org.terracotta.statistics

Class ValueStatistics

java.lang.Object

org.terracotta.statistics.ValueStatistics

public class ValueStatistics
extends Object

Author:

Mathieu Carbou

Constructor Summary

Constructors

Constructor and Description
ValueStatistics()

Method Summary

Modifier and Type	Method and Description
static <T extends Serializable> ConstantValueStatistic<T>	constant(StatisticType type, T value)
static <T extends Number> ValueStatistic<T>	counter(Supplier<T> supplier)
static <T extends Number> ValueStatistic<T>	gauge(Supplier<T> supplier)
static <T extends Serializable> ValueStatistic<T>	memoize(long delay, TimeUnit unit, ValueStatistic<T> valueStatistic) Returns a ValueStatistic that caches the value of a statistic for at least a specific amount of time.
static <T extends Serializable> ConstantValueStatistic<T>	nullValue(StatisticType type)
static <T extends Number> ValueStatistic<T>	rate(Supplier<T> supplier)
static <T extends Number> ValueStatistic<T>	ratio(Supplier<T> supplier)
static <T extends Serializable> ValueStatistic<T>	supply(StatisticType type, Supplier<T> supplier)
static <T extends Table> ValueStatistic<T>	table(Supplier<T> supplier)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ValueStatistics

public ValueStatistics()

Method Detail

nullValue

public static <T extends Serializable> ConstantValueStatistic<T> nullValue(StatisticType type)

constant

public static <T extends Serializable> ConstantValueStatistic<T> constant(StatisticType type,
                                                                          T value)

supply

public static <T extends Serializable> ValueStatistic<T> supply(StatisticType type,
                                                                Supplier<T> supplier)

gauge

public static <T extends Number> ValueStatistic<T> gauge(Supplier<T> supplier)

counter

public static <T extends Number> ValueStatistic<T> counter(Supplier<T> supplier)

rate

public static <T extends Number> ValueStatistic<T> rate(Supplier<T> supplier)

ratio

public static <T extends Number> ValueStatistic<T> ratio(Supplier<T> supplier)

table

public static <T extends Table> ValueStatistic<T> table(Supplier<T> supplier)

memoize

public static <T extends Serializable> ValueStatistic<T> memoize(long delay,
                                                                 TimeUnit unit,
                                                                 ValueStatistic<T> valueStatistic)

Returns a ValueStatistic that caches the value of a statistic for at least a specific amount of time.

This method does not block.

When the delay expires, if several threads are coming at the same time to read the expired value, then only one will do the update and set a new expiring delay and read the new value. The other threads can continue to read the current expired value for their next call until it gets updated.

If the caching delay is smaller than the time it takes for a statistic value to be computed, then it is possible that a new thread starts asking for a new value before the previous update is completed. In this case, there is no guarantee that the cached value will be updated in order because it depends on the time took to get the new value.

Type Parameters:

T - The statistic type

Parameters:

delay - The delay

unit - The unit of time

valueStatistic - The delegate statistic that will provide the value

Returns:

the memoizing statistic