towards PEERSTORE sqlite plugin

1 files changed, 270 insertions, 0 deletions

diff --git a/src/peerstore/plugin_peerstore_sqlite.c b/src/peerstore/plugin_peerstore_sqlite.c
new file mode 100644
index 000000000..ff6ae9f67
--- /dev/null
+++ b/src/peerstore/plugin_peerstore_sqlite.c
@@ -0,0 +1,270 @@
+/*
+ * This file is part of GNUnet
+ * (C) 2013 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 peerstore/plugin_peerstore_sqlite.c
+ * @brief sqlite-based peerstore backend
+ * @author Omar Tarabai
+ */
+
+#include "platform.h"
+#include "gnunet_peerstore_plugin.h"
+#include "gnunet_peerstore_service.h"
+#include "peerstore.h"
+#include <sqlite3.h>
+
+/**
+ * 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 1s 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 1000
+
+/**
+ * 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, level, cmd) do { GNUNET_log_from (level, "peerstore-sqlite", _("`%s' failed at %s:%d with error: %s\n"), cmd, __FILE__, __LINE__, sqlite3_errmsg(db->dbh)); } while(0)
+
+#define LOG(kind,...) GNUNET_log_from (kind, "peerstore-sqlite", __VA_ARGS__)
+
+/**
+ * Context for all functions in this plugin.
+ */
+struct Plugin
+{
+
+  /**
+   * Configuration handle
+   */
+  const struct GNUNET_CONFIGURATION_Handle *cfg;
+
+  /**
+   * Database filename.
+   */
+  char *fn;
+
+  /**
+   * Native SQLite database handle.
+   */
+  sqlite3 *dbh;
+
+  /**
+   * Precompiled SQL for inserting into peerstoredata
+   */
+  sqlite3_stmt *insert_peerstoredata;
+
+};
+
+/**
+ * @brief Prepare a SQL statement
+ *
+ * @param dbh handle to the database
+ * @param sql SQL statement, UTF-8 encoded
+ * @return 0 on success
+ */
+static int
+sql_exec (sqlite3 *dbh, const char *sql)
+{
+  int result;
+
+  result = sqlite3_exec (dbh, sql, NULL, NULL, NULL);
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Executed `%s' / %d\n", sql, result);
+  if (result != SQLITE_OK)
+    LOG (GNUNET_ERROR_TYPE_ERROR,
+   _("Error executing SQL query: %s\n  %s\n"),
+   sqlite3_errmsg (dbh), sql);
+  return result;
+}
+
+/**
+ * @brief Prepare a SQL statement
+ *
+ * @param dbh handle to the database
+ * @param sql SQL statement, UTF-8 encoded
+ * @param stmt set to the prepared statement
+ * @return 0 on success
+ */
+static int
+sql_prepare (sqlite3 *dbh, const char *sql, sqlite3_stmt **stmt)
+{
+  char *tail;
+  int result;
+
+  result = sqlite3_prepare_v2 (dbh, sql, strlen (sql), stmt,
+                               (const char **) &tail);
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Prepared `%s' / %p: %d\n", sql, *stmt, result);
+  if (result != SQLITE_OK)
+    LOG (GNUNET_ERROR_TYPE_ERROR,
+   _("Error preparing SQL query: %s\n  %s\n"),
+   sqlite3_errmsg (dbh), sql);
+  return result;
+}
+
+/**
+ * Initialize the database connections and associated
+ * data structures (create tables and indices
+ * as needed as well).
