Interface IZoneTreeMaintenance<TKey, TValue>

The interface for the maintenance of a ZoneTree.

Namespace: Tenray.ZoneTree

Assembly: ZoneTree.dll

Syntax

public interface IZoneTreeMaintenance<TKey, TValue>

Type Parameters

Name	Description
TKey	The key type
TValue	The value type

Properties

BottomSegments

Gets current bottom segments.

Declaration

IReadOnlyList<IDiskSegment<TKey, TValue>> BottomSegments { get; }

Property Value

Type	Description
IReadOnlyList<IDiskSegment<TKey, TValue>>

DiskSegment

Gets current disk segment.

Declaration

IDiskSegment<TKey, TValue> DiskSegment { get; }

Property Value

Type	Description
IDiskSegment<TKey, TValue>

InMemoryRecordCount

Retrieves the total number of records that lies in memory excluding the sparse array records of DiskSegment. In an LSM tree, records can be duplicated across different segments.

Declaration

long InMemoryRecordCount { get; }

Property Value

Type	Description
long

IsBottomSegmentsMerging

true if bottom segments merge operation is running, otherwise false.

Declaration

bool IsBottomSegmentsMerging { get; }

Property Value

Type	Description
bool

IsMerging

true if merge operation is running, otherwise false.

Declaration

bool IsMerging { get; }

Property Value

Type	Description
bool

MutableSegment

Gets current mutable segment. Mutable segment is the only writable part of the LSM tree.

Declaration

IMutableSegment<TKey, TValue> MutableSegment { get; }

Property Value

Type	Description
IMutableSegment<TKey, TValue>

MutableSegmentRecordCount

Retrieves the number of records in mutable segment.

Declaration

long MutableSegmentRecordCount { get; }

Property Value

Type	Description
long

ReadOnlySegments

Gets current readonly segments in-memory. MoveMutableSegmentForward operation moves writable segment to the read-only segments layer. The readonly segments remains in memory until merge operation done.

Declaration

IReadOnlyList<IReadOnlySegment<TKey, TValue>> ReadOnlySegments { get; }

Property Value

Type	Description
IReadOnlyList<IReadOnlySegment<TKey, TValue>>

ReadOnlySegmentsCount

Retrieves the number of read only segments.

Declaration

int ReadOnlySegmentsCount { get; }

Property Value

Type	Description
int

ReadOnlySegmentsRecordCount

Retrieves the number of records in read-only segments.

Declaration

long ReadOnlySegmentsRecordCount { get; }

Property Value

Type	Description
long

TotalRecordCount

Retrieves the total number of records that lies in memory and disk excluding the sparse array records of DiskSegments. In an LSM tree, records can be duplicated across different segments. Hence, this is not the actual unique record count of the tree. To get exact record count, a partial database scan is needed. Use Count() and CountFullScan() for actual record count.

Declaration

long TotalRecordCount { get; }

Property Value

Type	Description
long

Methods

DestroyTree()

Destroys the tree, deletes entire data and WAL store or folder.

Declaration

void DestroyTree()

MoveMutableSegmentForward()

Moves mutable segment into readonly segment. This will clear the writable region of the LSM tree. This method is thread safe and can be called from many threads.

Declaration

void MoveMutableSegmentForward()

ReleaseCircularKeyCacheRecords()

Releases expired circular cache key records.

Declaration

int ReleaseCircularKeyCacheRecords()

Returns

Type	Description
int	The total number of released cached records.

ReleaseCircularValueCacheRecords()

Releases expired circular cache value records.

Declaration

int ReleaseCircularValueCacheRecords()

Returns

Type	Description
int	The total number of released cached records.

ReleaseReadBuffers(long)

Releases internal read buffers that have not been used since the specified tick count.

Declaration

int ReleaseReadBuffers(long ticks)

Parameters

Type	Name	Description
long	ticks

Returns

Type	Description
int	The total number of released read buffers.

SaveMetaData()

Saves tree meta data and clears the meta wal record. After calling this method, the JSON meta file contains up to date tree meta data.

Saving meta file helps following:

1. Reduce the size of meta wal file.
2. Make Json meta file up to date to analyze parts of the LSM tree. Because Meta WAL file is not human readable.

It is up to user to decide when and how frequently save the meta file.

