mysql hacking

git-svn-id: https://gnunet.org/svn/gnunet@12444 140774ce-b5e7-0310-ab8b-a85725594a96

1 files changed, 310 insertions, 231 deletions

diff --git a/src/datastore/plugin_datastore_mysql.c b/src/datastore/plugin_datastore_mysql.c
index 234e2fd934..447ce71764 100644
--- a/src/datastore/plugin_datastore_mysql.c
+++ b/src/datastore/plugin_datastore_mysql.c
@@ -211,10 +211,45 @@ struct GNUNET_MysqlStatementHandle
 
 };
 
+/**
+ * Context for the universal iterator.
+ */
+struct NextRequestClosure;
+
+/**
+ * Type of a function that will prepare
+ * the next iteration.
+ *
+ * @param cls closure
+ * @param nc the next context; NULL for the last
+ *         call which gives the callback a chance to
+ *         clean up the closure
+ * @return GNUNET_OK on success, GNUNET_NO if there are
+ *         no more values, GNUNET_SYSERR on error
+ */
+typedef int (*PrepareFunction)(void *cls,
+			       struct NextRequestClosure *nc);
+
+
 struct NextRequestClosure
 {
   struct Plugin *plugin;
 
+  struct GNUNET_TIME_Absolute now;
+
+  /**
+   * Function to call to prepare the next
+   * iteration.
+   */
+  PrepareFunction prep;
+
+  /**
+   * Closure for prep.
+   */
+  void *prep_cls;
+
+  MYSQL_BIND rbind[7];
+
   unsigned int type;
   
   unsigned int iter_select;
@@ -254,7 +289,6 @@ struct Plugin
    */
   char *cnffile;
 
-
   /**
    * Closure of the 'next_task' (must be freed if 'next_task' is cancelled).
    */
@@ -380,6 +414,25 @@ get_my_cnf_path (const struct GNUNET_CONFIGURATION_Handle *cfg)
 }
 
 
+
+/**
+ * Free a prepared statement.
+ */
+static void
+prepared_statement_destroy (struct Plugin *plugin, 
+			    struct GNUNET_MysqlStatementHandle
+			    *s)
+{
+  GNUNET_CONTAINER_DLL_remove (plugin->shead,
+			       plugin->stail,
+			       s);
+  if (s->valid)
+    mysql_stmt_close (s->statement);
+  GNUNET_free (s->query);
+  GNUNET_free (s);
+}
+
+
 /**
  * Close database connection and all prepared statements (we got a DB
  * disconnect error).
@@ -390,16 +443,9 @@ iclose (struct Plugin *plugin)
   struct GNUNET_MysqlStatementHandle *spos;
 
   spos = plugin->shead;
-  while (spos != NULL)
-    {
-      if (spos->statement != NULL)
-	{
-	  mysql_stmt_close (spos->statement);
-	  spos->statement = NULL;
-	}
-      spos->valid = GNUNET_NO;
-      spos = spos->next;
-    }
+  while (NULL != plugin->shead)
+    prepared_statement_destroy (plugin,
+				plugin->shead);
   if (plugin->dbf != NULL)
     {
       mysql_close (plugin->dbf);
@@ -521,6 +567,7 @@ run_statement (struct Plugin *plugin,
 }
 
 
+#if 0
 /**
  * Run the given MySQL SELECT statement.  The statement
  * must have only a single result (one column, one row).
@@ -557,6 +604,7 @@ run_statement_select (struct Plugin *plugin,
   mysql_free_result (sql_res);
   return ret;
 }
+#endif
 
 
 /**
@@ -613,24 +661,7 @@ prepare_statement (struct Plugin *plugin,
     }
   ret->valid = GNUNET_YES;
   return GNUNET_OK;
-}
-
 
-/**
- * Free a prepared statement.
- */
-static void
-prepared_statement_destroy (struct Plugin *plugin, 
-			    struct GNUNET_MysqlStatementHandle
-			    *s)
-{
-  GNUNET_CONTAINER_DLL_remove (plugin->shead,
-			       plugin->stail,
-			       s);
-  if (s->valid)
-    mysql_stmt_close (s->statement);
-  GNUNET_free (s->query);
-  GNUNET_free (s);
 }
 
