/// <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.LockRead(); } 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> /// Searches for the first object that is greater 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 greater than the limit object. If null is returned, the search operation could /// not be performed.</returns> public async Task <IndexBTreeFileEnumerator <T> > FindFirstGreaterThan <T>(bool Locked, GenericObject Object) { byte[] Key = this.recordHandler.Serialize(GuidMax, Object, this.genericSerializer, MissingFieldAction.Last); if (Key.Length > this.indexFile.InlineObjectSizeLimit) { return(null); } IndexBTreeFileEnumerator <T> Result = null; await this.indexFile.Lock(); try { BlockInfo Leaf = await this.indexFile.FindLeafNodeLocked(Key); Result = new IndexBTreeFileEnumerator <T>(this, Locked, this.recordHandler, Leaf); if (!Locked) { await this.indexFile.Release(); } } catch (Exception ex) { if (Result != null) { Result.Dispose(); Result = null; } else { await this.indexFile.Release(); } System.Runtime.ExceptionServices.ExceptionDispatchInfo.Capture(ex).Throw(); } return(Result); }