*/
#include "private.h"
#include <ccan/likely/likely.h>
+#include <ccan/ilog/ilog.h>
#include <time.h>
#include <assert.h>
#include <limits.h>
-/* We have to be able to fit a free record here. */
-#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. */
-void tdb_zone_init(struct tdb_context *tdb)
+static unsigned fls64(uint64_t val)
{
- /*
- * We read num_zones without a proper lock, so we could have
- * gotten a partial read. Since zone_bits is 1 byte long, we
- * can trust that; even if it's increased, the number of zones
- * cannot have decreased. And using the map size means we
- * will not start with a zone which hasn't been filled yet.
- */
- tdb->last_zone = quick_random(tdb)
- % ((tdb->map_size >> tdb->header.v.zone_bits) + 1);
+ return ilog64(val);
}
-static unsigned fls64(uint64_t val)
+static unsigned ffs64(uint64_t val)
{
-#if HAVE_BUILTIN_CLZL
- if (val <= ULONG_MAX) {
- /* This is significantly faster! */
- return val ? sizeof(long) * CHAR_BIT - __builtin_clzl(val) : 0;
- } else {
-#endif
- uint64_t r = 64;
+#if HAVE_BUILTIN_FFSLL
+ return __builtin_ffsll(val);
+#else
+ unsigned r = 0;
if (!val)
return 0;
- if (!(val & 0xffffffff00000000ull)) {
- val <<= 32;
- r -= 32;
+
+ if (!(val & 0xffffffff)) {
+ val >>= 32;
+ r += 32;
}
- if (!(val & 0xffff000000000000ull)) {
- val <<= 16;
- r -= 16;
+ if (!(val & 0xffff)) {
+ val >>= 16;
+ r += 16;
}
- if (!(val & 0xff00000000000000ull)) {
- val <<= 8;
- r -= 8;
+ if (!(val & 0xff)) {
+ val >>= 8;
+ r += 8;
}
- if (!(val & 0xf000000000000000ull)) {
- val <<= 4;
- r -= 4;
+ if (!(val & 0xf)) {
+ val >>= 4;
+ r += 4;
}
- if (!(val & 0xc000000000000000ull)) {
- val <<= 2;
- r -= 2;
+ if (!(val & 0x3)) {
+ val >>= 2;
+ r += 2;
}
- if (!(val & 0x8000000000000000ull)) {
- val <<= 1;
- r -= 1;
+ if (!(val & 0x1)) {
+ val >>= 1;
+ r += 1;
}
return r;
-#if HAVE_BUILTIN_CLZL
- }
#endif
}
/* 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;
/* We can't have records smaller than this. */
- assert(data_len >= MIN_DATA_LEN);
+ assert(data_len >= TDB_MIN_DATA_LEN);
/* Ignoring the header... */
- if (data_len - MIN_DATA_LEN <= 64) {
- /* 0 in bucket 0, 8 in bucket 1... 64 in bucket 6. */
- bucket = (data_len - MIN_DATA_LEN) / 8;
+ if (data_len - TDB_MIN_DATA_LEN <= 64) {
+ /* 0 in bucket 0, 8 in bucket 1... 64 in bucket 8. */
+ bucket = (data_len - TDB_MIN_DATA_LEN) / 8;
} else {
/* After that we go power of 2. */
- bucket = fls64(data_len - MIN_DATA_LEN) + 2;
+ bucket = fls64(data_len - TDB_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)
+/* Binary search for the zone for this offset. */
+static tdb_off_t off_to_zone(struct tdb_context *tdb, tdb_off_t off,
+ struct free_zone_header *zhdr)
+{
+ tdb_off_t start, end;
+
+ start = sizeof(struct tdb_header);
+ end = start + (1ULL << fls64(tdb->map_size - start));
+
+ for (;;) {
+ if (tdb_read_convert(tdb, start, zhdr, sizeof(*zhdr)) == -1)
+ return TDB_OFF_ERR;
+
+ /* Is it inside this zone? */
+ if (off < start + (1ULL << zhdr->zone_bits))
+ return start;
+
+ /* In practice, start + end won't overflow. */
+ if (off >= (start + end) / 2)
+ start = (start + end) / 2;
+ else
+ end = (start + end) / 2;
+ }
+}
+
+static tdb_off_t last_zone(struct tdb_context *tdb,
+ struct free_zone_header *zhdr)
+{
+ return off_to_zone(tdb, tdb->map_size - 1, zhdr);
+}
+
+int tdb_zone_init(struct tdb_context *tdb)
