[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, 12 insertions, 8 deletions

diff --git a/src/datastore/gnunet-service-datastore.c b/src/datastore/gnunet-service-datastore.c
index dabec3d6d..af33c4412 100644
--- a/src/datastore/gnunet-service-datastore.c
+++ b/src/datastore/gnunet-service-datastore.c
@@ -984,12 +984,13 @@ handle_put (void *cls,
                         size,
                         &vhash);
     plugin->api->get_key (plugin->api->cls,
-                          0,
-                          &dm->key,
-                          &vhash,
+                          0,
+                          false,
+                          &dm->key,
+                          &vhash,
                           ntohl (dm->type),
-                          &check_present,
-                          pc);
+                          &check_present,
+                          pc);
     GNUNET_SERVICE_client_continue (client);
     return;
   }
@@ -1018,7 +1019,8 @@ handle_get (void *cls,
                             1,
                             GNUNET_NO);
   plugin->api->get_key (plugin->api->cls,
-                        GNUNET_ntohll (msg->offset),
+                        GNUNET_ntohll (msg->next_uid),
+                        msg->random,
                         NULL,
                         NULL,
                         ntohl (msg->type),
@@ -1069,7 +1071,8 @@ handle_get_key (void *cls,
     return;
   }
   plugin->api->get_key (plugin->api->cls,
-                        GNUNET_ntohll (msg->offset),
+                        GNUNET_ntohll (msg->next_uid),
+                        msg->random,
                         &msg->key,
                         NULL,
                         ntohl (msg->type),
@@ -1131,7 +1134,7 @@ handle_get_zero_anonymity (void *cls,
                             1,
                             GNUNET_NO);
   plugin->api->get_zero_anonymity (plugin->api->cls,
-                                   GNUNET_ntohll (msg->offset),
+                                   GNUNET_ntohll (msg->next_uid),
                                    type,
                                    &transmit_item,
                                    client);
@@ -1241,6 +1244,7 @@ handle_remove (void *cls,
               (uint32_t) ntohl (dm->type));
   plugin->api->get_key (plugin->api->cls,
                         0,
+                        false,
                         &dm->key,
                         &vhash,
                         (enum GNUNET_BLOCK_Type) ntohl (dm->type),