#define MIN_DATA_LEN \
(sizeof(struct tdb_free_record) - sizeof(struct tdb_used_record))
-/* We have a series of free lists, each one covering a "zone" of the file.
- *
- * For each zone we have a series of per-size buckets, and a final bucket for
- * "too big".
- *
- * It's possible to move the free_list_head, but *only* under the allrecord
- * lock. */
-static tdb_off_t free_list_off(struct tdb_context *tdb, unsigned int list)
-{
- return tdb->header.v.free_off + list * sizeof(tdb_off_t);
-}
-
-/* We're a library: playing with srandom() is unfriendly. srandom_r
- * probably lacks portability. We don't need very random here. */
-static unsigned int quick_random(struct tdb_context *tdb)
-{
- return getpid() + time(NULL) + (unsigned long)tdb;
-}
-
-/* Start by using a random zone to spread the load. */
-uint64_t random_free_zone(struct tdb_context *tdb)
-{
- /* num_zones might be out of date, but can only increase */
- return quick_random(tdb) % tdb->header.v.num_zones;
-}
-
static unsigned fls64(uint64_t val)
{
#if HAVE_BUILTIN_CLZL
}
/* In which bucket would we find a particular record size? (ignoring header) */
-unsigned int size_to_bucket(struct tdb_context *tdb, tdb_len_t data_len)
+unsigned int size_to_bucket(unsigned int zone_bits, tdb_len_t data_len)
{
unsigned int bucket;
bucket = fls64(data_len - MIN_DATA_LEN) + 2;
}
- if (unlikely(bucket > tdb->header.v.free_buckets))
- bucket = tdb->header.v.free_buckets;
+ if (unlikely(bucket > BUCKETS_FOR_ZONE(zone_bits)))
+ bucket = BUCKETS_FOR_ZONE(zone_bits);
return bucket;
}
-/* What zone does a block belong in? */
-tdb_off_t zone_of(struct tdb_context *tdb, tdb_off_t off)
+/* Subtract 1-byte tailer and header. Then round up to next power of 2. */
+static unsigned max_zone_bits(struct tdb_context *tdb)
+{
+ return fls64(tdb->map_size-1-sizeof(struct tdb_header)-1) + 1;
+}
+
+/* Start by using a random zone to spread the load: returns the offset. */
+static uint64_t random_zone(struct tdb_context *tdb)
{
- assert(tdb->header_uptodate);
+ struct free_zone_header zhdr;
+ tdb_off_t off = sizeof(struct tdb_header);
+ tdb_len_t half_bits;
+ uint64_t randbits = 0;
+ unsigned int i;
- return off >> tdb->header.v.zone_bits;
+ for (i = 0; i < 64; i += fls64(RAND_MAX))
+ randbits ^= ((uint64_t)random()) << i;
+
+ /* FIXME: Does this work? Test! */
+ half_bits = max_zone_bits(tdb) - 1;
+ do {
+ /* Pick left or right side (not outside file) */
+ if ((randbits & 1)
+ && !tdb->methods->oob(tdb, off + (1ULL << half_bits)
+ + sizeof(zhdr), true)) {
+ off += 1ULL << half_bits;
+ }
+ randbits >>= 1;
+
+ if (tdb_read_convert(tdb, off, &zhdr, sizeof(zhdr)) == -1)
+ return TDB_OFF_ERR;
+
+ if (zhdr.zone_bits == half_bits)
+ return off;
+
+ half_bits--;
+ } while (half_bits >= INITIAL_ZONE_BITS);
+
+ tdb->ecode = TDB_ERR_CORRUPT;
+ tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
+ "random_zone: zone at %llu smaller than %u bits?",
+ (long long)off, INITIAL_ZONE_BITS);
+ return TDB_OFF_ERR;
}
-/* Returns fl->max_bucket + 1, or list number to search. */
+int tdb_zone_init(struct tdb_context *tdb)
+{
+ tdb->zone_off = random_zone(tdb);
+ if (tdb->zone_off == TDB_OFF_ERR)