{
- assert(tdb->header_uptodate);
+ unsigned int i;
+ uint64_t randoff = 0;
+
+ /* We start in a random zone, to spread the load. */
+ for (i = 0; i < 64; i += fls64(RAND_MAX))
+ randoff ^= ((uint64_t)random()) << i;
+ randoff = sizeof(struct tdb_header)
+ + (randoff % (tdb->map_size - sizeof(struct tdb_header)));
- return off >> tdb->header.v.zone_bits;
+ tdb->zone_off = off_to_zone(tdb, randoff, &tdb->zhdr);
+ if (tdb->zone_off == TDB_OFF_ERR)
+ 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;
-
/* 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 + 1 - bucket);
- return bucket + off;
+ return tdb_find_nonzero_off(tdb, bucket_off(tdb->zone_off, 0),
+ bucket,
+ BUCKETS_FOR_ZONE(tdb->zhdr.zone_bits) + 1);
}
+/* 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, tdb_off_t r_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);
}
+
+#ifdef DEBUG
+ if (tdb_read_off(tdb, off) != r_off) {
+ tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
+ "remove_from_list: %llu bad prev in list %llu\n",
+ (long long)r_off, (long long)b_off);
+ return -1;
+ }
+#endif
+
/* r->prev->next = r->next */
if (tdb_write_off(tdb, off, r->next)) {
return -1;
if (r->next != 0) {
off = r->next + offsetof(struct tdb_free_record, prev);
/* r->next->prev = r->prev */
+
+#ifdef DEBUG
+ if (tdb_read_off(tdb, off) != r_off) {
+ tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
+ "remove_from_list: %llu bad list %llu\n",
+ (long long)r_off, (long long)b_off);
+ return -1;
+ }
+#endif
+
if (tdb_write_off(tdb, off, r->prev)) {
return -1;
}
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;
if (new->next) {
+#ifdef DEBUG
+ if (tdb_read_off(tdb,
+ new->next
+ + offsetof(struct tdb_free_record, prev))
+ != 0) {
+ tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
+ "enqueue_in_free: %llu bad head prev %llu\n",
+ (long long)new->next, (long long)b_off);
+ return -1;
+ }
+#endif
/* next->prev = new. */
if (tdb_write_off(tdb, new->next
+ offsetof(struct tdb_free_record, prev),
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 < 64);
- 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;
}
+static size_t adjust_size(size_t keylen, size_t datalen)
+{
+ size_t size = keylen + datalen;
+
+ if (size < TDB_MIN_DATA_LEN)
+ size = TDB_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 int to_used_record(struct tdb_context *tdb,
- tdb_off_t off,
- tdb_len_t needed,
- tdb_len_t total_len,
- tdb_len_t *actual)
+static size_t record_leftover(size_t keylen, size_t datalen,
+ bool want_extra, size_t total_len)
{
- struct tdb_used_record used;
- tdb_len_t leftover;
+ ssize_t leftover;
- leftover = total_len - needed;
- if (leftover < sizeof(struct tdb_free_record))
- leftover = 0;
+ if (want_extra)
+ datalen += datalen / 2;
+ leftover = total_len - adjust_size(keylen, datalen);
- *actual = total_len - leftover;
+ if (leftover < (ssize_t)sizeof(struct tdb_free_record))
+ return 0;
- if (leftover) {
- if (add_free_record(tdb, off + sizeof(used) + *actual,
- total_len - needed))
- return -1;
- }
- return 0;
+ return leftover;
}
-/* 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;
+ tdb_off_t zone_end, end;
- while (!tdb->methods->oob(tdb, end + sizeof(*r), 1)) {
- tdb_off_t nlist;
+ end = off + sizeof(struct tdb_used_record) + data_len;
+ zone_end = zone_off + (1ULL << zone_bits);