 
@@ -925,65 +956,17 @@ return_ok (void *cls, unsigned int num_values, MYSQL_BIND * values)
 }
 
 
-/**
- * Continuation of "sqlite_next_request".
- *
- * @param next_cls the next context
- * @param tc the task context (unused)
- */
-static void 
-sqlite_next_request_cont (void *next_cls,
-			  const struct GNUNET_SCHEDULER_TaskContext *tc)
+static int
+iterator_helper_prepare (void *cls,
+			 struct NextRequestClosure *nrc)
 {
-  struct NextRequestClosure *nrc = next_cls;
   struct Plugin *plugin;
   int ret;
-  unsigned int size;
-  unsigned int type;
-  unsigned int priority;
-  unsigned int anonymity;
-  unsigned long long exp;
-  unsigned long long vkey;
-  unsigned long hashSize;
-  GNUNET_HashCode key;
-  struct GNUNET_TIME_Absolute now;
-  struct GNUNET_TIME_Absolute expiration;
-  MYSQL_BIND rbind[7];
-  unsigned int contentSize;
-  unsigned long length;
-  MYSQL_BIND dbind[1];
-  char datum[GNUNET_SERVER_MAX_MESSAGE_SIZE];
 
- AGAIN:
+  if (nrc == NULL)
+    return GNUNET_NO;
   plugin = nrc->plugin;
-  plugin->next_task = GNUNET_SCHEDULER_NO_TASK;
-  plugin->next_task_nc = NULL;
-  hashSize = sizeof (GNUNET_HashCode);
-  memset (rbind, 0, sizeof (rbind));
-  rbind[0].buffer_type = MYSQL_TYPE_LONG;
-  rbind[0].buffer = &size;
-  rbind[0].is_unsigned = 1;
-  rbind[1].buffer_type = MYSQL_TYPE_LONG;
-  rbind[1].buffer = &type;
-  rbind[1].is_unsigned = 1;
-  rbind[2].buffer_type = MYSQL_TYPE_LONG;
-  rbind[2].buffer = &priority;
-  rbind[2].is_unsigned = 1;
-  rbind[3].buffer_type = MYSQL_TYPE_LONG;
-  rbind[3].buffer = &anonymity;
-  rbind[3].is_unsigned = 1;
-  rbind[4].buffer_type = MYSQL_TYPE_LONGLONG;
-  rbind[4].buffer = &exp;
-  rbind[4].is_unsigned = 1;
-  rbind[5].buffer_type = MYSQL_TYPE_BLOB;
-  rbind[5].buffer = &key;
-  rbind[5].buffer_length = hashSize;
-  rbind[5].length = &hashSize;
-  rbind[6].buffer_type = MYSQL_TYPE_LONGLONG;
-  rbind[6].buffer = &vkey;
-  rbind[6].is_unsigned = GNUNET_YES;
-
-  now = GNUNET_TIME_absolute_get ();
+  ret = GNUNET_SYSERR;
   switch (nrc->iter_select)
     {
     case 0:
@@ -991,7 +974,7 @@ sqlite_next_request_cont (void *next_cls,
       ret = prepared_statement_run_select (plugin,
 					   plugin->iter[nrc->iter_select],
 					   7,
-					   rbind,
+					   nrc->rbind,
 					   &return_ok,
 					   NULL,
 					   MYSQL_TYPE_LONG,
@@ -1011,7 +994,7 @@ sqlite_next_request_cont (void *next_cls,
       ret = prepared_statement_run_select (plugin,
 					   plugin->iter[nrc->iter_select],
 					   7,
-					   rbind,
+					   nrc->rbind,
 					   &return_ok,
 					   NULL,
 					   MYSQL_TYPE_LONGLONG,
@@ -1031,7 +1014,7 @@ sqlite_next_request_cont (void *next_cls,
       ret = prepared_statement_run_select (plugin,
 					   plugin->iter[nrc->iter_select],
 					   7,
-					   rbind,
+					   nrc->rbind,
 					   &return_ok,
 					   NULL,
 					   MYSQL_TYPE_LONGLONG,
