]> git.ozlabs.org Git - ccan/blobdiff - ccan/tdb2/free.c
str: change example to match function being explained.
[ccan] / ccan / tdb2 / free.c
index 13db5933911073577e42d1175fcecd5b7da12efb..5d1bd3c6d1360d7c2a1b3498a58e3d7443ec0d18 100644 (file)
@@ -49,24 +49,24 @@ unsigned int size_to_bucket(tdb_len_t data_len)
        return bucket;
 }
 
-tdb_off_t first_flist(struct tdb_context *tdb)
+tdb_off_t first_ftable(struct tdb_context *tdb)
 {
-       return tdb_read_off(tdb, offsetof(struct tdb_header, free_list));
+       return tdb_read_off(tdb, offsetof(struct tdb_header, free_table));
 }
 
-tdb_off_t next_flist(struct tdb_context *tdb, tdb_off_t flist)
+tdb_off_t next_ftable(struct tdb_context *tdb, tdb_off_t ftable)
 {
-       return tdb_read_off(tdb, flist + offsetof(struct tdb_freelist, next));
+       return tdb_read_off(tdb, ftable + offsetof(struct tdb_freetable,next));
 }
 
-int tdb_flist_init(struct tdb_context *tdb)
+int tdb_ftable_init(struct tdb_context *tdb)
 {
        /* Use reservoir sampling algorithm to select a free list at random. */
        unsigned int rnd, max = 0, count = 0;
        tdb_off_t off;
 
-       tdb->flist_off = off = first_flist(tdb);
-       tdb->flist = 0;
+       tdb->ftable_off = off = first_ftable(tdb);
+       tdb->ftable = 0;
 
        while (off) {
                if (off == TDB_OFF_ERR)
@@ -74,38 +74,38 @@ int tdb_flist_init(struct tdb_context *tdb)
 
                rnd = random();
                if (rnd >= max) {
-                       tdb->flist_off = off;
-                       tdb->flist = count;
+                       tdb->ftable_off = off;
+                       tdb->ftable = count;
                        max = rnd;
                }
 
-               off = next_flist(tdb, off);
+               off = next_ftable(tdb, off);
                count++;
        }
        return 0;
 }
 
 /* Offset of a given bucket. */
-tdb_off_t bucket_off(tdb_off_t flist_off, unsigned bucket)
+tdb_off_t bucket_off(tdb_off_t ftable_off, unsigned bucket)
 {
-       return flist_off + offsetof(struct tdb_freelist, buckets)
+       return ftable_off + offsetof(struct tdb_freetable, buckets)
                + 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 flist_off,
+                               tdb_off_t ftable_off,
                                tdb_off_t bucket)
 {
        /* Speculatively search for a non-zero bucket. */
-       return tdb_find_nonzero_off(tdb, bucket_off(flist_off, 0),
+       return tdb_find_nonzero_off(tdb, bucket_off(ftable_off, 0),
                                    bucket, TDB_FREE_BUCKETS);
 }
 
 /* Remove from free bucket. */
 static int remove_from_list(struct tdb_context *tdb,
                            tdb_off_t b_off, tdb_off_t r_off,
-                           struct tdb_free_record *r)
+                           const struct tdb_free_record *r)
 {
        tdb_off_t off;
 
@@ -118,8 +118,8 @@ static int remove_from_list(struct tdb_context *tdb,
 
 #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",
+               tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_DEBUG_FATAL,
+                        "remove_from_list: %llu bad prev in list %llu",
                         (long long)r_off, (long long)b_off);
                return -1;
        }
@@ -136,9 +136,9 @@ static int remove_from_list(struct tdb_context *tdb,
 
 #ifdef DEBUG
                if (tdb_read_off(tdb, off) & TDB_OFF_MASK != 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);
+                       tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_DEBUG_FATAL,
+                                  "remove_from_list: %llu bad list %llu",
+                                  (long long)r_off, (long long)b_off);
                        return -1;
                }
 #endif
@@ -159,8 +159,8 @@ static int enqueue_in_free(struct tdb_context *tdb,
        struct tdb_free_record new;
        uint64_t magic = (TDB_FREE_MAGIC << (64 - TDB_OFF_UPPER_STEAL));
 
