fix RPS service: Provide closure for view insertion
[oweals/gnunet.git] / src / datacache / plugin_datacache_sqlite.c
index 5f534227fd9ae695549116e5d8beffeacdf1babf..dc4236a8b8fd4ba2254a81f716410b32fb4e3f6e 100644 (file)
@@ -1,21 +1,19 @@
 /*
      This file is part of GNUnet
-     (C) 2006, 2009 Christian Grothoff (and other contributing authors)
+     Copyright (C) 2006, 2009, 2015 GNUnet e.V.
 
-     GNUnet is free software; you can redistribute it and/or modify
-     it under the terms of the GNU General Public License as published
-     by the Free Software Foundation; either version 3, or (at your
-     option) any later version.
+     GNUnet is free software: you can redistribute it and/or modify it
+     under the terms of the GNU Affero General Public License as published
+     by the Free Software Foundation, either version 3 of the License,
+     or (at your option) any later version.
 
      GNUnet is distributed in the hope that it will be useful, but
      WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-     General Public License for more details.
+     Affero General Public License for more details.
 
-     You should have received a copy of the GNU General Public License
-     along with GNUnet; see the file COPYING.  If not, write to the
-     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-     Boston, MA 02111-1307, USA.
+     You should have received a copy of the GNU Affero General Public License
+     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 /**
 #include "platform.h"
 #include "gnunet_util_lib.h"
 #include "gnunet_datacache_plugin.h"
+#include "gnunet_sq_lib.h"
 #include <sqlite3.h>
 
-#define DEBUG_DATACACHE_SQLITE GNUNET_NO
+#define LOG(kind,...) GNUNET_log_from (kind, "datacache-sqlite", __VA_ARGS__)
+
+#define LOG_STRERROR_FILE(kind,op,fn) GNUNET_log_from_strerror_file (kind, "datacache-sqlite", op, fn)
+
 
 /**
  * How much overhead do we assume per entry in the
  * datacache?
  */
-#define OVERHEAD (sizeof(GNUNET_HashCode) + 32)
+#define OVERHEAD (sizeof(struct GNUNET_HashCode) + 36)
 
 /**
  * Context for all functions in this plugin.
@@ -55,103 +57,165 @@ struct Plugin
    * Filename used for the DB.
    */
   char *fn;
+
+  /**
+   * Prepared statement for #sqlite_plugin_put.
+   */
+  sqlite3_stmt *insert_stmt;
+
+  /**
+   * Prepared statement for #sqlite_plugin_get.
+   */
+  sqlite3_stmt *get_count_stmt;
+
+  /**
+   * Prepared statement for #sqlite_plugin_get.
+   */
+  sqlite3_stmt *get_stmt;
+
+  /**
+   * Prepared statement for #sqlite_plugin_del.
+   */
+  sqlite3_stmt *del_select_stmt;
+
+  /**
+   * Prepared statement for #sqlite_plugin_del.
+   */
+  sqlite3_stmt *del_expired_stmt;
+
+  /**
+   * Prepared statement for #sqlite_plugin_del.
+   */
+  sqlite3_stmt *del_stmt;
+
+  /**
+   * Prepared statement for #sqlite_plugin_get_random.
+   */
+  sqlite3_stmt *get_random_stmt;
+
+  /**
+   * Prepared statement for #sqlite_plugin_get_closest.
+   */
+  sqlite3_stmt *get_closest_stmt;
+
+  /**
+   * Number of key-value pairs in the database.
+   */
+  unsigned int num_items;
 };
 
 
 /**
- * Log an error message at log-level 'level' that indicates
- * a failure of the command 'cmd' on file 'filename'
- * with the message given by strerror(errno).
+ * Log an error message at log-level @a level that indicates
+ * a failure of the command @a cmd with the error from the database @a db
+ *
+ * @param db database handle
+ * @param level log level
+ * @param cmd failed command
  */
-#define LOG_SQLITE(db, level, cmd) do { GNUNET_log(level, _("`%s' failed at %s:%d with error: %s\n"), cmd, __FILE__, __LINE__, sqlite3_errmsg(db)); } while(0)
+#define LOG_SQLITE(db, level, cmd) do { LOG (level, _("`%s' failed at %s:%d with error: %s\n"), cmd, __FILE__, __LINE__, sqlite3_errmsg(db)); } while(0)
 
 
-#define SQLITE3_EXEC(db, cmd) do { emsg = NULL; if (SQLITE_OK != sqlite3_exec(db, cmd, NULL, NULL, &emsg)) { GNUNET_log(GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK, _("`%s' failed at %s:%d with error: %s\n"), "sqlite3_exec", __FILE__, __LINE__, emsg); sqlite3_free(emsg); } } while(0)
+/**
+ * Execute SQL statement.
+ *
+ * @param db database handle
+ * @param cmd SQL command to execute
+ */
+#define SQLITE3_EXEC(db, cmd) do { emsg = NULL; if (SQLITE_OK != sqlite3_exec(db, cmd, NULL, NULL, &emsg)) { LOG (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK, _("`%s' failed at %s:%d with error: %s\n"), "sqlite3_exec", __FILE__, __LINE__, emsg); sqlite3_free(emsg); } } while(0)
 
 
 /**
  * @brief Prepare a SQL statement
+ *
+ * @param dbh database handle
+ * @param zsql SQL statement text
+ * @param[out] ppStmt set to the prepared statement
+ * @return 0 on success
  */
 static int
-sq_prepare (sqlite3 * dbh, const char *zSql,    /* SQL statement, UTF-8 encoded */
-            sqlite3_stmt ** ppStmt)
+sq_prepare (sqlite3 *dbh,
+            const char *zSql,    /* SQL statement, UTF-8 encoded */
+            sqlite3_stmt **ppStmt)
 {                               /* OUT: Statement handle */
   char *dummy;
 
   return sqlite3_prepare (dbh,
-                          zSql, strlen (zSql), ppStmt, (const char **) &dummy);
+                          zSql,
+                          strlen (zSql),
+                          ppStmt,
+                          (const char **) &dummy);
 }
 
