+++ /dev/null
- /*
- Trivial Database 2: free list/block 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/likely/likely.h>
-#include <ccan/ilog/ilog.h>
-#include <time.h>
-#include <limits.h>
-
-static unsigned fls64(uint64_t val)
-{
- return ilog64(val);
-}
-
-/* In which bucket would we find a particular record size? (ignoring header) */
-unsigned int size_to_bucket(ntdb_len_t data_len)
-{
- unsigned int bucket;
-
- /* We can't have records smaller than this. */
- assert(data_len >= NTDB_MIN_DATA_LEN);
-
- /* Ignoring the header... */
- if (data_len - NTDB_MIN_DATA_LEN <= 64) {
- /* 0 in bucket 0, 8 in bucket 1... 64 in bucket 8. */
- bucket = (data_len - NTDB_MIN_DATA_LEN) / 8;
- } else {
- /* After that we go power of 2. */
- bucket = fls64(data_len - NTDB_MIN_DATA_LEN) + 2;
- }
-
- if (unlikely(bucket >= NTDB_FREE_BUCKETS))
- bucket = NTDB_FREE_BUCKETS - 1;
- return bucket;
-}
-
-ntdb_off_t first_ftable(struct ntdb_context *ntdb)
-{
- return ntdb_read_off(ntdb, offsetof(struct ntdb_header, free_table));
-}
-
-ntdb_off_t next_ftable(struct ntdb_context *ntdb, ntdb_off_t ftable)
-{
- return ntdb_read_off(ntdb, ftable + offsetof(struct ntdb_freetable,next));
-}
-
-enum NTDB_ERROR ntdb_ftable_init(struct ntdb_context *ntdb)
-{
- /* Use reservoir sampling algorithm to select a free list at random. */
- unsigned int rnd, max = 0, count = 0;
- ntdb_off_t off;
-
- ntdb->ftable_off = off = first_ftable(ntdb);
- ntdb->ftable = 0;
-
- while (off) {
- if (NTDB_OFF_IS_ERR(off)) {
- return NTDB_OFF_TO_ERR(off);
- }
-
- rnd = random();
- if (rnd >= max) {
- ntdb->ftable_off = off;
- ntdb->ftable = count;
- max = rnd;
- }
-
- off = next_ftable(ntdb, off);
- count++;
- }
- return NTDB_SUCCESS;
-}
-
-/* Offset of a given bucket. */
-ntdb_off_t bucket_off(ntdb_off_t ftable_off, unsigned bucket)
-{
- return ftable_off + offsetof(struct ntdb_freetable, buckets)
- + bucket * sizeof(ntdb_off_t);
-}
-
-/* Returns free_buckets + 1, or list number to search, or -ve error. */
-static ntdb_off_t find_free_head(struct ntdb_context *ntdb,
- ntdb_off_t ftable_off,
- ntdb_off_t bucket)
-{
- /* Speculatively search for a non-zero bucket. */
- return ntdb_find_nonzero_off(ntdb, bucket_off(ftable_off, 0),
- bucket, NTDB_FREE_BUCKETS);
-}
-
-static void check_list(struct ntdb_context *ntdb, ntdb_off_t b_off)
-{
-#ifdef CCAN_NTDB_DEBUG
- ntdb_off_t off, prev = 0, first;
- struct ntdb_free_record r;
-
- first = off = (ntdb_read_off(ntdb, b_off) & NTDB_OFF_MASK);
- while (off != 0) {
- ntdb_read_convert(ntdb, off, &r, sizeof(r));
- if (frec_magic(&r) != NTDB_FREE_MAGIC)
- abort();
- if (prev && frec_prev(&r) != prev)
- abort();
- prev = off;
- off = r.next;
- }
-
- if (first) {
- ntdb_read_convert(ntdb, first, &r, sizeof(r));
- if (frec_prev(&r) != prev)
- abort();
- }
-#endif
-}
-
-/* Remove from free bucket. */
-static enum NTDB_ERROR remove_from_list(struct ntdb_context *ntdb,
- ntdb_off_t b_off, ntdb_off_t r_off,
- const struct ntdb_free_record *r)
-{
- ntdb_off_t off, prev_next, head;
- enum NTDB_ERROR ecode;
-
- /* Is this only element in list? Zero out bucket, and we're done. */
- if (frec_prev(r) == r_off)
- return ntdb_write_off(ntdb, b_off, 0);
