reactor.core

接口 Scannable

所有已知子接口:

ConditionalTestSubscriber<T>, MockUtils.TestScannableConditionalSubscriber<T>, Sinks.Empty<T>, Sinks.Many<T>, Sinks.ManyWithUpstream<T>, Sinks.One<T>, TestSubscriber<T>

所有已知实现类:

DirectProcessor, EmitterProcessor, FakeDisposable, FluxOperator, FluxProcessor, MockUtils.TestScannableConnectableFlux, MonoOperator, MonoProcessor, Operators.DeferredSubscription, ReplayProcessor, UnicastProcessor

函数接口:

这是一个函数接口, 因此可用作 lambda 表达式或方法引用的赋值目标。

@FunctionalInterface
public interface Scannable

A Scannable component exposes state in a non strictly memory consistent way and results should be understood as best-effort hint of the underlying state. This is useful to retro-engineer a component graph such as a flux operator chain via Stream queries from actuals(), parents() and inners(). This allows for visiting patterns and possibly enable serviceability features.

Scannable is also a useful tool for the advanced user eager to learn which kind of state we usually manage in the package-scope schedulers or operators implementations.

作者:

Stephane Maldini

嵌套类概要

嵌套类

限定符和类型	接口和说明
static class	Scannable.Attr<T> Base class for Scannable attributes, which all can define a meaningful default.

字段概要

字段

限定符和类型	字段和说明
static java.util.regex.Pattern	OPERATOR_NAME_UNRELATED_WORDS_PATTERN The pattern for matching words unrelated to operator name.

方法概要

限定符和类型	方法和说明
default java.util.stream.Stream<? extends Scannable>	actuals() Return a Stream navigating the Subscriber chain (downward).
static Scannable	from(java.lang.Object o) Attempt to cast the Object to a Scannable.
default java.util.stream.Stream<? extends Scannable>	inners() Return a Stream of referenced inners (flatmap, multicast etc)
default boolean	isScanAvailable() Return true whether the component is available for scan(Attr) resolution.
default java.lang.String	name() Check this Scannable and its parents() for a user-defined name and return the first one that is reachable, or default to this Scannable stepName() if none.
default java.util.stream.Stream<? extends Scannable>	parents() Return a Stream navigating the Subscription chain (upward).
default <T> T	scan(Scannable.Attr<T> key) 内省方法，扫描返回自身组件 Scannable.Attr 的属性值 Introspect a component's specific state attribute, returning an associated value specific to that component, or the default value associated with the key, or null if the attribute doesn't make sense for that particular component and has no sensible default.
default <T> T	scanOrDefault(Scannable.Attr<T> key, T defaultValue) Introspect a component's specific state attribute.
java.lang.Object	scanUnsafe(Scannable.Attr key) This method is used internally by components to define their key-value mappings in a single place.
default java.lang.String	stepName() Return a meaningful String representation of this Scannable in its chain of parents() and actuals().
default java.util.stream.Stream<java.lang.String>	steps() List the step names in the chain of Scannable (including the current element), in their assembly order.
default java.util.stream.Stream<Tuple2<java.lang.String,java.lang.String>>	tags() Visit this Scannable and its parents(), starting by the furthest reachable parent, and return a Stream of the tags which includes duplicates and outputs tags in declaration order (grandparent tag(s) > parent tag(s) > current tag(s)).
default java.util.Map<java.lang.String,java.lang.String>	tagsDeduplicated() Visit this Scannable and its parents(), starting by the furthest reachable parent, deduplicate tags that have a common key by favoring the value declared last (current tag(s) > parent tag(s) > grandparent tag(s)) and return a Map of the deduplicated tags.

字段详细资料

OPERATOR_NAME_UNRELATED_WORDS_PATTERN

static final java.util.regex.Pattern OPERATOR_NAME_UNRELATED_WORDS_PATTERN

The pattern for matching words unrelated to operator name. Used to strip an operator name of various prefixes and suffixes.

方法详细资料

from

static Scannable from(@Nullable
                      java.lang.Object o)

Attempt to cast the Object to a Scannable. Return Scannable.Attr.NULL_SCAN if the value is null, or Scannable.Attr.UNAVAILABLE_SCAN if the value is not a Scannable. Both are constant Scannable that return false on isScanAvailable().