 
 /**
  * Store an item in the datastore.
  *
- * @param cls closure (our "struct Plugin")
- * @param key key to store data under
- * @param size number of bytes in data
+ * @param cls closure (our `struct Plugin`)
+ * @param key key to store @a data under
+ * @param xor_distance how close is @a key to our PID?
+ * @param size number of bytes in @a data
  * @param data data to store
  * @param type type of the value
  * @param discard_time when to discard the value in any case
- * @return 0 on error, number of bytes used otherwise
+ * @param path_info_len number of entries in @a path_info
+ * @param path_info array of peers that have processed the request
+ * @return 0 if duplicate, -1 on error, number of bytes used otherwise
  */
-static size_t
+static ssize_t
 sqlite_plugin_put (void *cls,
-                   const GNUNET_HashCode * key,
-                   size_t size,
+                  const struct GNUNET_HashCode *key,
+                   uint32_t xor_distance,
+                  size_t size,
                    const char *data,
-                   enum GNUNET_BLOCK_Type type,
-                   struct GNUNET_TIME_Absolute discard_time)
+                  enum GNUNET_BLOCK_Type type,
+                   struct GNUNET_TIME_Absolute discard_time,
+                  unsigned int path_info_len,
+                  const struct GNUNET_PeerIdentity *path_info)
 {
   struct Plugin *plugin = cls;
-  sqlite3_stmt *stmt;
-  int64_t dval;
-
-#if DEBUG_DATACACHE_SQLITE
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-              "Processing `%s' of %u bytes with key `%4s' and expiration %llums\n",
-              "PUT",
-              (unsigned int) size,
-              GNUNET_h2s (key),
-              (unsigned long long)
-              GNUNET_TIME_absolute_get_remaining (discard_time).rel_value);
-#endif
-  dval = (int64_t) discard_time.abs_value;
-  if (dval < 0)
-    dval = INT64_MAX;
-  if (sq_prepare (plugin->dbh,
-                  "INSERT INTO ds090 "
-                  "(type, expire, key, value) "
-                  "VALUES (?, ?, ?, ?)", &stmt) != SQLITE_OK)
-  {
-    GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
-                _("`%s' failed at %s:%d with error: %s\n"),
-                "sq_prepare", __FILE__, __LINE__, sqlite3_errmsg (plugin->dbh));
-    return 0;
-  }
-  if ((SQLITE_OK != sqlite3_bind_int (stmt, 1, type)) ||
-      (SQLITE_OK != sqlite3_bind_int64 (stmt, 2, dval)) ||
-      (SQLITE_OK != sqlite3_bind_blob (stmt, 3, key, sizeof (GNUNET_HashCode),
-                                       SQLITE_TRANSIENT)) ||
-      (SQLITE_OK != sqlite3_bind_blob (stmt, 4, data, size, SQLITE_TRANSIENT)))
+  uint32_t type32 = type;
+  struct GNUNET_SQ_QueryParam params[] = {
+    GNUNET_SQ_query_param_uint32 (&type32),
+    GNUNET_SQ_query_param_absolute_time (&discard_time),
+    GNUNET_SQ_query_param_auto_from_type (key),
+    GNUNET_SQ_query_param_uint32 (&xor_distance),
+    GNUNET_SQ_query_param_fixed_size (data, size),
+    GNUNET_SQ_query_param_fixed_size (path_info,
+                                      path_info_len * sizeof (struct GNUNET_PeerIdentity)),
+    GNUNET_SQ_query_param_end
+  };
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Processing PUT of %u bytes with key `%s' and expiration %s\n",
+       (unsigned int) size,
+       GNUNET_h2s (key),
+       GNUNET_STRINGS_relative_time_to_string (GNUNET_TIME_absolute_get_remaining (discard_time),
+                                               GNUNET_YES));
+  if (GNUNET_OK !=
+      GNUNET_SQ_bind (plugin->insert_stmt,
+                      params))
   {
     LOG_SQLITE (plugin->dbh,
                 GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
                 "sqlite3_bind_xxx");
-    sqlite3_finalize (stmt);
-    return 0;
+    GNUNET_SQ_reset (plugin->dbh,
+                     plugin->insert_stmt);
+    return -1;
   }
-  if (SQLITE_DONE != sqlite3_step (stmt))
+  if (SQLITE_DONE !=
+      sqlite3_step (plugin->insert_stmt))
   {
     LOG_SQLITE (plugin->dbh,
                 GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
                 "sqlite3_step");
-    sqlite3_finalize (stmt);
-    return 0;
+    GNUNET_SQ_reset (plugin->dbh,
+                     plugin->insert_stmt);
+    return -1;
   }
-  if (SQLITE_OK != sqlite3_finalize (stmt))
-    LOG_SQLITE (plugin->dbh,
-                GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
-                "sqlite3_finalize");
+  plugin->num_items++;
+  GNUNET_SQ_reset (plugin->dbh,
+                   plugin->insert_stmt);
   return size + OVERHEAD;
 }
 