+ return -1;
+ if (tdb_read_convert(tdb, tdb->zone_off,
+ &tdb->zhdr, sizeof(tdb->zhdr)) == -1)
+ return -1;
+ return 0;
+}
+
+/* Where's the header, given a zone size of 1 << zone_bits? */
+static tdb_off_t zone_off(tdb_off_t off, unsigned int zone_bits)
+{
+ off -= sizeof(struct tdb_header);
+ return (off & ~((1ULL << zone_bits) - 1)) + sizeof(struct tdb_header);
+}
+
+/* Offset of a given bucket. */
+/* FIXME: bucket can be "unsigned" everywhere, or even uint8/16. */
+tdb_off_t bucket_off(tdb_off_t zone_off, tdb_off_t bucket)
+{
+ return zone_off
+ + sizeof(struct free_zone_header)
+ + bucket * sizeof(tdb_off_t);
+}
+
+/* Returns free_buckets + 1, or list number to search. */
static tdb_off_t find_free_head(struct tdb_context *tdb, tdb_off_t bucket)
{
- tdb_off_t first, off;
+ tdb_off_t b;
/* Speculatively search for a non-zero bucket. */
- first = tdb->last_zone * (tdb->header.v.free_buckets+1) + bucket;
- off = tdb_find_nonzero_off(tdb, free_list_off(tdb, first),
- tdb->header.v.free_buckets - bucket);
- return bucket + off;
+ b = tdb_find_nonzero_off(tdb, bucket_off(tdb->zone_off, bucket),
+ BUCKETS_FOR_ZONE(tdb->zhdr.zone_bits) + 1
+ - bucket);
+ return bucket + b;
}
+/* Remove from free bucket. */
static int remove_from_list(struct tdb_context *tdb,
- tdb_off_t list, struct tdb_free_record *r)
+ tdb_off_t b_off, struct tdb_free_record *r)
{
tdb_off_t off;
/* Front of list? */
if (r->prev == 0) {
- off = free_list_off(tdb, list);
+ off = b_off;
} else {
off = r->prev + offsetof(struct tdb_free_record, next);
}
return 0;
}
-/* Enqueue in this free list. */
+/* Enqueue in this free bucket. */
static int enqueue_in_free(struct tdb_context *tdb,
- tdb_off_t list,
+ tdb_off_t b_off,
tdb_off_t off,
struct tdb_free_record *new)
{
new->prev = 0;
/* new->next = head. */
- new->next = tdb_read_off(tdb, free_list_off(tdb, list));
+ new->next = tdb_read_off(tdb, b_off);
if (new->next == TDB_OFF_ERR)
return -1;
return -1;
}
/* head = new */
- if (tdb_write_off(tdb, free_list_off(tdb, list), off) != 0)
+ if (tdb_write_off(tdb, b_off, off) != 0)
return -1;
-
+
return tdb_write_convert(tdb, off, new, sizeof(*new));
}
-/* List isn't locked. */
+/* List need not be locked. */
int add_free_record(struct tdb_context *tdb,
+ unsigned int zone_bits,
tdb_off_t off, tdb_len_t len_with_header)
{
struct tdb_free_record new;
- tdb_off_t list;
+ tdb_off_t b_off;
int ret;
assert(len_with_header >= sizeof(new));
+ assert(zone_bits < (1 << 6));
- new.magic = TDB_FREE_MAGIC;
+ new.magic_and_meta = TDB_FREE_MAGIC | zone_bits;
new.data_len = len_with_header - sizeof(struct tdb_used_record);
- tdb->last_zone = zone_of(tdb, off);
- list = tdb->last_zone * (tdb->header.v.free_buckets+1)
- + size_to_bucket(tdb, new.data_len);
-
- if (tdb_lock_free_list(tdb, list, TDB_LOCK_WAIT) != 0)
+ b_off = bucket_off(zone_off(off, zone_bits),
+ size_to_bucket(zone_bits, new.data_len));
+ if (tdb_lock_free_bucket(tdb, b_off, TDB_LOCK_WAIT) != 0)
return -1;
- ret = enqueue_in_free(tdb, list, off, &new);
- tdb_unlock_free_list(tdb, list);
+ ret = enqueue_in_free(tdb, b_off, off, &new);
+ tdb_unlock_free_bucket(tdb, b_off);
return ret;
}
