+++ /dev/null
- /*
- Trivial Database 2: hash handling
- Copyright (C) Rusty Russell 2010
-
- This library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 3 of the License, or (at your option) any later version.
-
- This library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public
- License along with this library; if not, see <http://www.gnu.org/licenses/>.
-*/
-#include "private.h"
-#include <ccan/hash/hash.h>
-#include <assert.h>
-
-/* Default hash function. */
-uint64_t tdb_jenkins_hash(const void *key, size_t length, uint64_t seed,
- void *unused)
-{
- uint64_t ret;
- /* hash64_stable assumes lower bits are more important; they are a
- * slightly better hash. We use the upper bits first, so swap them. */
- ret = hash64_stable((const unsigned char *)key, length, seed);
- return (ret >> 32) | (ret << 32);
-}
-
-uint64_t tdb_hash(struct tdb_context *tdb, const void *ptr, size_t len)
-{
- return tdb->hash_fn(ptr, len, tdb->hash_seed, tdb->hash_data);
-}
-
-uint64_t hash_record(struct tdb_context *tdb, tdb_off_t off)
-{
- const struct tdb_used_record *r;
- const void *key;
- uint64_t klen, hash;
-
- r = tdb_access_read(tdb, off, sizeof(*r), true);
- if (TDB_PTR_IS_ERR(r)) {
- /* FIXME */
- return 0;
- }
-
- klen = rec_key_length(r);
- tdb_access_release(tdb, r);
-
- key = tdb_access_read(tdb, off + sizeof(*r), klen, false);
- if (TDB_PTR_IS_ERR(key)) {
- return 0;
- }
-
- hash = tdb_hash(tdb, key, klen);
- tdb_access_release(tdb, key);
- return hash;
-}
-
-/* Get bits from a value. */
-static uint32_t bits_from(uint64_t val, unsigned start, unsigned num)
-{
- assert(num <= 32);
- return (val >> start) & ((1U << num) - 1);
-}
-
-/* We take bits from the top: that way we can lock whole sections of the hash
- * by using lock ranges. */
-static uint32_t use_bits(struct hash_info *h, unsigned num)
-{
- h->hash_used += num;
- return bits_from(h->h, 64 - h->hash_used, num);
-}
-
-static tdb_bool_err key_matches(struct tdb_context *tdb,
- const struct tdb_used_record *rec,
- tdb_off_t off,
- const struct tdb_data *key)
-{
- tdb_bool_err ret = false;
- const char *rkey;
-
- if (rec_key_length(rec) != key->dsize) {
- tdb->stats.compare_wrong_keylen++;
- return ret;
- }
-
- rkey = tdb_access_read(tdb, off + sizeof(*rec), key->dsize, false);
- if (TDB_PTR_IS_ERR(rkey)) {
- return (tdb_bool_err)TDB_PTR_ERR(rkey);
- }
- if (memcmp(rkey, key->dptr, key->dsize) == 0)
- ret = true;
- else
- tdb->stats.compare_wrong_keycmp++;
- tdb_access_release(tdb, rkey);
- return ret;
-}
-
-/* Does entry match? */
-static tdb_bool_err match(struct tdb_context *tdb,
- struct hash_info *h,
- const struct tdb_data *key,
- tdb_off_t val,
- struct tdb_used_record *rec)
-{
- tdb_off_t off;
- enum TDB_ERROR ecode;
-
- tdb->stats.compares++;
- /* Desired bucket must match. */
- if (h->home_bucket != (val & TDB_OFF_HASH_GROUP_MASK)) {
- tdb->stats.compare_wrong_bucket++;
- return false;
- }
-
- /* Top bits of offset == next bits of hash. */
