/// <summary>
/// Searches for the first object that is lasser than a hypothetical limit object.
/// </summary>
/// <typeparam name="T">The typed enumerator uses
/// the object serializer of <typeparamref name="T"/> to deserialize objects by default.</typeparam>
/// <param name="Locked">If the resulting enumerator should be opened in locked mode or not.</param>
/// <param name="Object">Limit object to search for.</param>
/// <returns>Enumerator that can be used to enumerate objects in index order. First object will be the first
/// object that is lesser than the limit object. If null is returned, the search operation could
/// not be performed.</returns>
public async Task <IndexBTreeFileEnumerator <T> > FindLastLesserThan <T>(bool Locked, GenericObject Object)
{
byte[] Key = this.recordHandler.Serialize(Guid.Empty, Object, this.genericSerializer, MissingFieldAction.First);
if (Key.Length > this.indexFile.InlineObjectSizeLimit)
{
return(null);
}
IndexBTreeFileEnumerator <T> Result = null;
try
{
Result = new IndexBTreeFileEnumerator <T>(this, this.recordHandler);
if (Locked)
{
await Result.Lock();
}
BlockInfo Leaf = await this.indexFile.FindLeafNodeLocked(Key);
Result.SetStartingPoint(Leaf);
}
catch (Exception ex)
{
if (Result != null)
{
Result.Dispose();
Result = null;
}
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Capture(ex).Throw();
}
return(Result);
}
/// <summary>
/// Returns an typed enumerator that iterates through the collection in the order specified by the index. The typed enumerator uses
/// the object serializer of <typeparamref name="T"/> to deserialize objects by default.
/// </summary>
/// <param name="Locked">If locked access to the file is requested.
///
/// If unlocked access is desired, any change to the database will invalidate the enumerator, and further access to the
/// enumerator will cause an <see cref="InvalidOperationException"/> to be thrown.
///
/// If locked access is desired, the database cannot be updated, until the enumerator has been dispose. Make sure to call
/// the <see cref="IndexBTreeFileEnumerator{T}.Dispose"/> method when done with the enumerator, to release the database
/// after use.</param>
/// <returns>An enumerator that can be used to iterate through the collection.</returns>
public async Task <IndexBTreeFileEnumerator <T> > GetTypedEnumerator <T>(bool Locked)
{
IndexBTreeFileEnumerator <T> e = new IndexBTreeFileEnumerator <T>(this, this.recordHandler);
if (Locked)
{
await e.Lock();
}
return(e);
}
/// <summary>
/// Returns an typed enumerator that iterates through the collection in the order specified by the index. The typed enumerator uses
/// the object serializer of <typeparamref name="T"/> to deserialize objects by default.
/// </summary>
/// <param name="LockType">
/// If locked access to the file is requested, and of what type.
///
/// If unlocked access is desired, any change to the database will invalidate the enumerator, and further access to the
/// enumerator will cause an <see cref="InvalidOperationException"/> to be thrown.
///
/// If read locked access is desired, the database cannot be updated, until the enumerator has been disposed.
/// If write locked access is desired, the database cannot be accessed at all, until the enumerator has been disposed.
///
/// Make sure to call the <see cref="ObjectBTreeFileEnumerator{T}.Dispose"/> method when done with the enumerator, to release
/// the database lock after use.
/// </param>
/// <param name="LockParent">If parent file is to be locked as well.</param>
/// <returns>An enumerator that can be used to iterate through the collection.</returns>
public async Task <IndexBTreeFileEnumerator <T> > GetTypedEnumerator <T>(LockType LockType, bool LockParent)
{
IndexBTreeFileEnumerator <T> e = await IndexBTreeFileEnumerator <T> .Create(this, this.recordHandler);
if (LockType != LockType.None)
{
await e.Lock(LockType, LockParent);
}
return(e);
}