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[oweals/gnunet.git] / src / datastore / plugin_datastore_mysql.c

/*
     This file is part of GNUnet
     (C) 2009, 2010 Christian Grothoff (and other contributing authors)

     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 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.

     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.
*/

/**
 * @file datastore/plugin_datastore_mysql.c
 * @brief mysql-based datastore backend
 * @author Igor Wronsky
 * @author Christian Grothoff
 *
 * NOTE: This db module does NOT work with mysql prior to 4.1 since
 * it uses prepared statements.  MySQL 5.0.46 promises to fix a bug
 * in MyISAM that is causing us grief.  At the time of this writing,
 * that version is yet to be released.  In anticipation, the code
 * will use MyISAM with 5.0.46 (and higher).  If you run such a
 * version, please run "make check" to verify that the MySQL bug
 * was actually fixed in your version (and if not, change the
 * code below to use MyISAM for gn071).
 *
 * HIGHLIGHTS
 *
 * Pros
 * + On up-to-date hardware where mysql can be used comfortably, this
 *   module will have better performance than the other db choices
 *   (according to our tests).
 * + Its often possible to recover the mysql database from internal
 *   inconsistencies. The other db choices do not support repair!
 * Cons
 * - Memory usage (Comment: "I have 1G and it never caused me trouble")
 * - Manual setup
 *
 * MANUAL SETUP INSTRUCTIONS
 *
 * 1) in /etc/gnunet.conf, set
 *    <pre>
 *
 *     sqstore = "sqstore_mysql"
 *
 *    </pre>
 * 2) Then access mysql as root,
 *    <pre>
 *
 *    $ mysql -u root -p
 *
 *    </pre>
 *    and do the following. [You should replace $USER with the username
 *    that will be running the gnunetd process].
 *    <pre>
 *
      CREATE DATABASE gnunet;
      GRANT select,insert,update,delete,create,alter,drop,create temporary tables
         ON gnunet.* TO $USER@localhost;
      SET PASSWORD FOR $USER@localhost=PASSWORD('$the_password_you_like');
      FLUSH PRIVILEGES;
 *
 *    </pre>
 * 3) In the $HOME directory of $USER, create a ".my.cnf" file
 *    with the following lines
 *    <pre>

      [client]
      user=$USER
      password=$the_password_you_like

 *    </pre>
 *
 * Thats it. Note that .my.cnf file is a security risk unless its on
 * a safe partition etc. The $HOME/.my.cnf can of course be a symbolic
 * link. Even greater security risk can be achieved by setting no
 * password for $USER.  Luckily $USER has only priviledges to mess
 * up GNUnet's tables, nothing else (unless you give him more,
 * of course).<p>
 *
 * 4) Still, perhaps you should briefly try if the DB connection
 *    works. First, login as $USER. Then use,
 *
 *    <pre>
 *    $ mysql -u $USER -p $the_password_you_like
 *    mysql> use gnunet;
 *    </pre>
 *
 *    If you get the message &quot;Database changed&quot; it probably works.
 *
 *    [If you get &quot;ERROR 2002: Can't connect to local MySQL server
 *     through socket '/tmp/mysql.sock' (2)&quot; it may be resolvable by
 *     &quot;ln -s /var/run/mysqld/mysqld.sock /tmp/mysql.sock&quot;
 *     so there may be some additional trouble depending on your mysql setup.]
 *
 * REPAIRING TABLES
 *
 * - Its probably healthy to check your tables for inconsistencies
 *   every now and then.
 * - If you get odd SEGVs on gnunetd startup, it might be that the mysql
 *   databases have been corrupted.
 * - The tables can be verified/fixed in two ways;
 *   1) by running mysqlcheck -A, or
 *   2) by executing (inside of mysql using the GNUnet database):
 *   mysql> REPAIR TABLE gn080;
 *   mysql> REPAIR TABLE gn072;
 *
 * PROBLEMS?
 *
 * If you have problems related to the mysql module, your best
 * friend is probably the mysql manual. The first thing to check
 * is that mysql is basically operational, that you can connect
 * to it, create tables, issue queries etc.
 *
 */

#include "platform.h"
#include "plugin_datastore.h"

#define DEBUG_MYSQL GNUNET_NO

#define MAX_DATUM_SIZE 65536

/**
 * Maximum number of supported parameters for a prepared
 * statement.  Increase if needed.
 */
#define MAX_PARAM 16

/**
 * Die with an error message that indicates
 * a failure of the command 'cmd' with the message given
 * by strerror(errno).
 */
#define DIE_MYSQL(cmd, dbh) do { GNUNET_log(GNUNET_ERROR_TYPE_ERROR, _("`%s' failed at %s:%d with error: %s\n"), cmd, __FILE__, __LINE__, mysql_error((dbh)->dbf)); abort(); } while(0);

/**
 * 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).
 */
#define LOG_MYSQL(level, cmd, dbh) do { GNUNET_log(level, _("`%s' failed at %s:%d with error: %s\n"), cmd, __FILE__, __LINE__, mysql_error((dbh)->dbf)); } while(0);


/* warning, slighly crazy mysql statements ahead.  Essentially, MySQL does not handle
   "OR" very well, so we need to use UNION instead.  And UNION does not
   automatically apply a LIMIT on the outermost clause, so we need to
   repeat ourselves quite a bit.  All hail the performance gods (and thanks
   to #mysql on freenode) */
#define SELECT_IT_LOW_PRIORITY "(SELECT size,type,prio,anonLevel,expire,hash,vkey FROM gn080 FORCE INDEX(prio) WHERE (prio = ? AND vkey > ?) "\
                               "ORDER BY prio ASC,vkey ASC LIMIT 1) "\
                               "UNION "\
                               "(SELECT size,type,prio,anonLevel,expire,hash,vkey FROM gn080 FORCE INDEX(prio) WHERE (prio > ? AND vkey != ?)"\
                               "ORDER BY prio ASC,vkey ASC LIMIT 1)"\
                               "ORDER BY prio ASC,vkey ASC LIMIT 1"

#define SELECT_IT_NON_ANONYMOUS "(SELECT size,type,prio,anonLevel,expire,hash,vkey FROM gn080 FORCE INDEX(prio) WHERE (prio = ? AND vkey < ?)"\
                                " AND anonLevel=0 ORDER BY prio DESC,vkey DESC LIMIT 1) "\
                                "UNION "\
                                "(SELECT size,type,prio,anonLevel,expire,hash,vkey FROM gn080 FORCE INDEX(prio) WHERE (prio < ? AND vkey != ?)"\
                                " AND anonLevel=0 ORDER BY prio DESC,vkey DESC LIMIT 1) "\
                                "ORDER BY prio DESC,vkey DESC LIMIT 1"

#define SELECT_IT_EXPIRATION_TIME "(SELECT size,type,prio,anonLevel,expire,hash,vkey FROM gn080 FORCE INDEX(expire) WHERE (expire = ? AND vkey > ?) "\
                                  "ORDER BY expire ASC,vkey ASC LIMIT 1) "\
                                  "UNION "\
                                  "(SELECT size,type,prio,anonLevel,expire,hash,vkey FROM gn080 FORCE INDEX(expire) WHERE (expire > ? AND vkey != ?) "\
                                  "ORDER BY expire ASC,vkey ASC LIMIT 1)"\
                                  "ORDER BY expire ASC,vkey ASC LIMIT 1"


