public SQLiteLogTable(ITaskScheduler scheduler, LogDataCache cache, string fileName)
{
if (scheduler == null)
throw new ArgumentNullException("scheduler");
if (cache == null)
throw new ArgumentNullException("cache");
if (fileName == null)
throw new ArgumentNullException("fileName");
_scheduler = scheduler;
_cache = cache;
_fileName = fileName;
_listeners = new LogTableListenerCollection(this);
_accessQueue = new LogDataAccessQueue<LogEntryIndex, LogEntry>();
_schema = new SQLiteSchema(string.Empty);
_task = _scheduler.StartPeriodic(Update, ToString());
}
/// <summary>
/// Reads the current schema from the given database and then forces a schema update
/// of all listeners in case the schema has changed compared to the previous one.
/// </summary>
/// <param name="connection"></param>
private void UpdateSchema(SQLiteConnection connection)
{
string tableName;
if (TryFindTable(connection, out tableName))
{
SQLiteSchema schema = GetSchema(connection, tableName);
TryChangeSchema(schema);
}
else
{
Log.WarnFormat("Unable to find a fitting table in database {0}", _fileName);
var schema = new SQLiteSchema(string.Empty);
TryChangeSchema(schema);
}
}
/// <summary>
/// Changes the schema of this table, if necessary.
/// </summary>
/// <param name="schema"></param>
private void TryChangeSchema(SQLiteSchema schema)
{
if (!Equals(_schema, schema))
{
Log.DebugFormat("Schema of {0} changed from {1} to {2}", _fileName,
_schema, schema);
_schema = schema;
_rowCount = 0;
_cache.Remove(this);
_listeners.OnSchemaChanged(_schema);
_listeners.OnRead(LogEntryIndex.Invalid, 0);
}
}