@@ -160,120 +224,156 @@ sqlite_plugin_put (void *cls,
  * Iterate over the results for a particular key
  * in the datastore.
  *
- * @param cls closure (our "struct Plugin")
+ * @param cls closure (our `struct Plugin`)
  * @param key
  * @param type entries of which type are relevant?
  * @param iter maybe NULL (to just count)
- * @param iter_cls closure for iter
+ * @param iter_cls closure for @a iter
  * @return the number of results found
  */
 static unsigned int
 sqlite_plugin_get (void *cls,
-                   const GNUNET_HashCode * key,
+                   const struct GNUNET_HashCode *key,
                    enum GNUNET_BLOCK_Type type,
-                   GNUNET_DATACACHE_Iterator iter, void *iter_cls)
+                   GNUNET_DATACACHE_Iterator iter,
+                   void *iter_cls)
 {
   struct Plugin *plugin = cls;
-  sqlite3_stmt *stmt;
+  uint32_t type32 = type;
   struct GNUNET_TIME_Absolute now;
   struct GNUNET_TIME_Absolute exp;
-  unsigned int size;
-  const char *dat;
+  size_t size;
+  void *dat;
   unsigned int cnt;
-  unsigned int off;
+  uint32_t off;
   unsigned int total;
-  char scratch[256];
-  int64_t ntime;
+  size_t psize;
+  struct GNUNET_PeerIdentity *path;
+  struct GNUNET_SQ_QueryParam params_count[] = {
+    GNUNET_SQ_query_param_auto_from_type (key),
+    GNUNET_SQ_query_param_uint32 (&type32),
+    GNUNET_SQ_query_param_absolute_time (&now),
+    GNUNET_SQ_query_param_end
+  };
+  struct GNUNET_SQ_QueryParam params_select[] = {
+    GNUNET_SQ_query_param_auto_from_type (key),
+    GNUNET_SQ_query_param_uint32 (&type32),
+    GNUNET_SQ_query_param_absolute_time (&now),
+    GNUNET_SQ_query_param_uint32 (&off),
+    GNUNET_SQ_query_param_end
+  };
+  struct GNUNET_SQ_ResultSpec rs[] = {
+    GNUNET_SQ_result_spec_variable_size (&dat,
+                                         &size),
+    GNUNET_SQ_result_spec_absolute_time (&exp),
+    GNUNET_SQ_result_spec_variable_size ((void **) &path,
+                                         &psize),
+    GNUNET_SQ_result_spec_end
+  };
 
   now = GNUNET_TIME_absolute_get ();
-#if DEBUG_DATACACHE_SQLITE
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-              "Processing `%s' for key `%4s'\n", "GET", GNUNET_h2s (key));
-#endif
-  if (sq_prepare (plugin->dbh,
-                  "SELECT count(*) FROM ds090 WHERE key=? AND type=? AND expire >= ?",
-                  &stmt) != SQLITE_OK)
-  {
-    GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
-                _("`%s' failed at %s:%d with error: %s\n"),
-                "sq_prepare", __FILE__, __LINE__, sqlite3_errmsg (plugin->dbh));
-    return 0;
-  }
-  ntime = (int64_t) now.abs_value;
-  GNUNET_assert (ntime >= 0);
-  if ((SQLITE_OK !=
-       sqlite3_bind_blob (stmt, 1, key, sizeof (GNUNET_HashCode),
-                          SQLITE_TRANSIENT)) ||
-      (SQLITE_OK !=
-       sqlite3_bind_int (stmt, 2, type)) ||
-      (SQLITE_OK != sqlite3_bind_int64 (stmt, 3, now.abs_value)))
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Processing GET for key `%s'\n",
+       GNUNET_h2s (key));
+
+  if (GNUNET_OK !=
+      GNUNET_SQ_bind (plugin->get_count_stmt,
+                      params_count))
   {
     LOG_SQLITE (plugin->dbh,
                 GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
                 "sqlite3_bind_xxx");
-    sqlite3_finalize (stmt);
+    GNUNET_SQ_reset (plugin->dbh,
+                     plugin->get_count_stmt);
     return 0;
   }
-
-  if (SQLITE_ROW != sqlite3_step (stmt))
+  if (SQLITE_ROW !=
+      sqlite3_step (plugin->get_count_stmt))
   {
-    LOG_SQLITE (plugin->dbh,
-                GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
+    LOG_SQLITE (plugin->dbh, GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
                 "sqlite_step");
-    sqlite3_finalize (stmt);
+    GNUNET_SQ_reset (plugin->dbh,
+                     plugin->get_count_stmt);
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "No content found when processing GET for key `%s'\n",
+         GNUNET_h2s (key));
     return 0;
   }
-  total = sqlite3_column_int (stmt, 0);
-  sqlite3_finalize (stmt);
-  if ((total == 0) || (iter == NULL))
+  total = sqlite3_column_int (plugin->get_count_stmt,
+                              0);
+  GNUNET_SQ_reset (plugin->dbh,
+                   plugin->get_count_stmt);
+  if ( (0 == total) ||
+       (NULL == iter) )
+  {
+    if (0 == total)
+      LOG (GNUNET_ERROR_TYPE_DEBUG,
+           "No content found when processing GET for key `%s'\n",
+           GNUNET_h2s (key));
     return total;
+  }
 