/* If we have enough left over to be useful, split that off. */
static int to_used_record(struct tdb_context *tdb,
+ unsigned int zone_bits,
tdb_off_t off,
tdb_len_t needed,
tdb_len_t total_len,
*actual = total_len - leftover;
if (leftover) {
- if (add_free_record(tdb, off + sizeof(used) + *actual,
+ if (add_free_record(tdb, zone_bits,
+ off + sizeof(used) + *actual,
total_len - needed))
return -1;
}
return 0;
}
-/* Note: we unlock the current list if we coalesce or fail. */
-static int coalesce(struct tdb_context *tdb, tdb_off_t off,
- tdb_off_t list, tdb_len_t data_len)
+/* Note: we unlock the current bucket if we coalesce or fail. */
+static int coalesce(struct tdb_context *tdb,
+ tdb_off_t zone_off, unsigned zone_bits,
+ tdb_off_t off, tdb_off_t b_off, tdb_len_t data_len)
{
struct tdb_free_record pad, *r;
tdb_off_t end = off + sizeof(struct tdb_used_record) + data_len;
- while (!tdb->methods->oob(tdb, end + sizeof(*r), 1)) {
- tdb_off_t nlist;
+ while (end < (zone_off + (1ULL << zone_bits))) {
+ tdb_off_t nb_off;
+ /* FIXME: do tdb_get here and below really win? */
r = tdb_get(tdb, end, &pad, sizeof(pad));
if (!r)
goto err;
- if (r->magic != TDB_FREE_MAGIC)
+ if (frec_magic(r) != TDB_FREE_MAGIC)
break;
- nlist = zone_of(tdb, end) * (tdb->header.v.free_buckets+1)
- + size_to_bucket(tdb, r->data_len);
+ nb_off = bucket_off(zone_off,
+ size_to_bucket(zone_bits, r->data_len));
/* We may be violating lock order here, so best effort. */
- if (tdb_lock_free_list(tdb, nlist, TDB_LOCK_NOWAIT) == -1)
+ if (tdb_lock_free_bucket(tdb, nb_off, TDB_LOCK_NOWAIT) == -1)
break;
/* Now we have lock, re-check. */
r = tdb_get(tdb, end, &pad, sizeof(pad));
if (!r) {
- tdb_unlock_free_list(tdb, nlist);
+ tdb_unlock_free_bucket(tdb, nb_off);
goto err;
}
- if (unlikely(r->magic != TDB_FREE_MAGIC)) {
- tdb_unlock_free_list(tdb, nlist);
+ if (unlikely(frec_magic(r) != TDB_FREE_MAGIC)) {
+ tdb_unlock_free_bucket(tdb, nb_off);
break;
}
- if (remove_from_list(tdb, list, r) == -1) {
- tdb_unlock_free_list(tdb, nlist);
+ if (remove_from_list(tdb, nb_off, r) == -1) {
+ tdb_unlock_free_bucket(tdb, nb_off);
goto err;
}
end += sizeof(struct tdb_used_record) + r->data_len;
- tdb_unlock_free_list(tdb, nlist);
+ tdb_unlock_free_bucket(tdb, nb_off);
}
/* Didn't find any adjacent free? */
if (!r)
goto err;
- if (remove_from_list(tdb, list, r) == -1)
+ if (r->data_len != data_len) {
+ tdb->ecode = TDB_ERR_CORRUPT;
+ tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
+ "coalesce: expected data len %llu not %llu\n",
+ (long long)data_len, (long long)r->data_len);
+ goto err;
+ }
+
+ if (remove_from_list(tdb, b_off, r) == -1)
goto err;
/* We have to drop this to avoid deadlocks. */
- tdb_unlock_free_list(tdb, list);
+ tdb_unlock_free_bucket(tdb, b_off);
- if (add_free_record(tdb, off, end - off) == -1)
+ if (add_free_record(tdb, zone_bits, off, end - off) == -1)
return -1;
return 1;
err:
- /* To unify error paths, we *always* unlock list. */
- tdb_unlock_free_list(tdb, list);
+ /* To unify error paths, we *always* unlock bucket on error. */
+ tdb_unlock_free_bucket(tdb, b_off);
return -1;
}
/* We need size bytes to put our key and data in. */