+ *
+ * @param plugin the plugin context (state for this module)
+ * @return GNUNET_OK on success
+ */
+static int
+database_setup (struct Plugin *plugin)
+{
+  char *filename;
+
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_filename (plugin->cfg, "peerstore-sqlite",
+                                               "FILENAME", &filename))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+             "peerstore-sqlite", "FILENAME");
+    return GNUNET_SYSERR;
+  }
+  if (GNUNET_OK != GNUNET_DISK_file_test (filename))
+  {
+    if (GNUNET_OK != GNUNET_DISK_directory_create_for_file (filename))
+    {
+      GNUNET_break (0);
+      GNUNET_free (filename);
+      return GNUNET_SYSERR;
+    }
+  }
+  /* filename should be UTF-8-encoded. If it isn't, it's a bug */
+  plugin->fn = filename;
+
+  /* Open database and precompile statements */
+  if (SQLITE_OK != sqlite3_open (plugin->fn, &plugin->dbh))
+  {
+    LOG (GNUNET_ERROR_TYPE_ERROR,
+   _("Unable to initialize SQLite: %s.\n"),
+   sqlite3_errmsg (plugin->dbh));
+    return GNUNET_SYSERR;
+  }
+
+  sql_exec (plugin->dbh, "PRAGMA temp_store=MEMORY");
+  sql_exec (plugin->dbh, "PRAGMA synchronous=NORMAL");
+  sql_exec (plugin->dbh, "PRAGMA legacy_file_format=OFF");
+  sql_exec (plugin->dbh, "PRAGMA auto_vacuum=INCREMENTAL");
+  sql_exec (plugin->dbh, "PRAGMA encoding=\"UTF-8\"");
+  sql_exec (plugin->dbh, "PRAGMA count_changes=OFF");
+  sql_exec (plugin->dbh, "PRAGMA page_size=4096");
+
+  sqlite3_busy_timeout (plugin->dbh, BUSY_TIMEOUT_MS);
+
+  /* Create tables */
+
+  sql_exec (plugin->dbh,
+            "CREATE TABLE IF NOT EXISTS peerstoredata (\n"
+            "  sub_system TEXT NOT NULL,\n"
+            "  peer_id BLOB NOT NULL,\n"
+            "  value BLOB NULL"
+            ");");
+
+  /* Prepare statements */
+
+  sql_prepare (plugin->dbh,
+               "INSERT INTO peerstoredata (sub_system, peer_id, value) VALUES (?,?,?);",
+               &plugin->insert_peerstoredata);
+
+  return GNUNET_OK;
+}
+
+/**
+ * Shutdown database connection and associate data
+ * structures.
+ * @param plugin the plugin context (state for this module)
+ */
+static void
+database_shutdown (struct Plugin *plugin)
+{
+  int result;
+  sqlite3_stmt *stmt;
+  while (NULL != (stmt = sqlite3_next_stmt (plugin->dbh, NULL)))
+  {
+    result = sqlite3_finalize (stmt);
+    if (SQLITE_OK != result)
+      LOG (GNUNET_ERROR_TYPE_WARNING,
+           "Failed to close statement %p: %d\n", stmt, result);
+  }
+  if (SQLITE_OK != sqlite3_close (plugin->dbh))
+    LOG_SQLITE (plugin, GNUNET_ERROR_TYPE_ERROR, "sqlite3_close");
+
+  GNUNET_free_non_null (plugin->fn);
+}
+
+/**
+ * Entry point for the plugin.
+ *
+ * @param cls The struct GNUNET_CONFIGURATION_Handle.
+ * @return NULL on error, otherwise the plugin context
+ */
+void *
+libgnunet_plugin_peerstore_sqlite_init (void *cls)
+{
+  static struct Plugin plugin;
+  const struct GNUNET_CONFIGURATION_Handle *cfg = cls;
+  struct GNUNET_PEERSTORE_PluginFunctions *api;
+
+  if (NULL != plugin.cfg)
+    return NULL;                /* can only initialize once! */
+  memset (&plugin, 0, sizeof (struct Plugin));
+  plugin.cfg = cfg;
+  if (GNUNET_OK != database_setup (&plugin))
+  {
+    database_shutdown (&plugin);
+    return NULL;
+  }
+  api = GNUNET_new (struct GNUNET_PEERSTORE_PluginFunctions);
+  api->cls = &plugin;
+  LOG(GNUNET_ERROR_TYPE_INFO, "Sqlite plugin is running\n");
+  return api;
+}
+
+/**
+ * Exit point from the plugin.
+ *
+ * @param cls The plugin context (as returned by "init")
+ * @return Always NULL
+ */
+void *
+libgnunet_plugin_peerstore_sqlite_done (void *cls)
+{
+  struct GNUNET_PEERSTORE_PluginFunctions *api = cls;
+  struct Plugin *plugin = api->cls;
+
+  database_shutdown (plugin);
+  plugin->cfg = NULL;
+  GNUNET_free (api);
+  LOG (GNUNET_ERROR_TYPE_INFO, "Sqlite plugin is finished\n");
+  return NULL;
+
+}
+
+/* end of plugin_peerstore_sqlite.c */