-
- /* off = &r->prev->next */
- off = frec_prev(r) + offsetof(struct ntdb_free_record, next);
-
- /* Get prev->next */
- prev_next = ntdb_read_off(ntdb, off);
- if (NTDB_OFF_IS_ERR(prev_next))
- return NTDB_OFF_TO_ERR(prev_next);
-
- /* If prev->next == 0, we were head: update bucket to point to next. */
- if (prev_next == 0) {
- /* We must preserve upper bits. */
- head = ntdb_read_off(ntdb, b_off);
- if (NTDB_OFF_IS_ERR(head))
- return NTDB_OFF_TO_ERR(head);
-
- if ((head & NTDB_OFF_MASK) != r_off) {
- return ntdb_logerr(ntdb, NTDB_ERR_CORRUPT, NTDB_LOG_ERROR,
- "remove_from_list:"
- " %llu head %llu on list %llu",
- (long long)r_off,
- (long long)head,
- (long long)b_off);
- }
- head = ((head & ~NTDB_OFF_MASK) | r->next);
- ecode = ntdb_write_off(ntdb, b_off, head);
- if (ecode != NTDB_SUCCESS)
- return ecode;
- } else {
- /* r->prev->next = r->next */
- ecode = ntdb_write_off(ntdb, off, r->next);
- if (ecode != NTDB_SUCCESS)
- return ecode;
- }
-
- /* If we were the tail, off = &head->prev. */
- if (r->next == 0) {
- head = ntdb_read_off(ntdb, b_off);
- if (NTDB_OFF_IS_ERR(head))
- return NTDB_OFF_TO_ERR(head);
- head &= NTDB_OFF_MASK;
- off = head + offsetof(struct ntdb_free_record, magic_and_prev);
- } else {
- /* off = &r->next->prev */
- off = r->next + offsetof(struct ntdb_free_record,
- magic_and_prev);
- }
-
-#ifdef CCAN_NTDB_DEBUG
- /* *off == r */
- if ((ntdb_read_off(ntdb, off) & NTDB_OFF_MASK) != r_off) {
- return ntdb_logerr(ntdb, NTDB_ERR_CORRUPT, NTDB_LOG_ERROR,
- "remove_from_list:"
- " %llu bad prev in list %llu",
- (long long)r_off, (long long)b_off);
- }
-#endif
- /* r->next->prev = r->prev */
- return ntdb_write_off(ntdb, off, r->magic_and_prev);
-}
-
-/* Enqueue in this free bucket: sets coalesce if we've added 128
- * entries to it. */
-static enum NTDB_ERROR enqueue_in_free(struct ntdb_context *ntdb,
- ntdb_off_t b_off,
- ntdb_off_t off,
- ntdb_len_t len,
- bool *coalesce)
-{
- struct ntdb_free_record new;
- enum NTDB_ERROR ecode;
- ntdb_off_t prev, head;
- uint64_t magic = (NTDB_FREE_MAGIC << (64 - NTDB_OFF_UPPER_STEAL));
-
- head = ntdb_read_off(ntdb, b_off);
- if (NTDB_OFF_IS_ERR(head))
- return NTDB_OFF_TO_ERR(head);
-
- /* We only need to set ftable_and_len; rest is set in enqueue_in_free */
- new.ftable_and_len = ((uint64_t)ntdb->ftable
- << (64 - NTDB_OFF_UPPER_STEAL))
- | len;
-
- /* new->next = head. */
- new.next = (head & NTDB_OFF_MASK);
-
- /* First element? Prev points to ourselves. */
- if (!new.next) {
- new.magic_and_prev = (magic | off);
- } else {
- /* new->prev = next->prev */
- prev = ntdb_read_off(ntdb,
- new.next + offsetof(struct ntdb_free_record,
- magic_and_prev));
- new.magic_and_prev = prev;
- if (frec_magic(&new) != NTDB_FREE_MAGIC) {
- return ntdb_logerr(ntdb, NTDB_ERR_CORRUPT, NTDB_LOG_ERROR,
- "enqueue_in_free: %llu bad head"
- " prev %llu",
- (long long)new.next,
- (long long)prev);
- }
- /* next->prev = new. */
- ecode = ntdb_write_off(ntdb, new.next
- + offsetof(struct ntdb_free_record,
- magic_and_prev),
- off | magic);
- if (ecode != NTDB_SUCCESS) {
- return ecode;
- }
-
-#ifdef CCAN_NTDB_DEBUG
- prev = ntdb_read_off(ntdb, frec_prev(&new)