static tdb_off_t lock_and_alloc(struct tdb_context *tdb,
- tdb_off_t bucket, size_t size,
+ tdb_off_t zone_off,
+ unsigned zone_bits,
+ tdb_off_t bucket,
+ size_t size,
tdb_len_t *actual)
{
- tdb_off_t list;
- tdb_off_t off, prev, best_off;
+ tdb_off_t off, b_off,best_off;
struct tdb_free_record pad, best = { 0 }, *r;
double multiplier;
again:
- list = tdb->last_zone * (tdb->header.v.free_buckets+1) + bucket;
+ b_off = bucket_off(zone_off, bucket);
- /* Lock this list. */
- if (tdb_lock_free_list(tdb, list, TDB_LOCK_WAIT) == -1) {
+ /* Lock this bucket. */
+ if (tdb_lock_free_bucket(tdb, b_off, TDB_LOCK_WAIT) == -1) {
return TDB_OFF_ERR;
}
- prev = free_list_off(tdb, list);
- off = tdb_read_off(tdb, prev);
-
- if (unlikely(off == TDB_OFF_ERR))
- goto unlock_err;
-
best.data_len = -1ULL;
best_off = 0;
+ /* FIXME: Start with larger multiplier if we're growing. */
multiplier = 1.0;
/* Walk the list to see if any are large enough, getting less fussy
* as we go. */
- while (off) {
- prev = off;
- off = tdb_read_off(tdb, prev);
- if (unlikely(off == TDB_OFF_ERR))
- goto unlock_err;
+ off = tdb_read_off(tdb, b_off);
+ if (unlikely(off == TDB_OFF_ERR))
+ goto unlock_err;
+ while (off) {
+ /* FIXME: Does tdb_get win anything here? */
r = tdb_get(tdb, off, &pad, sizeof(*r));
if (!r)
goto unlock_err;
- if (r->magic != TDB_FREE_MAGIC) {
+
+ if (frec_magic(r) != TDB_FREE_MAGIC) {
tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
"lock_and_alloc: %llu non-free 0x%llx\n",
- (long long)off, (long long)r->magic);
+ (long long)off, (long long)r->magic_and_meta);
goto unlock_err;
}
best = *r;
}
- if (best.data_len < size * multiplier && best_off) {
- /* We're happy with this size: take it. */
- if (remove_from_list(tdb, list, &best) != 0)
- goto unlock_err;
- tdb_unlock_free_list(tdb, list);
+ if (best.data_len < size * multiplier && best_off)
+ goto use_best;
- if (to_used_record(tdb, best_off, size, best.data_len,
- actual)) {
- return -1;
- }
- return best_off;
- }
multiplier *= 1.01;
/* Since we're going slow anyway, try coalescing here. */
- switch (coalesce(tdb, off, list, r->data_len)) {
+ switch (coalesce(tdb, zone_off, zone_bits, off, b_off,
+ r->data_len)) {
case -1:
/* This has already unlocked on error. */
return -1;
/* This has unlocked list, restart. */
goto again;
}
+ off = r->next;
+ }
+
+ /* If we found anything at all, use it. */
+ if (best_off) {
+ use_best:
+ /* We're happy with this size: take it. */
+ if (remove_from_list(tdb, b_off, &best) != 0)
+ goto unlock_err;
+ tdb_unlock_free_bucket(tdb, b_off);
+
+ if (to_used_record(tdb, zone_bits, best_off, size,
+ best.data_len, actual)) {
+ return -1;
+ }
+ return best_off;
}
- tdb_unlock_free_list(tdb, list);
+ tdb_unlock_free_bucket(tdb, b_off);
return 0;
unlock_err:
- tdb_unlock_free_list(tdb, list);
+ tdb_unlock_free_bucket(tdb, b_off);
return TDB_OFF_ERR;
}
-/* We want a really big chunk. Look through every zone's oversize bucket */
-static tdb_off_t huge_alloc(struct tdb_context *tdb, size_t size,
- tdb_len_t *actual)
+static bool next_zone(struct tdb_context *tdb)
{
- tdb_off_t i, off;
+ tdb_off_t next = tdb->zone_off + (1ULL << tdb->zhdr.zone_bits);
- do {