@@ -1041,7 +1024,7 @@ sqlite_next_request_cont (void *next_cls,
 					   &nrc->last_vkey,
 					   GNUNET_YES,
 					   MYSQL_TYPE_LONGLONG,
-					   &now.value,
+					   &nrc->now.value,
 					   GNUNET_YES,
 					   MYSQL_TYPE_LONGLONG,
 					   &nrc->last_expire,
@@ -1050,15 +1033,80 @@ sqlite_next_request_cont (void *next_cls,
 					   &nrc->last_vkey,
 					   GNUNET_YES,
 					   MYSQL_TYPE_LONGLONG,
-					   &now.value,
+					   &nrc->now.value,
 					   GNUNET_YES, -1);
       break;
     default:
       GNUNET_assert (0);
-      return;
     }
+  return ret;
+}
+
+
+/**
+ * Continuation of "sqlite_next_request".
+ *
+ * @param next_cls the next context
+ * @param tc the task context (unused)
+ */
+static void 
+sqlite_next_request_cont (void *next_cls,
+			  const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  struct NextRequestClosure *nrc = next_cls;
+  struct Plugin *plugin;
+  int ret;
+  unsigned int size;
+  unsigned int type;
+  unsigned int priority;
+  unsigned int anonymity;
+  unsigned long long exp;
+  unsigned long long vkey;
+  unsigned long hashSize;
+  GNUNET_HashCode key;
+  struct GNUNET_TIME_Absolute expiration;
+  unsigned int contentSize;
+  unsigned long length;
+  MYSQL_BIND *rbind; /* size 7 */
+  MYSQL_BIND dbind[1];
+  char datum[GNUNET_SERVER_MAX_MESSAGE_SIZE];
+
+  plugin = nrc->plugin;
+  plugin->next_task = GNUNET_SCHEDULER_NO_TASK;
+  plugin->next_task_nc = NULL;
+
+ AGAIN:
+  ret = nrc->prep (nrc->prep_cls,
+		   nrc);
   if (ret != GNUNET_OK)
     goto END_SET;
+  nrc->now = GNUNET_TIME_absolute_get ();
+  hashSize = sizeof (GNUNET_HashCode);
+  memset (nrc->rbind, 0, sizeof (nrc->rbind));
+  rbind = nrc->rbind;
+  rbind[0].buffer_type = MYSQL_TYPE_LONG;
+  rbind[0].buffer = &size;
+  rbind[0].is_unsigned = 1;
+  rbind[1].buffer_type = MYSQL_TYPE_LONG;
+  rbind[1].buffer = &type;
+  rbind[1].is_unsigned = 1;
+  rbind[2].buffer_type = MYSQL_TYPE_LONG;
+  rbind[2].buffer = &priority;
+  rbind[2].is_unsigned = 1;
+  rbind[3].buffer_type = MYSQL_TYPE_LONG;
+  rbind[3].buffer = &anonymity;
+  rbind[3].is_unsigned = 1;
+  rbind[4].buffer_type = MYSQL_TYPE_LONGLONG;
+  rbind[4].buffer = &exp;
+  rbind[4].is_unsigned = 1;
+  rbind[5].buffer_type = MYSQL_TYPE_BLOB;
+  rbind[5].buffer = &key;
+  rbind[5].buffer_length = hashSize;
+  rbind[5].length = &hashSize;
+  rbind[6].buffer_type = MYSQL_TYPE_LONGLONG;
+  rbind[6].buffer = &vkey;
+  rbind[6].is_unsigned = GNUNET_YES;
+
   nrc->last_vkey = vkey;
   nrc->last_prio = priority;
   nrc->last_expire = exp;
@@ -1142,7 +1190,11 @@ sqlite_next_request_cont (void *next_cls,
   return;
  END_SET:
   /* call dviter with "end of set" */
-  return;
+  nrc->dviter (nrc->dviter_cls, 
+	       NULL, NULL, 0, NULL, 0, 0, 0, 
+	       GNUNET_TIME_UNIT_ZERO_ABS, 0);
+  nrc->prep (nrc->prep_cls, NULL);
+  GNUNET_free (nrc);
 }
 