   cnt = 0;
-  off = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, total);
+  off = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
+                                  total);
   while (cnt < total)
   {
     off = (off + 1) % total;
-    GNUNET_snprintf (scratch,
-                     sizeof (scratch),
-                     "SELECT value,expire FROM ds090 WHERE key=? AND type=? AND expire >= ? LIMIT 1 OFFSET %u",
-                     off);
-    if (sq_prepare (plugin->dbh, scratch, &stmt) != SQLITE_OK)
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
-                  _("`%s' failed at %s:%d with error: %s\n"),
-                  "sq_prepare", __FILE__, __LINE__,
-                  sqlite3_errmsg (plugin->dbh));
-      return cnt;
-    }
-    if ((SQLITE_OK !=
-         sqlite3_bind_blob (stmt, 1, key, sizeof (GNUNET_HashCode),
-                            SQLITE_TRANSIENT)) ||
-        (SQLITE_OK !=
-         sqlite3_bind_int (stmt, 2, type)) ||
-        (SQLITE_OK != sqlite3_bind_int64 (stmt, 3, now.abs_value)))
+    if (GNUNET_OK !=
+        GNUNET_SQ_bind (plugin->get_stmt,
+                        params_select))
     {
       LOG_SQLITE (plugin->dbh,
                   GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
                   "sqlite3_bind_xxx");
-      sqlite3_finalize (stmt);
+      GNUNET_SQ_reset (plugin->dbh,
+                       plugin->get_stmt);
       return cnt;
     }
-    if (sqlite3_step (stmt) != SQLITE_ROW)
+    if (SQLITE_ROW !=
+        sqlite3_step (plugin->get_stmt))
+      break;
+    if (GNUNET_OK !=
+        GNUNET_SQ_extract_result (plugin->get_stmt,
+                                  rs))
+    {
+      GNUNET_break (0);
+      GNUNET_SQ_reset (plugin->dbh,
+                       plugin->get_stmt);
       break;
-    size = sqlite3_column_bytes (stmt, 0);
-    dat = sqlite3_column_blob (stmt, 0);
-    exp.abs_value = sqlite3_column_int64 (stmt, 1);
-    ntime = (int64_t) exp.abs_value;
-    if (ntime == INT64_MAX)
-      exp = GNUNET_TIME_UNIT_FOREVER_ABS;
+    }
+    if (0 != psize % sizeof (struct GNUNET_PeerIdentity))
+    {
+      GNUNET_break (0);
+      psize = 0;
+      path = NULL;
+    }
+    psize /= sizeof (struct GNUNET_PeerIdentity);
     cnt++;
-    if (GNUNET_OK != iter (iter_cls, exp, key, size, dat, type))
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Found %u-byte result when processing GET for key `%s'\n",
+         (unsigned int) size,
+         GNUNET_h2s (key));
+    if (GNUNET_OK != iter (iter_cls,
+                           key,
+                           size,
+                           dat,
+                           type,
+                           exp,
+                           psize,
+                           path))
     {
-      sqlite3_finalize (stmt);
+      GNUNET_SQ_cleanup_result (rs);
+      GNUNET_SQ_reset (plugin->dbh,
+                       plugin->get_stmt);
       break;
     }
-    sqlite3_finalize (stmt);
+    GNUNET_SQ_cleanup_result (rs);
+    GNUNET_SQ_reset (plugin->dbh,
+                     plugin->get_stmt);
   }
+  GNUNET_SQ_reset (plugin->dbh,
+                   plugin->get_stmt);
   return cnt;
 }
 