- for (i = 0; i < tdb->header.v.num_zones; i++) {
- /* Try getting one from list. */
- off = lock_and_alloc(tdb, tdb->header.v.free_buckets,
- size, actual);
- if (off == TDB_OFF_ERR)
- return TDB_OFF_ERR;
- if (off != 0)
- return off;
- /* FIXME: Coalesce! */
- }
- } while (tdb_expand(tdb, 0, size, false) == 0);
+ /* We must have a header. */
+ if (tdb->methods->oob(tdb, next + sizeof(tdb->zhdr), true))
+ return false;
- return TDB_OFF_ERR;
+ tdb->zone_off = next;
+ return tdb_read_convert(tdb, next, &tdb->zhdr, sizeof(tdb->zhdr)) == 0;
}
+/* Offset returned is within current zone (which it may alter). */
static tdb_off_t get_free(struct tdb_context *tdb, size_t size,
tdb_len_t *actual)
{
- tdb_off_t off, bucket;
- unsigned int num_empty, step = 0;
-
- bucket = size_to_bucket(tdb, size);
+ tdb_off_t start_zone = tdb->zone_off, off;
+ bool wrapped = false;
- /* If we're after something bigger than a single zone, handle
- * specially. */
- if (unlikely(sizeof(struct tdb_used_record) + size
- >= (1ULL << tdb->header.v.zone_bits))) {
- return huge_alloc(tdb, size, actual);
- }
-
- /* Number of zones we search is proportional to the log of them. */
- for (num_empty = 0; num_empty < fls64(tdb->header.v.num_zones);
- num_empty++) {
+ while (!wrapped || tdb->zone_off != start_zone) {
tdb_off_t b;
+ /* Shortcut for really huge allocations... */
+ if ((size >> tdb->zhdr.zone_bits) != 0)
+ continue;
+
/* Start at exact size bucket, and search up... */
- for (b = bucket; b <= tdb->header.v.num_zones; b++) {
- b = find_free_head(tdb, b);
-
- /* Non-empty list? Try getting block. */
- if (b <= tdb->header.v.num_zones) {
- /* Try getting one from list. */
- off = lock_and_alloc(tdb, b, size, actual);
- if (off == TDB_OFF_ERR)
- return TDB_OFF_ERR;
- if (off != 0)
- return off;
- /* Didn't work. Try next bucket. */
- }
+ b = size_to_bucket(tdb->zhdr.zone_bits, size);
+ for (b = find_free_head(tdb, b);
+ b <= BUCKETS_FOR_ZONE(tdb->zhdr.zone_bits);
+ b += find_free_head(tdb, b + 1)) {
+ /* Try getting one from list. */
+ off = lock_and_alloc(tdb, tdb->zone_off,
+ tdb->zhdr.zone_bits,
+ b, size, actual);
+ if (off == TDB_OFF_ERR)
+ return TDB_OFF_ERR;
+ if (off != 0)
+ return off;
+ /* Didn't work. Try next bucket. */
}
- /* Try another zone, at pseudo random. Avoid duplicates by
- using an odd step. */
- if (step == 0)
- step = ((quick_random(tdb)) % 65536) * 2 + 1;
- tdb->last_zone = (tdb->last_zone + step)
- % tdb->header.v.num_zones;
+ /* Didn't work, try next zone, if it exists. */
+ if (!next_zone(tdb)) {
+ wrapped = true;
+ tdb->zone_off = sizeof(struct tdb_header);
+ if (tdb_read_convert(tdb, tdb->zone_off,
+ &tdb->zhdr, sizeof(tdb->zhdr))) {
+ return TDB_OFF_ERR;
+ }
+ }
}
return 0;
}
int set_header(struct tdb_context *tdb,
struct tdb_used_record *rec,
uint64_t keylen, uint64_t datalen,
- uint64_t actuallen, uint64_t hash)
+ uint64_t actuallen, uint64_t hash,
+ unsigned int zone_bits)
{
uint64_t keybits = (fls64(keylen) + 1) / 2;
- /* Use top bits of hash, so it's independent of hash table size. */
+ /* Use bottom bits of hash, so it's independent of hash table size. */
rec->magic_and_meta
- = (actuallen - (keylen + datalen))