- + offsetof(struct ntdb_free_record, next));
- if (prev != 0) {
- return ntdb_logerr(ntdb, NTDB_ERR_CORRUPT, NTDB_LOG_ERROR,
- "enqueue_in_free:"
- " %llu bad tail next ptr %llu",
- (long long)frec_prev(&new)
- + offsetof(struct ntdb_free_record,
- next),
- (long long)prev);
- }
-#endif
- }
-
- /* Update enqueue count, but don't set high bit: see NTDB_OFF_IS_ERR */
- if (*coalesce)
- head += (1ULL << (64 - NTDB_OFF_UPPER_STEAL));
- head &= ~(NTDB_OFF_MASK | (1ULL << 63));
- head |= off;
-
- ecode = ntdb_write_off(ntdb, b_off, head);
- if (ecode != NTDB_SUCCESS) {
- return ecode;
- }
-
- /* It's time to coalesce if counter wrapped. */
- if (*coalesce)
- *coalesce = ((head & ~NTDB_OFF_MASK) == 0);
-
- return ntdb_write_convert(ntdb, off, &new, sizeof(new));
-}
-
-static ntdb_off_t ftable_offset(struct ntdb_context *ntdb, unsigned int ftable)
-{
- ntdb_off_t off;
- unsigned int i;
-
- if (likely(ntdb->ftable == ftable))
- return ntdb->ftable_off;
-
- off = first_ftable(ntdb);
- for (i = 0; i < ftable; i++) {
- if (NTDB_OFF_IS_ERR(off)) {
- break;
- }
- off = next_ftable(ntdb, off);
- }
- return off;
-}
-
-/* Note: we unlock the current bucket if fail (-ve), or coalesce (+ve) and
- * need to blatt the *protect record (which is set to an error). */
-static ntdb_len_t coalesce(struct ntdb_context *ntdb,
- ntdb_off_t off, ntdb_off_t b_off,
- ntdb_len_t data_len,
- ntdb_off_t *protect)
-{
- ntdb_off_t end;
- struct ntdb_free_record rec;
- enum NTDB_ERROR ecode;
-
- ntdb->stats.alloc_coalesce_tried++;
- end = off + sizeof(struct ntdb_used_record) + data_len;
-
- while (end < ntdb->file->map_size) {
- const struct ntdb_free_record *r;
- ntdb_off_t nb_off;
- unsigned ftable, bucket;
-
- r = ntdb_access_read(ntdb, end, sizeof(*r), true);
- if (NTDB_PTR_IS_ERR(r)) {
- ecode = NTDB_PTR_ERR(r);
- goto err;
- }
-
- if (frec_magic(r) != NTDB_FREE_MAGIC
- || frec_ftable(r) == NTDB_FTABLE_NONE) {
- ntdb_access_release(ntdb, r);
- break;
- }
-
- ftable = frec_ftable(r);
- bucket = size_to_bucket(frec_len(r));
- nb_off = ftable_offset(ntdb, ftable);
- if (NTDB_OFF_IS_ERR(nb_off)) {
- ntdb_access_release(ntdb, r);
- ecode = NTDB_OFF_TO_ERR(nb_off);
- goto err;
- }
- nb_off = bucket_off(nb_off, bucket);
- ntdb_access_release(ntdb, r);
-
- /* We may be violating lock order here, so best effort. */
- if (ntdb_lock_free_bucket(ntdb, nb_off, NTDB_LOCK_NOWAIT)
- != NTDB_SUCCESS) {
- ntdb->stats.alloc_coalesce_lockfail++;
- break;
- }
-
- /* Now we have lock, re-check. */
- ecode = ntdb_read_convert(ntdb, end, &rec, sizeof(rec));
- if (ecode != NTDB_SUCCESS) {
- ntdb_unlock_free_bucket(ntdb, nb_off);
- goto err;
- }
-
- if (unlikely(frec_magic(&rec) != NTDB_FREE_MAGIC)) {
- ntdb->stats.alloc_coalesce_race++;
- ntdb_unlock_free_bucket(ntdb, nb_off);
- break;
- }
-
- if (unlikely(frec_ftable(&rec) != ftable)
- || unlikely(size_to_bucket(frec_len(&rec)) != bucket)) {
- ntdb->stats.alloc_coalesce_race++;
- ntdb_unlock_free_bucket(ntdb, nb_off);
- break;
- }
-
- /* Did we just mess up a record you were hoping to use? */
- if (end == *protect) {
- ntdb->stats.alloc_coalesce_iterate_clash++;
- *protect = NTDB_ERR_TO_OFF(NTDB_ERR_NOEXIST);
- }
-
