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/* table-lookup.vala
*
* Copyright © 2011 Collabora Ltd.
* By Siegfried-Angel Gevatter Pujals <siegfried@gevatter.com>
*
* Based upon a Python implementation (2009-2011) by:
* Siegfried-Angel Gevatter Pujals <siegfried@gevatter.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 2.1 of the License, or
* (at your option) any later version.
*
* This program 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 Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
namespace Zeitgeist.SQLite
{
public class TableLookup : Object
{
unowned Zeitgeist.SQLite.Database database;
unowned Sqlite.Database db;
private string table;
private HashTable<int, string> id_to_value;
private HashTable<string, int> value_to_id;
private Sqlite.Statement insertion_stmt;
private Sqlite.Statement retrieval_stmt;
public TableLookup (Database database, string table_name)
throws EngineError
{
this.database = database;
db = database.database;
table = table_name;
id_to_value = new HashTable<int, string>(direct_hash, direct_equal);
value_to_id = new HashTable<string, int>(str_hash, str_equal);
int rc;
string sql;
rc = db.exec ("SELECT id, value FROM " + table,
(n_columns, values, column_names) =>
{
id_to_value.insert (int.parse(values[0]), values[1]);
value_to_id.insert (values[1], int.parse(values[0]));
return 0;
}, null);
database.assert_query_success (rc,
"Can't init %s table".printf (table));
sql = "INSERT INTO " + table + " (value) VALUES (?)";
rc = db.prepare_v2 (sql, -1, out insertion_stmt);
database.assert_query_success (rc, "Error creating insertion_stmt");
sql = "SELECT value FROM " + table + " WHERE id=?";
rc = db.prepare_v2 (sql, -1, out retrieval_stmt);
database.assert_query_success (rc, "Error creating retrieval_stmt");
}
/**
* Searches the table for the given ID, returns -1 if not found.
*
* @see id_for_string
*/
public int id_try_string (string name)
{
int id = value_to_id.lookup (name);
if (id == 0)
return -1;
return id;
}
/**
* Searches the table for the given ID, inserts a new one if not found.
*
* @see id_try_string
*
*/
public int id_for_string (string name) throws EngineError
{
int id = value_to_id.lookup (name);
if (id == 0)
{
int rc;
insertion_stmt.reset ();
insertion_stmt.bind_text (1, name);
rc = insertion_stmt.step ();
database.assert_query_success (rc, "Error in id_for_string",
Sqlite.DONE);
id = (int) db.last_insert_rowid ();
id_to_value.insert (id, name);
value_to_id.insert (name, id);
}
return id;
}
public unowned string get_value (int id) throws EngineError
{
// When we fetch an event, it either was already in the database
// at the time Zeitgeist started or it was inserted later -using
// Zeitgeist-, so here we always have the data in memory already.
unowned string val = id_to_value.lookup (id);
if (val != null) return val;
// Unless this is a standalone reader in a separate process, in
// which case the values won't be kept updated, so we need to
// query the DB if we don't find it.
int rc;
string? text = null;
retrieval_stmt.reset ();
retrieval_stmt.bind_int64 (1, id);
if ((rc = retrieval_stmt.step()) == Sqlite.ROW)
{
text = retrieval_stmt.column_text (0);
id_to_value.insert (id, text);
value_to_id.insert (text, id);
rc = retrieval_stmt.step ();
}
database.assert_query_success (rc, "Error in get_value",
Sqlite.DONE);
if (text == null)
{
critical ("Error getting data from table: %d, %s\n",
rc, db.errmsg ());
}
return id_to_value.lookup (id);
}
public void remove (int id)
{
string name = id_to_value.lookup (id);
id_to_value.remove (id);
value_to_id.remove (name);
}
}
}
// vim:expandtab:ts=4:sw=4
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