+ if (tdb->methods->oob(tdb, zone_end, true))
+ zone_end = tdb->map_size;
+
+ while (end < zone_end) {
+ 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 (unlikely(bucket_off(zone_off,
+ size_to_bucket(zone_bits, r->data_len))
+ != nb_off)) {
+ tdb_unlock_free_bucket(tdb, nb_off);
break;
}
- if (remove_from_list(tdb, nlist, r) == -1) {
- tdb_unlock_free_list(tdb, nlist);
+ if (remove_from_list(tdb, nb_off, end, 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? */
goto err;
}
- if (remove_from_list(tdb, list, r) == -1)
+ if (remove_from_list(tdb, b_off, off, r) == -1)
goto err;
- /* We have to drop this to avoid deadlocks. */
- tdb_unlock_free_list(tdb, list);
+ r = tdb_access_write(tdb, off, sizeof(*r), true);
+ if (!r)
+ goto err;
+
+ /* We have to drop this to avoid deadlocks, so make sure record
+ * doesn't get coalesced by someone else! */
+ r->magic_and_meta = TDB_COALESCING_MAGIC | zone_bits;
+ r->data_len = end - off - sizeof(struct tdb_used_record);
+ if (tdb_access_commit(tdb, r) != 0)
+ goto err;
+
+ 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_len_t *actual)
+ tdb_off_t zone_off,
+ unsigned zone_bits,
+ tdb_off_t bucket,
+ size_t keylen, size_t datalen,
+ bool want_extra,
+ unsigned hashlow)
{
- tdb_off_t list;
- tdb_off_t off, best_off;
+ tdb_off_t off, b_off,best_off;
struct tdb_free_record pad, best = { 0 }, *r;
double multiplier;
+ size_t size = adjust_size(keylen, datalen);
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) {
+ /* FIXME: Try non-blocking wait first, to measure contention.
+ * If we're contented, try switching zones, and don't enlarge zone
+ * next time (we want more zones). */
+ /* Lock this bucket. */
+ if (tdb_lock_free_bucket(tdb, b_off, TDB_LOCK_WAIT) == -1) {
return TDB_OFF_ERR;
}
best.data_len = -1ULL;
best_off = 0;
- multiplier = 1.0;
+
+ /* 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 = tdb_read_off(tdb, free_list_off(tdb, list));
+ 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;
}
}
if (best.data_len < size * multiplier && best_off)
- goto use_best;
+ break;
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;
/* If we found anything at all, use it. */
if (best_off) {
- use_best:
+ struct tdb_used_record rec;
+ size_t leftover;
+
/* We're happy with this size: take it. */
- if (remove_from_list(tdb, list, &best) != 0)
+ if (remove_from_list(tdb, b_off, best_off, &best) != 0)
goto unlock_err;
- tdb_unlock_free_list(tdb, list);
- if (to_used_record(tdb, best_off, size, best.data_len,
- actual)) {
- return -1;
+ leftover = record_leftover(keylen, datalen, want_extra,
+ best.data_len);
+
+ assert(keylen + datalen + leftover <= best.data_len);
+ /* We need to mark non-free before we drop lock, otherwise
+ * coalesce() could try to merge it! */
+ if (set_header(tdb, &rec, keylen, datalen,
+ best.data_len - leftover,
+ hashlow, zone_bits) != 0)
+ goto unlock_err;
+
+ if (tdb_write_convert(tdb, best_off, &rec, sizeof(rec)) != 0)
+ goto unlock_err;
+
+ tdb_unlock_free_bucket(tdb, b_off);
+
+ if (leftover) {
+ if (add_free_record(tdb, zone_bits,
+ best_off + sizeof(rec)
+ + best.data_len - leftover,
+ leftover))
+ return TDB_OFF_ERR;
}
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);
- 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! */
- }
- return 0;
+ /* We must have a header. */