参数:

o - a reference to cast

返回:

the casted Scannable, or one of two default Scannable instances that aren't actually scannable (one for nulls, one for non-scannable references)

actuals

default java.util.stream.Stream<? extends Scannable> actuals()

Return a Stream navigating the Subscriber chain (downward). The current Scannable is not included.

返回:

a Stream navigating the Subscriber chain (downward, current Scannable not included).

inners

default java.util.stream.Stream<? extends Scannable> inners()

Return a Stream of referenced inners (flatmap, multicast etc)

返回:

a Stream of referenced inners (flatmap, multicast etc)

isScanAvailable

default boolean isScanAvailable()

Return true whether the component is available for scan(Attr) resolution.

返回:

true whether the component is available for scan(Attr) resolution.

name

default java.lang.String name()

Check this Scannable and its parents() for a user-defined name and return the first one that is reachable, or default to this Scannable stepName() if none.

返回:

the name of the first parent that has one defined (including this scannable)

stepName

default java.lang.String stepName()

Return a meaningful String representation of this Scannable in its chain of parents() and actuals().

steps

default java.util.stream.Stream<java.lang.String> steps()

List the step names in the chain of Scannable (including the current element), in their assembly order. This traverses the chain of Scannable both upstream (parents()) and downstream (actuals()).

1. if the current Scannable is a Subscriber, the chain can reach down to the final subscriber, provided it is Scannable (eg. lambda subscriber)
2. if it is an operator the chain can reach up to the source, if it is a Reactor source (that is Scannable).

返回:

a Stream of stepName() for each discovered step in the Scannable chain

parents

default java.util.stream.Stream<? extends Scannable> parents()

Return a Stream navigating the Subscription chain (upward). The current Scannable is not included.

返回:

a Stream navigating the Subscription chain (upward, current Scannable not included).

scanUnsafe

@Nullable
java.lang.Object scanUnsafe(Scannable.Attr key)

This method is used internally by components to define their key-value mappings in a single place. Although it is ignoring the generic type of the Scannable.Attr key, implementors should take care to return values of the correct type, and return null if no specific value is available.

For public consumption of attributes, prefer using scan(Attr), which will return a typed value and fall back to the key's default if the component didn't define any mapping.

参数:

key - a Scannable.Attr to resolve for the component.

返回:

the value associated to the key for that specific component, or null if none.

scan

@Nullable
default <T> T scan(Scannable.Attr<T> key)

内省方法，扫描返回自身组件 Scannable.Attr 的属性值

Introspect a component's specific state attribute, returning an associated value specific to that component, or the default value associated with the key, or null if the attribute doesn't make sense for that particular component and has no sensible default.

参数:

key - a Scannable.Attr to resolve for the component.

返回:

a value associated to the key or null if unmatched or unresolved

scanOrDefault

default <T> T scanOrDefault(Scannable.Attr<T> key,
                            T defaultValue)

Introspect a component's specific state attribute. If there's no specific value in the component for that key, fall back to returning the provided non null default.

参数:

key - a Scannable.Attr to resolve for the component.

defaultValue - a fallback value if key resolve to null

返回:

a value associated to the key or the provided default if unmatched or unresolved

tags

default java.util.stream.Stream<Tuple2<java.lang.String,java.lang.String>> tags()

Visit this Scannable and its parents(), starting by the furthest reachable parent, and return a Stream of the tags which includes duplicates and outputs tags in declaration order (grandparent tag(s) > parent tag(s) > current tag(s)).

Tags can only be discovered until no parent can be inspected, which happens either when the source publisher has been reached or when a non-reactor intermediate operator is present in the parent chain (i.e. a stage that is not Scannable for Scannable.Attr.PARENT).

返回:

the stream of tags for this Scannable and its reachable parents, including duplicates

另请参阅:

tagsDeduplicated()

tagsDeduplicated

default java.util.Map<java.lang.String,java.lang.String> tagsDeduplicated()

Visit this Scannable and its parents(), starting by the furthest reachable parent, deduplicate tags that have a common key by favoring the value declared last (current tag(s) > parent tag(s) > grandparent tag(s)) and return a Map of the deduplicated tags. Note that while the values are the "latest", the key iteration order reflects the tags' declaration order.

Tags can only be discovered until no parent can be inspected, which happens either when the source publisher has been reached or when a non-reactor intermediate operator is present in the parent chain (i.e. a stage that is not Scannable for Scannable.Attr.PARENT).

返回:

a Map of deduplicated tags from this Scannable and its reachable parents

另请参阅:

tags()