#define SELECT_IT_MIGRATION_ORDER "(SELECT size,type,prio,anonLevel,expire,hash,vkey FROM gn080 FORCE INDEX(expire) WHERE (expire = ? AND vkey < ?)"\
                                  " AND expire > ? AND type!=3"\
                                  " ORDER BY expire DESC,vkey DESC LIMIT 1) "\
                                  "UNION "\
                                  "(SELECT size,type,prio,anonLevel,expire,hash,vkey FROM gn080 FORCE INDEX(expire) WHERE (expire < ? AND vkey != ?)"\
                                  " AND expire > ? AND type!=3"\
                                  " ORDER BY expire DESC,vkey DESC LIMIT 1)"\
                                  "ORDER BY expire DESC,vkey DESC LIMIT 1"

#define SELECT_SIZE "SELECT sum(size) FROM gn080"


struct GNUNET_MysqlStatementHandle
{
  struct GNUNET_MysqlStatementHandle *next;

  struct GNUNET_MysqlStatementHandle *prev;

  char *query;

  MYSQL_STMT *statement;

  int valid;

};


/**
 * Context for all functions in this plugin.
 */
struct Plugin 
{
  /**
   * Our execution environment.
   */
  struct GNUNET_DATASTORE_PluginEnvironment *env;

  MYSQL *dbf;
  
  struct GNUNET_MysqlStatementHandle *shead;

  struct GNUNET_MysqlStatementHandle *stail;

  /**
   * Filename of "my.cnf" (msyql configuration).
   */
  char *cnffile;

  /**
   * Statements dealing with gn072 table 
   */
#define SELECT_VALUE "SELECT value FROM gn072 WHERE vkey=?"
  struct GNUNET_MysqlStatementHandle *select_value;

#define DELETE_VALUE "DELETE FROM gn072 WHERE vkey=?"o
  struct GNUNET_MysqlStatementHandle *delete_value;

#define INSERT_VALUE "INSERT INTO gn072 (value) VALUES (?)"
  struct GNUNET_MysqlStatementHandle *insert_value;

  /**
   * Statements dealing with gn080 table 
   */
#define INSERT_ENTRY "INSERT INTO gn080 (size,type,prio,anonLevel,expire,hash,vhash,vkey) VALUES (?,?,?,?,?,?,?,?)"
  struct GNUNET_MysqlStatementHandle *insert_entry;
  
#define DELETE_ENTRY_BY_VKEY "DELETE FROM gn080 WHERE vkey=?"
  struct GNUNET_MysqlStatementHandle *delete_entry_by_vkey;
  
#define SELECT_ENTRY_BY_HASH "SELECT size,type,prio,anonLevel,expire,hash,vkey FROM gn080 FORCE INDEX (hash_vkey) WHERE hash=? AND vkey > ? ORDER BY vkey ASC LIMIT 1 OFFSET ?"
  struct GNUNET_MysqlStatementHandle *select_entry_by_hash;
  
#define SELECT_ENTRY_BY_HASH_AND_VHASH "SELECT size,type,prio,anonLevel,expire,hash,vkey FROM gn080 FORCE INDEX (hash_vhash_vkey) WHERE hash=? AND vhash=? AND vkey > ? ORDER BY vkey ASC LIMIT 1 OFFSET ?"
  struct GNUNET_MysqlStatementHandle *select_entry_by_hash_and_vhash;

#define SELECT_ENTRY_BY_HASH_AND_TYPE "SELECT size,type,prio,anonLevel,expire,hash,vkey FROM gn080 FORCE INDEX (hash_vkey) WHERE hash=? AND vkey > ? AND type=? ORDER BY vkey ASC LIMIT 1 OFFSET ?"
  struct GNUNET_MysqlStatementHandle *select_entry_by_hash_and_type;
  
#define SELECT_ENTRY_BY_HASH_VHASH_AND_TYPE "SELECT size,type,prio,anonLevel,expire,hash,vkey FROM gn080 FORCE INDEX (hash_vhash_vkey) WHERE hash=? AND vhash=? AND vkey > ? AND type=? ORDER BY vkey ASC LIMIT 1 OFFSET ?"
  struct GNUNET_MysqlStatementHandle *select_entry_by_hash_vhash_and_type;
  
#define COUNT_ENTRY_BY_HASH "SELECT count(*) FROM gn080 FORCE INDEX (hash) WHERE hash=?"
  struct GNUNET_MysqlStatementHandle *count_entry_by_hash;

#define COUNT_ENTRY_BY_HASH_AND_VHASH "SELECT count(*) FROM gn080 FORCE INDEX (hash_vhash_vkey) WHERE hash=? AND vhash=?"
  struct GNUNET_MysqlStatementHandle *count_entry_by_hash_and_vhash;

#define COUNT_ENTRY_BY_HASH_AND_TYPE "SELECT count(*) FROM gn080 FORCE INDEX (hash) WHERE hash=? AND type=?"
  struct GNUNET_MysqlStatementHandle *count_entry_by_hash_and_type;

#define COUNT_ENTRY_BY_HASH_VHASH_AND_TYPE "SELECT count(*) FROM gn080 FORCE INDEX (hash_vhash) WHERE hash=? AND vhash=? AND type=?"
  struct GNUNET_MysqlStatementHandle *count_entry_by_hash_vhash_and_type;

#define UPDATE_ENTRY "UPDATE gn080 SET prio=prio+?,expire=IF(expire>=?,expire,?) WHERE vkey=?"
  struct GNUNET_MysqlStatementHandle *update_entry;

  struct GNUNET_MysqlStatementHandle *iter[4];

  //static unsigned int stat_size;

  /**
   * Size of the mysql database on disk.
   */
  unsigned long long content_size;

};


/**
 * Obtain the location of ".my.cnf".
 * @return NULL on error
 */
static char *
get_my_cnf_path (struct GNUNET_ConfigurationHandle *cfg)
{
  char *cnffile;
  char *home_dir;
  struct stat st;
#ifndef WINDOWS
  struct passwd *pw;
#endif

#ifndef WINDOWS
  pw = getpwuid (getuid ());
  if (!pw)
    {
      GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, 
                           "getpwuid");
      return NULL;
    }
  home_dir = GNUNET_strdup (pw->pw_dir);
#else
  home_dir = (char *) GNUNET_malloc (_MAX_PATH + 1);
  plibc_conv_to_win_path ("~/", home_dir);
#endif
  GNUNET_asprintf (&cnffile, "%s/.my.cnf", home_dir);
  GNUNET_free (home_dir);
  GNUNET_CONFIUGRATION_get_value_filename (cfg,
                                           "MYSQL", "CONFIG", cnffile,
                                           &home_dir);
  GNUNET_free (cnffile);
  cnffile = home_dir;
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              _("Trying to use file `%s' for MySQL configuration.\n"),
              cnffile);
  if ((0 != STAT (cnffile, &st)) ||
      (0 != ACCESS (cnffile, R_OK)) || (!S_ISREG (st.st_mode)))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  _("Could not access file `%s': %s\n"), cnffile,
                  STRERROR (errno));
      GNUNET_free (cnffile);
      return NULL;
    }
  return cnffile;
}