 
@@ -1199,7 +1251,7 @@ iterateHelper (struct Plugin *plugin,
   nrc->iter_select = iter_select;
   nrc->dviter = dviter;
   nrc->dviter_cls = dviter_cls;
-
+  nrc->prep = &iterator_helper_prepare;
   if (is_asc)
     {
       nrc->last_prio = 0;
@@ -1334,6 +1386,128 @@ mysql_plugin_iter_low_priority (void *cls,
 }
 
 
+struct GetContext
+{
+  GNUNET_HashCode key;
+  GNUNET_HashCode vhash;
+
+  unsigned int prio;
+  unsigned int anonymity;
+  unsigned int limit_off;
+  unsigned long long expiration;
+  unsigned long long vkey;
+  unsigned long long total;
+  int off;
+  int count;
+  int have_vhash;
+  unsigned long size; /* OBSOLETE! */
+  unsigned long hashSize;
+};
+
+
+static int
+get_statement_prepare (void *cls,
+		       struct NextRequestClosure *nrc)
+{
+  struct GetContext *gc = cls;
+  struct Plugin *plugin;
+  MYSQL_BIND *rbind;
+  int ret;
+
+  if (NULL == nrc)
+    {
+      GNUNET_free (gc);
+      return GNUNET_NO;
+    }
+  if (gc->count == gc->total)
+    return GNUNET_NO;
+  plugin = nrc->plugin;
+  memset (nrc->rbind, 0, sizeof (nrc->rbind));
+  gc->hashSize = sizeof (GNUNET_HashCode);
+  rbind = nrc->rbind;
+  rbind[0].buffer_type = MYSQL_TYPE_LONG;
+  rbind[0].buffer = &gc->size;
+  rbind[0].is_unsigned = GNUNET_YES;
+  rbind[1].buffer_type = MYSQL_TYPE_LONG;
+  rbind[1].buffer = &nrc->type;
+  rbind[1].is_unsigned = GNUNET_YES;
+  rbind[2].buffer_type = MYSQL_TYPE_LONG;
+  rbind[2].buffer = &nrc->last_prio;
+  rbind[2].is_unsigned = GNUNET_YES;
+  rbind[3].buffer_type = MYSQL_TYPE_LONG;
+  rbind[3].buffer = &gc->anonymity;
+  rbind[3].is_unsigned = GNUNET_YES;
+  rbind[4].buffer_type = MYSQL_TYPE_LONGLONG;
+  rbind[4].buffer = &gc->expiration;
+  rbind[4].is_unsigned = GNUNET_YES;
+  rbind[5].buffer_type = MYSQL_TYPE_BLOB;
+  rbind[5].buffer = &gc->key;
+  rbind[5].buffer_length = gc->hashSize;
+  rbind[5].length = &gc->hashSize;
+  rbind[6].buffer_type = MYSQL_TYPE_LONGLONG;
+  rbind[6].buffer = &gc->vkey;
+  rbind[6].is_unsigned = GNUNET_YES;
+  if (gc->count == 0)
+    gc->limit_off = gc->off;
+  else
+    gc->limit_off = 0;
+  
+  if (nrc->type != 0)
+    {
+      if (gc->have_vhash)
+	{
+	  ret =
+	    prepared_statement_run_select
+	    (plugin,
+	     plugin->select_entry_by_hash_vhash_and_type, 7, nrc->rbind, &return_ok,
+	     NULL, MYSQL_TYPE_BLOB, &gc->key, gc->hashSize, &gc->hashSize,
+	     MYSQL_TYPE_BLOB, &gc->vhash, gc->hashSize, &gc->hashSize,
+	     MYSQL_TYPE_LONGLONG, &nrc->last_vkey, GNUNET_YES, MYSQL_TYPE_LONG,
+	     &nrc->type, GNUNET_YES, MYSQL_TYPE_LONG, &gc->limit_off, GNUNET_YES,
+	     -1);
+	}
+      else
+	{
+	  ret =
+	    prepared_statement_run_select
+	    (plugin,
+	     plugin->select_entry_by_hash_and_type, 7, nrc->rbind, &return_ok, NULL,
+	     MYSQL_TYPE_BLOB, &gc->key, gc->hashSize, &gc->hashSize,
+	     MYSQL_TYPE_LONGLONG, &nrc->last_vkey, GNUNET_YES, MYSQL_TYPE_LONG,
+	     &nrc->type, GNUNET_YES, MYSQL_TYPE_LONG, &gc->limit_off, GNUNET_YES,
+	     -1);
+	}
+    }
+  else
+    {
+      if (gc->have_vhash)
+	{
+	  ret =
+	    prepared_statement_run_select
+	    (plugin,
+	     plugin->select_entry_by_hash_and_vhash, 7, nrc->rbind, &return_ok, NULL,
+	     MYSQL_TYPE_BLOB, &gc->key, gc->hashSize, &gc->hashSize, MYSQL_TYPE_BLOB,
+	     &gc->vhash, gc->hashSize, &gc->hashSize, MYSQL_TYPE_LONGLONG,
+	     &nrc->last_vkey, GNUNET_YES, MYSQL_TYPE_LONG, &gc->limit_off,
+	     GNUNET_YES, -1);
+	}
+      else
+	{
+	  ret =
+	    prepared_statement_run_select
+	    (plugin,
+	     plugin->select_entry_by_hash, 7, nrc->rbind, &return_ok, NULL,
+	     MYSQL_TYPE_BLOB, &gc->key, gc->hashSize, &gc->hashSize,
+	     MYSQL_TYPE_LONGLONG, &nrc->last_vkey, GNUNET_YES, MYSQL_TYPE_LONG,
+	     &gc->limit_off, GNUNET_YES, -1);
+	}
+    }
+  if (gc->count + gc->off == gc->total)
+    nrc->last_vkey = 0;          /* back to start */
+  return ret;
+}
+
+
 /**
  * Iterate over the results for a particular key
  * in the datastore.
@@ -1359,21 +1533,12 @@ mysql_plugin_get (void *cls,
 		  PluginIterator iter, void *iter_cls)
 {
   struct Plugin *plugin = cls;
-  int count;
-  unsigned long long total;
-  int off;
   int ret;
-  unsigned int size;
-  unsigned int rtype;
-  unsigned int prio;
-  unsigned int level;
-  unsigned int limit_off;
-  unsigned long long expiration;
-  unsigned long long vkey;
-  unsigned long long last_vkey;
+  MYSQL_BIND cbind[1];
+  struct GetContext *gc;
+  struct NextRequestClosure *nrc;
+  unsigned long long total;
   unsigned long hashSize;
-  unsigned long hashSize2;
-  MYSQL_BIND rbind[7];
 
