[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, 14 insertions, 6 deletions

diff --git a/src/datastore/test_datastore_api_management.c b/src/datastore/test_datastore_api_management.c
index 9a3e5446b..de4dc657f 100644
--- a/src/datastore/test_datastore_api_management.c
+++ b/src/datastore/test_datastore_api_management.c
@@ -58,7 +58,6 @@ struct CpsRunContext
   const struct GNUNET_CONFIGURATION_Handle *cfg;
   void *data;
   enum RunPhase phase;
-  uint64_t offset;
 };
 
 
@@ -159,7 +158,6 @@ check_value (void *cls, const struct GNUNET_HashCode * key, size_t size,
   GNUNET_assert (priority == get_priority (i));
   GNUNET_assert (anonymity == get_anonymity (i));
   GNUNET_assert (expiration.abs_value_us == get_expiration (i).abs_value_us);
-  crc->offset++;
   crc->i--;
   if (crc->i == 0)
     crc->phase = RP_DONE;
@@ -221,8 +219,13 @@ run_continuation (void *cls)
     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Executing `%s' number %u\n", "GET",
                 crc->i);
     GNUNET_CRYPTO_hash (&crc->i, sizeof (int), &crc->key);
-    GNUNET_DATASTORE_get_key (datastore, crc->offset++, &crc->key,
-                              get_type (crc->i), 1, 1,
+    GNUNET_DATASTORE_get_key (datastore,
+                              0,
+                              false,
+                              &crc->key,
+                              get_type (crc->i),
+                              1,
+                              1,
                               &check_value,
                               crc);
     break;
@@ -230,8 +233,13 @@ run_continuation (void *cls)
     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Executing `%s' number %u\n", "GET(f)",
                 crc->i);
     GNUNET_CRYPTO_hash (&crc->i, sizeof (int), &crc->key);
-    GNUNET_DATASTORE_get_key (datastore, crc->offset++, &crc->key,
-                              get_type (crc->i), 1, 1,
+    GNUNET_DATASTORE_get_key (datastore,
+                              0,
+                              false,
+                              &crc->key,
+                              get_type (crc->i),
+                              1,
+                              1,
                               &check_nothing,
                               crc);
     break;