@@ -281,111 +381,314 @@ sqlite_plugin_get (void *cls,
 /**
  * Delete the entry with the lowest expiration value
  * from the datacache right now.
- * 
- * @param cls closure (our "struct Plugin")
- * @return GNUNET_OK on success, GNUNET_SYSERR on error
+ *
+ * @param cls closure (our `struct Plugin`)
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
  */
 static int
 sqlite_plugin_del (void *cls)
 {
   struct Plugin *plugin = cls;
-  unsigned int dsize;
-  unsigned int dtype;
-  sqlite3_stmt *stmt;
-  sqlite3_stmt *dstmt;
-  char blob[65536];
-  GNUNET_HashCode hc;
-
-#if DEBUG_DATACACHE_SQLITE
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Processing `%s'\n", "DEL");
-#endif
-  stmt = NULL;
-  dstmt = NULL;
-  if (sq_prepare (plugin->dbh,
-                  "SELECT type, key, value FROM ds090 ORDER BY expire ASC LIMIT 1",
-                  &stmt) != SQLITE_OK)
+  uint64_t rowid;
+  void *data;
+  size_t dsize;
+  struct GNUNET_HashCode hc;
+  struct GNUNET_TIME_Absolute now;
+  struct GNUNET_SQ_ResultSpec rs[] = {
+    GNUNET_SQ_result_spec_uint64 (&rowid),
+    GNUNET_SQ_result_spec_auto_from_type (&hc),
+    GNUNET_SQ_result_spec_variable_size ((void **) &data,
+                                         &dsize),
+    GNUNET_SQ_result_spec_end
+  };
+  struct GNUNET_SQ_QueryParam params[] = {
+    GNUNET_SQ_query_param_uint64 (&rowid),
+    GNUNET_SQ_query_param_end
+  };
+  struct GNUNET_SQ_QueryParam time_params[] = {
+    GNUNET_SQ_query_param_absolute_time (&now),
+    GNUNET_SQ_query_param_end
+  };
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Processing DEL\n");
+  now = GNUNET_TIME_absolute_get ();
+  if (GNUNET_OK !=
+      GNUNET_SQ_bind (plugin->del_expired_stmt,
+                      time_params))
   {
-    GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
-                _("`%s' failed at %s:%d with error: %s\n"),
-                "sq_prepare", __FILE__, __LINE__, sqlite3_errmsg (plugin->dbh));
-    if (stmt != NULL)
-      (void) sqlite3_finalize (stmt);
+    LOG_SQLITE (plugin->dbh,
+                GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
+                "sqlite3_bind");
+    GNUNET_SQ_reset (plugin->dbh,
+                     plugin->del_expired_stmt);
     return GNUNET_SYSERR;
   }
-  if (SQLITE_ROW != sqlite3_step (stmt))
+  if ( (SQLITE_ROW !=
+        sqlite3_step (plugin->del_expired_stmt)) ||
+       (GNUNET_OK !=
+        GNUNET_SQ_extract_result (plugin->del_expired_stmt,
+                                  rs)) )
   {
-    GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
-                _("`%s' failed at %s:%d with error: %s\n"),
-                "sqlite3_step", __FILE__, __LINE__,
-                sqlite3_errmsg (plugin->dbh));
-    (void) sqlite3_finalize (stmt);
-    return GNUNET_SYSERR;
+    GNUNET_SQ_reset (plugin->dbh,
+                     plugin->del_expired_stmt);
+    if (SQLITE_ROW !=
+        sqlite3_step (plugin->del_select_stmt))
+    {
+      LOG_SQLITE (plugin->dbh,
+                  GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
+                  "sqlite3_step");
+      GNUNET_SQ_reset (plugin->dbh,
+                       plugin->del_select_stmt);
+      return GNUNET_SYSERR;
+    }
+    if (GNUNET_OK !=
+        GNUNET_SQ_extract_result (plugin->del_select_stmt,
+                                  rs))
+    {
+      GNUNET_SQ_reset (plugin->dbh,
+                       plugin->del_select_stmt);
+      GNUNET_break (0);
+      return GNUNET_SYSERR;
+    }
   }
-  dtype = sqlite3_column_int (stmt, 0);
-  GNUNET_break (sqlite3_column_bytes (stmt, 1) == sizeof (GNUNET_HashCode));
-  dsize = sqlite3_column_bytes (stmt, 2);
-  GNUNET_assert (dsize <= sizeof (blob));
-  memcpy (blob, sqlite3_column_blob (stmt, 2), dsize);
-  memcpy (&hc, sqlite3_column_blob (stmt, 1), sizeof (GNUNET_HashCode));
-  if (SQLITE_OK != sqlite3_finalize (stmt))
-    GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
-                _("`%s' failed at %s:%d with error: %s\n"),
-                "sqlite3_step", __FILE__, __LINE__,
-                sqlite3_errmsg (plugin->dbh));
-  if (sq_prepare (plugin->dbh,
-                  "DELETE FROM ds090 "
-                  "WHERE key=? AND value=? AND type=?", &dstmt) != SQLITE_OK)
+  GNUNET_SQ_cleanup_result (rs);
+  GNUNET_SQ_reset (plugin->dbh,
+                   plugin->del_select_stmt);
+  if (GNUNET_OK !=
+      GNUNET_SQ_bind (plugin->del_stmt,
+                      params))
   {
-    GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
-                _("`%s' failed at %s:%d with error: %s\n"),
-                "sq_prepare", __FILE__, __LINE__, sqlite3_errmsg (plugin->dbh));
-    if (stmt != NULL)
-      (void) sqlite3_finalize (stmt);
+    LOG_SQLITE (plugin->dbh,
+                GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
+                "sqlite3_bind");
+    GNUNET_SQ_reset (plugin->dbh,
+                     plugin->del_stmt);
     return GNUNET_SYSERR;
   }
-  if ((SQLITE_OK !=
-       sqlite3_bind_blob (dstmt,
-                          1, &hc,
-                          sizeof (GNUNET_HashCode),
-                          SQLITE_TRANSIENT)) ||
-      (SQLITE_OK !=
-       sqlite3_bind_blob (dstmt,
-                          2, blob,
-                          dsize,
-                          SQLITE_TRANSIENT)) ||
-      (SQLITE_OK != sqlite3_bind_int (dstmt, 3, dtype)))
+  if (SQLITE_DONE !=
+      sqlite3_step (plugin->del_stmt))
   {
-    GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
-                _("`%s' failed at %s:%d with error: %s\n"),
-                "sqlite3_bind", __FILE__, __LINE__,
-                sqlite3_errmsg (plugin->dbh));
-    (void) sqlite3_finalize (dstmt);
+    LOG_SQLITE (plugin->dbh,
+                GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
+                "sqlite3_step");
+    GNUNET_SQ_reset (plugin->dbh,
+                     plugin->del_stmt);
     return GNUNET_SYSERR;
   }
-  if (sqlite3_step (dstmt) != SQLITE_DONE)
+  plugin->num_items--;
+  plugin->env->delete_notify (plugin->env->cls,
+                              &hc,
+                              dsize + OVERHEAD);
+  GNUNET_SQ_reset (plugin->dbh,
+                   plugin->del_stmt);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Obtain a random key-value pair from the datacache.
+ *
+ * @param cls closure (our `struct Plugin`)
+ * @param iter maybe NULL (to just count)
+ * @param iter_cls closure for @a iter