- ecode = remove_from_list(ntdb, nb_off, end, &rec);
- check_list(ntdb, nb_off);
- if (ecode != NTDB_SUCCESS) {
- ntdb_unlock_free_bucket(ntdb, nb_off);
- goto err;
- }
-
- end += sizeof(struct ntdb_used_record) + frec_len(&rec);
- ntdb_unlock_free_bucket(ntdb, nb_off);
- ntdb->stats.alloc_coalesce_num_merged++;
- }
-
- /* Didn't find any adjacent free? */
- if (end == off + sizeof(struct ntdb_used_record) + data_len)
- return 0;
-
- /* Before we expand, check this isn't one you wanted protected? */
- if (off == *protect) {
- *protect = NTDB_ERR_TO_OFF(NTDB_ERR_EXISTS);
- ntdb->stats.alloc_coalesce_iterate_clash++;
- }
-
- /* OK, expand initial record */
- ecode = ntdb_read_convert(ntdb, off, &rec, sizeof(rec));
- if (ecode != NTDB_SUCCESS) {
- goto err;
- }
-
- if (frec_len(&rec) != data_len) {
- ecode = ntdb_logerr(ntdb, NTDB_ERR_CORRUPT, NTDB_LOG_ERROR,
- "coalesce: expected data len %zu not %zu",
- (size_t)data_len, (size_t)frec_len(&rec));
- goto err;
- }
-
- ecode = remove_from_list(ntdb, b_off, off, &rec);
- check_list(ntdb, b_off);
- if (ecode != NTDB_SUCCESS) {
- goto err;
- }
-
- /* Try locking violation first. We don't allow coalesce recursion! */
- ecode = add_free_record(ntdb, off, end - off, NTDB_LOCK_NOWAIT, false);
- if (ecode != NTDB_SUCCESS) {
- /* Need to drop lock. Can't rely on anything stable. */
- ntdb->stats.alloc_coalesce_lockfail++;
- *protect = NTDB_ERR_TO_OFF(NTDB_ERR_CORRUPT);
-
- /* We have to drop this to avoid deadlocks, so make sure record
- * doesn't get coalesced by someone else! */
- rec.ftable_and_len = (NTDB_FTABLE_NONE
- << (64 - NTDB_OFF_UPPER_STEAL))
- | (end - off - sizeof(struct ntdb_used_record));
- ecode = ntdb_write_off(ntdb,
- off + offsetof(struct ntdb_free_record,
- ftable_and_len),
- rec.ftable_and_len);
- if (ecode != NTDB_SUCCESS) {
- goto err;
- }
-
- ntdb_unlock_free_bucket(ntdb, b_off);
-
- ecode = add_free_record(ntdb, off, end - off, NTDB_LOCK_WAIT,
- false);
- if (ecode != NTDB_SUCCESS) {
- return NTDB_ERR_TO_OFF(ecode);
- }
- } else if (NTDB_OFF_IS_ERR(*protect)) {
- /* For simplicity, we always drop lock if they can't continue */
- ntdb_unlock_free_bucket(ntdb, b_off);
- }
- ntdb->stats.alloc_coalesce_succeeded++;
-
- /* Return usable length. */
- return end - off - sizeof(struct ntdb_used_record);
-
-err:
- /* To unify error paths, we *always* unlock bucket on error. */
- ntdb_unlock_free_bucket(ntdb, b_off);
- return NTDB_ERR_TO_OFF(ecode);
-}
-
-/* List is locked: we unlock it. */
-static enum NTDB_ERROR coalesce_list(struct ntdb_context *ntdb,
- ntdb_off_t ftable_off,
- ntdb_off_t b_off,
- unsigned int limit)
-{
- enum NTDB_ERROR ecode;
- ntdb_off_t off;
-
- off = ntdb_read_off(ntdb, b_off);
- if (NTDB_OFF_IS_ERR(off)) {
- ecode = NTDB_OFF_TO_ERR(off);
- goto unlock_err;
- }
- /* A little bit of paranoia: counter should be 0. */
- off &= NTDB_OFF_MASK;
-
- while (off && limit--) {
- struct ntdb_free_record rec;
- ntdb_len_t coal;
- ntdb_off_t next;
-
- ecode = ntdb_read_convert(ntdb, off, &rec, sizeof(rec));
- if (ecode != NTDB_SUCCESS)
- goto unlock_err;
-
- next = rec.next;
- coal = coalesce(ntdb, off, b_off, frec_len(&rec), &next);
- if (NTDB_OFF_IS_ERR(coal)) {