/**
 * Close database connection and all prepared statements (we got a DB
 * disconnect error).
 */
static int
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;
    }
  if (plugin->dbf != NULL)
    {
      mysql_close (plugin->dbf);
      plugin->dbf = NULL;
    }
  return GNUNET_OK;
}


/**
 * Open the connection with the database (and initialize
 * our default options).
 *
 * @return GNUNET_OK on success
 */
static int
iopen (struct Plugin *ret)
{
  char *mysql_dbname;
  char *mysql_server;
  char *mysql_user;
  char *mysql_password;
  unsigned long long mysql_port;
  my_bool reconnect;
  unsigned int timeout;

  ret->dbf = mysql_init (NULL);
  if (ret->dbf == NULL)
    return GNUNET_SYSERR;
  if (ret->cnffile != NULL)
    mysql_options (ret->dbf, MYSQL_READ_DEFAULT_FILE, ret->cnffile);
  mysql_options (ret->dbf, MYSQL_READ_DEFAULT_GROUP, "client");
  reconnect = 0;
  mysql_options (ret->dbf, MYSQL_OPT_RECONNECT, &reconnect);
  mysql_options (ret->dbf,
                 MYSQL_OPT_CONNECT_TIMEOUT, (const void *) &timeout);
  timeout = 60; /* in seconds */
  mysql_options (ret->dbf, MYSQL_OPT_READ_TIMEOUT, (const void *) &timeout);
  mysql_options (ret->dbf, MYSQL_OPT_WRITE_TIMEOUT, (const void *) &timeout);
  mysql_dbname = NULL;
  if (GNUNET_YES == GNUNET_CONFIGURATION_have_value (ret->env->cfg,
                                                     "MYSQL", "DATABASE"))
    GNUNET_assert (GNUNET_OK == 
                   GNUNET_CONFIGURATION_get_value_string (ret->env->cfg,
                                                          "MYSQL", "DATABASE", 
                                                          &mysql_dbname));
  else
    mysql_dbname = GNUNET_strdup ("gnunet");
  mysql_user = NULL;
  if (GNUNET_YES == GNUNET_CONFIGURATION_have_value (ret->env->cfg,
                                                     "MYSQL", "USER"))
    {
      GNUNET_break (GNUNET_OK == 
                    GNUNET_CONFIGURATION_get_value_string (ret->env->cfg,
                                                           "MYSQL", "USER", 
                                                           &mysql_user));
    }
  mysql_password = NULL;
  if (GNUNET_YES == GNUNET_CONFIGURATION_have_value (ret->env->cfg,
                                                     "MYSQL", "PASSWORD"))
    {
      GNUNET_break (GNUNET_OK ==
                    GNUNET_CONFIGURATION_get_value_string (ret->cfg,
                                                           "MYSQL", "PASSWORD",
                                                           &mysql_password));
    }
  mysql_server = NULL;
  if (GNUNET_YES == GNUNET_CONFIGURATION_have_value (ret->cfg,
                                                     "MYSQL", "HOST"))
    {
      GNUNET_break (GNUNET_OK == 
                    GNUNET_CONFIGURATION_get_value_string (ret->cfg,
                                                           "MYSQL", "HOST", "",
                                                           &mysql_server));
    }
  mysql_port = 0;
  if (GNUNET_YES == GNUNET_CONFIGURATION_have_value (ret->cfg,
                                                     "MYSQL", "PORT"))
    {
      GNUNET_break (GNUNET_OK ==
                    GNUNET_CONFIGURATION_get_value_number (ret->cfg, "MYSQL",
                                                           "PORT", &mysql_port));
    }

  GNUNET_assert (mysql_dbname != NULL);
  mysql_real_connect (ret->dbf, mysql_server, mysql_user, mysql_password,
                      mysql_dbname, (unsigned int) mysql_port, NULL, 0);
  GNUNET_free (mysql_dbname);
  if (mysql_error (ret->dbf)[0])
    {
      LOG_MYSQL (GNUNET_ERROR_TYPE_ERROR,
                 "mysql_real_connect", ret);
      return GNUNET_SYSERR;
    }
  ret->valid = GNUNET_YES;
  return GNUNET_OK;
}


/**
 * Run the given MySQL statement.
 *
 * @return GNUNET_OK on success, GNUNET_SYSERR on error
 */
static int
run_statement (struct Plugin *plugin,
               const char *statement)
{
  if ((NULL == plugin->dbh) && (GNUNET_OK != iopen (plugin)))
    return GNUNET_SYSERR;
  mysql_query (plugin->dbf, statement);
  if (mysql_error (plugin->dbf)[0])
    {
      LOG_MYSQL (GNUNET_ERROR_TYPE_ERROR,
                 "mysql_query", plugin);
      iclose (plugin);
      return GNUNET_SYSERR;
    }
  return GNUNET_OK;
}


/**
 * Run the given MySQL SELECT statement.  The statement
 * must have only a single result (one column, one row).
 *
 * @return result on success, NULL on error
 */
static char *
run_statement_select (struct Plugin *plugin,
                      const char *statement)
{
  MYSQL_RES *sql_res;
  MYSQL_ROW sql_row;
  char *ret;
  
  if ((NULL == plugin->dbh) && (GNUNET_OK != iopen (plugin)))
    return NULL;
  mysql_query (plugin->dbf, statement);
  if ((mysql_error (plugin->dbf)[0]) ||
      (!(sql_res = mysql_use_result (plugin->dbf))) ||
      (!(sql_row = mysql_fetch_row (sql_res))))
    {
      LOG_MYSQL (GNUNET_ERROR_TYPE_ERROR,
                 "mysql_query", plugin);
      return NULL;
    }
  if ((mysql_num_fields (sql_res) != 1) || (sql_row[0] == NULL))
    {
      GNUNET_break (mysql_num_fields (sql_res) == 1);
      if (sql_res != NULL)
        mysql_free_result (sql_res);
      return NULL;
    }
  ret = GNUNET_strdup (sql_row[0]);
  mysql_free_result (sql_res);
  return ret;
}


/**
 * Create a prepared statement.
 *
 * @return NULL on error
 */
static struct GNUNET_MysqlStatementHandle *
prepared_statement_create (struct Plugin *plugin, 
                           const char *statement)
{
  struct GNUNET_MysqlStatementHandle *ret;

  ret = GNUNET_malloc (sizeof (struct GNUNET_MysqlStatementHandle));
  ret->query = GNUNET_strdup (statement);
  GNUNET_CONTAINER_DLL_insert (plugin->shead,
                               plugin->stail,
                               ret);
  return ret;
}


/**
 * Prepare a statement for running.
 *
 * @return GNUNET_OK on success
 */
static int
prepare_statement (struct Plugin *plugin, 
                   struct GNUNET_MysqlStatementHandle *ret)
{
  if (GNUNET_YES == ret->valid)
    return GNUNET_OK;
  if ((NULL == plugin->dbh) && 
      (GNUNET_OK != iopen (plugin)))
    return GNUNET_SYSERR;
  ret->statement = mysql_stmt_init (plugin->dbf);
  if (ret->statement == NULL)
    {
      iclose (plugin);
      return GNUNET_SYSERR;
    }
  if (mysql_stmt_prepare (ret->statement, 
                          ret->query,
                          strlen (ret->query)))
    {
      LOG_MYSQL (GNUNET_ERROR_TYPE_ERROR,
                 "mysql_stmt_prepare", 
                 plugin);
      mysql_stmt_close (ret->statement);
      ret->statement = NULL;
      iclose (plugin);
      return GNUNET_SYSERR;
    }
  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);
}


