Package org.apache.hadoop.yarn.server.resourcemanager.placement

Class VariableContext

java.lang.Object

org.apache.hadoop.yarn.server.resourcemanager.placement.VariableContext

public class VariableContext
extends java.lang.Object

This class is a key-value store for the variables and their respective values during an application placement. The class gives support for immutable variables, which can be set only once, and has helper methods for replacing the variables with their respective values in provided strings. We don't extend the map interface, because we don't need all the features a map provides, this class tries to be as simple as possible.

Constructor Summary

Constructors

Constructor	Description
VariableContext()

Method Summary

Modifier and Type	Method	Description
boolean	containsKey(java.lang.String name)	Check if a variable is part of the context.
java.lang.String	get(java.lang.String name)	Returns the value of a variable, null values are replaced with "".
java.util.Set<java.lang.String>	getExtraDataset(java.lang.String name)	Returns the dataset referenced by the name.
java.lang.String	getOriginal(java.lang.String name)
boolean	isImmutable(java.lang.String name)	Checks if the provided variable is immutable.
VariableContext	put(java.lang.String name, java.lang.String value)	Adds a variable with value to the context or overrides an already existing one.
VariableContext	putConditional(java.lang.String name, MappingRuleConditionalVariable variable)	This method is used to add a conditional variable to the variable context.
void	putExtraDataset(java.lang.String name, java.util.Set<java.lang.String> set)	Adds a set to the context, each name can only be added once.
void	putOriginal(java.lang.String name, java.lang.String value)
java.lang.String	replacePathVariables(java.lang.String input)	This method will consider the input as a queue path, which is a String separated by dot ('.') characters.
java.lang.String	replaceVariables(java.lang.String input)	This method replaces all variables in the provided string.
VariableContext	setImmutables(java.lang.String... variableNames)	Can be used to provide an array of strings which contains the names of the variables which should be immutable.
VariableContext	setImmutables(java.util.Set<java.lang.String> variableNames)	Can be used to provide a set which contains the name of the variables which should be immutable.

Methods inherited from class java.lang.Object

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

Constructor Detail

VariableContext

public VariableContext()

Method Detail

isImmutable

public boolean isImmutable(java.lang.String name)

Checks if the provided variable is immutable.

Parameters:

name - Name of the variable to check

Returns:

true if the variable is immutable

setImmutables

public VariableContext setImmutables(java.util.Set<java.lang.String> variableNames)

Can be used to provide a set which contains the name of the variables which should be immutable.

Parameters:

variableNames - Set containing the names of the immutable variables

Returns:

same instance of VariableContext for daisy chaining.

Throws:

java.lang.IllegalStateException - if the immutable set is already provided.

setImmutables

public VariableContext setImmutables(java.lang.String... variableNames)

Can be used to provide an array of strings which contains the names of the variables which should be immutable. An immutable set will be created from the array.

Parameters:

variableNames - Set containing the names of the immutable variables

Returns:

same instance of VariableContext for daisy chaining.

Throws:

java.lang.IllegalStateException - if the immutable set is already provided.

put

public VariableContext put(java.lang.String name,
                           java.lang.String value)

Adds a variable with value to the context or overrides an already existing one. If the variable is already set and immutable an IllegalStateException is thrown.

Parameters:

name - Name of the variable to be added to the context

value - Value of the variable

Returns:

same instance of VariableContext for daisy chaining.

Throws:

java.lang.IllegalStateException - if the variable is immutable and already set

putOriginal

public void putOriginal(java.lang.String name,
                        java.lang.String value)

putConditional

public VariableContext putConditional(java.lang.String name,
                                      MappingRuleConditionalVariable variable)

This method is used to add a conditional variable to the variable context.

Parameters:

name - Name of the variable

variable - The conditional variable evaluator

Returns:

VariableContext for daisy chaining

get

public java.lang.String get(java.lang.String name)

Returns the value of a variable, null values are replaced with "".

Parameters:

name - Name of the variable

Returns:

The value of the variable

getOriginal

public java.lang.String getOriginal(java.lang.String name)

putExtraDataset

public void putExtraDataset(java.lang.String name,
                            java.util.Set<java.lang.String> set)

Adds a set to the context, each name can only be added once. The extra dataset is different from the regular variables because it cannot be referenced via tokens in the paths or any other input. However matchers and actions can explicitly access these datasets and can make decisions based on them.

Parameters:

name - Name which can be used to reference the collection

set - The dataset to be stored

getExtraDataset

public java.util.Set<java.lang.String> getExtraDataset(java.lang.String name)

Returns the dataset referenced by the name.

Parameters:

name - Name of the set to be returned.

Returns:

the dataset referenced by the name.

containsKey

public boolean containsKey(java.lang.String name)

Check if a variable is part of the context.

Parameters:

name - Name of the variable to be checked

Returns:

True if the variable is added to the context, false otherwise

replaceVariables

public java.lang.String replaceVariables(java.lang.String input)

This method replaces all variables in the provided string. The variables are reverse ordered by the length of their names in order to avoid partial replaces when a shorter named variable is a substring of a longer named variable. All variables will be replaced in the string. Null values will be considered as empty strings during the replace. If the input is null, null will be returned.

Parameters:

input - The string with variables

Returns:

A string with all the variables substituted with their respective values.

replacePathVariables

public java.lang.String replacePathVariables(java.lang.String input)

This method will consider the input as a queue path, which is a String separated by dot ('.') characters. The input will be split along the dots and all parts will be replaced individually. Replace only occur if a part exactly matches a variable name, no composite names or additional characters are supported. e.g. With variables %user and %default "%user.%default" will be substituted while "%user%default.something" won't. Null values will be considered as empty strings during the replace. If the input is null, null will be returned.

Parameters:

input - The string with variables

Returns:

A string with all the variable only path parts substituted with their respective values.