- if (bits_from(val, TDB_OFF_HASH_EXTRA_BIT, TDB_OFF_UPPER_STEAL_EXTRA)
- != bits_from(h->h, 64 - h->hash_used - TDB_OFF_UPPER_STEAL_EXTRA,
- TDB_OFF_UPPER_STEAL_EXTRA)) {
- tdb->stats.compare_wrong_offsetbits++;
- return false;
- }
-
- off = val & TDB_OFF_MASK;
- ecode = tdb_read_convert(tdb, off, rec, sizeof(*rec));
- if (ecode != TDB_SUCCESS) {
- return (tdb_bool_err)ecode;
- }
-
- if ((h->h & ((1 << 11)-1)) != rec_hash(rec)) {
- tdb->stats.compare_wrong_rechash++;
- return false;
- }
-
- return key_matches(tdb, rec, off, key);
-}
-
-static tdb_off_t hbucket_off(tdb_off_t group_start, unsigned bucket)
-{
- return group_start
- + (bucket % (1 << TDB_HASH_GROUP_BITS)) * sizeof(tdb_off_t);
-}
-
-bool is_subhash(tdb_off_t val)
-{
- return (val >> TDB_OFF_UPPER_STEAL_SUBHASH_BIT) & 1;
-}
-
-/* FIXME: Guess the depth, don't over-lock! */
-static tdb_off_t hlock_range(tdb_off_t group, tdb_off_t *size)
-{
- *size = 1ULL << (64 - (TDB_TOPLEVEL_HASH_BITS - TDB_HASH_GROUP_BITS));
- return group << (64 - (TDB_TOPLEVEL_HASH_BITS - TDB_HASH_GROUP_BITS));
-}
-
-static tdb_off_t COLD find_in_chain(struct tdb_context *tdb,
- struct tdb_data key,
- tdb_off_t chain,
- struct hash_info *h,
- struct tdb_used_record *rec,
- struct traverse_info *tinfo)
-{
- tdb_off_t off, next;
- enum TDB_ERROR ecode;
-
- /* In case nothing is free, we set these to zero. */
- h->home_bucket = h->found_bucket = 0;
-
- for (off = chain; off; off = next) {
- unsigned int i;
-
- h->group_start = off;
- ecode = tdb_read_convert(tdb, off, h->group, sizeof(h->group));
- if (ecode != TDB_SUCCESS) {
- return TDB_ERR_TO_OFF(ecode);
- }
-
- for (i = 0; i < (1 << TDB_HASH_GROUP_BITS); i++) {
- tdb_off_t recoff;
- if (!h->group[i]) {
- /* Remember this empty bucket. */
- h->home_bucket = h->found_bucket = i;
- continue;
- }
-
- /* We can insert extra bits via add_to_hash
- * empty bucket logic. */
- recoff = h->group[i] & TDB_OFF_MASK;
- ecode = tdb_read_convert(tdb, recoff, rec,
- sizeof(*rec));
- if (ecode != TDB_SUCCESS) {
- return TDB_ERR_TO_OFF(ecode);
- }
-
- ecode = TDB_OFF_TO_ERR(key_matches(tdb, rec, recoff,
- &key));
- if (ecode < 0) {
- return TDB_ERR_TO_OFF(ecode);
- }
- if (ecode == (enum TDB_ERROR)1) {
- h->home_bucket = h->found_bucket = i;
-
- if (tinfo) {
- tinfo->levels[tinfo->num_levels]
- .hashtable = off;
- tinfo->levels[tinfo->num_levels]
- .total_buckets
- = 1 << TDB_HASH_GROUP_BITS;
- tinfo->levels[tinfo->num_levels].entry
- = i;
- tinfo->num_levels++;
- }
- return recoff;
- }
- }
- next = tdb_read_off(tdb, off
- + offsetof(struct tdb_chain, next));
- if (TDB_OFF_IS_ERR(next)) {
- return next;
- }
- if (next)
- next += sizeof(struct tdb_used_record);
- }
- return 0;
-}
-
-/* This is the core routine which searches the hashtable for an entry.
- * On error, no locks are held and -ve is returned.
- * Otherwise, hinfo is filled in (and the optional tinfo).
- * If not found, the return value is 0.