Declaration

void SaveMetaData()

StartBottomSegmentsMergeOperation(int, int)

Merges selected bottom segments into a single bottom disk segment.

Declaration

Thread StartBottomSegmentsMergeOperation(int fromIndex, int toIndex)

Parameters

Type	Name	Description
int	fromIndex	The lower bound
int	toIndex	The upper bound

Returns

Type	Description
Thread

StartMergeOperation()

Merges available in-memory read-only segments to the disk segment.

Declaration

Thread StartMergeOperation()

Returns

Type	Description
Thread

TryCancelBottomSegmentsMergeOperation()

Attempts to cancel bottom segments merge operation.

Declaration

void TryCancelBottomSegmentsMergeOperation()

TryCancelMergeOperation()

Attempts to cancel merge operation.

Declaration

void TryCancelMergeOperation()

Events

OnBottomSegmentsMergeOperationEnded

Event is fired when bottom segments merge operation is completed.

Declaration

event BottomSegmentsMergeOperationEnded<TKey, TValue> OnBottomSegmentsMergeOperationEnded

Event Type

Type	Description
BottomSegmentsMergeOperationEnded<TKey, TValue>

OnBottomSegmentsMergeOperationStarted

Event is fired when bottom segments merge operation is completed.

Declaration

event BottomSegmentsMergeOperationStarted<TKey, TValue> OnBottomSegmentsMergeOperationStarted

Event Type

Type	Description
BottomSegmentsMergeOperationStarted<TKey, TValue>

OnCanNotDropDiskSegment

Event is fired when a disk segment cannot be dropped. This does not harm the database consistency. The cleanup task can be done later.

Declaration

event CanNotDropDiskSegment<TKey, TValue> OnCanNotDropDiskSegment

Event Type

Type	Description
CanNotDropDiskSegment<TKey, TValue>

OnCanNotDropDiskSegmentCreator

Event is fired when a disk segment creator cannot be dropped. This does not harm the database consistency. The cleanup task can be done later.

Declaration

event CanNotDropDiskSegmentCreator<TKey, TValue> OnCanNotDropDiskSegmentCreator

Event Type

Type	Description
CanNotDropDiskSegmentCreator<TKey, TValue>

OnCanNotDropReadOnlySegment

Event is fired when a write ahead log cannot be dropped. This does not harm the database consistency. The cleanup task can be done later.

Declaration

event CanNotDropReadOnlySegment<TKey, TValue> OnCanNotDropReadOnlySegment

Event Type

Type	Description
CanNotDropReadOnlySegment<TKey, TValue>

OnDiskSegmentActivated

Event is fired when the new disk segment is activated.

Declaration

event DiskSegmentCreated<TKey, TValue> OnDiskSegmentActivated

Event Type

Type	Description
DiskSegmentCreated<TKey, TValue>

OnDiskSegmentCreated

Event is fired when the new disk segment is created. This is the best moment to initialize a sparse array. SparseArray is an in memory array that reduces disk reads. It is the best practice to call DiskSegment.InitSparseArray() when this event is fired.

Declaration

event DiskSegmentCreated<TKey, TValue> OnDiskSegmentCreated

Event Type

Type	Description
DiskSegmentCreated<TKey, TValue>

OnMergeOperationEnded

Event is fired when merge operation is completed.

Declaration

event MergeOperationEnded<TKey, TValue> OnMergeOperationEnded

Event Type

Type	Description
MergeOperationEnded<TKey, TValue>

OnMergeOperationStarted

Event is fired when merge operation is started.

Declaration

event MergeOperationStarted<TKey, TValue> OnMergeOperationStarted

Event Type

Type	Description
MergeOperationStarted<TKey, TValue>

OnMutableSegmentMovedForward

Event is fired when mutable segment is moved forward.

Declaration

event MutableSegmentMovedForward<TKey, TValue> OnMutableSegmentMovedForward

Event Type

Type	Description
MutableSegmentMovedForward<TKey, TValue>

OnZoneTreeIsDisposing

Event is fired when the ZoneTree is disposing.

Declaration

event ZoneTreeIsDisposing<TKey, TValue> OnZoneTreeIsDisposing

Event Type

Type	Description
ZoneTreeIsDisposing<TKey, TValue>