+ * @return the number of results found, zero (datacache empty) or one
+ */
+static unsigned int
+sqlite_plugin_get_random (void *cls,
+                          GNUNET_DATACACHE_Iterator iter,
+                          void *iter_cls)
+{
+  struct Plugin *plugin = cls;
+  struct GNUNET_TIME_Absolute exp;
+  size_t size;
+  void *dat;
+  uint32_t off;
+  size_t psize;
+  uint32_t type;
+  struct GNUNET_PeerIdentity *path;
+  struct GNUNET_HashCode key;
+  struct GNUNET_SQ_QueryParam params[] = {
+    GNUNET_SQ_query_param_uint32 (&off),
+    GNUNET_SQ_query_param_end
+  };
+  struct GNUNET_SQ_ResultSpec rs[] = {
+    GNUNET_SQ_result_spec_variable_size (&dat,
+                                         &size),
+    GNUNET_SQ_result_spec_absolute_time (&exp),
+    GNUNET_SQ_result_spec_variable_size ((void **) &path,
+                                         &psize),
+    GNUNET_SQ_result_spec_auto_from_type (&key),
+    GNUNET_SQ_result_spec_uint32 (&type),
+    GNUNET_SQ_result_spec_end
+  };
+
+  if (0 == plugin->num_items)
+    return 0;
+  if (NULL == iter)
+    return 1;
+  off = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
+                                  plugin->num_items);
+  if (GNUNET_OK !=
+      GNUNET_SQ_bind (plugin->get_random_stmt,
+                      params))
   {
-    GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
-                _("`%s' failed at %s:%d with error: %s\n"),
-                "sqlite3_step", __FILE__, __LINE__,
-                sqlite3_errmsg (plugin->dbh));
-    (void) sqlite3_finalize (dstmt);
-    return GNUNET_SYSERR;
+    return 0;
   }
-  plugin->env->delete_notify (plugin->env->cls, &hc, dsize + OVERHEAD);
-  if (SQLITE_OK != sqlite3_finalize (dstmt))
-    GNUNET_log (GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
-                _("`%s' failed at %s:%d with error: %s\n"),
-                "sqlite3_finalize", __FILE__, __LINE__,
-                sqlite3_errmsg (plugin->dbh));
-  return GNUNET_OK;
+  if (SQLITE_ROW !=
+      sqlite3_step (plugin->get_random_stmt))
+  {
+    GNUNET_break (0);
+    GNUNET_SQ_reset (plugin->dbh,
+                     plugin->get_random_stmt);
+    return 0;
+  }
+  if (GNUNET_OK !=
+      GNUNET_SQ_extract_result (plugin->get_random_stmt,
+                                rs))
+  {
+    GNUNET_break (0);
+    GNUNET_SQ_reset (plugin->dbh,
+                     plugin->get_random_stmt);
+    return 0;
+  }
+  if (0 != psize % sizeof (struct GNUNET_PeerIdentity))
+  {
+    GNUNET_break (0);
+    psize = 0;
+    path = NULL;
+  }
+  psize /= sizeof (struct GNUNET_PeerIdentity);
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Found %u-byte result with key %s when processing GET-RANDOM\n",
+       (unsigned int) size,
+       GNUNET_h2s (&key));
+  (void) iter (iter_cls,
+               &key,
+               size,
+               dat,
+               (enum GNUNET_BLOCK_Type) type,
+               exp,
+               psize,
+               path);
+  GNUNET_SQ_cleanup_result (rs);
+  GNUNET_SQ_reset (plugin->dbh,
+                   plugin->get_random_stmt);
+  return 1;
+}
+
+
+/**
+ * Iterate over the results that are "close" to a particular key in
+ * the datacache.  "close" is defined as numerically larger than @a
+ * key (when interpreted as a circular address space), with small
+ * distance.
+ *
+ * @param cls closure (internal context for the plugin)
+ * @param key area of the keyspace to look into
+ * @param num_results number of results that should be returned to @a iter
+ * @param iter maybe NULL (to just count)
+ * @param iter_cls closure for @a iter
+ * @return the number of results found
+ */
+static unsigned int
+sqlite_plugin_get_closest (void *cls,
+                           const struct GNUNET_HashCode *key,
+                           unsigned int num_results,
+                           GNUNET_DATACACHE_Iterator iter,
+                           void *iter_cls)
+{
+  struct Plugin *plugin = cls;
+  uint32_t num_results32 = num_results;
+  struct GNUNET_TIME_Absolute now;
+  struct GNUNET_TIME_Absolute exp;
+  size_t size;
+  void *dat;
+  unsigned int cnt;
+  size_t psize;
+  uint32_t type;
+  struct GNUNET_HashCode hc;
+  struct GNUNET_PeerIdentity *path;
+  struct GNUNET_SQ_QueryParam params[] = {
+    GNUNET_SQ_query_param_auto_from_type (key),
+    GNUNET_SQ_query_param_absolute_time (&now),
+    GNUNET_SQ_query_param_uint32 (&num_results32),
+    GNUNET_SQ_query_param_end
+  };
+  struct GNUNET_SQ_ResultSpec rs[] = {
+    GNUNET_SQ_result_spec_variable_size (&dat,
+                                         &size),
+    GNUNET_SQ_result_spec_absolute_time (&exp),
+    GNUNET_SQ_result_spec_variable_size ((void **) &path,
+                                         &psize),
+    GNUNET_SQ_result_spec_uint32 (&type),
+    GNUNET_SQ_result_spec_auto_from_type (&hc),
+    GNUNET_SQ_result_spec_end
+  };
+
+  now = GNUNET_TIME_absolute_get ();
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Processing GET_CLOSEST for key `%s'\n",
+       GNUNET_h2s (key));
+  if (GNUNET_OK !=
+      GNUNET_SQ_bind (plugin->get_closest_stmt,
+                      params))
+  {
+    LOG_SQLITE (plugin->dbh,
+                GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
+                "sqlite3_bind_xxx");
+    GNUNET_SQ_reset (plugin->dbh,
+                     plugin->get_closest_stmt);
+    return 0;
+  }
+  cnt = 0;
+  while (SQLITE_ROW ==
+         sqlite3_step (plugin->get_closest_stmt))
+  {
+    if (GNUNET_OK !=
+        GNUNET_SQ_extract_result (plugin->get_closest_stmt,
+                                  rs))
+    {
+      GNUNET_break (0);
+      break;
+    }
+    if (0 != psize % sizeof (struct GNUNET_PeerIdentity))
+    {
+      GNUNET_break (0);
+      psize = 0;
+      path = NULL;
+    }
+    psize /= sizeof (struct GNUNET_PeerIdentity);
+    cnt++;
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Found %u-byte result at %s when processing GET_CLOSE\n",
+         (unsigned int) size,
+         GNUNET_h2s (&hc));
+    if (GNUNET_OK != iter (iter_cls,
+                           &hc,
+                           size,
+                           dat,
+                           type,
+                           exp,
+                           psize,
+                           path))
+    {
+      GNUNET_SQ_cleanup_result (rs);
+      break;
+    }
+    GNUNET_SQ_cleanup_result (rs);
+  }
+  GNUNET_SQ_reset (plugin->dbh,
+                   plugin->get_closest_stmt);
+  return cnt;
 }
 
