com.netflix.spectator.api

Class Utils

java.lang.Object

com.netflix.spectator.api.Utils

public final class Utils
extends java.lang.Object

Helper functions for working with a sequence of measurements.

Method Summary

Modifier and Type	Method and Description
static <K,V> V	computeIfAbsent(java.util.concurrent.ConcurrentMap<K,V> map, K k, java.util.function.Function<K,V> f) This method should be used instead of the ConcurrentMap.computeIfAbsent(Object, Function) call to minimize thread contention.
static java.lang.Iterable<Measurement>	filter(java.lang.Iterable<Measurement> ms, java.util.function.Predicate<Measurement> p) Returns a new iterable restricted to measurements that match the predicate.
static java.lang.Iterable<Measurement>	filter(java.lang.Iterable<Measurement> ms, java.lang.String k, java.lang.String v) Returns a new iterable restricted to measurements that match the predicate.
static java.lang.Iterable<Measurement>	filter(java.lang.Iterable<Measurement> ms, Tag t) Returns a new iterable restricted to measurements that match the predicate.
static Measurement	first(java.lang.Iterable<Measurement> ms, java.util.function.Predicate<Measurement> p) Returns the first measurement that matches the predicate.
static Measurement	first(java.lang.Iterable<Measurement> ms, java.lang.String k, java.lang.String v) Returns the first measurement with a given tag value.
static Measurement	first(java.lang.Iterable<Measurement> ms, Tag t) Returns the first measurement with a given tag value.
static java.lang.String	getTagValue(Id id, java.lang.String k) Returns the value associated with with a given key or null if no such key is present in the set of tags.
static java.lang.String	getTagValue(java.lang.Iterable<Tag> tags, java.lang.String k) Returns the value associated with with a given key or null if no such key is present in the set of tags.
static Id	normalize(Id id) Returns a new id with the tag list sorted by key and with no duplicate keys.
static void	propagateTypeError(Registry registry, Id id, java.lang.Class<?> desiredClass, java.lang.Class<?> actualClass) Propagate a type error exception.
static <T> int	size(java.lang.Iterable<T> iter) Returns the size of an iterable.
static <T> java.util.List<T>	toList(java.lang.Iterable<T> iter) Returns a list with a copy of the data from the iterable.
static <T> java.util.List<T>	toList(java.util.Iterator<T> iter) Returns a list with the data from the iterator.

Methods inherited from class java.lang.Object

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

Method Detail

normalize

public static Id normalize(Id id)

Returns a new id with the tag list sorted by key and with no duplicate keys.

getTagValue

public static java.lang.String getTagValue(Id id,
                                           java.lang.String k)

Returns the value associated with with a given key or null if no such key is present in the set of tags.

Parameters:

id - Identifier with a set of tags to search.

k - Key to search for.

Returns:

Value for the key or null if the key is not present.

getTagValue

public static java.lang.String getTagValue(java.lang.Iterable<Tag> tags,
                                           java.lang.String k)

Returns the value associated with with a given key or null if no such key is present in the set of tags.

Parameters:

tags - Set of tags to search.

k - Key to search for.

Returns:

Value for the key or null if the key is not present.

first

public static Measurement first(java.lang.Iterable<Measurement> ms,
                                Tag t)

Returns the first measurement with a given tag value.

Parameters:

ms - A set of measurements.

t - The key and value to search for.

Returns:

Measurement or null if no matches are found.

first

public static Measurement first(java.lang.Iterable<Measurement> ms,
                                java.lang.String k,
                                java.lang.String v)

Returns the first measurement with a given tag value.

Parameters:

ms - A set of measurements.

k - Key to search for.

v - Value that should be associated with k on the ids.

Returns:

Measurement or null if no matches are found.

first

public static Measurement first(java.lang.Iterable<Measurement> ms,
                                java.util.function.Predicate<Measurement> p)

Returns the first measurement that matches the predicate.

Parameters:

ms - A set of measurements.

p - Predicate to use for selecting values.

Returns:

Measurement or null if no matches are found.

filter

public static java.lang.Iterable<Measurement> filter(java.lang.Iterable<Measurement> ms,
                                                     Tag t)

Returns a new iterable restricted to measurements that match the predicate.

Parameters:

ms - A set of measurements.

t - The key and value to search for.

Returns:

Measurements matching the predicate.

filter

public static java.lang.Iterable<Measurement> filter(java.lang.Iterable<Measurement> ms,
                                                     java.lang.String k,
                                                     java.lang.String v)

Returns a new iterable restricted to measurements that match the predicate.

Parameters:

ms - A set of measurements.

k - Key to search for.

v - Value that should be associated with k on the ids.

Returns:

Measurements matching the predicate.

filter

public static java.lang.Iterable<Measurement> filter(java.lang.Iterable<Measurement> ms,
                                                     java.util.function.Predicate<Measurement> p)

Returns a new iterable restricted to measurements that match the predicate.

Parameters:

ms - A set of measurements.

p - Predicate to use for selecting values.

Returns:

Measurements matching the predicate.

toList

public static <T> java.util.List<T> toList(java.lang.Iterable<T> iter)

Returns a list with a copy of the data from the iterable.

toList

public static <T> java.util.List<T> toList(java.util.Iterator<T> iter)

Returns a list with the data from the iterator.

size

public static <T> int size(java.lang.Iterable<T> iter)

Returns the size of an iterable. This method should only be used with fixed size collections. It will attempt to find an efficient method to get the size before falling back to a traversal of the iterable.

computeIfAbsent

public static <K,V> V computeIfAbsent(java.util.concurrent.ConcurrentMap<K,V> map,
                                      K k,
                                      java.util.function.Function<K,V> f)

This method should be used instead of the ConcurrentMap.computeIfAbsent(Object, Function) call to minimize thread contention. This method does not require locking for the common case where the key exists, but potentially performs additional computation when absent.

propagateTypeError

public static void propagateTypeError(Registry registry,
                                      Id id,
                                      java.lang.Class<?> desiredClass,
                                      java.lang.Class<?> actualClass)

Propagate a type error exception. Used in situations where an existing id has already been registered but with a different class.