-       /* We only need to set flist_and_len; rest is set in enqueue_in_free */
-       new.flist_and_len = ((uint64_t)tdb->flist << (64 - TDB_OFF_UPPER_STEAL))
+       /* We only need to set ftable_and_len; rest is set in enqueue_in_free */
+       new.ftable_and_len = ((uint64_t)tdb->ftable << (64 - TDB_OFF_UPPER_STEAL))
                | len;
        /* prev = 0. */
        new.magic_and_prev = magic;
@@ -176,9 +176,10 @@ static int enqueue_in_free(struct tdb_context *tdb,
                                 new.next + offsetof(struct tdb_free_record,
                                                     magic_and_prev))
                    != magic) {
-                       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);
+                       tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_DEBUG_FATAL,
+                                  "enqueue_in_free: %llu bad head"
+                                  " prev %llu",
+                                  (long long)new.next, (long long)b_off);
                        return -1;
                }
 #endif
@@ -208,7 +209,7 @@ int add_free_record(struct tdb_context *tdb,
 
        len = len_with_header - sizeof(struct tdb_used_record);
 
-       b_off = bucket_off(tdb->flist_off, size_to_bucket(len));
+       b_off = bucket_off(tdb->ftable_off, size_to_bucket(len));
        if (tdb_lock_free_bucket(tdb, b_off, TDB_LOCK_WAIT) != 0)
                return -1;
 
@@ -244,14 +245,17 @@ static size_t record_leftover(size_t keylen, size_t datalen,
        return leftover;
 }
 
-/* FIXME: Shortcut common case where tdb->flist == flist */
-static tdb_off_t flist_offset(struct tdb_context *tdb, unsigned int flist)
+static tdb_off_t ftable_offset(struct tdb_context *tdb, unsigned int ftable)
 {
-       tdb_off_t off = first_flist(tdb);
+       tdb_off_t off;
        unsigned int i;
 
-       for (i = 0; i < flist; i++)
-               off = next_flist(tdb, off);
+       if (likely(tdb->ftable == ftable))
+               return tdb->ftable_off;
+
+       off = first_ftable(tdb);
+       for (i = 0; i < ftable; i++)
+               off = next_ftable(tdb, off);
        return off;
 }
 
@@ -259,90 +263,95 @@ static tdb_off_t flist_offset(struct tdb_context *tdb, unsigned int flist)
 static int coalesce(struct tdb_context *tdb,
                    tdb_off_t off, tdb_off_t b_off, tdb_len_t data_len)
 {
-       struct tdb_free_record pad, *r;
        tdb_off_t end;
+       struct tdb_free_record rec;
 
+       add_stat(tdb, alloc_coalesce_tried, 1);
        end = off + sizeof(struct tdb_used_record) + data_len;
 
        while (end < tdb->map_size) {
+               const struct tdb_free_record *r;
                tdb_off_t nb_off;
-               unsigned flist, bucket;
+               unsigned ftable, bucket;
 
-               /* FIXME: do tdb_get here and below really win? */
-               r = tdb_get(tdb, end, &pad, sizeof(pad));
+               r = tdb_access_read(tdb, end, sizeof(*r), true);
                if (!r)
                        goto err;
 
-               if (frec_magic(r) != TDB_FREE_MAGIC)
+               if (frec_magic(r) != TDB_FREE_MAGIC
+                   || frec_ftable(r) == TDB_FTABLE_NONE) {
+                       tdb_access_release(tdb, r);
                        break;
+               }
 
-               flist = frec_flist(r);
+               ftable = frec_ftable(r);
                bucket = size_to_bucket(frec_len(r));
-               nb_off = bucket_off(flist_offset(tdb, flist), bucket);
+               nb_off = bucket_off(ftable_offset(tdb, ftable), bucket);
+               tdb_access_release(tdb, r);
 
                /* We may be violating lock order here, so best effort. */
-               if (tdb_lock_free_bucket(tdb, nb_off, TDB_LOCK_NOWAIT) == -1)
+               if (tdb_lock_free_bucket(tdb, nb_off, TDB_LOCK_NOWAIT) == -1) {
+                       add_stat(tdb, alloc_coalesce_lockfail, 1);
                        break;
+               }
 
                /* Now we have lock, re-check. */
-               r = tdb_get(tdb, end, &pad, sizeof(pad));
-               if (!r) {
+               if (tdb_read_convert(tdb, end, &rec, sizeof(rec))) {
                        tdb_unlock_free_bucket(tdb, nb_off);
                        goto err;
                }
 
-               if (unlikely(frec_magic(r) != TDB_FREE_MAGIC)) {
+               if (unlikely(frec_magic(&rec) != TDB_FREE_MAGIC)) {
+                       add_stat(tdb, alloc_coalesce_race, 1);
                        tdb_unlock_free_bucket(tdb, nb_off);
                        break;
                }
 