 
 /**
  * Entry point for the plugin.
  *
- * @param cls closure (the "struct GNUNET_DATACACHE_PluginEnvironmnet")
- * @return the plugin's closure (our "struct Plugin")
+ * @param cls closure (the `struct GNUNET_DATACACHE_PluginEnvironment`)
+ * @return the plugin's closure (our `struct Plugin`)
  */
 void *
 libgnunet_plugin_datacache_sqlite_init (void *cls)
@@ -398,60 +701,129 @@ libgnunet_plugin_datacache_sqlite_init (void *cls)
   sqlite3 *dbh;
   char *emsg;
 
-  fn = GNUNET_DISK_mktemp ("gnunet-datacache");
-  if (fn == NULL)
+  if (GNUNET_YES ==
+      GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
+                                           "datacache-sqlite",
+                                           "IN_MEMORY"))
   {
-    GNUNET_break (0);
-    return NULL;
+    if (SQLITE_OK != sqlite3_open (":memory:", &dbh))
+      return NULL;
+    fn_utf8 = NULL;
   }
-#ifdef ENABLE_NLS
-  fn_utf8 = GNUNET_STRINGS_to_utf8 (fn, strlen (fn), nl_langinfo (CODESET));
-#else
-  /* good luck */
-  fn_utf8 = GNUNET_STRINGS_to_utf8 (fn, strlen (fn), "UTF-8");
-#endif
-  if (SQLITE_OK != sqlite3_open (fn_utf8, &dbh))
+  else
   {
+    fn = GNUNET_DISK_mktemp ("gnunet-datacache");
+    if (fn == NULL)
+      {
+       GNUNET_break (0);
+       return NULL;
+      }
+    /* fn should be UTF-8-encoded. If it isn't, it's a bug. */
+    fn_utf8 = GNUNET_strdup (fn);
+    if (SQLITE_OK != sqlite3_open (fn_utf8, &dbh))
+    {
+      GNUNET_free (fn);
+      GNUNET_free (fn_utf8);
+      return NULL;
+    }
     GNUNET_free (fn);
-    GNUNET_free (fn_utf8);
-    return NULL;
   }
-  GNUNET_free (fn);
 
   SQLITE3_EXEC (dbh, "PRAGMA temp_store=MEMORY");
   SQLITE3_EXEC (dbh, "PRAGMA locking_mode=EXCLUSIVE");
   SQLITE3_EXEC (dbh, "PRAGMA journal_mode=OFF");
   SQLITE3_EXEC (dbh, "PRAGMA synchronous=OFF");
-  SQLITE3_EXEC (dbh, "PRAGMA count_changes=OFF");
   SQLITE3_EXEC (dbh, "PRAGMA page_size=4092");
+  if (GNUNET_YES ==
+      GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
+                                           "datacache-sqlite",
+                                           "IN_MEMORY"))
+    SQLITE3_EXEC (dbh, "PRAGMA sqlite_temp_store=3");
+
   SQLITE3_EXEC (dbh,
-                "CREATE TABLE ds090 ("
+                "CREATE TABLE ds091 ("
                 "  type INTEGER NOT NULL DEFAULT 0,"
-                "  expire INTEGER NOT NULL DEFAULT 0,"
+                "  expire INTEGER NOT NULL,"
                 "  key BLOB NOT NULL DEFAULT '',"
-                "  value BLOB NOT NULL DEFAULT '')");
-  SQLITE3_EXEC (dbh, "CREATE INDEX idx_hashidx ON ds090 (key,type,expire)");
-  plugin = GNUNET_malloc (sizeof (struct Plugin));
+                "  prox INTEGER NOT NULL,"
+                "  value BLOB NOT NULL,"
+               "  path BLOB DEFAULT '')");
+  SQLITE3_EXEC (dbh, "CREATE INDEX idx_hashidx ON ds091 (key,type,expire)");
+  SQLITE3_EXEC (dbh, "CREATE INDEX idx_prox_expire ON ds091 (prox,expire)");
+  SQLITE3_EXEC (dbh, "CREATE INDEX idx_expire_only ON ds091 (expire)");
+  plugin = GNUNET_new (struct Plugin);
   plugin->env = env;
   plugin->dbh = dbh;
   plugin->fn = fn_utf8;
-  api = GNUNET_malloc (sizeof (struct GNUNET_DATACACHE_PluginFunctions));
+
+  if ( (SQLITE_OK !=
+        sq_prepare (plugin->dbh,
+                    "INSERT INTO ds091 (type, expire, key, prox, value, path) "
+                    "VALUES (?, ?, ?, ?, ?, ?)",
+                    &plugin->insert_stmt)) ||
+       (SQLITE_OK !=
+        sq_prepare (plugin->dbh,
+                    "SELECT count(*) FROM ds091 "
+                    "WHERE key=? AND type=? AND expire >= ?",
+                    &plugin->get_count_stmt)) ||
+       (SQLITE_OK !=
+        sq_prepare (plugin->dbh,
+                    "SELECT value,expire,path FROM ds091"
+                    " WHERE key=? AND type=? AND expire >= ? LIMIT 1 OFFSET ?",
+                    &plugin->get_stmt)) ||
+       (SQLITE_OK !=
+        sq_prepare (plugin->dbh,
+                    "SELECT _ROWID_,key,value FROM ds091"
+                    " WHERE expire < ?"
+                    " ORDER BY expire ASC LIMIT 1",
+                    &plugin->del_expired_stmt)) ||
+       (SQLITE_OK !=
+        sq_prepare (plugin->dbh,
+                    "SELECT _ROWID_,key,value FROM ds091"
+                    " ORDER BY prox ASC, expire ASC LIMIT 1",
+                    &plugin->del_select_stmt)) ||
+       (SQLITE_OK !=
+        sq_prepare (plugin->dbh,
+                    "DELETE FROM ds091 WHERE _ROWID_=?",
+                    &plugin->del_stmt)) ||
+       (SQLITE_OK !=
+        sq_prepare (plugin->dbh,
+                    "SELECT value,expire,path,key,type FROM ds091 "
+                    "ORDER BY key LIMIT 1 OFFSET ?",
+                    &plugin->get_random_stmt)) ||
+       (SQLITE_OK !=
+        sq_prepare (plugin->dbh,
+                    "SELECT value,expire,path,type,key FROM ds091 "
+                    "WHERE key>=? AND expire >= ? ORDER BY KEY ASC LIMIT ?",
+                    &plugin->get_closest_stmt))
+       )
+  {
+    LOG_SQLITE (plugin->dbh,
+                GNUNET_ERROR_TYPE_ERROR | GNUNET_ERROR_TYPE_BULK,
+                "sq_prepare");
+    GNUNET_break (SQLITE_OK ==
+                  sqlite3_close (plugin->dbh));
+    GNUNET_free (plugin);
+    return NULL;
+  }
+
+  api = GNUNET_new (struct GNUNET_DATACACHE_PluginFunctions);
   api->cls = plugin;
   api->get = &sqlite_plugin_get;
   api->put = &sqlite_plugin_put;
   api->del = &sqlite_plugin_del;
-  GNUNET_log_from (GNUNET_ERROR_TYPE_INFO,
-                   "sqlite", _("Sqlite datacache running\n"));
+  api->get_random = &sqlite_plugin_get_random;
+  api->get_closest = &sqlite_plugin_get_closest;
+  LOG (GNUNET_ERROR_TYPE_INFO,
+       "Sqlite datacache running\n");
   return api;
 }
 
