path: root/src/datastore/plugin_datastore_sqlite.c

 /*
  * This file is part of GNUnet
  * (C) 2009, 2011 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_sqlite.c
 * @brief sqlite-based datastore backend
 * @author Christian Grothoff
 */

#include "platform.h"
#include "gnunet_datastore_plugin.h"
#include <sqlite3.h>


/**
 * We allocate items on the stack at times.  To prevent a stack
 * overflow, we impose a limit on the maximum size for the data per
 * item.  64k should be enough.
 */
#define MAX_ITEM_SIZE 65536

/**
 * After how many ms "busy" should a DB operation fail for good?
 * A low value makes sure that we are more responsive to requests
 * (especially PUTs).  A high value guarantees a higher success
 * rate (SELECTs in iterate can take several seconds despite LIMIT=1).
 *
 * The default value of 250ms should ensure that users do not experience
 * huge latencies while at the same time allowing operations to succeed
 * with reasonable probability.
 */
#define BUSY_TIMEOUT_MS 250


/**
 * 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_SQLITE(db, msg, level, cmd) do { GNUNET_log_from (level, "sqlite", _("`%s' failed at %s:%d with error: %s\n"), cmd, __FILE__, __LINE__, sqlite3_errmsg(db->dbh)); if (msg != NULL) GNUNET_asprintf(msg, _("`%s' failed at %s:%u with error: %s"), cmd, __FILE__, __LINE__, sqlite3_errmsg(db->dbh)); } while(0)



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

  /**
   * Database filename.
   */
  char *fn;

  /**
   * Native SQLite database handle.
   */
  sqlite3 *dbh;

  /**
   * Precompiled SQL for deletion.
   */
  sqlite3_stmt *delRow;

  /**
   * Precompiled SQL for update.
   */
  sqlite3_stmt *updPrio;

  /**
   * Get maximum repl value in database.
   */
  sqlite3_stmt *maxRepl;

  /**
   * Precompiled SQL for replication decrement.
   */
  sqlite3_stmt *updRepl;

  /**
   * Precompiled SQL for replication selection.
   */
  sqlite3_stmt *selRepl;

  /**
   * Precompiled SQL for expiration selection.
   */
  sqlite3_stmt *selExpi;

  /**
   * Precompiled SQL for expiration selection.
   */
  sqlite3_stmt *selZeroAnon;

  /**
   * Precompiled SQL for insertion.
   */
  sqlite3_stmt *insertContent;

  /**
   * Should the database be dropped on shutdown?
   */
  int drop_on_shutdown;

};


/**
 * @brief Prepare a SQL statement
 *
 * @param dbh handle to the database
 * @param zSql SQL statement, UTF-8 encoded
 * @param ppStmt set to the prepared statement
 * @return 0 on success
 */
static int
sq_prepare (sqlite3 * dbh, const char *zSql, sqlite3_stmt ** ppStmt)
{
  char *dummy;
  int result;

  result =
      sqlite3_prepare_v2 (dbh, zSql, strlen (zSql), ppStmt,
                          (const char **) &dummy);
  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "sqlite",
                   "Prepared `%s' / %p: %d\n", zSql, *ppStmt, result);
  return result;
}


/**
 * Create our database indices.
 *
 * @param dbh handle to the database
 */
static void
create_indices (sqlite3 * dbh)
{
  /* create indices */
  if ((SQLITE_OK !=
       sqlite3_exec (dbh, "CREATE INDEX IF NOT EXISTS idx_hash ON gn090 (hash)",
                     NULL, NULL, NULL)) ||
      (SQLITE_OK !=
       sqlite3_exec (dbh,
                     "CREATE INDEX IF NOT EXISTS idx_hash_vhash ON gn090 (hash,vhash)",
                     NULL, NULL, NULL)) ||
      (SQLITE_OK !=
       sqlite3_exec (dbh,
                     "CREATE INDEX IF NOT EXISTS idx_expire_repl ON gn090 (expire ASC,repl DESC)",
                     NULL, NULL, NULL)) ||
      (SQLITE_OK !=
       sqlite3_exec (