-               if (unlikely(frec_flist(r) != flist)
-                   || unlikely(size_to_bucket(frec_len(r)) != bucket)) {
+               if (unlikely(frec_ftable(&rec) != ftable)
+                   || unlikely(size_to_bucket(frec_len(&rec)) != bucket)) {
+                       add_stat(tdb, alloc_coalesce_race, 1);
                        tdb_unlock_free_bucket(tdb, nb_off);
                        break;
                }
 
-               if (remove_from_list(tdb, nb_off, end, r) == -1) {
+               if (remove_from_list(tdb, nb_off, end, &rec) == -1) {
                        tdb_unlock_free_bucket(tdb, nb_off);
                        goto err;
                }
 
-               end += sizeof(struct tdb_used_record) + frec_len(r);
+               end += sizeof(struct tdb_used_record) + frec_len(&rec);
                tdb_unlock_free_bucket(tdb, nb_off);
+               add_stat(tdb, alloc_coalesce_num_merged, 1);
        }
 
        /* Didn't find any adjacent free? */
        if (end == off + sizeof(struct tdb_used_record) + data_len)
                return 0;
 
-       /* OK, expand record */
-       r = tdb_get(tdb, off, &pad, sizeof(pad));
-       if (!r)
+       /* OK, expand initial record */
+       if (tdb_read_convert(tdb, off, &rec, sizeof(rec)))
                goto err;
 
-       if (frec_len(r) != 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)frec_len(r));
+       if (frec_len(&rec) != data_len) {
+               tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_DEBUG_FATAL,
+                          "coalesce: expected data len %zu not %zu",
+                          (size_t)data_len, (size_t)frec_len(&rec));
                goto err;
        }
 
-       if (remove_from_list(tdb, b_off, off, r) == -1)
-               goto err;
-
-       r = tdb_access_write(tdb, off, sizeof(*r), true);
-       if (!r)
+       if (remove_from_list(tdb, b_off, off, &rec) == -1)
                goto err;
 
        /* We have to drop this to avoid deadlocks, so make sure record
         * doesn't get coalesced by someone else! */
-       r->magic_and_prev = TDB_COALESCING_MAGIC << (64 - TDB_OFF_UPPER_STEAL);
-       /* FIXME: Use 255 as invalid free list? */
-       r->flist_and_len = end - off - sizeof(struct tdb_used_record);
-       if (tdb_access_commit(tdb, r) != 0)
+       rec.ftable_and_len = (TDB_FTABLE_NONE << (64 - TDB_OFF_UPPER_STEAL))
+               | (end - off - sizeof(struct tdb_used_record));
+       if (tdb_write_off(tdb, off + offsetof(struct tdb_free_record,
+                                             ftable_and_len),
+                         rec.ftable_and_len) != 0)
                goto err;
 
+       add_stat(tdb, alloc_coalesce_succeeded, 1);
        tdb_unlock_free_bucket(tdb, b_off);
 
        if (add_free_record(tdb, off, end - off) == -1)
@@ -357,19 +366,21 @@ err:
 
 /* 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 flist_off,
+                               tdb_off_t ftable_off,
                                tdb_off_t bucket,
                                size_t keylen, size_t datalen,
                                bool want_extra,
+                               unsigned magic,
                                unsigned hashlow)
 {
        tdb_off_t off, b_off,best_off;
-       struct tdb_free_record pad, best = { 0 }, *r;
+       struct tdb_free_record best = { 0 };
        double multiplier;
        size_t size = adjust_size(keylen, datalen);
 
+       add_stat(tdb, allocs, 1);
 again:
-       b_off = bucket_off(flist_off, bucket);
+       b_off = bucket_off(ftable_off, bucket);
 
        /* FIXME: Try non-blocking wait first, to measure contention. */
        /* Lock this bucket. */
@@ -377,7 +388,7 @@ again:
                return TDB_OFF_ERR;
        }
 
-       best.flist_and_len = -1ULL;
+       best.ftable_and_len = -1ULL;
        best_off = 0;
 
        /* Get slack if we're after extra. */
@@ -393,14 +404,18 @@ again:
                goto unlock_err;
 
        while (off) {
-               /* FIXME: Does tdb_get win anything here? */
-               r = tdb_get(tdb, off, &pad, sizeof(*r));
+               const struct tdb_free_record *r;
+               tdb_len_t len;
+               tdb_off_t next;
+
+               r = tdb_access_read(tdb, off, sizeof(*r), true);
                if (!r)
                        goto unlock_err;
 