/**
 * Bind the parameters for the given MySQL statement
 * and run it.
 *
 * @param s statement to bind and run
 * @param ap arguments for the binding
 * @return GNUNET_SYSERR on error, GNUNET_OK on success
 */
static int
init_params (struct Plugin *plugin,
             struct GNUNET_MysqlStatementHandle *s,
             va_list ap)
{
  MYSQL_BIND qbind[MAX_PARAM];
  unsigned int pc;
  unsigned int off;
  enum enum_field_types ft;

  pc = mysql_stmt_param_count (s->statement);
  if (pc > MAX_PARAM)
    {
      /* increase internal constant! */
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  memset (qbind, 0, sizeof (qbind));
  off = 0;
  ft = 0;
  while ((pc > 0) && (-1 != (ft = va_arg (ap, enum enum_field_types))))
    {
      qbind[off].buffer_type = ft;
      switch (ft)
        {
        case MYSQL_TYPE_FLOAT:
          qbind[off].buffer = va_arg (ap, float *);
          break;
        case MYSQL_TYPE_LONGLONG:
          qbind[off].buffer = va_arg (ap, unsigned long long *);
          qbind[off].is_unsigned = va_arg (ap, int);
          break;
        case MYSQL_TYPE_LONG:
          qbind[off].buffer = va_arg (ap, unsigned int *);
          qbind[off].is_unsigned = va_arg (ap, int);
          break;
        case MYSQL_TYPE_VAR_STRING:
        case MYSQL_TYPE_STRING:
        case MYSQL_TYPE_BLOB:
          qbind[off].buffer = va_arg (ap, void *);
          qbind[off].buffer_length = va_arg (ap, unsigned long);
          qbind[off].length = va_arg (ap, unsigned long *);
          break;
        default:
          /* unsupported type */
          GNUNET_break (0);
          return GNUNET_SYSERR;
        }
      pc--;
      off++;
    }
  if (!((pc == 0) && (ft != -1) && (va_arg (ap, int) == -1)))
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  if (mysql_stmt_bind_param (s->statement, qbind))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  _("`%s' failed at %s:%d with error: %s\n"),
                  "mysql_stmt_bind_param",
                  __FILE__, __LINE__, mysql_stmt_error (s->statement));
      iclose (plugin);
      return GNUNET_SYSERR;
    }
  if (mysql_stmt_execute (s->statement))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  _("`%s' failed at %s:%d with error: %s\n"),
                  "mysql_stmt_execute",
                  __FILE__, __LINE__, mysql_stmt_error (s->statement));
      iclose (plugin);
      return GNUNET_SYSERR;
    }
  return GNUNET_OK;
}

/**
 * Type of a callback that will be called for each
 * data set returned from MySQL.
 *
 * @param cls user-defined argument
 * @param num_values number of elements in values
 * @param values values returned by MySQL
 * @return GNUNET_OK to continue iterating, GNUNET_SYSERR to abort
 */
typedef int (*GNUNET_MysqlDataProcessor) (void *cls,
                                          unsigned int num_values,
                                          MYSQL_BIND * values);


/**
 * Run a prepared SELECT statement.
 *
 * @param result_size number of elements in results array
 * @param results pointer to already initialized MYSQL_BIND
 *        array (of sufficient size) for passing results
 * @param processor function to call on each result
 * @param processor_cls extra argument to processor
 * @param ... pairs and triplets of "MYSQL_TYPE_XXX" keys and their respective
 *        values (size + buffer-reference for pointers); terminated
 *        with "-1"
 * @return GNUNET_SYSERR on error, otherwise
 *         the number of successfully affected (or queried) rows
 */
static int
prepared_statement_run_select (struct Plugin *plugin,
                               struct GNUNET_MysqlStatementHandle
                               *s,
                               unsigned int result_size,
                               MYSQL_BIND * results,
                               GNUNET_MysqlDataProcessor
                               processor, void *processor_cls,
                               ...)
{
  va_list ap;
  int ret;
  unsigned int rsize;
  int total;

  if (GNUNET_OK != prepare_statement (plugin, s))
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  va_start (ap, processor_cls);
  if (GNUNET_OK != init_params (plugin, s, ap))
    {
      GNUNET_break (0);
      va_end (ap);
      return GNUNET_SYSERR;
    }
  va_end (ap);
  rsize = mysql_stmt_field_count (s->statement);
  if (rsize > result_size)
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  if (mysql_stmt_bind_result (s->statement, results))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  _("`%s' failed at %s:%d with error: %s\n"),
                  "mysql_stmt_bind_result",
                  __FILE__, __LINE__, mysql_stmt_error (s->statement));
      iclose (plugin);
      return GNUNET_SYSERR;
    }

  total = 0;
  while (1)
    {
      ret = mysql_stmt_fetch (s->statement);
      if (ret == MYSQL_NO_DATA)
        break;
      if (ret != 0)
        {
          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                      _("`%s' failed at %s:%d with error: %s\n"),
                      "mysql_stmt_fetch",
                      __FILE__, __LINE__, mysql_stmt_error (s->statement));
          iclose (plugin);
          return GNUNET_SYSERR;
        }
      if (processor != NULL)
        if (GNUNET_OK != processor (processor_cls, rsize, results))
          break;
      total++;
    }
  mysql_stmt_reset (s->statement);
  return total;
}


/**
 * Run a prepared statement that does NOT produce results.
 *
 * @param ... pairs and triplets of "MYSQL_TYPE_XXX" keys and their respective
 *        values (size + buffer-reference for pointers); terminated
 *        with "-1"
 * @param insert_id NULL or address where to store the row ID of whatever
 *        was inserted (only for INSERT statements!)
 * @return GNUNET_SYSERR on error, otherwise
 *         the number of successfully affected rows
 */
static int
prepared_statement_run (struct Plugin *plugin,
                        struct GNUNET_MysqlStatementHandle *s,
                        unsigned long long *insert_id, ...)
{
  va_list ap;
  int affected;

  if (GNUNET_OK != prepare_statement (plugin, s))
    return GNUNET_SYSERR;
  va_start (ap, insert_id);
  if (GNUNET_OK != init_params (plugin, s, ap))
    {
      va_end (ap);
      return GNUNET_SYSERR;
    }
  va_end (ap);
  affected = mysql_stmt_affected_rows (s->statement);
  if (NULL != insert_id)
    *insert_id = (unsigned long long) mysql_stmt_insert_id (s->statement);
  mysql_stmt_reset (s->statement);
  return affected;
}


/**
 * Delete an value from the gn072 table.
 *
 * @param vkey vkey identifying the value to delete
 * @return GNUNET_OK on success, GNUNET_NO if no such value exists, GNUNET_SYSERR on error
 */
static int
do_delete_value (unsigned long long vkey)
{
  int ret;

  ret = GNUNET_MYSQL_prepared_statement_run (delete_value,
                                             NULL,
                                             MYSQL_TYPE_LONGLONG,
                                             &vkey, GNUNET_YES, -1);
  if (ret > 0)
    ret = GNUNET_OK;
  return ret;
}