+ if (tdb->methods->oob(tdb, next + sizeof(tdb->zhdr), true))
+ return false;
+
+ tdb->zone_off = next;
+ return tdb_read_convert(tdb, next, &tdb->zhdr, sizeof(tdb->zhdr)) == 0;
}
-static tdb_off_t get_free(struct tdb_context *tdb, size_t size,
- tdb_len_t *actual)
+/* Offset returned is within current zone (which it may alter). */
+static tdb_off_t get_free(struct tdb_context *tdb,
+ size_t keylen, size_t datalen, bool want_extra,
+ unsigned hashlow)
{
- tdb_off_t off, bucket;
- unsigned int num_empty, step = 0;
+ tdb_off_t start_zone = tdb->zone_off, off;
+ bool wrapped = false;
+ size_t size = adjust_size(keylen, datalen);
- bucket = size_to_bucket(tdb, size);
-
- /* 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);
- }
+ /* If they are growing, add 50% to get to higher bucket. */
+ if (want_extra)
+ size += datalen / 2;
- /* 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++) {
+ /* FIXME: If we don't get a hit in the first bucket we want,
+ * try changing zones for next time. That should help wear
+ * zones evenly, so we don't need to search all of them before
+ * expanding. */
+ while (!wrapped || tdb->zone_off != start_zone) {
tdb_off_t b;
+ /* Shortcut for really huge allocations... */
+ if ((size >> tdb->zhdr.zone_bits) != 0)
+ goto next;
+
/* Start at exact size bucket, and search up... */
- for (b = bucket; b <= tdb->header.v.free_buckets; b++) {
- b = find_free_head(tdb, b);
-
- /* Non-empty list? Try getting block. */
- if (b <= tdb->header.v.free_buckets) {
- /* 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, keylen, datalen, want_extra,
+ hashlow);
+ 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;
+ next:
+ /* 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, unsigned hashlow,
+ 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
+ | ((hashlow & ((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 tdb_len_t adjust_size(size_t keylen, size_t datalen, bool growing)
+static bool zones_contended(struct tdb_context *tdb)
{
- tdb_len_t size = keylen + datalen;
-
- if (size < MIN_DATA_LEN)
- size = MIN_DATA_LEN;
-
- /* Overallocate if this is coming from an enlarging store. */
- if (growing)
- size += datalen / 2;
+ return false;
+}
- /* Round to next uint64_t boundary. */
- return (size + (sizeof(uint64_t) - 1ULL)) & ~(sizeof(uint64_t) - 1ULL);
+/* 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);
}
-/* If this fails, try tdb_expand. */
-tdb_off_t alloc(struct tdb_context *tdb, size_t keylen, size_t datalen,
- uint64_t hash, bool growing)
+/* 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;
- tdb_len_t size, actual;
- struct tdb_used_record rec;
+ unsigned int num_buckets, zone_bits;
+ tdb_len_t wanted, expand;
+ struct free_zone_header zhdr;
- /* We don't want header to change during this! */
- assert(tdb->header_uptodate);
-
- size = adjust_size(keylen, datalen, growing);
-
- off = get_free(tdb, size, &actual);
- if (unlikely(off == TDB_OFF_ERR || off == 0))
- return off;
+ /* We need room for the record header too. */
+ wanted = sizeof(struct tdb_used_record) + size;
- /* 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);
- return TDB_OFF_ERR;
- }
+ /* Only one person can expand file at a time. */
+ if (tdb_lock_expand(tdb, F_WRLCK) != 0)
+ return -1;
- if (tdb_write_convert(tdb, off, &rec, sizeof(rec)) != 0)
- return TDB_OFF_ERR;
