protected IObservable <Unit> Initialize()
{
var ret = Observable.Create <Unit>(subj =>
{
// NB: This is in its own try block because depending on the
// platform, we may not have a modern SQLite3, where these
// PRAGMAs are supported. These aren't critical, so let them
// fail silently
try
{
// NB: Setting journal_mode returns a row, nfi
Connection.ExecuteScalar <int>("PRAGMA journal_mode=WAL");
Connection.Execute("PRAGMA temp_store=MEMORY");
Connection.Execute("PRAGMA synchronous=OFF");
}
catch (SQLiteException)
{
}
try
{
Connection.CreateTable <CacheElement>();
var schemaVersion = GetSchemaVersion();
if (schemaVersion < 2)
{
Connection.Execute("ALTER TABLE CacheElement RENAME TO VersionOneCacheElement;");
Connection.CreateTable <CacheElement>();
var sql = "INSERT INTO CacheElement SELECT Key,TypeName,Value,Expiration,\"{0}\" AS CreatedAt FROM VersionOneCacheElement;";
Connection.Execute(string.Format(sql, BlobCache.TaskpoolScheduler.Now.UtcDateTime.Ticks));
Connection.Execute("DROP TABLE VersionOneCacheElement;");
Connection.Insert(new SchemaInfo()
{
Version = 2,
});
}
// NB: We have to do this here because you can't prepare
// statements until you've got the backing table
opQueue = new SqliteOperationQueue(Connection, Scheduler);
queueThread = opQueue.Start();
subj.OnNext(Unit.Default);
subj.OnCompleted();
}
catch (Exception ex)
{
subj.OnError(ex);
}
return(Disposable.Empty);
});
return(ret.PublishLast().PermaRef());
}
internal void ReplaceOperationQueue(SqliteOperationQueue queue)
{
_initializer.Wait();
opQueue.Dispose();
opQueue = queue;
opQueue.Start();
}