- | ((hash >> 53) << 32)
+ = zone_bits
+ | ((hash & ((1 << 5)-1)) << 6)
+ | ((actuallen - (keylen + datalen)) << 11)
| (keybits << 43)
| (TDB_MAGIC << 48);
rec->key_and_data_len = (keylen | (datalen << (keybits*2)));
return 0;
}
+static bool zones_happy(struct tdb_context *tdb)
+{
+ /* FIXME: look at distribution of zones. */
+ return true;
+}
+
+/* Assume we want buckets up to the comfort factor. */
+static tdb_len_t overhead(unsigned int zone_bits)
+{
+ return sizeof(struct free_zone_header)
+ + (BUCKETS_FOR_ZONE(zone_bits) + 1) * sizeof(tdb_off_t);
+}
+
+/* Expand the database (by adding a zone). */
+static int tdb_expand(struct tdb_context *tdb, tdb_len_t size)
+{
+ uint64_t old_size;
+ tdb_off_t off;
+ uint8_t zone_bits;
+ unsigned int num_buckets;
+ tdb_len_t wanted;
+ struct free_zone_header zhdr;
+ bool enlarge_zone;
+
+ /* We need room for the record header too. */
+ wanted = sizeof(struct tdb_used_record) + size;
+
+ /* Only one person can expand file at a time. */
+ if (tdb_lock_expand(tdb, F_WRLCK) != 0)
+ return -1;
+
+ /* Someone else may have expanded the file, so retry. */
+ old_size = tdb->map_size;
+ tdb->methods->oob(tdb, tdb->map_size + 1, true);
+ if (tdb->map_size != old_size)
+ goto success;
+
+ /* zone bits tailer char is protected by EXPAND lock. */
+ if (tdb->methods->read(tdb, old_size - 1, &zone_bits, 1) == -1)
+ goto fail;
+
+ /* If zones aren't working well, add larger zone if possible. */
+ enlarge_zone = !zones_happy(tdb);
+
+ /* New zone can be between zone_bits or larger if we're on the right
+ * boundary. */
+ for (;;) {
+ /* Does this fit the allocation comfortably? */
+ if ((1ULL << zone_bits) >= overhead(zone_bits) + wanted) {
+ /* Only let enlarge_zone enlarge us once. */
+ if (!enlarge_zone)
+ break;
+ enlarge_zone = false;
+ }
+ if ((old_size - 1 - sizeof(struct tdb_header))
+ & (1 << zone_bits))
+ break;
+ zone_bits++;
+ }
+
+ zhdr.zone_bits = zone_bits;
+ num_buckets = BUCKETS_FOR_ZONE(zone_bits);
+
+ if (tdb->methods->expand_file(tdb, 1ULL << zone_bits) == -1)
+ goto fail;
+
+ /* Write new tailer. */
+ if (tdb->methods->write(tdb, tdb->map_size - 1, &zone_bits, 1) == -1)
+ goto fail;
+
+ /* Write new zone header (just before old tailer). */
+ off = old_size - 1;
+ if (tdb_write_convert(tdb, off, &zhdr, sizeof(zhdr)) == -1)
+ goto fail;
+
+ /* Now write empty buckets. */
+ off += sizeof(zhdr);
+ if (zero_out(tdb, off, (num_buckets+1) * sizeof(tdb_off_t)) == -1)
+ goto fail;
+ off += (num_buckets+1) * sizeof(tdb_off_t);
+
+ /* Now add the rest as our free record. */
+ if (add_free_record(tdb, zone_bits, off, tdb->map_size-1-off) == -1)
+ goto fail;
+
+ /* Try allocating from this zone now. */
+ tdb->zone_off = old_size - 1;
+ tdb->zhdr = zhdr;
+
+success:
+ tdb_unlock_expand(tdb, F_WRLCK);
+ return 0;
+
+fail:
+ tdb_unlock_expand(tdb, F_WRLCK);
+ return -1;
+}
+
static tdb_len_t adjust_size(size_t keylen, size_t datalen, bool growing)
{
tdb_len_t size = keylen + datalen;
return (size + (sizeof(uint64_t) - 1ULL)) & ~(sizeof(uint64_t) - 1ULL);
}
-/* If this fails, try tdb_expand. */
+/* This won't fail: it will expand the database if it has to. */