- * If found, the return value is the offset, and *rec is the record. */
-tdb_off_t find_and_lock(struct tdb_context *tdb,
- struct tdb_data key,
- int ltype,
- struct hash_info *h,
- struct tdb_used_record *rec,
- struct traverse_info *tinfo)
-{
- uint32_t i, group;
- tdb_off_t hashtable;
- enum TDB_ERROR ecode;
-
- h->h = tdb_hash(tdb, key.dptr, key.dsize);
- h->hash_used = 0;
- group = use_bits(h, TDB_TOPLEVEL_HASH_BITS - TDB_HASH_GROUP_BITS);
- h->home_bucket = use_bits(h, TDB_HASH_GROUP_BITS);
-
- h->hlock_start = hlock_range(group, &h->hlock_range);
- ecode = tdb_lock_hashes(tdb, h->hlock_start, h->hlock_range, ltype,
- TDB_LOCK_WAIT);
- if (ecode != TDB_SUCCESS) {
- return TDB_ERR_TO_OFF(ecode);
- }
-
- hashtable = offsetof(struct tdb_header, hashtable);
- if (tinfo) {
- tinfo->toplevel_group = group;
- tinfo->num_levels = 1;
- tinfo->levels[0].entry = 0;
- tinfo->levels[0].hashtable = hashtable
- + (group << TDB_HASH_GROUP_BITS) * sizeof(tdb_off_t);
- tinfo->levels[0].total_buckets = 1 << TDB_HASH_GROUP_BITS;
- }
-
- while (h->hash_used <= 64) {
- /* Read in the hash group. */
- h->group_start = hashtable
- + group * (sizeof(tdb_off_t) << TDB_HASH_GROUP_BITS);
-
- ecode = tdb_read_convert(tdb, h->group_start, &h->group,
- sizeof(h->group));
- if (ecode != TDB_SUCCESS) {
- goto fail;
- }
-
- /* Pointer to another hash table? Go down... */
- if (is_subhash(h->group[h->home_bucket])) {
- hashtable = (h->group[h->home_bucket] & TDB_OFF_MASK)
- + sizeof(struct tdb_used_record);
- if (tinfo) {
- /* When we come back, use *next* bucket */
- tinfo->levels[tinfo->num_levels-1].entry
- += h->home_bucket + 1;
- }
- group = use_bits(h, TDB_SUBLEVEL_HASH_BITS
- - TDB_HASH_GROUP_BITS);
- h->home_bucket = use_bits(h, TDB_HASH_GROUP_BITS);
- if (tinfo) {
- tinfo->levels[tinfo->num_levels].hashtable
- = hashtable;
- tinfo->levels[tinfo->num_levels].total_buckets
- = 1 << TDB_SUBLEVEL_HASH_BITS;
- tinfo->levels[tinfo->num_levels].entry
- = group << TDB_HASH_GROUP_BITS;
- tinfo->num_levels++;
- }
- continue;
- }
-
- /* It's in this group: search (until 0 or all searched) */
- for (i = 0, h->found_bucket = h->home_bucket;
- i < (1 << TDB_HASH_GROUP_BITS);
- i++, h->found_bucket = ((h->found_bucket+1)
- % (1 << TDB_HASH_GROUP_BITS))) {
- tdb_bool_err berr;
- if (is_subhash(h->group[h->found_bucket]))
- continue;
-
- if (!h->group[h->found_bucket])
- break;
-
- berr = match(tdb, h, &key, h->group[h->found_bucket],
- rec);
- if (berr < 0) {
- ecode = TDB_OFF_TO_ERR(berr);
- goto fail;
- }
- if (berr) {
- if (tinfo) {
- tinfo->levels[tinfo->num_levels-1].entry
- += h->found_bucket;
- }
- return h->group[h->found_bucket] & TDB_OFF_MASK;
- }
- }
- /* Didn't find it: h indicates where it would go. */
- return 0;
- }
-
- return find_in_chain(tdb, key, hashtable, h, rec, tinfo);
-
-fail:
- tdb_unlock_hashes(tdb, h->hlock_start, h->hlock_range, ltype);
- return TDB_ERR_TO_OFF(ecode);
-}
-
-/* I wrote a simple test, expanding a hash to 2GB, for the following
- * cases:
- * 1) Expanding all the buckets at once,
- * 2) Expanding the bucket we wanted to place the new entry into.
- * 3) Expanding the most-populated bucket,
- *
- * I measured the worst/average/best density during this process.
- * 1) 3%/16%/30%
- * 2) 4%/20%/38%
- * 3) 6%/22%/41%
- *
- * So we figure out the busiest bucket for the moment.
