--- /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