tdb_off_t alloc(struct tdb_context *tdb, size_t keylen, size_t datalen,
uint64_t hash, bool growing)
{
tdb_len_t size, actual;
struct tdb_used_record rec;
- /* We don't want header to change during this! */
- assert(tdb->header_uptodate);
+ /* We can't hold pointers during this: we could unmap! */
+ assert(!tdb->direct_access);
size = adjust_size(keylen, datalen, growing);
+again:
off = get_free(tdb, size, &actual);
- if (unlikely(off == TDB_OFF_ERR || off == 0))
+ if (unlikely(off == TDB_OFF_ERR))
return off;
+ if (unlikely(off == 0)) {
+ if (tdb_expand(tdb, size) == -1)
+ return TDB_OFF_ERR;
+ goto again;
+ }
+
/* Some supergiant values can't be encoded. */
- if (set_header(tdb, &rec, keylen, datalen, actual, hash) != 0) {
- add_free_record(tdb, off, sizeof(rec) + actual);
+ /* FIXME: Check before, and limit actual in get_free. */
+ if (set_header(tdb, &rec, keylen, datalen, actual, hash,
+ tdb->zhdr.zone_bits) != 0) {
+ add_free_record(tdb, tdb->zhdr.zone_bits, off,
+ sizeof(rec) + actual);
return TDB_OFF_ERR;
}
return off;
}
-
-static bool larger_buckets_might_help(struct tdb_context *tdb)
-{
- /* If our buckets are already covering 1/8 of a zone, don't
- * bother (note: might become an 1/16 of a zone if we double
- * zone size). */
- tdb_len_t size = (1ULL << tdb->header.v.zone_bits) / 8;
-
- if (size >= MIN_DATA_LEN
- && size_to_bucket(tdb, size) < tdb->header.v.free_buckets) {
- return false;
- }
-
- /* FIXME: Put stats in tdb_context or examine db itself! */
- /* It's fairly cheap to do as we expand database. */
- return true;
-}
-
-static bool zones_happy(struct tdb_context *tdb)
-{
- /* FIXME: look at distribution of zones. */
- return true;
-}
-
-/* Expand the database. */
-int tdb_expand(struct tdb_context *tdb, tdb_len_t klen, tdb_len_t dlen,
- bool growing)
-{
- uint64_t new_num_buckets, new_num_zones, new_zone_bits;
- uint64_t old_num_total, i;
- tdb_len_t add, freebucket_size, needed;
- tdb_off_t off, old_free_off;
- const tdb_off_t *oldf;
- struct tdb_used_record fhdr;
-
- /* We need room for the record header too. */
- needed = sizeof(struct tdb_used_record)
- + adjust_size(klen, dlen, growing);
-
- /* FIXME: this is overkill. An expand lock? */
- if (tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false) == -1)
- return -1;
-
- /* Someone may have expanded for us. */
- if (update_header(tdb))
- goto success;
-
- /* Make sure we have the latest size. */
- tdb->methods->oob(tdb, tdb->map_size + 1, true);
-
- /* Did we enlarge zones without enlarging file? */
- if (tdb->map_size < tdb->header.v.num_zones<<tdb->header.v.zone_bits) {
- add = (tdb->header.v.num_zones<<tdb->header.v.zone_bits)
- - tdb->map_size;
- /* Updates tdb->map_size. */
- if (tdb->methods->expand_file(tdb, tdb->map_size, add) == -1)
- goto fail;
- if (add_free_record(tdb, tdb->map_size - add, add) == -1)
- goto fail;
- if (add >= needed) {
- /* Allocate from this zone. */
- tdb->last_zone = zone_of(tdb, tdb->map_size - add);
- goto success;
- }
- }
-
- /* Slow path. Should we increase the number of buckets? */
- new_num_buckets = tdb->header.v.free_buckets;
- if (larger_buckets_might_help(tdb))
- new_num_buckets++;
-