- */
-static unsigned fullest_bucket(struct tdb_context *tdb,
- const tdb_off_t *group,
- unsigned new_bucket)
-{
- unsigned counts[1 << TDB_HASH_GROUP_BITS] = { 0 };
- unsigned int i, best_bucket;
-
- /* Count the new entry. */
- counts[new_bucket]++;
- best_bucket = new_bucket;
-
- for (i = 0; i < (1 << TDB_HASH_GROUP_BITS); i++) {
- unsigned this_bucket;
-
- if (is_subhash(group[i]))
- continue;
- this_bucket = group[i] & TDB_OFF_HASH_GROUP_MASK;
- if (++counts[this_bucket] > counts[best_bucket])
- best_bucket = this_bucket;
- }
-
- return best_bucket;
-}
-
-static bool put_into_group(tdb_off_t *group,
- unsigned bucket, tdb_off_t encoded)
-{
- unsigned int i;
-
- for (i = 0; i < (1 << TDB_HASH_GROUP_BITS); i++) {
- unsigned b = (bucket + i) % (1 << TDB_HASH_GROUP_BITS);
-
- if (group[b] == 0) {
- group[b] = encoded;
- return true;
- }
- }
- return false;
-}
-
-static void force_into_group(tdb_off_t *group,
- unsigned bucket, tdb_off_t encoded)
-{
- if (!put_into_group(group, bucket, encoded))
- abort();
-}
-
-static tdb_off_t encode_offset(tdb_off_t new_off, struct hash_info *h)
-{
- return h->home_bucket
- | new_off
- | ((uint64_t)bits_from(h->h,
- 64 - h->hash_used - TDB_OFF_UPPER_STEAL_EXTRA,
- TDB_OFF_UPPER_STEAL_EXTRA)
- << TDB_OFF_HASH_EXTRA_BIT);
-}
-
-/* Simply overwrite the hash entry we found before. */
-enum TDB_ERROR replace_in_hash(struct tdb_context *tdb,
- struct hash_info *h,
- tdb_off_t new_off)
-{
- return tdb_write_off(tdb, hbucket_off(h->group_start, h->found_bucket),
- encode_offset(new_off, h));
-}
-
-/* We slot in anywhere that's empty in the chain. */
-static enum TDB_ERROR COLD add_to_chain(struct tdb_context *tdb,
- tdb_off_t subhash,
- tdb_off_t new_off)
-{
- tdb_off_t entry;
- enum TDB_ERROR ecode;
-
- entry = tdb_find_zero_off(tdb, subhash, 1<<TDB_HASH_GROUP_BITS);
- if (TDB_OFF_IS_ERR(entry)) {
- return TDB_OFF_TO_ERR(entry);
- }
-
- if (entry == 1 << TDB_HASH_GROUP_BITS) {
- tdb_off_t next;
-
- next = tdb_read_off(tdb, subhash
- + offsetof(struct tdb_chain, next));
- if (TDB_OFF_IS_ERR(next)) {
- return TDB_OFF_TO_ERR(next);
- }
-
- if (!next) {
- next = alloc(tdb, 0, sizeof(struct tdb_chain), 0,
- TDB_CHAIN_MAGIC, false);
- if (TDB_OFF_IS_ERR(next))
- return TDB_OFF_TO_ERR(next);
- ecode = zero_out(tdb,
- next+sizeof(struct tdb_used_record),
- sizeof(struct tdb_chain));
- if (ecode != TDB_SUCCESS) {
- return ecode;
- }
- ecode = tdb_write_off(tdb, subhash
- + offsetof(struct tdb_chain,
- next),
- next);
- if (ecode != TDB_SUCCESS) {
- return ecode;
- }
- }
- return add_to_chain(tdb, next, new_off);
- }
-
- return tdb_write_off(tdb, subhash + entry * sizeof(tdb_off_t),
- new_off);
-}
-
-/* Add into a newly created subhash. */
-static enum TDB_ERROR add_to_subhash(struct tdb_context *tdb, tdb_off_t subhash,
- unsigned hash_used, tdb_off_t val)
-{
- tdb_off_t off = (val & TDB_OFF_MASK), *group;
- struct hash_info h;
- unsigned int gnum;
-
- h.hash_used = hash_used;
-