- /* This has already unlocked on error. */
- return NTDB_OFF_TO_ERR(coal);
- }
- if (NTDB_OFF_IS_ERR(next)) {
- /* Coalescing had to unlock, so stop. */
- return NTDB_SUCCESS;
- }
- /* Keep going if we're doing well... */
- limit += size_to_bucket(coal / 16 + NTDB_MIN_DATA_LEN);
- off = next;
- }
-
- /* Now, move those elements to the tail of the list so we get something
- * else next time. */
- if (off) {
- struct ntdb_free_record oldhrec, newhrec, oldtrec, newtrec;
- ntdb_off_t oldhoff, oldtoff, newtoff;
-
- /* The record we were up to is the new head. */
- ecode = ntdb_read_convert(ntdb, off, &newhrec, sizeof(newhrec));
- if (ecode != NTDB_SUCCESS)
- goto unlock_err;
-
- /* Get the new tail. */
- newtoff = frec_prev(&newhrec);
- ecode = ntdb_read_convert(ntdb, newtoff, &newtrec,
- sizeof(newtrec));
- if (ecode != NTDB_SUCCESS)
- goto unlock_err;
-
- /* Get the old head. */
- oldhoff = ntdb_read_off(ntdb, b_off);
- if (NTDB_OFF_IS_ERR(oldhoff)) {
- ecode = NTDB_OFF_TO_ERR(oldhoff);
- goto unlock_err;
- }
-
- /* This could happen if they all coalesced away. */
- if (oldhoff == off)
- goto out;
-
- ecode = ntdb_read_convert(ntdb, oldhoff, &oldhrec,
- sizeof(oldhrec));
- if (ecode != NTDB_SUCCESS)
- goto unlock_err;
-
- /* Get the old tail. */
- oldtoff = frec_prev(&oldhrec);
- ecode = ntdb_read_convert(ntdb, oldtoff, &oldtrec,
- sizeof(oldtrec));
- if (ecode != NTDB_SUCCESS)
- goto unlock_err;
-
- /* Old tail's next points to old head. */
- oldtrec.next = oldhoff;
-
- /* Old head's prev points to old tail. */
- oldhrec.magic_and_prev
- = (NTDB_FREE_MAGIC << (64 - NTDB_OFF_UPPER_STEAL))
- | oldtoff;
-
- /* New tail's next is 0. */
- newtrec.next = 0;
-
- /* Write out the modified versions. */
- ecode = ntdb_write_convert(ntdb, oldtoff, &oldtrec,
- sizeof(oldtrec));
- if (ecode != NTDB_SUCCESS)
- goto unlock_err;
-
- ecode = ntdb_write_convert(ntdb, oldhoff, &oldhrec,
- sizeof(oldhrec));
- if (ecode != NTDB_SUCCESS)
- goto unlock_err;
-
- ecode = ntdb_write_convert(ntdb, newtoff, &newtrec,
- sizeof(newtrec));
- if (ecode != NTDB_SUCCESS)
- goto unlock_err;
-
- /* And finally link in new head. */
- ecode = ntdb_write_off(ntdb, b_off, off);
- if (ecode != NTDB_SUCCESS)
- goto unlock_err;
- }
-out:
- ntdb_unlock_free_bucket(ntdb, b_off);
- return NTDB_SUCCESS;
-
-unlock_err:
- ntdb_unlock_free_bucket(ntdb, b_off);
- return ecode;
-}
-
-/* List must not be locked if coalesce_ok is set. */
-enum NTDB_ERROR add_free_record(struct ntdb_context *ntdb,
- ntdb_off_t off, ntdb_len_t len_with_header,
- enum ntdb_lock_flags waitflag,
- bool coalesce_ok)
-{
- ntdb_off_t b_off;
- ntdb_len_t len;
- enum NTDB_ERROR ecode;
-
- assert(len_with_header >= sizeof(struct ntdb_free_record));
-
- len = len_with_header - sizeof(struct ntdb_used_record);
-
- b_off = bucket_off(ntdb->ftable_off, size_to_bucket(len));
- ecode = ntdb_lock_free_bucket(ntdb, b_off, waitflag);
- if (ecode != NTDB_SUCCESS) {
- return ecode;
- }
-
- ecode = enqueue_in_free(ntdb, b_off, off, len, &coalesce_ok);
- check_list(ntdb, b_off);
-
- /* Coalescing unlocks free list. */
- if (!ecode && coalesce_ok)
- ecode = coalesce_list(ntdb, ntdb->ftable_off, b_off, 2);
- else
