[datastore] Fix #3743

This change adds support for key == NULL to the datastore plugins
and replaces the offset argument with a next_uid and random arguments to
increase performance in the key == NULL case.

With the offset argument a datastore plugin would have to count all
matching keys before fetching the key at the right offset, which would
iterate over the entire database in the case of key == NULL.

The offset argument was used in two ways: to iterate over a set of
matching values and to start iteration at a random matching value. The new API
seperates these into two arguments: if random is true it will return a
random matching value, otherwise next_uid can be set to uid + 1 to return the
next matching value.

The random argument was not added to get_zero_anonymity. This function
is used to periodically insert zero anonymity values into the DHT. I
don't think it's necessary to randomize this.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/datastore/gnunet-datastore.c b/src/datastore/gnunet-datastore.c
index 509c7f8b1..c93bc8dd3 100644
--- a/src/datastore/gnunet-datastore.c
+++ b/src/datastore/gnunet-datastore.c
@@ -171,7 +171,7 @@ static void
 do_get ()
 {
   qe = GNUNET_DATASTORE_get_key (db_src,
-                                 offset,
+                                 0, false,
                                  NULL, GNUNET_BLOCK_TYPE_ANY,
                                  0, 1,
                                  &do_put, NULL);