                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",
+                       tdb_access_release(tdb, r);
+                       tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_DEBUG_FATAL,
+                                "lock_and_alloc: %llu non-free 0x%llx",
                                 (long long)off, (long long)r->magic_and_prev);
                        goto unlock_err;
                }
@@ -410,13 +425,19 @@ again:
                        best = *r;
                }
 
-               if (frec_len(&best) < size * multiplier && best_off)
+               if (frec_len(&best) < size * multiplier && best_off) {
+                       tdb_access_release(tdb, r);
                        break;
+               }
 
                multiplier *= 1.01;
 
+               next = r->next;
+               len = frec_len(r);
+               tdb_access_release(tdb, r);
+
                /* Since we're going slow anyway, try coalescing here. */
-               switch (coalesce(tdb, off, b_off, frec_len(r))) {
+               switch (coalesce(tdb, off, b_off, len)) {
                case -1:
                        /* This has already unlocked on error. */
                        return -1;
@@ -424,7 +445,7 @@ again:
                        /* This has unlocked list, restart. */
                        goto again;
                }
-               off = r->next;
+               off = next;
        }
 
        /* If we found anything at all, use it. */
@@ -442,23 +463,25 @@ again:
                assert(keylen + datalen + leftover <= frec_len(&best));
                /* We need to mark non-free before we drop lock, otherwise
                 * coalesce() could try to merge it! */
-               if (set_used_header(tdb, &rec, keylen, datalen,
-                                   frec_len(&best) - leftover,
-                                   hashlow) != 0)
+               if (set_header(tdb, &rec, magic, keylen, datalen,
+                              frec_len(&best) - leftover, hashlow) != 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);
-
+               /* Bucket of leftover will be <= current bucket, so nested
+                * locking is allowed. */
                if (leftover) {
+                       add_stat(tdb, alloc_leftover, 1);
                        if (add_free_record(tdb,
                                            best_off + sizeof(rec)
                                            + frec_len(&best) - leftover,
                                            leftover))
-                               return TDB_OFF_ERR;
+                               best_off = TDB_OFF_ERR;
                }
+               tdb_unlock_free_bucket(tdb, b_off);
+
                return best_off;
        }
 
@@ -473,10 +496,10 @@ unlock_err:
 /* Get a free block from current free list, or 0 if none. */
 static tdb_off_t get_free(struct tdb_context *tdb,
                          size_t keylen, size_t datalen, bool want_extra,
-                         unsigned hashlow)
+                         unsigned magic, unsigned hashlow)
 {
-       tdb_off_t off, flist_off;
-       unsigned start_b, b, flist;
+       tdb_off_t off, ftable_off;
+       unsigned start_b, b, ftable;
        bool wrapped = false;
 
        /* If they are growing, add 50% to get to higher bucket. */
@@ -486,45 +509,50 @@ static tdb_off_t get_free(struct tdb_context *tdb,
        else
                start_b = size_to_bucket(adjust_size(keylen, datalen));
 
-       flist_off = tdb->flist_off;
-       flist = tdb->flist;
-       while (!wrapped || flist_off != tdb->flist_off) {
+       ftable_off = tdb->ftable_off;
+       ftable = tdb->ftable;
+       while (!wrapped || ftable_off != tdb->ftable_off) {
                /* Start at exact size bucket, and search up... */
-               for (b = find_free_head(tdb, flist_off, start_b);
+               for (b = find_free_head(tdb, ftable_off, start_b);
                     b < TDB_FREE_BUCKETS;
-                    b = find_free_head(tdb, flist_off, b + 1)) {
+                    b = find_free_head(tdb, ftable_off, b + 1)) {
                        /* Try getting one from list. */
-                       off = lock_and_alloc(tdb, flist_off,
+                       off = lock_and_alloc(tdb, ftable_off,
                                             b, keylen, datalen, want_extra,
-                                            hashlow);
+                                            magic, hashlow);
                        if (off == TDB_OFF_ERR)
                                return TDB_OFF_ERR;
                        if (off != 0) {
+                               if (b == start_b)
+                                       add_stat(tdb, alloc_bucket_exact, 1);
+                               if (b == TDB_FREE_BUCKETS - 1)
+                                       add_stat(tdb, alloc_bucket_max, 1);
                                /* Worked?  Stay using this list. */
-                               tdb->flist_off = flist_off;
-                               tdb->flist = flist;
+                               tdb->ftable_off = ftable_off;
+                               tdb->ftable = ftable;
                                return off;
                        }
                        /* Didn't work.  Try next bucket. */
                }
 