- if (hash_used + TDB_SUBLEVEL_HASH_BITS > 64)
- return add_to_chain(tdb, subhash, off);
-
- h.h = hash_record(tdb, off);
- gnum = use_bits(&h, TDB_SUBLEVEL_HASH_BITS-TDB_HASH_GROUP_BITS);
- h.group_start = subhash
- + gnum * (sizeof(tdb_off_t) << TDB_HASH_GROUP_BITS);
- h.home_bucket = use_bits(&h, TDB_HASH_GROUP_BITS);
-
- group = tdb_access_write(tdb, h.group_start,
- sizeof(*group) << TDB_HASH_GROUP_BITS, true);
- if (TDB_PTR_IS_ERR(group)) {
- return TDB_PTR_ERR(group);
- }
- force_into_group(group, h.home_bucket, encode_offset(off, &h));
- return tdb_access_commit(tdb, group);
-}
-
-static enum TDB_ERROR expand_group(struct tdb_context *tdb, struct hash_info *h)
-{
- unsigned bucket, num_vals, i, magic;
- size_t subsize;
- tdb_off_t subhash;
- tdb_off_t vals[1 << TDB_HASH_GROUP_BITS];
- enum TDB_ERROR ecode;
-
- /* Attach new empty subhash under fullest bucket. */
- bucket = fullest_bucket(tdb, h->group, h->home_bucket);
-
- if (h->hash_used == 64) {
- tdb->stats.alloc_chain++;
- subsize = sizeof(struct tdb_chain);
- magic = TDB_CHAIN_MAGIC;
- } else {
- tdb->stats.alloc_subhash++;
- subsize = (sizeof(tdb_off_t) << TDB_SUBLEVEL_HASH_BITS);
- magic = TDB_HTABLE_MAGIC;
- }
-
- subhash = alloc(tdb, 0, subsize, 0, magic, false);
- if (TDB_OFF_IS_ERR(subhash)) {
- return TDB_OFF_TO_ERR(subhash);
- }
-
- ecode = zero_out(tdb, subhash + sizeof(struct tdb_used_record),
- subsize);
- if (ecode != TDB_SUCCESS) {
- return ecode;
- }
-
- /* Remove any which are destined for bucket or are in wrong place. */
- num_vals = 0;
- for (i = 0; i < (1 << TDB_HASH_GROUP_BITS); i++) {
- unsigned home_bucket = h->group[i] & TDB_OFF_HASH_GROUP_MASK;
- if (!h->group[i] || is_subhash(h->group[i]))
- continue;
- if (home_bucket == bucket || home_bucket != i) {
- vals[num_vals++] = h->group[i];
- h->group[i] = 0;
- }
- }
- /* FIXME: This assert is valid, but we do this during unit test :( */
- /* assert(num_vals); */
-
- /* Overwrite expanded bucket with subhash pointer. */
- h->group[bucket] = subhash | (1ULL << TDB_OFF_UPPER_STEAL_SUBHASH_BIT);
-
- /* Point to actual contents of record. */
- subhash += sizeof(struct tdb_used_record);
-
- /* Put values back. */
- for (i = 0; i < num_vals; i++) {
- unsigned this_bucket = vals[i] & TDB_OFF_HASH_GROUP_MASK;
-
- if (this_bucket == bucket) {
- ecode = add_to_subhash(tdb, subhash, h->hash_used,
- vals[i]);
- if (ecode != TDB_SUCCESS)
- return ecode;
- } else {
- /* There should be room to put this back. */
- force_into_group(h->group, this_bucket, vals[i]);
- }
- }
- return TDB_SUCCESS;
-}
-
-enum TDB_ERROR delete_from_hash(struct tdb_context *tdb, struct hash_info *h)
-{
- unsigned int i, num_movers = 0;
- tdb_off_t movers[1 << TDB_HASH_GROUP_BITS];
-
- h->group[h->found_bucket] = 0;
- for (i = 1; i < (1 << TDB_HASH_GROUP_BITS); i++) {
- unsigned this_bucket;
-
- this_bucket = (h->found_bucket+i) % (1 << TDB_HASH_GROUP_BITS);
- /* Empty bucket? We're done. */
- if (!h->group[this_bucket])
- break;
-