   if (iter == NULL) 
     return;
@@ -1385,12 +1550,11 @@ mysql_plugin_get (void *cls,
       return;
     }
   hashSize = sizeof (GNUNET_HashCode);
-  hashSize2 = sizeof (GNUNET_HashCode);
-  memset (rbind, 0, sizeof (rbind));
+  memset (cbind, 0, sizeof (cbind));
   total = -1;
-  rbind[0].buffer_type = MYSQL_TYPE_LONGLONG;
-  rbind[0].buffer = &total;
-  rbind[0].is_unsigned = GNUNET_YES;
+  cbind[0].buffer_type = MYSQL_TYPE_LONGLONG;
+  cbind[0].buffer = &total;
+  cbind[0].is_unsigned = GNUNET_YES;
   if (type != 0)
     {
       if (vhash != NULL)
@@ -1398,9 +1562,9 @@ mysql_plugin_get (void *cls,
           ret =
             prepared_statement_run_select
             (plugin,
-	     plugin->count_entry_by_hash_vhash_and_type, 1, rbind, &return_ok, NULL,
-             MYSQL_TYPE_BLOB, key, hashSize2, &hashSize2, MYSQL_TYPE_BLOB,
-             vhash, hashSize2, &hashSize2, MYSQL_TYPE_LONG, &type, GNUNET_YES,
+	     plugin->count_entry_by_hash_vhash_and_type, 1, cbind, &return_ok, NULL,
+             MYSQL_TYPE_BLOB, key, hashSize, &hashSize, MYSQL_TYPE_BLOB,
+             vhash, hashSize, &hashSize, MYSQL_TYPE_LONG, &type, GNUNET_YES,
              -1);
         }
       else
@@ -1408,8 +1572,8 @@ mysql_plugin_get (void *cls,
           ret =
             prepared_statement_run_select
             (plugin,
-	     plugin->count_entry_by_hash_and_type, 1, rbind, &return_ok, NULL,
-             MYSQL_TYPE_BLOB, key, hashSize2, &hashSize2, MYSQL_TYPE_LONG,
+	     plugin->count_entry_by_hash_and_type, 1, cbind, &return_ok, NULL,
+             MYSQL_TYPE_BLOB, key, hashSize, &hashSize, MYSQL_TYPE_LONG,
              &type, GNUNET_YES, -1);
 