/**
 * Insert a value into the gn072 table.
 *
 * @param value the value to insert
 * @param size size of the value
 * @param vkey vkey identifying the value henceforth (set)
 * @return GNUNET_OK on success, GNUNET_SYSERR on error
 */
static int
do_insert_value (const void *value, unsigned int size,
                 unsigned long long *vkey)
{
  unsigned long length = size;

  return GNUNET_MYSQL_prepared_statement_run (insert_value,
                                              vkey,
                                              MYSQL_TYPE_BLOB,
                                              value, length, &length, -1);
}

/**
 * Delete an entry from the gn080 table.
 *
 * @param vkey vkey identifying the entry to delete
 * @return GNUNET_OK on success, GNUNET_NO if no such value exists, GNUNET_SYSERR on error
 */
static int
do_delete_entry_by_vkey (unsigned long long vkey)
{
  int ret;

  ret = GNUNET_MYSQL_prepared_statement_run (delete_entry_by_vkey,
                                             NULL,
                                             MYSQL_TYPE_LONGLONG,
                                             &vkey, GNUNET_YES, -1);
  if (ret > 0)
    ret = GNUNET_OK;
  return ret;
}

static int
return_ok (void *cls, unsigned int num_values, MYSQL_BIND * values)
{
  return GNUNET_OK;
}

/**
 * Given a full (SELECT *) result set from gn080 table,
 * assemble it into a GNUNET_DatastoreValue representation.
 *
 * Call *without* holding the lock, but while within
 * mysql_thread_start/end.
 *
 * @param result location where mysql_stmt_fetch stored the results
 * @return NULL on error
 */
static GNUNET_DatastoreValue *
assembleDatum (MYSQL_BIND * result)
{
  GNUNET_DatastoreValue *datum;
  unsigned int contentSize;
  unsigned int type;
  unsigned int prio;
  unsigned int level;
  unsigned long long exp;
  unsigned long long vkey;
  unsigned long length;
  MYSQL_BIND rbind[1];
  int ret;

  if ((result[0].buffer_type != MYSQL_TYPE_LONG) ||
      (!result[0].is_unsigned) ||
      (result[1].buffer_type != MYSQL_TYPE_LONG) ||
      (!result[1].is_unsigned) ||
      (result[2].buffer_type != MYSQL_TYPE_LONG) ||
      (!result[2].is_unsigned) ||
      (result[3].buffer_type != MYSQL_TYPE_LONG) ||
      (!result[3].is_unsigned) ||
      (result[4].buffer_type != MYSQL_TYPE_LONGLONG) ||
      (!result[4].is_unsigned) ||
      (result[5].buffer_type != MYSQL_TYPE_BLOB) ||
      (result[5].buffer_length != sizeof (GNUNET_HashCode)) ||
      (*result[5].length != sizeof (GNUNET_HashCode)) ||
      (result[6].buffer_type != MYSQL_TYPE_LONGLONG) ||
      (!result[6].is_unsigned))
    {
      GNUNET_break (0);
      return NULL;              /* error */
    }

  contentSize = *(unsigned int *) result[0].buffer;
  if (contentSize < sizeof (GNUNET_DatastoreValue))
    return NULL;                /* error */
  if (contentSize > GNUNET_MAX_BUFFER_SIZE)
    {
       GNUNET_break (0); /* far too big */
       return NULL;
    }
  contentSize -= sizeof (GNUNET_DatastoreValue);
  type = *(unsigned int *) result[1].buffer;
  prio = *(unsigned int *) result[2].buffer;
  level = *(unsigned int *) result[3].buffer;
  exp = *(unsigned long long *) result[4].buffer;
  vkey = *(unsigned long long *) result[6].buffer;
  datum = GNUNET_malloc (sizeof (GNUNET_DatastoreValue) + contentSize);
  datum->size = htonl (contentSize + sizeof (GNUNET_DatastoreValue));
  datum->type = htonl (type);
  datum->priority = htonl (prio);
  datum->anonymity_level = htonl (level);
  datum->expiration_time = GNUNET_htonll (exp);

  /* now do query on gn072 */
  length = contentSize;
  memset (rbind, 0, sizeof (rbind));
  rbind[0].buffer_type = MYSQL_TYPE_BLOB;
  rbind[0].buffer_length = contentSize;
  rbind[0].length = &length;
  rbind[0].buffer = &datum[1];
  ret = GNUNET_MYSQL_prepared_statement_run_select (select_value,
                                                    1,
                                                    rbind,
                                                    &return_ok,
                                                    NULL,
                                                    MYSQL_TYPE_LONGLONG,
                                                    &vkey, GNUNET_YES, -1);
  GNUNET_break (ret <= 1);     /* should only have one result! */
  if (ret > 0)
    ret = GNUNET_OK;
  if ((ret != GNUNET_OK) ||
      (rbind[0].buffer_length != contentSize) || (length != contentSize))
    {
      GNUNET_break (ret != 0); /* should have one result! */
      GNUNET_break (length == contentSize);    /* length should match! */
      GNUNET_break (rbind[0].buffer_length == contentSize);    /* length should be internally consistent! */
      do_delete_value (vkey);
      if (ret != 0)
        do_delete_entry_by_vkey (vkey);
      content_size -= ntohl (datum->size);
      GNUNET_free (datum);
      return NULL;
    }
  return datum;
}


/**
 * Iterate over the items in the datastore
 * using the given query to select and order
 * the items.
 *
 * @param type entries of which type should be considered?
 *        Use 0 for any type.
 * @param iter never NULL
 * @param is_asc are we using ascending order?
 * @return the number of results, GNUNET_SYSERR if the
 *   iter is non-NULL and aborted the iteration
 */
static int
iterateHelper (struct Plugin *plugin,
               unsigned int type,
               int is_asc,
               unsigned int iter_select, GNUNET_DatastoreValueIterator dviter,
               void *closure)
{
  GNUNET_DatastoreValue *datum;
  int count;
  int ret;
  unsigned int last_prio;
  unsigned long long last_expire;
  unsigned long long last_vkey;
  unsigned int size;
  unsigned int rtype;
  unsigned int prio;
  unsigned int level;
  unsigned long long expiration;
  unsigned long long vkey;
  unsigned long hashSize;
  GNUNET_HashCode key;
  GNUNET_CronTime now;
  MYSQL_BIND rbind[7];