-               /* Hmm, try next list. */
-               flist_off = next_flist(tdb, flist_off);
-               flist++;
-               if (flist_off == 0) {
+               /* Hmm, try next table. */
+               ftable_off = next_ftable(tdb, ftable_off);
+               ftable++;
+
+               if (ftable_off == 0) {
                        wrapped = true;
-                       flist_off = first_flist(tdb);
-                       flist = 0;
+                       ftable_off = first_ftable(tdb);
+                       ftable = 0;
                }
        }
 
        return 0;
 }
 
-int set_used_header(struct tdb_context *tdb,
-                   struct tdb_used_record *rec,
-                   uint64_t keylen, uint64_t datalen,
-                   uint64_t actuallen, unsigned hashlow)
+int set_header(struct tdb_context *tdb,
+              struct tdb_used_record *rec,
+              unsigned magic, uint64_t keylen, uint64_t datalen,
+              uint64_t actuallen, unsigned hashlow)
 {
        uint64_t keybits = (fls64(keylen) + 1) / 2;
 
@@ -532,16 +560,15 @@ int set_used_header(struct tdb_context *tdb,
        rec->magic_and_meta = (hashlow & ((1 << 11)-1))
                | ((actuallen - (keylen + datalen)) << 11)
                | (keybits << 43)
-               | (TDB_MAGIC << 48);
+               | ((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)) {
-               tdb->ecode = TDB_ERR_IO;
-               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                        "Could not encode k=%llu,d=%llu,a=%llu\n",
+               tdb_logerr(tdb, TDB_ERR_IO, TDB_DEBUG_ERROR,
+                        "Could not encode k=%llu,d=%llu,a=%llu",
                         (long long)keylen, (long long)datalen,
                         (long long)actuallen);
                return -1;
@@ -561,11 +588,19 @@ static int tdb_expand(struct tdb_context *tdb, tdb_len_t size)
        /* Need to hold a hash lock to expand DB: transactions rely on it. */
        if (!(tdb->flags & TDB_NOLOCK)
            && !tdb->allrecord_lock.count && !tdb_has_hash_locks(tdb)) {
-               tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
-                        "tdb_expand: must hold lock during expand\n");
+               tdb_logerr(tdb, TDB_ERR_LOCK, TDB_DEBUG_ERROR,
+                          "tdb_expand: must hold lock during expand");
                return -1;
        }
 
+       /* always make room for at least 100 more records, and at
+           least 25% more space. */
+       if (size * TDB_EXTENSION_FACTOR > tdb->map_size / 4)
+               wanted = size * TDB_EXTENSION_FACTOR;
+       else
+               wanted = tdb->map_size / 4;
+       wanted = adjust_size(0, wanted);
+
        /* Only one person can expand file at a time. */
        if (tdb_lock_expand(tdb, F_WRLCK) != 0)
                return -1;
@@ -578,7 +613,7 @@ static int tdb_expand(struct tdb_context *tdb, tdb_len_t size)
                return 0;
        }
 
-       if (tdb->methods->expand_file(tdb, wanted*TDB_EXTENSION_FACTOR) == -1) {
+       if (tdb->methods->expand_file(tdb, wanted) == -1) {
                tdb_unlock_expand(tdb, F_WRLCK);
                return -1;
        }
@@ -586,12 +621,13 @@ static int tdb_expand(struct tdb_context *tdb, tdb_len_t size)
        /* We need to drop this lock before adding free record. */
        tdb_unlock_expand(tdb, F_WRLCK);
 
-       return add_free_record(tdb, old_size, wanted * TDB_EXTENSION_FACTOR);
+       add_stat(tdb, expands, 1);
+       return add_free_record(tdb, old_size, wanted);
 }
 
 /* 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 hash, unsigned magic, bool growing)
 {
        tdb_off_t off;
 
@@ -599,7 +635,7 @@ tdb_off_t alloc(struct tdb_context *tdb, size_t keylen, size_t datalen,
        assert(!tdb->direct_access);
 
        for (;;) {
-               off = get_free(tdb, keylen, datalen, growing, hash);
+               off = get_free(tdb, keylen, datalen, growing, magic, hash);
                if (likely(off != 0))
                        break;