- /* Ignore subhashes. */
- if (is_subhash(h->group[this_bucket]))
- continue;
-
- /* If this one is not happy where it is, we'll move it. */
- if ((h->group[this_bucket] & TDB_OFF_HASH_GROUP_MASK)
- != this_bucket) {
- movers[num_movers++] = h->group[this_bucket];
- h->group[this_bucket] = 0;
- }
- }
-
- /* Put back the ones we erased. */
- for (i = 0; i < num_movers; i++) {
- force_into_group(h->group, movers[i] & TDB_OFF_HASH_GROUP_MASK,
- movers[i]);
- }
-
- /* Now we write back the hash group */
- return tdb_write_convert(tdb, h->group_start,
- h->group, sizeof(h->group));
-}
-
-enum TDB_ERROR add_to_hash(struct tdb_context *tdb, struct hash_info *h,
- tdb_off_t new_off)
-{
- enum TDB_ERROR ecode;
-
- /* We hit an empty bucket during search? That's where it goes. */
- if (!h->group[h->found_bucket]) {
- h->group[h->found_bucket] = encode_offset(new_off, h);
- /* Write back the modified group. */
- return tdb_write_convert(tdb, h->group_start,
- h->group, sizeof(h->group));
- }
-
- if (h->hash_used > 64)
- return add_to_chain(tdb, h->group_start, new_off);
-
- /* We're full. Expand. */
- ecode = expand_group(tdb, h);
- if (ecode != TDB_SUCCESS) {
- return ecode;
- }
-
- if (is_subhash(h->group[h->home_bucket])) {
- /* We were expanded! */
- tdb_off_t hashtable;
- unsigned int gnum;
-
- /* Write back the modified group. */
- ecode = tdb_write_convert(tdb, h->group_start, h->group,
- sizeof(h->group));
- if (ecode != TDB_SUCCESS) {
- return ecode;
- }
-
- /* Move hashinfo down a level. */
- hashtable = (h->group[h->home_bucket] & TDB_OFF_MASK)
- + sizeof(struct tdb_used_record);
- gnum = use_bits(h,TDB_SUBLEVEL_HASH_BITS - TDB_HASH_GROUP_BITS);
- h->home_bucket = use_bits(h, TDB_HASH_GROUP_BITS);
- h->group_start = hashtable
- + gnum * (sizeof(tdb_off_t) << TDB_HASH_GROUP_BITS);
- ecode = tdb_read_convert(tdb, h->group_start, &h->group,
- sizeof(h->group));
- if (ecode != TDB_SUCCESS) {
- return ecode;
- }
- }
-
- /* Expanding the group must have made room if it didn't choose this
- * bucket. */
- if (put_into_group(h->group, h->home_bucket, encode_offset(new_off,h))){
- return tdb_write_convert(tdb, h->group_start,
- h->group, sizeof(h->group));
- }
-
- /* This can happen if all hashes in group (and us) dropped into same
- * group in subhash. */
- return add_to_hash(tdb, h, new_off);
-}
-
-/* Traverse support: returns offset of record, or 0 or -ve error. */
-static tdb_off_t iterate_hash(struct tdb_context *tdb,
- struct traverse_info *tinfo)
-{
- tdb_off_t off, val, i;
- struct traverse_level *tlevel;
-
- tlevel = &tinfo->levels[tinfo->num_levels-1];
-
-again:
- for (i = tdb_find_nonzero_off(tdb, tlevel->hashtable,
- tlevel->entry, tlevel->total_buckets);
- i != tlevel->total_buckets;
- i = tdb_find_nonzero_off(tdb, tlevel->hashtable,
- i+1, tlevel->total_buckets)) {
- if (TDB_OFF_IS_ERR(i)) {
- return i;
- }
-
- val = tdb_read_off(tdb, tlevel->hashtable+sizeof(tdb_off_t)*i);
- if (TDB_OFF_IS_ERR(val)) {
- return val;
- }
