diff options
Diffstat (limited to 'lib/ntdb/free.c')
| -rw-r--r-- | lib/ntdb/free.c | 976 |
1 files changed, 976 insertions, 0 deletions
diff --git a/lib/ntdb/free.c b/lib/ntdb/free.c new file mode 100644 index 0000000000..0fe6c73775 --- /dev/null +++ b/lib/ntdb/free.c @@ -0,0 +1,976 @@ + /* + 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 <assert.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, + unsigned hashlow) +{ + 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_len_t len; + 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; + len = frec_len(r); + 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, hashlow); + 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, unsigned hashlow) +{ + 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, hashlow); + 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, unsigned hashlow) +{ + uint64_t keybits = (fls64(keylen) + 1) / 2; + + /* Use bottom bits of hash, so it's independent of hash table size. */ + rec->magic_and_meta = (hashlow & ((1 << 11)-1)) + | ((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; + } + + /* Round the database up to a multiple of the page size */ + if (new_size < top_size) + new_size = top_size; + 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->io->oob(ntdb, ntdb->file->map_size, 1, true); + if (ntdb->file->map_size != old_size) { + ntdb_unlock_expand(ntdb, F_WRLCK); + return NTDB_SUCCESS; + } + + /* Overallocate. */ + wanted = ntdb_expand_adjust(old_size, size); + /* We need room for the record header too. */ + wanted = adjust_size(0, sizeof(struct ntdb_used_record) + wanted); + + 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, + uint64_t hash, unsigned magic, bool growing) +{ + ntdb_off_t off; + + /* We can't hold pointers during this: we could unmap! */ + assert(!ntdb->direct_access); + + for (;;) { + enum NTDB_ERROR ecode; + off = get_free(ntdb, keylen, datalen, growing, magic, hash); + 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; +} |