-// explain SELECT type FROM gn090 WHERE NOT EXISTS (SELECT 1 from gn090 WHERE expire < 42 LIMIT 1) OR expire < 42 ORDER BY repl DESC, Random() LIMIT 1;
-
 
 /**
  * Exit point from the plugin.
  *
- * @param cls closure (our "struct Plugin")
+ * @param cls closure (our `struct Plugin`)
  * @return NULL
  */
 void *
@@ -466,44 +838,53 @@ libgnunet_plugin_datacache_sqlite_done (void *cls)
 #endif
 
 #if !WINDOWS || defined(__CYGWIN__)
-  if (0 != UNLINK (plugin->fn))
-    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING, "unlink", plugin->fn);
-  GNUNET_free (plugin->fn);
+  if ( (NULL != plugin->fn) &&
+       (0 != UNLINK (plugin->fn)) )
+    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING,
+                       "unlink",
+                       plugin->fn);
+  GNUNET_free_non_null (plugin->fn);
 #endif
+  sqlite3_finalize (plugin->insert_stmt);
+  sqlite3_finalize (plugin->get_count_stmt);
+  sqlite3_finalize (plugin->get_stmt);
+  sqlite3_finalize (plugin->del_select_stmt);
+  sqlite3_finalize (plugin->del_expired_stmt);
+  sqlite3_finalize (plugin->del_stmt);
+  sqlite3_finalize (plugin->get_random_stmt);
+  sqlite3_finalize (plugin->get_closest_stmt);
   result = sqlite3_close (plugin->dbh);
 #if SQLITE_VERSION_NUMBER >= 3007000
-  if (result == SQLITE_BUSY)
+  if (SQLITE_BUSY == result)
   {
-    GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING,
-                     "sqlite",
-                     _
-                     ("Tried to close sqlite without finalizing all prepared statements.\n"));
+    LOG (GNUNET_ERROR_TYPE_WARNING,
+         _("Tried to close sqlite without finalizing all prepared statements.\n"));
     stmt = sqlite3_next_stmt (plugin->dbh, NULL);
-    while (stmt != NULL)
+    while (NULL != stmt)
     {
-#if DEBUG_SQLITE
-      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
-                       "sqlite", "Closing statement %p\n", stmt);
-#endif
       result = sqlite3_finalize (stmt);
-#if DEBUG_SQLITE
       if (result != SQLITE_OK)
-        GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
-                         "sqlite",
-                         "Failed to close statement %p: %d\n", stmt, result);
-#endif
+        LOG (GNUNET_ERROR_TYPE_WARNING,
+             "Failed to close statement %p: %d\n",
+             stmt,
+             result);
       stmt = sqlite3_next_stmt (plugin->dbh, NULL);
     }
     result = sqlite3_close (plugin->dbh);
   }
 #endif
   if (SQLITE_OK != result)
-    LOG_SQLITE (plugin->dbh, GNUNET_ERROR_TYPE_ERROR, "sqlite3_close");
+    LOG_SQLITE (plugin->dbh,
+                GNUNET_ERROR_TYPE_ERROR,
+                "sqlite3_close");
 
 #if WINDOWS && !defined(__CYGWIN__)
-  if (0 != UNLINK (plugin->fn))
-    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING, "unlink", plugin->fn);
-  GNUNET_free (plugin->fn);
+  if ( (NULL != plugin->fn) &&
+       (0 != UNLINK (plugin->fn)) )
+    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING,
+                       "unlink",
+                       plugin->fn);
+  GNUNET_free_non_null (plugin->fn);
 #endif
   GNUNET_free (plugin);
   GNUNET_free (api);