- /* Now we'll need room for the new free buckets, too. Assume
- * worst case (zones expand). */
- needed += sizeof(fhdr)
- + ((tdb->header.v.num_zones+1)
- * (new_num_buckets+1) * sizeof(tdb_off_t));
-
- /* If we need less that one zone, and they're working well, just add
- * another one. */
- if (needed < (1UL<<tdb->header.v.zone_bits) && zones_happy(tdb)) {
- new_num_zones = tdb->header.v.num_zones+1;
- new_zone_bits = tdb->header.v.zone_bits;
- add = 1ULL << tdb->header.v.zone_bits;
- } else {
- /* Increase the zone size. */
- new_num_zones = tdb->header.v.num_zones;
- new_zone_bits = tdb->header.v.zone_bits+1;
- while ((new_num_zones << new_zone_bits) - tdb->map_size
- < needed) {
- new_zone_bits++;
- }
-
- /* We expand by enough zones to meet the need. */
- add = (needed + (1ULL << new_zone_bits)-1)
- & ~((1ULL << new_zone_bits)-1);
- }
-
- /* Updates tdb->map_size. */
- if (tdb->methods->expand_file(tdb, tdb->map_size, add) == -1)
- goto fail;
-
- /* Use first part as new free bucket array. */
- off = tdb->map_size - add;
- freebucket_size = new_num_zones
- * (new_num_buckets + 1) * sizeof(tdb_off_t);
-
- /* Write header. */
- if (set_header(tdb, &fhdr, 0, freebucket_size, freebucket_size, 0))
- goto fail;
- if (tdb_write_convert(tdb, off, &fhdr, sizeof(fhdr)) == -1)
- goto fail;
-
- /* Adjust off to point to start of buckets, add to be remainder. */
- add -= freebucket_size + sizeof(fhdr);
- off += sizeof(fhdr);
-
- /* Access the old zones. */
- old_num_total = tdb->header.v.num_zones*(tdb->header.v.free_buckets+1);
- old_free_off = tdb->header.v.free_off;
- oldf = tdb_access_read(tdb, old_free_off,
- old_num_total * sizeof(tdb_off_t));
- if (!oldf)
- goto fail;
-
- /* Switch to using our new zone. */
- if (zero_out(tdb, off, new_num_zones * (new_num_buckets + 1)) == -1)
- goto fail_release;
- tdb->header.v.free_off = off;
- tdb->header.v.num_zones = new_num_zones;
- tdb->header.v.free_buckets = new_num_buckets;
-
- /* FIXME: If zone size hasn't changed, can simply copy pointers. */
- /* FIXME: Coalesce? */
- for (i = 0; i < old_num_total; i++) {
- tdb_off_t next;
- struct tdb_free_record rec;
- tdb_off_t list;
-
- for (off = oldf[i]; off; off = next) {
- if (tdb_read_convert(tdb, off, &rec, sizeof(rec)))
- goto fail_release;
-
- list = zone_of(tdb, off)
- * (tdb->header.v.free_buckets+1)
- + size_to_bucket(tdb, rec.data_len);
- next = rec.next;
-
- if (enqueue_in_free(tdb, list, off, &rec) == -1)
- goto fail_release;
- }
- }
-
-
- /* Free up the old free buckets. */
- old_free_off -= sizeof(fhdr);
- if (tdb_read_convert(tdb, old_free_off, &fhdr, sizeof(fhdr)) == -1)
- goto fail_release;
- if (add_free_record(tdb, old_free_off,
- rec_data_length(&fhdr)+rec_extra_padding(&fhdr)))
- goto fail_release;
-
- /* Add the rest as a new free record. */
- if (add_free_record(tdb, tdb->map_size - add, add) == -1)
- goto fail_release;
-
- /* Start allocating from where the new space is. */
- tdb->last_zone = zone_of(tdb, tdb->map_size - add);
- tdb_access_release(tdb, oldf);
-success:
- tdb_allrecord_unlock(tdb, F_WRLCK);
- return 0;
-
-fail_release:
- tdb_access_release(tdb, oldf);
-fail:
- tdb_allrecord_unlock(tdb, F_WRLCK);
- return -1;
-}