-
- off = val & TDB_OFF_MASK;
-
- /* This makes the delete-all-in-traverse case work
- * (and simplifies our logic a little). */
- if (off == tinfo->prev)
- continue;
-
- tlevel->entry = i;
-
- if (!is_subhash(val)) {
- /* Found one. */
- tinfo->prev = off;
- return off;
- }
-
- /* When we come back, we want the next one */
- tlevel->entry++;
- tinfo->num_levels++;
- tlevel++;
- tlevel->hashtable = off + sizeof(struct tdb_used_record);
- tlevel->entry = 0;
- /* Next level is a chain? */
- if (unlikely(tinfo->num_levels == TDB_MAX_LEVELS + 1))
- tlevel->total_buckets = (1 << TDB_HASH_GROUP_BITS);
- else
- tlevel->total_buckets = (1 << TDB_SUBLEVEL_HASH_BITS);
- goto again;
- }
-
- /* Nothing there? */
- if (tinfo->num_levels == 1)
- return 0;
-
- /* Handle chained entries. */
- if (unlikely(tinfo->num_levels == TDB_MAX_LEVELS + 1)) {
- tlevel->hashtable = tdb_read_off(tdb, tlevel->hashtable
- + offsetof(struct tdb_chain,
- next));
- if (TDB_OFF_IS_ERR(tlevel->hashtable)) {
- return tlevel->hashtable;
- }
- if (tlevel->hashtable) {
- tlevel->hashtable += sizeof(struct tdb_used_record);
- tlevel->entry = 0;
- goto again;
- }
- }
-
- /* Go back up and keep searching. */
- tinfo->num_levels--;
- tlevel--;
- goto again;
-}
-
-/* Return success if we find something, TDB_ERR_NOEXIST if none. */
-enum TDB_ERROR next_in_hash(struct tdb_context *tdb,
- struct traverse_info *tinfo,
- TDB_DATA *kbuf, size_t *dlen)
-{
- const unsigned group_bits = TDB_TOPLEVEL_HASH_BITS-TDB_HASH_GROUP_BITS;
- tdb_off_t hl_start, hl_range, off;
- enum TDB_ERROR ecode;
-
- while (tinfo->toplevel_group < (1 << group_bits)) {
- hl_start = (tdb_off_t)tinfo->toplevel_group
- << (64 - group_bits);
- hl_range = 1ULL << group_bits;
- ecode = tdb_lock_hashes(tdb, hl_start, hl_range, F_RDLCK,
- TDB_LOCK_WAIT);
- if (ecode != TDB_SUCCESS) {
- return ecode;
- }
-
- off = iterate_hash(tdb, tinfo);
- if (off) {
- struct tdb_used_record rec;
-
- if (TDB_OFF_IS_ERR(off)) {
- ecode = TDB_OFF_TO_ERR(off);
- goto fail;
- }
-
- ecode = tdb_read_convert(tdb, off, &rec, sizeof(rec));
- if (ecode != TDB_SUCCESS) {
- goto fail;
- }
- if (rec_magic(&rec) != TDB_USED_MAGIC) {
- ecode = tdb_logerr(tdb, TDB_ERR_CORRUPT,
- TDB_LOG_ERROR,
- "next_in_hash:"
- " corrupt record at %llu",
- (long long)off);
- goto fail;
- }
-
- kbuf->dsize = rec_key_length(&rec);
-
- /* They want data as well? */
- if (dlen) {
- *dlen = rec_data_length(&rec);
- kbuf->dptr = tdb_alloc_read(tdb,
- off + sizeof(rec),
- kbuf->dsize
- + *dlen);
- } else {
- kbuf->dptr = tdb_alloc_read(tdb,
- off + sizeof(rec),
- kbuf->dsize);
- }
- tdb_unlock_hashes(tdb, hl_start, hl_range, F_RDLCK);
- if (TDB_PTR_IS_ERR(kbuf->dptr)) {
- return TDB_PTR_ERR(kbuf->dptr);
- }
- return TDB_SUCCESS;
- }
-
- tdb_unlock_hashes(tdb, hl_start, hl_range, F_RDLCK);
-
- tinfo->toplevel_group++;
- tinfo->levels[0].hashtable
- += (sizeof(tdb_off_t) << TDB_HASH_GROUP_BITS);
- tinfo->levels[0].entry = 0;
- }
- return TDB_ERR_NOEXIST;