  if (is_asc)
    {
      last_prio = 0;
      last_vkey = 0;
      last_expire = 0;
    }
  else
    {
      last_prio = 0x7FFFFFFFL;
      last_vkey = 0x7FFFFFFFFFFFFFFFLL; /* MySQL only supports 63 bits */
      last_expire = 0x7FFFFFFFFFFFFFFFLL;       /* MySQL only supports 63 bits */
    }
  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 = &rtype;
  rbind[1].is_unsigned = 1;
  rbind[2].buffer_type = MYSQL_TYPE_LONG;
  rbind[2].buffer = &prio;
  rbind[2].is_unsigned = 1;
  rbind[3].buffer_type = MYSQL_TYPE_LONG;
  rbind[3].buffer = &level;
  rbind[3].is_unsigned = 1;
  rbind[4].buffer_type = MYSQL_TYPE_LONGLONG;
  rbind[4].buffer = &expiration;
  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_get_time ();
  count = 0;
  while (1)
    {
      switch (iter_select)
        {
        case 0:
        case 1:
          ret = prepared_statement_run_select (iter[iter_select],
                                               7,
                                               rbind,
                                               &return_ok,
                                               NULL,
                                               MYSQL_TYPE_LONG,
                                               &last_prio,
                                               GNUNET_YES,
                                               MYSQL_TYPE_LONGLONG,
                                               &last_vkey,
                                               GNUNET_YES,
                                               MYSQL_TYPE_LONG,
                                               &last_prio,
                                               GNUNET_YES,
                                               MYSQL_TYPE_LONGLONG,
                                               &last_vkey,
                                               GNUNET_YES, -1);
          break;
        case 2:
          ret = prepared_statement_run_select (iter[iter_select],
                                               7,
                                               rbind,
                                               &return_ok,
                                               NULL,
                                               MYSQL_TYPE_LONGLONG,
                                               &last_expire,
                                               GNUNET_YES,
                                               MYSQL_TYPE_LONGLONG,
                                               &last_vkey,
                                               GNUNET_YES,
                                               MYSQL_TYPE_LONGLONG,
                                               &last_expire,
                                               GNUNET_YES,
                                               MYSQL_TYPE_LONGLONG,
                                               &last_vkey,
                                               GNUNET_YES, -1);
          break;
        case 3:
          ret = prepared_statement_run_select (iter[iter_select],
                                               7,
                                               rbind,
                                               &return_ok,
                                               NULL,
                                               MYSQL_TYPE_LONGLONG,
                                               &last_expire,
                                               GNUNET_YES,
                                               MYSQL_TYPE_LONGLONG,
                                               &last_vkey,
                                               GNUNET_YES,
                                               MYSQL_TYPE_LONGLONG,
                                               &now,
                                               GNUNET_YES,
                                               MYSQL_TYPE_LONGLONG,
                                               &last_expire,
                                               GNUNET_YES,
                                               MYSQL_TYPE_LONGLONG,
                                               &last_vkey,
                                               GNUNET_YES,
                                               MYSQL_TYPE_LONGLONG,
                                               &now,
                                               GNUNET_YES, -1);
          break;
        default:
          GNUNET_break (0);
          return GNUNET_SYSERR;
        }
      if (ret != GNUNET_OK)
        break;
      last_vkey = vkey;
      last_prio = prio;
      last_expire = expiration;
      count++;
      if (dviter != NULL)
        {
          datum = assembleDatum (rbind);
          if (datum == NULL)
            continue;
          ret = dviter (&key, datum, closure, vkey);
          if (ret == GNUNET_SYSERR)
            {
              GNUNET_free (datum);
              break;
            }
          if (ret == GNUNET_NO)
            {
              do_delete_value (vkey);
              do_delete_entry_by_vkey (vkey);
              content_size -= ntohl (datum->size);
            }
          GNUNET_free (datum);
        }
    }
  return count;
}



/**
 * Get an estimate of how much space the database is
 * currently using.
 *
 * @param cls our "struct Plugin*"
 * @return number of bytes used on disk
 */
static unsigned long long
mysql_plugin_get_size (void *cls)
{
  struct Plugin *plugin = cls;
  return plugin->content_size;
}


/**
 * Store an item in the datastore.
 *
 * @param cls closure
 * @param key key for the item
 * @param size number of bytes in data
 * @param data content stored
 * @param type type of the content
 * @param priority priority of the content
 * @param anonymity anonymity-level for the content
 * @param expiration expiration time for the content
 * @param msg set to error message
 * @return GNUNET_OK on success
 */
static int
mysql_plugin_put (void *cls,
                     const GNUNET_HashCode * key,
                     uint32_t size,
                     const void *data,
                     enum GNUNET_BLOCK_Type type,
                     uint32_t priority,
                     uint32_t anonymity,
                     struct GNUNET_TIME_Absolute expiration,
                     char **msg)
{
  struct Plugin *plugin = cls;

  unsigned long contentSize;
  unsigned long hashSize;
  unsigned long hashSize2;
  unsigned int size;
  unsigned int type;
  unsigned int prio;
  unsigned int level;
  unsigned long long expiration;
  unsigned long long vkey;
  GNUNET_HashCode vhash;

  if (((ntohl (value->size) < sizeof (GNUNET_DatastoreValue))) ||
      ((ntohl (value->size) - sizeof (GNUNET_DatastoreValue)) >
       MAX_DATUM_SIZE))
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  hashSize = sizeof (GNUNET_HashCode);
  hashSize2 = sizeof (GNUNET_HashCode);
  size = ntohl (value->size);
  type = ntohl (value->type);
  prio = ntohl (value->priority);
  level = ntohl (value->anonymity_level);
  expiration = GNUNET_ntohll (value->expiration_time);
  contentSize = ntohl (value->size) - sizeof (GNUNET_DatastoreValue);
  GNUNET_hash (&value[1], contentSize, &vhash);

  if (GNUNET_OK != do_insert_value (&value[1], contentSize, &vkey))
    return GNUNET_SYSERR;
  if (GNUNET_OK !=
      prepared_statement_run (insert_entry,
                              NULL,
                              MYSQL_TYPE_LONG,
                              &size,
                              GNUNET_YES,
                              MYSQL_TYPE_LONG,
                              &type,
                              GNUNET_YES,
                              MYSQL_TYPE_LONG,
                              &prio,
                              GNUNET_YES,
                              MYSQL_TYPE_LONG,
                              &level,
                              GNUNET_YES,
                              MYSQL_TYPE_LONGLONG,
                              &expiration,
                              GNUNET_YES,
                              MYSQL_TYPE_BLOB,
                              key,
                              hashSize,
                              &hashSize,
                              MYSQL_TYPE_BLOB,
                              &vhash,
                              hashSize2,
                              &hashSize2,
                              MYSQL_TYPE_LONGLONG,
                              &vkey, GNUNET_YES, -1))
    {
      do_delete_value (vkey);
      return GNUNET_SYSERR;
    }
  plugin->content_size += ntohl (value->size);
  return GNUNET_OK;
}


/**
 * Function invoked on behalf of a "PluginIterator"
 * asking the database plugin to call the iterator
 * with the next item.
 *
 * @param next_cls whatever argument was given
 *        to the PluginIterator as "next_cls".
 * @param end_it set to GNUNET_YES if we
 *        should terminate the iteration early
 *        (iterator should be still called once more
 *         to signal the end of the iteration).
 */
static void 
mysql_plugin_next_request (void *next_cls,
                       int end_it)
{
  struct Plugin *plugin = cls;
  GNUNET_break (0);
}