- ntdb_unlock_free_bucket(ntdb, b_off);
- return ecode;
-}
-
-static size_t adjust_size(size_t keylen, size_t datalen)
-{
- size_t size = keylen + datalen;
-
- if (size < NTDB_MIN_DATA_LEN)
- size = NTDB_MIN_DATA_LEN;
-
- /* Round to next uint64_t boundary. */
- return (size + (sizeof(uint64_t) - 1ULL)) & ~(sizeof(uint64_t) - 1ULL);
-}
-
-/* If we have enough left over to be useful, split that off. */
-static size_t record_leftover(size_t keylen, size_t datalen,
- bool want_extra, size_t total_len)
-{
- ssize_t leftover;
-
- if (want_extra)
- datalen += datalen / 2;
- leftover = total_len - adjust_size(keylen, datalen);
-
- if (leftover < (ssize_t)sizeof(struct ntdb_free_record))
- return 0;
-
- return leftover;
-}
-
-/* We need size bytes to put our key and data in. */
-static ntdb_off_t lock_and_alloc(struct ntdb_context *ntdb,
- ntdb_off_t ftable_off,
- ntdb_off_t bucket,
- size_t keylen, size_t datalen,
- bool want_extra,
- unsigned magic)
-{
- ntdb_off_t off, b_off,best_off;
- struct ntdb_free_record best = { 0 };
- double multiplier;
- size_t size = adjust_size(keylen, datalen);
- enum NTDB_ERROR ecode;
-
- ntdb->stats.allocs++;
- b_off = bucket_off(ftable_off, bucket);
-
- /* FIXME: Try non-blocking wait first, to measure contention. */
- /* Lock this bucket. */
- ecode = ntdb_lock_free_bucket(ntdb, b_off, NTDB_LOCK_WAIT);
- if (ecode != NTDB_SUCCESS) {
- return NTDB_ERR_TO_OFF(ecode);
- }
-
- best.ftable_and_len = -1ULL;
- best_off = 0;
-
- /* Get slack if we're after extra. */
- if (want_extra)
- multiplier = 1.5;
- else
- multiplier = 1.0;
-
- /* Walk the list to see if any are large enough, getting less fussy
- * as we go. */
- off = ntdb_read_off(ntdb, b_off);
- if (NTDB_OFF_IS_ERR(off)) {
- ecode = NTDB_OFF_TO_ERR(off);
- goto unlock_err;
- }
- off &= NTDB_OFF_MASK;
-
- while (off) {
- const struct ntdb_free_record *r;
- ntdb_off_t next;
-
- r = ntdb_access_read(ntdb, off, sizeof(*r), true);
- if (NTDB_PTR_IS_ERR(r)) {
- ecode = NTDB_PTR_ERR(r);
- goto unlock_err;
- }
-
- if (frec_magic(r) != NTDB_FREE_MAGIC) {
- ecode = ntdb_logerr(ntdb, NTDB_ERR_CORRUPT, NTDB_LOG_ERROR,
- "lock_and_alloc:"
- " %llu non-free 0x%llx",
- (long long)off,
- (long long)r->magic_and_prev);
- ntdb_access_release(ntdb, r);
- goto unlock_err;
- }
-
- if (frec_len(r) >= size && frec_len(r) < frec_len(&best)) {
- best_off = off;
- best = *r;
- }
-
- if (frec_len(&best) <= size * multiplier && best_off) {
- ntdb_access_release(ntdb, r);
- break;
- }
-
- multiplier *= 1.01;
-
- next = r->next;
- ntdb_access_release(ntdb, r);
- off = next;
- }
-
- /* If we found anything at all, use it. */
- if (best_off) {
- struct ntdb_used_record rec;
- size_t leftover;
-
- /* We're happy with this size: take it. */
- ecode = remove_from_list(ntdb, b_off, best_off, &best);
- check_list(ntdb, b_off);
- if (ecode != NTDB_SUCCESS) {
- goto unlock_err;
- }
-
- leftover = record_leftover(keylen, datalen, want_extra,
- frec_len(&best));
-
- assert(keylen + datalen + leftover <= frec_len(&best));
- /* We need to mark non-free before we drop lock, otherwise
- * coalesce() could try to merge it! */
- ecode = set_header(ntdb, &rec, magic, keylen, datalen,
