tdb2: tdb_expand on empty database now tested.

[ccan] / ccan / tdb2 / free.c

diff --git a/ccan/tdb2/free.c b/ccan/tdb2/free.c
index 83d916fc6986ceec757131b51b44a8c13eaa022a..e486dcb7ddc2feaf825963a5c2fd30c06dd78808 100644 (file)
--- a/ccan/tdb2/free.c
+++ b/ccan/tdb2/free.c
@@ -45,10 +45,17 @@ static unsigned int quick_random(struct tdb_context *tdb)
 }
 
 /* Start by using a random zone to spread the load. */
-uint64_t random_free_zone(struct tdb_context *tdb)
+void tdb_zone_init(struct tdb_context *tdb)
 {
-       /* num_zones might be out of date, but can only increase */
-       return quick_random(tdb) % tdb->header.v.num_zones;
+       /*
+        * 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);
 }
 
 static unsigned fls64(uint64_t val)
@@ -559,33 +566,42 @@ 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;
+       uint64_t i, old_num_total, old_num_zones, old_size, old_zone_bits;
        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);
 
+       /* 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 (update_header(tdb))
+       if (old_zone_bits != tdb->header.v.zone_bits
+           || old_num_zones != tdb->header.v.num_zones)
                goto success;
 
-       /* Make sure we have the latest size. */
+       /* 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;
 
        /* 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)
+               if (tdb->methods->expand_file(tdb, add) == -1)
                        goto fail;
                if (add_free_record(tdb, tdb->map_size - add, add) == -1)
                        goto fail;
@@ -628,7 +644,7 @@ int tdb_expand(struct tdb_context *tdb, tdb_len_t klen, tdb_len_t dlen,
        }
 
        /* Updates tdb->map_size. */
-       if (tdb->methods->expand_file(tdb, tdb->map_size, add) == -1)
+       if (tdb->methods->expand_file(tdb, add) == -1)
                goto fail;
 
        /* Use first part as new free bucket array. */