tdb2: don't hold access to tdb mmap during traverse.

[ccan] / ccan / tdb2 / hash.c

diff --git a/ccan/tdb2/hash.c b/ccan/tdb2/hash.c
index 0cc93760d1613fa44c4a2681133f27aeadb50c19..71ede4dbffda9e6a31786a9224d1e5ec16dc042a 100644 (file)
--- a/ccan/tdb2/hash.c
+++ b/ccan/tdb2/hash.c
@@ -450,74 +450,55 @@ int add_to_hash(struct tdb_context *tdb, struct hash_info *h, tdb_off_t new_off)
        return add_to_hash(tdb, h, new_off);
 }
 
        return add_to_hash(tdb, h, new_off);
 }
 

-/* No point holding references/copies of db once we drop lock. */
-static void release_entries(struct tdb_context *tdb,
-                           struct traverse_info *tinfo)
-{
-       unsigned int i;
-
-       for (i = 0; i < tinfo->num_levels; i++) {
-               if (tinfo->levels[i].entries) {
-                       tdb_access_release(tdb, tinfo->levels[i].entries);
-                       tinfo->levels[i].entries = NULL;
-               }
-       }
-}
-

 /* Traverse support: returns offset of record, or 0 or TDB_OFF_ERR. */
 static tdb_off_t iterate_hash(struct tdb_context *tdb,
                              struct traverse_info *tinfo)
 {
 /* Traverse support: returns offset of record, or 0 or TDB_OFF_ERR. */
 static tdb_off_t iterate_hash(struct tdb_context *tdb,
                              struct traverse_info *tinfo)
 {

-       tdb_off_t off;
+       tdb_off_t off, val;

        unsigned int i;
        struct traverse_level *tlevel;
 
        tlevel = &tinfo->levels[tinfo->num_levels-1];
 
 again:
        unsigned int i;
        struct traverse_level *tlevel;
 
        tlevel = &tinfo->levels[tinfo->num_levels-1];
 
 again:

-       if (!tlevel->entries) {
-               tlevel->entries = tdb_access_read(tdb, tlevel->hashtable,
-                                                 sizeof(tdb_off_t)
-                                                 * tlevel->total_buckets,
-                                                 true);
-               if (!tlevel->entries)
+       for (i = tdb_find_nonzero_off(tdb, tlevel->hashtable,
+                                     tlevel->entry, tlevel->total_buckets);
+            i != tlevel->total_buckets;
+            i = tdb_find_nonzero_off(tdb, tlevel->hashtable,
+                                     i+1, tlevel->total_buckets)) {
+               val = tdb_read_off(tdb, tlevel->hashtable+sizeof(tdb_off_t)*i);
+               if (unlikely(val == TDB_OFF_ERR))

                        return TDB_OFF_ERR;
                        return TDB_OFF_ERR;

-       }

 
 

-       /* FIXME: Use tdb_find_nonzero_off? */ 
-       for (i = tlevel->entry; i < tlevel->total_buckets; i++) {
-               if (!tlevel->entries[i] || tlevel->entries[i] == tinfo->prev)
+               /* This makes the delete-all-in-traverse case work
+                * (and simplifies our logic a little). */
+               if (val == tinfo->prev)

                        continue;
 
                tlevel->entry = i;
                        continue;
 
                tlevel->entry = i;

-               off = tlevel->entries[i] & TDB_OFF_MASK;
+               off = val & TDB_OFF_MASK;

 
 

-               if (!is_subhash(tlevel->entries[i])) {
+               if (!is_subhash(val)) {

                        /* Found one. */
                        /* Found one. */

-                       tinfo->prev = tlevel->entries[i];
-                       release_entries(tdb, tinfo);
+                       tinfo->prev = val;

                        return off;
                }
 
                        return off;
                }
 

-               /* When we come back, we want tne next one */
+               /* When we come back, we want the next one */

                tlevel->entry++;
                tinfo->num_levels++;
                tlevel++;
                tlevel->hashtable = off + sizeof(struct tdb_used_record);
                tlevel->entry = 0;
                tlevel->entry++;
                tinfo->num_levels++;
                tlevel++;
                tlevel->hashtable = off + sizeof(struct tdb_used_record);
                tlevel->entry = 0;

-               tlevel->entries = NULL;

                tlevel->total_buckets = (1 << TDB_SUBLEVEL_HASH_BITS);
                goto again;
        }
 
        /* Nothing there? */
                tlevel->total_buckets = (1 << TDB_SUBLEVEL_HASH_BITS);
                goto again;
        }
 
        /* Nothing there? */

-       if (tinfo->num_levels == 1) {
-               release_entries(tdb, tinfo);
+       if (tinfo->num_levels == 1)

                return 0;
                return 0;

-       }

 
        /* Go back up and keep searching. */
 
        /* Go back up and keep searching. */

-       tdb_access_release(tdb, tlevel->entries);

        tinfo->num_levels--;
        tlevel--;
        goto again;
        tinfo->num_levels--;
        tlevel--;
        goto again;


@@ -586,7 +567,6 @@ int first_in_hash(struct tdb_context *tdb, int ltype,
        tinfo->toplevel_group = 0;
        tinfo->num_levels = 1;
        tinfo->levels[0].hashtable = offsetof(struct tdb_header, hashtable);
        tinfo->toplevel_group = 0;
        tinfo->num_levels = 1;
        tinfo->levels[0].hashtable = offsetof(struct tdb_header, hashtable);

-       tinfo->levels[0].entries = NULL;

        tinfo->levels[0].entry = 0;
        tinfo->levels[0].total_buckets = (1 << TDB_HASH_GROUP_BITS);
 
        tinfo->levels[0].entry = 0;
        tinfo->levels[0].total_buckets = (1 << TDB_HASH_GROUP_BITS);