         }
@@ -1421,9 +1585,9 @@ mysql_plugin_get (void *cls,
           ret =
             prepared_statement_run_select
             (plugin,
-	     plugin->count_entry_by_hash_and_vhash, 1, rbind, &return_ok, NULL,
-             MYSQL_TYPE_BLOB, key, hashSize2, &hashSize2, MYSQL_TYPE_BLOB,
-             vhash, hashSize2, &hashSize2, -1);
+	     plugin->count_entry_by_hash_and_vhash, 1, cbind, &return_ok, NULL,
+             MYSQL_TYPE_BLOB, key, hashSize, &hashSize, MYSQL_TYPE_BLOB,
+             vhash, hashSize, &hashSize, -1);
 
         }
       else
@@ -1431,126 +1595,40 @@ mysql_plugin_get (void *cls,
           ret =
             prepared_statement_run_select (plugin,
 					   plugin->count_entry_by_hash,
-					   1, rbind, &return_ok,
+					   1, cbind, &return_ok,
 					   NULL, MYSQL_TYPE_BLOB,
-					   key, hashSize2,
-					   &hashSize2, -1);
+					   key, hashSize,
+					   &hashSize, -1);
         }
     }
-  if ((ret != GNUNET_OK) || (-1 == total))
-    return;
-  if (total == 0)
-    return;
-
-  last_vkey = 0;
-  count = 0;
-  off = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, total);
-
-  memset (rbind, 0, sizeof (rbind));
-  rbind[0].buffer_type = MYSQL_TYPE_LONG;
-  rbind[0].buffer = &size;
-  rbind[0].is_unsigned = GNUNET_YES;
-  rbind[1].buffer_type = MYSQL_TYPE_LONG;
-  rbind[1].buffer = &rtype;
-  rbind[1].is_unsigned = GNUNET_YES;
-  rbind[2].buffer_type = MYSQL_TYPE_LONG;
-  rbind[2].buffer = &prio;
-  rbind[2].is_unsigned = GNUNET_YES;
-  rbind[3].buffer_type = MYSQL_TYPE_LONG;
-  rbind[3].buffer = &level;
-  rbind[3].is_unsigned = GNUNET_YES;
-  rbind[4].buffer_type = MYSQL_TYPE_LONGLONG;
-  rbind[4].buffer = &expiration;
-  rbind[4].is_unsigned = GNUNET_YES;
-  rbind[5].buffer_type = MYSQL_TYPE_BLOB;
-  rbind[5].buffer = (void*) key;
-  rbind[5].buffer_length = hashSize;
-  rbind[5].length = &hashSize;
-  rbind[6].buffer_type = MYSQL_TYPE_LONGLONG;
-  rbind[6].buffer = &vkey;
-  rbind[6].is_unsigned = GNUNET_YES;
-  while (1)
+  if ((ret != GNUNET_OK) || (-1 == total) || (0 == total))
     {
-      if (count == 0)
-        limit_off = off;
-      else
-        limit_off = 0;
-      if (type != 0)
-        {
-          if (vhash != NULL)
-            {
-              ret =
-                prepared_statement_run_select
-                (plugin,
-		 plugin->select_entry_by_hash_vhash_and_type, 7, rbind, &return_ok,
-                 NULL, MYSQL_TYPE_BLOB, key, hashSize, &hashSize,
-                 MYSQL_TYPE_BLOB, vhash, hashSize2, &hashSize2,
-                 MYSQL_TYPE_LONGLONG, &last_vkey, GNUNET_YES, MYSQL_TYPE_LONG,
-                 &type, GNUNET_YES, MYSQL_TYPE_LONG, &limit_off, GNUNET_YES,
-                 -1);
-            }
-          else
-            {
-              ret =
-                prepared_statement_run_select
-                (plugin,
-		 plugin->select_entry_by_hash_and_type, 7, rbind, &return_ok, NULL,
