arena;
    PRLock *mutex;

    /*
     * The invariant that mutex protects is:
     *   The count accurately reflects the hashtable state.
     */

    PLHashTable *plHashTable;
    PRUint32 count;
};

static PLHashNumber
nss_identity_hash(const void *key)
{
    return (PLHashNumber)((char *)key - (char *)NULL);
}

static PLHashNumber
nss_item_hash(const void *key)
{
    unsigned int i;
    PLHashNumber h;
    NSSItem *it = (NSSItem *)key;
    h = 0;
    for (i = 0; i < it->size; i++)
        h = PR_ROTATE_LEFT32(h, 4) ^ ((unsigned char *)it->data)[i];
    return h;
}

static int
nss_compare_items(const void *v1, const void *v2)
{
    PRStatus ignore;
    return (int)nssItem_Equal((NSSItem *)v1, (NSSItem *)v2, &ignore);
}

/*
 * nssHash_create
 *
 */
NSS_IMPLEMENT nssHash *
nssHash_Create(NSSArena *arenaOpt, PRUint32 numBuckets, PLHashFunction keyHash,
               PLHashComparator keyCompare, PLHashComparator valueCompare)
{
    nssHash *rv;
    NSSArena *arena;
    PRBool i_alloced;

#ifdef NSSDEBUG
    if (arenaOpt && PR_SUCCESS != nssArena_verifyPointer(arenaOpt)) {
        nss_SetError(NSS_ERROR_INVALID_POINTER);
        return (nssHash *)NULL;
    }
#endif /* NSSDEBUG */

    if (arenaOpt) {
        arena = arenaOpt;
        i_alloced = PR_FALSE;
    } else {
        arena = nssArena_Create();
        i_alloced = PR_TRUE;
    }

    rv = nss_ZNEW(arena, nssHash);
    if ((nssHash *)NULL == rv) {
        goto loser;
    }

    rv->mutex = PZ_NewLock(nssILockOther);
    if ((PZLock *)NULL == rv->mutex) {
        goto loser;
    }

    rv->plHashTable =
        PL_NewHashTable(numBuckets, keyHash, keyCompare, valueCompare,
                        &nssArenaHashAllocOps, arena);
    if ((PLHashTable *)NULL == rv->plHashTable) {
        (void)PZ_DestroyLock(rv->mutex);
        goto loser;
    }

    rv->count = 0;
    rv->arena = arena;
    rv->i_alloced_arena = i_alloced;

    return rv;
loser:
    (void)nss_ZFreeIf(rv);
    return (nssHash *)NULL;
}

/*
 * nssHash_CreatePointer
 *
 */
NSS_IMPLEMENT nssHash *
nssHash_CreatePointer(NSSArena *arenaOpt, PRUint32 numBuckets)
{
    return nssHash_Create(arenaOpt, numBuckets, nss_identity_hash,
                          PL_CompareValues, PL_CompareValues);
}

/*
 * nssHash_CreateString
 *
 */
NSS_IMPLEMENT nssHash *
nssHash_CreateString(NSSArena *arenaOpt, PRUint32 numBuckets)
{
    return nssHash_Create(arenaOpt, numBuckets, PL_HashString,
                          PL_CompareStrings, PL_CompareStrings);
}

/*
 * nssHash_CreateItem
 *
 */
NSS_IMPLEMENT nssHash *
nssHash_CreateItem(NSSArena *arenaOpt, PRUint32 numBuckets)
{
    return nssHash_Create(arenaOpt, numBuckets, nss_item_hash,
                          nss_compare_items, PL_CompareValues);
}

/*
 * nssHash_Destroy
 *
 */
NSS_IMPLEMENT void
nssHash_Destroy(nssHash *hash)
{
    (void)PZ_DestroyLock(hash->mutex);
    PL_HashTableDestroy(hash->plHashTable);
    if (hash->i_alloced_arena) {
        nssArena_Destroy(hash->arena);
    } else {
        nss_ZFreeIf(hash);
    }
}

/*
 * nssHash_Add
 *
 */
NSS_IMPLEMENT PRStatus
nssHash_Add(nssHash *hash, const void *key, const void *value)
{
    PRStatus error = PR_FAILURE;
    PLHashEntry *he;

    PZ_Lock(hash->mutex);

    he = PL_HashTableAdd(hash->plHashTable, key, (void *)value);
    if ((PLHashEntry *)NULL == he) {
        nss_SetError(NSS_ERROR_NO_MEMORY);
    } else if (he->value != value) {
        nss_SetError(NSS_ERROR_HASH_COLLISION);
    } else {
        hash->count++;
        error = PR_SUCCESS;
    }

    (void)PZ_Unlock(hash->mutex);

    return error;
}

/*
 * nssHash_Remove
 *
 */
NSS_IMPLEMENT void
nssHash_Remove(nssHash *hash, const void *it)
{
    PRBool found;

    PZ_Lock(hash->mutex);

    found = PL_HashTableRemove(hash->plHashTable, it);
    if (found) {
        hash->count--;
    }

    (void)PZ_Unlock(hash->mutex);
    return;
}

/*
 * nssHash_Count
 *
 */
NSS_IMPLEMENT PRUint32
nssHash_Count(nssHash *hash)
{
    PRUint32 count;

    PZ_Lock(hash->mutex);

    count = hash->count;

    (void)PZ_Unlock(hash->mutex);

    return count;
}

/*
 * nssHash_Exists
 *
 */
NSS_IMPLEMENT PRBool
nssHash_Exists(nssHash *hash, const void *it)
{
    void *value;

    PZ_Lock(hash->mutex);

    value = PL_HashTableLookup(hash->plHashTable, it);

    (void)PZ_Unlock(hash->mutex);

    if ((void *)NULL == value) {
        return PR_FALSE;
    } else {
        return PR_TRUE;
    }
}

/*
 * nssHash_Lookup
 *
 */
NSS_IMPLEMENT void *
nssHash_Lookup(nssHash *hash, const void *it)
{
    void *rv;

    PZ_Lock(hash->mutex);

    rv = PL_HashTableLookup(hash->plHashTable, it);

    (void)PZ_Unlock(hash->mutex);

    return rv;
}

struct arg_str {
    nssHashIterator fcn;
    void *closure;
};

static PRIntn
nss_hash_enumerator(PLHashEntry *he, PRIntn index, void *arg)
{
    struct arg_str *as = (struct arg_str *)arg;
    as->fcn(he->key, he->value, as->closure);
    return HT_ENUMERATE_NEXT;
}

/*
 * nssHash_Iterate
 *
 * NOTE that the iteration function will be called with the hashtable locked.
 */
NSS_IMPLEMENT void
nssHash_Iterate(nssHash *hash, nssHashIterator fcn, void *closure)
{
    struct arg_str as;
    as.fcn = fcn;
    as.closure = closure;

    PZ_Lock(hash->mutex);

    PL_HashTableEnumerateEntries(hash->plHashTable, nss_hash_enumerator, &as);

    (void)PZ_Unlock(hash->mutex);

    return;
}