- frec_len(&best) - leftover);
- if (ecode != NTDB_SUCCESS) {
- goto unlock_err;
- }
-
- ecode = ntdb_write_convert(ntdb, best_off, &rec, sizeof(rec));
- if (ecode != NTDB_SUCCESS) {
- goto unlock_err;
- }
-
- /* For futureproofing, we put a 0 in any unused space. */
- if (rec_extra_padding(&rec)) {
- ecode = ntdb->io->twrite(ntdb, best_off + sizeof(rec)
- + keylen + datalen, "", 1);
- if (ecode != NTDB_SUCCESS) {
- goto unlock_err;
- }
- }
-
- /* Bucket of leftover will be <= current bucket, so nested
- * locking is allowed. */
- if (leftover) {
- ntdb->stats.alloc_leftover++;
- ecode = add_free_record(ntdb,
- best_off + sizeof(rec)
- + frec_len(&best) - leftover,
- leftover, NTDB_LOCK_WAIT, false);
- if (ecode != NTDB_SUCCESS) {
- best_off = NTDB_ERR_TO_OFF(ecode);
- }
- }
- ntdb_unlock_free_bucket(ntdb, b_off);
-
- return best_off;
- }
-
- ntdb_unlock_free_bucket(ntdb, b_off);
- return 0;
-
-unlock_err:
- ntdb_unlock_free_bucket(ntdb, b_off);
- return NTDB_ERR_TO_OFF(ecode);
-}
-
-/* Get a free block from current free list, or 0 if none, -ve on error. */
-static ntdb_off_t get_free(struct ntdb_context *ntdb,
- size_t keylen, size_t datalen, bool want_extra,
- unsigned magic)
-{
- ntdb_off_t off, ftable_off;
- ntdb_off_t start_b, b, ftable;
- bool wrapped = false;
-
- /* If they are growing, add 50% to get to higher bucket. */
- if (want_extra)
- start_b = size_to_bucket(adjust_size(keylen,
- datalen + datalen / 2));
- else
- start_b = size_to_bucket(adjust_size(keylen, datalen));
-
- ftable_off = ntdb->ftable_off;
- ftable = ntdb->ftable;
- while (!wrapped || ftable_off != ntdb->ftable_off) {
- /* Start at exact size bucket, and search up... */
- for (b = find_free_head(ntdb, ftable_off, start_b);
- b < NTDB_FREE_BUCKETS;
- b = find_free_head(ntdb, ftable_off, b + 1)) {
- /* Try getting one from list. */
- off = lock_and_alloc(ntdb, ftable_off,
- b, keylen, datalen, want_extra,
- magic);
- if (NTDB_OFF_IS_ERR(off))
- return off;
- if (off != 0) {
- if (b == start_b)
- ntdb->stats.alloc_bucket_exact++;
- if (b == NTDB_FREE_BUCKETS - 1)
- ntdb->stats.alloc_bucket_max++;
- /* Worked? Stay using this list. */
- ntdb->ftable_off = ftable_off;
- ntdb->ftable = ftable;
- return off;
- }
- /* Didn't work. Try next bucket. */
- }
-
- if (NTDB_OFF_IS_ERR(b)) {
- return b;
- }
-
- /* Hmm, try next table. */
- ftable_off = next_ftable(ntdb, ftable_off);
- if (NTDB_OFF_IS_ERR(ftable_off)) {
- return ftable_off;
- }
- ftable++;
-
- if (ftable_off == 0) {
- wrapped = true;
- ftable_off = first_ftable(ntdb);
- if (NTDB_OFF_IS_ERR(ftable_off)) {
- return ftable_off;
- }
- ftable = 0;
- }
- }
-
- return 0;
-}
-
-enum NTDB_ERROR set_header(struct ntdb_context *ntdb,
- struct ntdb_used_record *rec,
- unsigned magic, uint64_t keylen, uint64_t datalen,
- uint64_t actuallen)
-{
- uint64_t keybits = (fls64(keylen) + 1) / 2;
-
- rec->magic_and_meta = ((actuallen - (keylen + datalen)) << 11)
- | (keybits << 43)
- | ((uint64_t)magic << 48);
- rec->key_and_data_len = (keylen | (datalen << (keybits*2)));
-
- /* Encoding can fail on big values. */
- if (rec_key_length(rec) != keylen
- || rec_data_length(rec) != datalen
