Class LockTableOptions

Namespace

DynaSharp.Coordination

Assembly

DynaSharp.Coordination.dll

What a LockTable adds to the items of its locks: a label that tells operators which process holds a lock, and a time to live for the items of locks that are no longer used. Both are off by default, and neither is ever part of a condition, so processes with different options contend for the same locks as equals.

public sealed class LockTableOptions

Inheritance

object

LockTableOptions

Inherited Members

object.GetType()

object.ToString()

object.Equals(object)

object.Equals(object, object)

object.ReferenceEquals(object, object)

object.GetHashCode()

Constructors

LockTableOptions()

public LockTableOptions()

Fields

MaxHolderLabelLength

The longest HolderLabel, in characters.

public const int MaxHolderLabelLength = 256

Field Value

int

Properties

HolderLabel

Gets a label of this process, such as the name of its pod or host, which every lease writes into the item of its lock as the attribute holder, for operators who ask who holds it. null, the default, writes none.

public string? HolderLabel { get; init; }

Property Value

string

Remarks

The logs of the takeover and of the terms of a leader name it too. A release removes it, and an acquire without a label removes the label of the holder before. The label is shown to operators, in the table and in the logs, but never in a metric or on a span. So it must not carry data: no user id, no secret, nothing that is not a name of the process. From 1 to MaxHolderLabelLength characters.

TimeToLiveAttribute

Gets the name of the time to live attribute of the table, so that DynamoDB deletes the item of a lock that nobody has used for TimeToLiveRetention. null, the default, lets lock items live forever.

public string? TimeToLiveAttribute { get; init; }

Property Value

string

Remarks

What is written. Every write of a lock (acquire, renewal, release) sets that attribute to the wall clock of the process plus TimeToLiveRetention, in seconds since the epoch. This is for a table with a lock per entity, thousands of items that would otherwise stay forever. Time to live must be turned on for the table, on this attribute; this option only writes it. A lock whose item was deleted starts its fencing token at 1 again, so a system that keeps the highest token it has seen refuses its holders until the count passes what it saw: fencing across that gap is not guaranteed. Keep locks whose tokens a system outside DynamoDB checks without it.

A lease is renewed at least every 8 hours, and the retention is at least a day, so the item of a held lock is never due, as long as the clock of the holder is not off by more than the retention less the lease. The attribute must not be one of the lock or one of the keys of the table.

TimeToLiveRetention

Gets how long after its last write a lock item is due for deletion, with TimeToLiveAttribute: from 1 day, 30 days by default. DynamoDB deletes an item some time after it is due, often within days.

public TimeSpan TimeToLiveRetention { get; init; }

Property Value

TimeSpan