/**
 * Iterate over the results for a particular key
 * in the datastore.
 *
 * @param cls closure
 * @param key maybe NULL (to match all entries)
 * @param vhash hash of the value, maybe NULL (to
 *        match all values that have the right key).
 *        Note that for DBlocks there is no difference
 *        betwen key and vhash, but for other blocks
 *        there may be!
 * @param type entries of which type are relevant?
 *     Use 0 for any type.
 * @param iter function to call on each matching value;
 *        will be called once with a NULL value at the end
 * @param iter_cls closure for iter
 */
static void
mysql_plugin_get (void *cls,
                  const GNUNET_HashCode * key,
                  const GNUNET_HashCode * vhash,
                  enum GNUNET_BLOCK_Type type,
                  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;
  GNUNET_DatastoreValue *datum;
  GNUNET_HashCode key;
  unsigned long hashSize;
  unsigned long hashSize2;
  MYSQL_BIND rbind[7];

  if (key == NULL)
    return iterateLowPriority (type, iter, closure);
  hashSize = sizeof (GNUNET_HashCode);
  hashSize2 = sizeof (GNUNET_HashCode);
  memset (rbind, 0, sizeof (rbind));
  total = -1;
  rbind[0].buffer_type = MYSQL_TYPE_LONGLONG;
  rbind[0].buffer = &total;
  rbind[0].is_unsigned = GNUNET_YES;
  if (type != 0)
    {
      if (vhash != NULL)
        {
          ret =
            prepared_statement_run_select
            (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,
             -1);
        }
      else
        {
          ret =
            prepared_statement_run_select
            (count_entry_by_hash_and_type, 1, rbind, &return_ok, NULL,
             MYSQL_TYPE_BLOB, key, hashSize2, &hashSize2, MYSQL_TYPE_LONG,
             &type, GNUNET_YES, -1);

        }
    }
  else
    {
      if (vhash != NULL)
        {
          ret =
            prepared_statement_run_select
            (count_entry_by_hash_and_vhash, 1, rbind, &return_ok, NULL,
             MYSQL_TYPE_BLOB, key, hashSize2, &hashSize2, MYSQL_TYPE_BLOB,
             vhash, hashSize2, &hashSize2, -1);

        }
      else
        {
          ret =
            GNUNET_MYSQL_prepared_statement_run_select (count_entry_by_hash,
                                                        1, rbind, &return_ok,
                                                        NULL, MYSQL_TYPE_BLOB,
                                                        key, hashSize2,
                                                        &hashSize2, -1);
        }
    }
  if ((ret != GNUNET_OK) || (-1 == total))
    return GNUNET_SYSERR;
  if ((iter == NULL) || (total == 0))
    return (int) total;

  last_vkey = 0;
  count = 0;
  off = GNUNET_random_u32 (GNUNET_RANDOM_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 = &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 (count == 0)
        limit_off = off;
      else
        limit_off = 0;
      if (type != 0)
        {
          if (vhash != NULL)
            {
              ret =
                prepared_statement_run_select
                (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
                (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
                (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
                (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;
      datum = assembleDatum (rbind);
      if (datum == NULL)
        continue;
      count++;
      ret = iter (&key, datum, closure, vkey);
      if (ret == GNUNET_SYSERR)
        {
          GNUNET_free (datum);
          break;
        }
      if (ret == GNUNET_NO)
        {
          do_delete_value (vkey);
          do_delete_entry_by_vkey (vkey);
          content_size -= ntohl (datum->size);
        }
      GNUNET_free (datum);
      if (count + off == total)
        last_vkey = 0;          /* back to start */
      if (count == total)
        break;
    }
}


/**
 * Update the priority for a particular key in the datastore.  If
 * the expiration time in value is different than the time found in
 * the datastore, the higher value should be kept.  For the
 * anonymity level, the lower value is to be used.  The specified
 * priority should be added to the existing priority, ignoring the
 * priority in value.
 *
 * Note that it is possible for multiple values to match this put.
 * In that case, all of the respective values are updated.
 *
 * @param cls our "struct Plugin*"
 * @param uid unique identifier of the datum
 * @param delta by how much should the priority
 *     change?  If priority + delta < 0 the
 *     priority should be set to 0 (never go
 *     negative).
 * @param expire new expiration time should be the
 *     MAX of any existing expiration time and
 *     this value
 * @param msg set to error message
 * @return GNUNET_OK on success
 */
static int
mysql_plugin_update (void *cls,
                     uint64_t uid,
                     int delta, 
                     struct GNUNET_TIME_Absolute expire,
                     char **msg)
{
  struct Plugin *plugin = cls;
  unsigned long long vkey = uid;

  return prepared_statement_run (plugin,
                                 plugin->update_entry,
                                 NULL,
                                 MYSQL_TYPE_LONG,
                                 &delta,
                                 GNUNET_NO,
                                 MYSQL_TYPE_LONGLONG,
                                 &expire.value,
                                 GNUNET_YES,
                                 MYSQL_TYPE_LONGLONG,
                                 &expire.value,
                                 GNUNET_YES,
                                 MYSQL_TYPE_LONGLONG,
                                 &vkey,
                                 GNUNET_YES, -1);
}


/**
 * Select a subset of the items in the datastore and call
 * the given iterator for each of them.
 *
 * @param cls our "struct Plugin*"
 * @param type entries of which type should be considered?
 *        Use 0 for any type.
 * @param iter function to call on each matching value;
 *        will be called once with a NULL value at the end
 * @param iter_cls closure for iter
 */
static void
mysql_plugin_iter_low_priority (void *cls,
                                   enum GNUNET_BLOCK_Type type,
                                   PluginIterator iter,
                                   void *iter_cls)
{
  struct Plugin *plugin = cls;
  iterateHelper (plugin, type, GNUNET_YES, 
                 0, iter, iter_cls); 
}


/**
 * Select a subset of the items in the datastore and call
 * the given iterator for each of them.
 *
 * @param cls our "struct Plugin*"
 * @param type entries of which type should be considered?
 *        Use 0 for any type.
 * @param iter function to call on each matching value;
 *        will be called once with a NULL value at the end
 * @param iter_cls closure for iter
 */
static void
mysql_plugin_iter_zero_anonymity (void *cls,
                                     enum GNUNET_BLOCK_Type type,
                                     PluginIterator iter,
                                     void *iter_cls)
{
  struct Plugin *plugin = cls;
  iterateHelper (plugin, type, GNUNET_NO, 1, iter, closure);
}


/**
 * Select a subset of the items in the datastore and call
 * the given iterator for each of them.
 *
 * @param cls our "struct Plugin*"
 * @param type entries of which type should be considered?
 *        Use 0 for any type.
 * @param iter function to call on each matching value;
 *        will be called once with a NULL value at the end
 * @param iter_cls closure for iter
 */
static void
mysql_plugin_iter_ascending_expiration (void *cls,
                                           enum GNUNET_BLOCK_Type type,
                                           PluginIterator iter,
                                        void *iter_cls)
{
  struct Plugin *plugin = cls;
  iterateHelper (plugin, type, GNUNET_YES, 2, iter, closure);
}


/**
 * Select a subset of the items in the datastore and call
 * the given iterator for each of them.
 *
 * @param cls our "struct Plugin*"
 * @param type entries of which type should be considered?
 *        Use 0 for any type.
 * @param iter function to call on each matching value;
 *        will be called once with a NULL value at the end
 * @param iter_cls closure for iter
 */
static void
mysql_plugin_iter_migration_order (void *cls,
                                      enum GNUNET_BLOCK_Type type,
                                      PluginIterator iter,
                                      void *iter_cls)
{
  struct Plugin *plugin = cls;
  iterateHelper (plugin, 0, GNUNET_NO, 3, iter, closure);
}