-
- return off;
-}
+ /* 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;
-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;
+ /* Treat last zone as minimum reasonable zone size. */
+ off = last_zone(tdb, &zhdr);
+ if (off == TDB_OFF_ERR)
+ goto fail;
- if (size >= MIN_DATA_LEN
- && size_to_bucket(tdb, size) < tdb->header.v.free_buckets) {
- return false;
+ /* Zone isn't fully expanded? */
+ if (tdb->map_size < off + (1ULL << zhdr.zone_bits)) {
+ expand = off + (1ULL << zhdr.zone_bits) - tdb->map_size;
+ /* Expand more than we want. */
+ if (expand > (wanted << TDB_COMFORT_FACTOR_BITS))
+ expand = (wanted << TDB_COMFORT_FACTOR_BITS);
+ if (tdb->methods->expand_file(tdb, expand) == -1)
+ goto fail;
+ /* We need to drop this lock before adding free record. */
+ tdb_unlock_expand(tdb, F_WRLCK);
+
+ /* Allocate from here. */
+ tdb->zone_off = off;
+ tdb->zhdr = zhdr;
+
+ /* FIXME: If this isn't sufficient, we search again... */
+ return add_free_record(tdb, zhdr.zone_bits,
+ tdb->map_size - expand, expand);
}
- /* 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;
-}
-
-/* Returns how much extra room we get, or TDB_OFF_ERR. */
-static tdb_len_t expand_to_fill_zones(struct tdb_context *tdb)
-{
- tdb_len_t add;
+ /* We are never allowed to cross a power-of-two boundary, and our
+ * minimum zone size is 1 << INITIAL_ZONE_BITS.
+ *
+ * If our filesize is 128k, we can add a 64k or a 128k zone. If it's
+ * 192k, we can only add a 64k zone.
+ *
+ * In other words, our max zone size is (1 << (ffs(filesize) - 1)) */
+ zone_bits = ffs64(old_size - sizeof(struct tdb_header)) - 1;
+ assert(zone_bits >= INITIAL_ZONE_BITS);
+
+ /* Big zones generally good, but more zones wanted if contended. */
+ if (zones_contended(tdb)) {
+ /* If it suffices, make zone same size as last one. */
+ if (zhdr.zone_bits < zone_bits
+ && (1ULL << zhdr.zone_bits) >= overhead(zone_bits)+wanted)
+ zone_bits = zhdr.zone_bits;
+ }
- /* We can enlarge zones without enlarging file to match. */
- add = (tdb->header.v.num_zones<<tdb->header.v.zone_bits)
- - tdb->map_size;
- if (add <= sizeof(struct tdb_free_record))
- return 0;
+ zhdr.zone_bits = zone_bits;
+ num_buckets = BUCKETS_FOR_ZONE(zone_bits);
- /* Updates tdb->map_size. */
- if (tdb->methods->expand_file(tdb, add) == -1)
- return TDB_OFF_ERR;
- if (add_free_record(tdb, tdb->map_size - add, add) == -1)
- return TDB_OFF_ERR;
- return add;
-}
+ /* Expand the file by more than we need right now. */
+ expand = 1ULL << zone_bits;
+ if (expand > overhead(zone_bits) + (wanted << TDB_COMFORT_FACTOR_BITS))
+ expand = overhead(zone_bits)
+ + (wanted << TDB_COMFORT_FACTOR_BITS);
-static int update_zones(struct tdb_context *tdb,
- uint64_t new_num_zones,
- uint64_t new_zone_bits,
- uint64_t new_num_buckets,
- tdb_len_t add)
-{
- tdb_len_t freebucket_size;
- const tdb_off_t *oldf;
- tdb_off_t i, off, old_num_total, old_free_off;
- struct tdb_used_record fhdr;
-
- /* Updates tdb->map_size. */
- if (tdb->methods->expand_file(tdb, add) == -1)
- return -1;
+ if (tdb->methods->expand_file(tdb, expand) == -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 new zone header (at old end). */
+ off = old_size;
+ if (tdb_write_convert(tdb, off, &zhdr, sizeof(zhdr)) == -1)
+ goto fail;
- /* Write header. */
- if (set_header(tdb, &fhdr, 0, freebucket_size, freebucket_size, 0))