-                 MYSQL_TYPE_BLOB, key, hashSize, &hashSize,
-                 MYSQL_TYPE_LONGLONG, &last_vkey, GNUNET_YES, MYSQL_TYPE_LONG,
-                 &type, GNUNET_YES, MYSQL_TYPE_LONG, &limit_off, GNUNET_YES,
-                 -1);
-            }
-        }
-      else
-        {
-          if (vhash != NULL)
-            {
-              ret =
-                prepared_statement_run_select
-                (plugin,
-		 plugin->select_entry_by_hash_and_vhash, 7, rbind, &return_ok, NULL,
-                 MYSQL_TYPE_BLOB, key, hashSize, &hashSize, MYSQL_TYPE_BLOB,
-                 vhash, hashSize2, &hashSize2, MYSQL_TYPE_LONGLONG,
-                 &last_vkey, GNUNET_YES, MYSQL_TYPE_LONG, &limit_off,
-                 GNUNET_YES, -1);
-            }
-          else
-            {
-              ret =
-                prepared_statement_run_select
-                (plugin,
-		 plugin->select_entry_by_hash, 7, rbind, &return_ok, NULL,
-                 MYSQL_TYPE_BLOB, key, hashSize, &hashSize,
-                 MYSQL_TYPE_LONGLONG, &last_vkey, GNUNET_YES, MYSQL_TYPE_LONG,
-                 &limit_off, GNUNET_YES, -1);
-            }
-        }
-      if (ret != GNUNET_OK)
-        break;
-      last_vkey = vkey;
-#if FIXME
-      datum = assembleDatum (rbind);
-      if (datum == NULL)
-        continue;
-      count++;
-      ret = iter (iter_cls, key, datum, vkey);
-#endif
-      ret = GNUNET_SYSERR;
-      if (ret == GNUNET_SYSERR)
-        {
-          break;
-        }
-      if (ret == GNUNET_NO)
-        {
-          do_delete_value (plugin, vkey);
-          do_delete_entry_by_vkey (plugin, vkey);
-          plugin->content_size -= size;
-        }
-      if (count + off == total)
-        last_vkey = 0;          /* back to start */
-      if (count == total)
-        break;
+      iter (iter_cls, 
+	    NULL, NULL, 0, NULL, 0, 0, 0, 
+	    GNUNET_TIME_UNIT_ZERO_ABS, 0);
+      return;
+    }
+  gc = GNUNET_malloc (sizeof (struct GetContext));
+  gc->key = *key;
+  if (vhash != NULL)
+    {
+      gc->have_vhash = GNUNET_YES;
+      gc->vhash = *vhash;
     }
+  gc->total = total;
+  gc->off = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, total);
+  
+
+  nrc = GNUNET_malloc (sizeof (struct NextRequestClosure));
+  nrc->plugin = plugin;
+  nrc->type = type;  
+  nrc->iter_select = -1;
+  nrc->dviter = iter;
+  nrc->dviter_cls = iter_cls;
+  nrc->prep = &get_statement_prepare;
+  nrc->prep_cls = gc;
+  nrc->last_vkey = 0; // FIXME: used to be 'vkey', why? where did vkey come from?
+  mysql_plugin_next_request (nrc, GNUNET_NO);
 }
 
 
@@ -1821,6 +1899,7 @@ libgnunet_plugin_datastore_mysql_done (void *cls)
       GNUNET_SCHEDULER_cancel (plugin->env->sched,
 			       plugin->next_task);
       plugin->next_task = GNUNET_SCHEDULER_NO_TASK;
+      plugin->next_task_nc->prep (plugin->next_task_nc->prep_cls, NULL);
       GNUNET_free (plugin->next_task_nc);
       plugin->next_task_nc = NULL;
     }