/**
 * Select a subset of the items in the datastore and call
 * the given iterator for each of them.
 *
 * @param cls our "struct Plugin*"
 * @param type entries of which type should be considered?
 *        Use 0 for any type.
 * @param iter function to call on each matching value;
 *        will be called once with a NULL value at the end
 * @param iter_cls closure for iter
 */
static void
mysql_plugin_iter_all_now (void *cls,
                              enum GNUNET_BLOCK_Type type,
                              PluginIterator iter,
                              void *iter_cls)
{
  struct Plugin *plugin = cls;
  iterateHelper (plugin, 0, GNUNET_YES, 0, iter, closure);
}


/**
 * Drop database.
 */
static void 
mysql_plugin_drop (void *cls)
{
  struct Plugin *plugin = cls;

  if ((GNUNET_OK != run_statement (plugin,
                                   "DROP TABLE gn080")) ||
      (GNUNET_OK != run_statement (plugin,
                                   "DROP TABLE gn072")))
    return;                     /* error */
  plugin->content_size = 0;
}


/**
 * Entry point for the plugin.
 *
 * @param cls the "struct GNUNET_DATASTORE_PluginEnvironment*"
 * @return our "struct Plugin*"
 */
void *
libgnunet_plugin_datastore_mysql_init (void *cls)
{
  struct GNUNET_DATASTORE_PluginEnvironment *env = cls;
  struct GNUNET_DATASTORE_PluginFunctions *api;
  struct Plugin *plugin;

  plugin = GNUNET_malloc (sizeof (struct Plugin));
  plugin->env = env;
  plugin->cnffile = get_my_cnf_path (env->cfg);
  if (GNUNET_OK != iopen (plugin))
    {
      iclose (plugin);
      GNUNET_free_non_null (plugin->cnffile);
      GNUNET_free (plugin);
      return NULL;
    }
#define MRUNS(a) (GNUNET_OK != run_statement (plugin, a) )
#define PINIT(a,b) (NULL == (a = prepared_statement_create(plugin, b)))
  if (MRUNS ("CREATE TABLE IF NOT EXISTS gn080 ("
             " size INT(11) UNSIGNED NOT NULL DEFAULT 0,"
             " type INT(11) UNSIGNED NOT NULL DEFAULT 0,"
             " prio INT(11) UNSIGNED NOT NULL DEFAULT 0,"
             " anonLevel INT(11) UNSIGNED NOT NULL DEFAULT 0,"
             " expire BIGINT UNSIGNED NOT NULL DEFAULT 0,"
             " hash BINARY(64) NOT NULL DEFAULT '',"
             " vhash BINARY(64) NOT NULL DEFAULT '',"
             " vkey BIGINT UNSIGNED NOT NULL DEFAULT 0,"
             " INDEX hash (hash(64)),"
             " INDEX hash_vhash_vkey (hash(64),vhash(64),vkey),"
             " INDEX hash_vkey (hash(64),vkey),"
             " INDEX vkey (vkey),"
             " INDEX prio (prio,vkey),"
             " INDEX expire (expire,vkey,type),"
             " INDEX anonLevel (anonLevel,prio,vkey,type)"
             ") ENGINE=InnoDB") ||
      MRUNS ("CREATE TABLE IF NOT EXISTS gn072 ("
             " vkey BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY,"
             " value BLOB NOT NULL DEFAULT '') ENGINE=MyISAM") ||
      MRUNS ("SET AUTOCOMMIT = 1") ||
      PINIT (plugin->select_value, SELECT_VALUE) ||
      PINIT (plugin->delete_value, DELETE_VALUE) ||
      PINIT (plugin->insert_value, INSERT_VALUE) ||
      PINIT (plugin->insert_entry, INSERT_ENTRY) ||
      PINIT (plugin->delete_entry_by_vkey, DELETE_ENTRY_BY_VKEY) ||
      PINIT (plugin->select_entry_by_hash, SELECT_ENTRY_BY_HASH) ||
      PINIT (plugin->select_entry_by_hash_and_vhash, SELECT_ENTRY_BY_HASH_AND_VHASH)
      || PINIT (plugin->select_entry_by_hash_and_type, SELECT_ENTRY_BY_HASH_AND_TYPE)
      || PINIT (plugin->select_entry_by_hash_vhash_and_type,
                SELECT_ENTRY_BY_HASH_VHASH_AND_TYPE)
      || PINIT (plugin->count_entry_by_hash, COUNT_ENTRY_BY_HASH)
      || PINIT (plugin->count_entry_by_hash_and_vhash, COUNT_ENTRY_BY_HASH_AND_VHASH)
      || PINIT (plugin->count_entry_by_hash_and_type, COUNT_ENTRY_BY_HASH_AND_TYPE)
      || PINIT (plugin->count_entry_by_hash_vhash_and_type,
                COUNT_ENTRY_BY_HASH_VHASH_AND_TYPE)
      || PINIT (plugin->update_entry, UPDATE_ENTRY)
      || PINIT (plugin->iter[0], SELECT_IT_LOW_PRIORITY)
      || PINIT (plugin->iter[1], SELECT_IT_NON_ANONYMOUS)
      || PINIT (plugin->iter[2], SELECT_IT_EXPIRATION_TIME)
      || PINIT (plugin->iter[3], SELECT_IT_MIGRATION_ORDER))
    {
      GNUNET_MYSQL_database_close (db);
      db = NULL;
      return GNUNET_SYSERR;
    }
#undef PINIT
#undef MRUNS


  api = GNUNET_malloc (sizeof (struct GNUNET_DATASTORE_PluginFunctions));
  api->cls = plugin;
  api->get_size = &mysql_plugin_get_size;
  api->put = &mysql_plugin_put;
  api->next_request = &mysql_plugin_next_request;
  api->get = &mysql_plugin_get;
  api->update = &mysql_plugin_update;
  api->iter_low_priority = &mysql_plugin_iter_low_priority;
  api->iter_zero_anonymity = &mysql_plugin_iter_zero_anonymity;
  api->iter_ascending_expiration = &mysql_plugin_iter_ascending_expiration;
  api->iter_migration_order = &mysql_plugin_iter_migration_order;
  api->iter_all_now = &mysql_plugin_iter_all_now;
  api->drop = &mysql_plugin_drop;
  GNUNET_log_from (GNUNET_ERROR_TYPE_INFO,
                   "mysql", _("Mysql database running\n"));
  return api;
}


/**
 * Exit point from the plugin.
 * @param cls our "struct Plugin*"
 * @return always NULL
 */
void *
libgnunet_plugin_datastore_mysql_done (void *cls)
{
  struct GNUNET_DATASTORE_PluginFunctions *api = cls;
  struct Plugin *plugin = api->cls;

  iclose (plugin);
  GNUNET_free_non_null (plugin->cnffile);
  GNUNET_free (plugin);
  GNUNET_free (plugin);
  GNUNET_free (api);
  mysql_library_end ();
  return NULL;
}

/* end of plugin_datastore_mysql.c */