- return -1;
- if (tdb_write_convert(tdb, off, &fhdr, sizeof(fhdr)) == -1)
- return -1;
+ /* 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);
- /* Adjust off to point to start of buckets, add to be remainder. */
- add -= freebucket_size + sizeof(fhdr);
- off += sizeof(fhdr);
+ /* Now add the rest as our free record. */
+ if (add_free_record(tdb, zone_bits, off, expand - overhead(zone_bits))
+ == -1)
+ goto fail;
- /* 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), true);
- if (!oldf)
- return -1;
+ /* Try allocating from this zone now. */
+ tdb->zone_off = old_size;
+ tdb->zhdr = zhdr;
- /* Switch to using our new zone. */
- if (zero_out(tdb, off, freebucket_size) == -1)
- goto fail_release;
-
- tdb->header.v.free_off = off;
- tdb->header.v.num_zones = new_num_zones;
- tdb->header.v.zone_bits = new_zone_bits;
- 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;
- }
- }
+success:
+ tdb_unlock_expand(tdb, F_WRLCK);
+ return 0;
- /* 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,
- sizeof(fhdr)
- + 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);
- return write_header(tdb);
-
-fail_release:
- tdb_access_release(tdb, oldf);
+fail:
+ tdb_unlock_expand(tdb, F_WRLCK);
return -1;
}
-/* Expand the database. */
-int tdb_expand(struct tdb_context *tdb, tdb_len_t klen, tdb_len_t dlen,
- bool growing)
+/* 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)
{
- uint64_t new_num_buckets, new_num_zones, new_zone_bits;
- uint64_t old_num_zones, old_size, old_zone_bits;
- tdb_len_t add, needed;
-
- /* We need room for the record header too. */
- needed = sizeof(struct tdb_used_record)
- + adjust_size(klen, dlen, growing);
-
- /* tdb_allrecord_lock will update header; did zones change? */
- old_zone_bits = tdb->header.v.zone_bits;
- old_num_zones = tdb->header.v.num_zones;
-
- /* 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 (old_zone_bits != tdb->header.v.zone_bits
- || old_num_zones != tdb->header.v.num_zones)
- goto success;
-
- /* They may have also expanded the underlying size (otherwise we'd
- * have expanded our mmap to look at those offsets already). */
- old_size = tdb->map_size;
- tdb->methods->oob(tdb, tdb->map_size + 1, true);
- if (tdb->map_size != old_size)
- goto success;
-
- add = expand_to_fill_zones(tdb);
- if (add == TDB_OFF_ERR)
- goto fail;
+ tdb_off_t off;
- if (add >= needed) {
- /* Allocate from this zone. */
- tdb->last_zone = zone_of(tdb, tdb->map_size - add);
- goto success;
- }
+ /* We can't hold pointers during this: we could unmap! */
+ assert(!tdb->direct_access);
- /* 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(struct tdb_used_record)
- + ((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++;
- }
+ for (;;) {
+ off = get_free(tdb, keylen, datalen, growing, hash);
+ if (likely(off != 0))
+ break;
- /* We expand by enough full zones to meet the need. */
- add = ((tdb->map_size + needed + (1ULL << new_zone_bits)-1)
- & ~((1ULL << new_zone_bits)-1))
- - tdb->map_size;
+ if (tdb_expand(tdb, adjust_size(keylen, datalen)))
+ return TDB_OFF_ERR;
}
- if (update_zones(tdb, new_num_zones, new_zone_bits, new_num_buckets,
- add) == -1)
- goto fail;
-
-success:
- tdb_allrecord_unlock(tdb, F_WRLCK);
- return 0;
-
-fail:
- tdb_allrecord_unlock(tdb, F_WRLCK);
- return -1;
+ return off;
}
projects / ccan / blobdiff