-
-fail:
- tdb_unlock_hashes(tdb, hl_start, hl_range, F_RDLCK);
- return ecode;
-
-}
-
-enum TDB_ERROR first_in_hash(struct tdb_context *tdb,
- struct traverse_info *tinfo,
- TDB_DATA *kbuf, size_t *dlen)
-{
- tinfo->prev = 0;
- tinfo->toplevel_group = 0;
- tinfo->num_levels = 1;
- tinfo->levels[0].hashtable = offsetof(struct tdb_header, hashtable);
- tinfo->levels[0].entry = 0;
- tinfo->levels[0].total_buckets = (1 << TDB_HASH_GROUP_BITS);
-
- return next_in_hash(tdb, tinfo, kbuf, dlen);
-}
-
-/* Even if the entry isn't in this hash bucket, you'd have to lock this
- * bucket to find it. */
-static enum TDB_ERROR chainlock(struct tdb_context *tdb, const TDB_DATA *key,
- int ltype, enum tdb_lock_flags waitflag,
- const char *func)
-{
- enum TDB_ERROR ecode;
- uint64_t h = tdb_hash(tdb, key->dptr, key->dsize);
- tdb_off_t lockstart, locksize;
- unsigned int group, gbits;
-
- gbits = TDB_TOPLEVEL_HASH_BITS - TDB_HASH_GROUP_BITS;
- group = bits_from(h, 64 - gbits, gbits);
-
- lockstart = hlock_range(group, &locksize);
-
- ecode = tdb_lock_hashes(tdb, lockstart, locksize, ltype, waitflag);
- tdb_trace_1rec(tdb, func, *key);
- return ecode;
-}
-
-/* lock/unlock one hash chain. This is meant to be used to reduce
- contention - it cannot guarantee how many records will be locked */
-enum TDB_ERROR tdb_chainlock(struct tdb_context *tdb, TDB_DATA key)
-{
- if (tdb->flags & TDB_VERSION1) {
- if (tdb1_chainlock(tdb, key) == -1)
- return tdb->last_error;
- return TDB_SUCCESS;
- }
- return tdb->last_error = chainlock(tdb, &key, F_WRLCK, TDB_LOCK_WAIT,
- "tdb_chainlock");
-}
-
-void tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key)
-{
- uint64_t h = tdb_hash(tdb, key.dptr, key.dsize);
- tdb_off_t lockstart, locksize;
- unsigned int group, gbits;
-
- if (tdb->flags & TDB_VERSION1) {
- tdb1_chainunlock(tdb, key);
- return;
- }
-
- gbits = TDB_TOPLEVEL_HASH_BITS - TDB_HASH_GROUP_BITS;
- group = bits_from(h, 64 - gbits, gbits);
-
- lockstart = hlock_range(group, &locksize);
-
- tdb_trace_1rec(tdb, "tdb_chainunlock", key);
- tdb_unlock_hashes(tdb, lockstart, locksize, F_WRLCK);
-}
-
-enum TDB_ERROR tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key)
-{
- if (tdb->flags & TDB_VERSION1) {
- if (tdb1_chainlock_read(tdb, key) == -1)
- return tdb->last_error;
- return TDB_SUCCESS;
- }
- return tdb->last_error = chainlock(tdb, &key, F_RDLCK, TDB_LOCK_WAIT,
- "tdb_chainlock_read");
-}
-
-void tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key)
-{
- uint64_t h = tdb_hash(tdb, key.dptr, key.dsize);
- tdb_off_t lockstart, locksize;
- unsigned int group, gbits;
-
- if (tdb->flags & TDB_VERSION1) {
- tdb1_chainunlock_read(tdb, key);
- return;
- }
- gbits = TDB_TOPLEVEL_HASH_BITS - TDB_HASH_GROUP_BITS;
- group = bits_from(h, 64 - gbits, gbits);
-
- lockstart = hlock_range(group, &locksize);
-
- tdb_trace_1rec(tdb, "tdb_chainunlock_read", key);
- tdb_unlock_hashes(tdb, lockstart, locksize, F_RDLCK);
-}
projects / ccan / blobdiff