- || rec_extra_padding(rec) != actuallen - (keylen + datalen)) {
- return ntdb_logerr(ntdb, NTDB_ERR_IO, NTDB_LOG_ERROR,
- "Could not encode k=%llu,d=%llu,a=%llu",
- (long long)keylen, (long long)datalen,
- (long long)actuallen);
- }
- return NTDB_SUCCESS;
-}
-
-/* You need 'size', this tells you how much you should expand by. */
-ntdb_off_t ntdb_expand_adjust(ntdb_off_t map_size, ntdb_off_t size)
-{
- ntdb_off_t new_size, top_size;
-
- /* limit size in order to avoid using up huge amounts of memory for
- * in memory tdbs if an oddball huge record creeps in */
- if (size > 100 * 1024) {
- top_size = map_size + size * 2;
- } else {
- top_size = map_size + size * 100;
- }
-
- /* always make room for at least top_size more records, and at
- least 25% more space. if the DB is smaller than 100MiB,
- otherwise grow it by 10% only. */
- if (map_size > 100 * 1024 * 1024) {
- new_size = map_size * 1.10;
- } else {
- new_size = map_size * 1.25;
- }
-
- if (new_size < top_size)
- new_size = top_size;
-
- /* We always make the file a multiple of transaction page
- * size. This guarantees that the transaction recovery area
- * is always aligned, otherwise the transaction code can overwrite
- * itself. */
- new_size = (new_size + NTDB_PGSIZE-1) & ~(NTDB_PGSIZE-1);
- return new_size - map_size;
-}
-
-/* Expand the database. */
-static enum NTDB_ERROR ntdb_expand(struct ntdb_context *ntdb, ntdb_len_t size)
-{
- uint64_t old_size;
- ntdb_len_t wanted;
- enum NTDB_ERROR ecode;
-
- /* Need to hold a hash lock to expand DB: transactions rely on it. */
- if (!(ntdb->flags & NTDB_NOLOCK)
- && !ntdb->file->allrecord_lock.count && !ntdb_has_hash_locks(ntdb)) {
- return ntdb_logerr(ntdb, NTDB_ERR_LOCK, NTDB_LOG_ERROR,
- "ntdb_expand: must hold lock during expand");
- }
-
- /* Only one person can expand file at a time. */
- ecode = ntdb_lock_expand(ntdb, F_WRLCK);
- if (ecode != NTDB_SUCCESS) {
- return ecode;
- }
-
- /* Someone else may have expanded the file, so retry. */
- old_size = ntdb->file->map_size;
- ntdb_oob(ntdb, ntdb->file->map_size, 1, true);
- if (ntdb->file->map_size != old_size) {
- ntdb_unlock_expand(ntdb, F_WRLCK);
- return NTDB_SUCCESS;
- }
-
- /* We need room for the record header too. */
- size = adjust_size(0, sizeof(struct ntdb_used_record) + size);
- /* Overallocate. */
- wanted = ntdb_expand_adjust(old_size, size);
-
- ecode = ntdb->io->expand_file(ntdb, wanted);
- if (ecode != NTDB_SUCCESS) {
- ntdb_unlock_expand(ntdb, F_WRLCK);
- return ecode;
- }
-
- /* We need to drop this lock before adding free record. */
- ntdb_unlock_expand(ntdb, F_WRLCK);
-
- ntdb->stats.expands++;
- return add_free_record(ntdb, old_size, wanted, NTDB_LOCK_WAIT, true);
-}
-
-/* This won't fail: it will expand the database if it has to. */
-ntdb_off_t alloc(struct ntdb_context *ntdb, size_t keylen, size_t datalen,
- unsigned magic, bool growing)
-{
- ntdb_off_t off;
-
- for (;;) {
- enum NTDB_ERROR ecode;
- off = get_free(ntdb, keylen, datalen, growing, magic);
- if (likely(off != 0))
- break;
-
- ecode = ntdb_expand(ntdb, adjust_size(keylen, datalen));
- if (ecode != NTDB_SUCCESS) {
- return NTDB_ERR_TO_OFF(ecode);
- }
- }
-
- return off;
-}
projects / ccan / blobdiff