ru.vyarus.dropwizard.guice.module.context

Class SharedConfigurationState

java.lang.Object

ru.vyarus.dropwizard.guice.module.context.SharedConfigurationState

public class SharedConfigurationState
extends java.lang.Object

Application-wide shared state assumed to be used in configuration phase. For example, in complex cases when bundles must share some global state (otherwise it would require to maintain some ThreadLocal field in bundle). But other cases could arise too. Intended to be used for very rare cases: use it only if you can't avoid shared state in configuration time (for example, like guicey gsp bundle, which requires global configuration, accessible by multiple bundles).

Internally, guicey use it to store created Injector and make it available statically (see InjectorLookup).

Universal sharing place should simplify testing in the future: if new global state will appear, there would be no need to reset anything in tests (to clear state, for example, on testing errors). One "dirty" place to replace all separate hacks.

Shared state could be accessed statically with get(Application), or within GuiceyBundle. Guicey hooks could use GuiceBundle.Builder.withSharedState(java.util.function.Consumer) to access application state. Alternatively, dropwizard Environment may be used for resolution: get(Environment).

Classes are used as state keys to simplify usage (in most cases, bundle class will be used as key). Shared value could be set only once (to prevent complex situations with state substitutions). It is advised to initialize shared value only in initialization phase (to avoid potential static access errors).

Objects available in shared state by default: Bootstrap, Configuration, Environment, ConfigurationTree, Injector

Since:

26.09.2019

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	CONTEXT_APPLICATION_PROPERTY Attribute name used to store application instance in application context attributes.

Constructor Summary

Constructors

Constructor and Description
SharedConfigurationState()

Method Summary

Modifier and Type	Method and Description
protected void	assignTo(io.dropwizard.Application application) Called on initialization phase to assign registry instance to application (to be able to statically reference registry).
static void	clear() Clears stored injectors references.
static java.util.Optional<SharedConfigurationState>	get(io.dropwizard.Application application) Static lookup for entire application registry.
<V> V	get(java.lang.Class<?> key) Note: in spite of fact that class is used for key, actual value is stored with full class name string.
<V> V	get(java.lang.Class<?> key, java.util.function.Supplier<V> defaultValue) Get value or declare default if value not set yet.
static java.util.Optional<SharedConfigurationState>	get(io.dropwizard.setup.Environment environment) Static lookup for entire application registry by environment instance.
java.util.Set<java.lang.String>	getKeys() Note: each key is a full name of registration class.
static SharedConfigurationState	getOrFail(io.dropwizard.Application application, java.lang.String message, java.lang.Object... args) Shortcut for get(Application) to immediately fail if registry is not available.
<V> V	getOrFail(java.lang.Class<?> key, java.lang.String message, java.lang.Object... args) Shortcut for get(Class) to immediately fail if value not set.
static SharedConfigurationState	getOrFail(io.dropwizard.setup.Environment environment, java.lang.String message, java.lang.Object... args) Shortcut for get(Environment) to immediately fail if registry is not available.
protected void	listen(io.dropwizard.setup.Environment environment) Called on run phase to assign to application lifecycle and listen for shutdown.
static <V> java.util.Optional<V>	lookup(io.dropwizard.Application application, java.lang.Class<?> key) Static lookup for registry value.
static <V> java.util.Optional<V>	lookup(io.dropwizard.setup.Environment environment, java.lang.Class<?> key) Static lookup for registry value by environment instance.
static <V> V	lookupOrFail(io.dropwizard.Application application, java.lang.Class<?> key, java.lang.String message, java.lang.Object... args) Shortcut for lookup(Application, Class) to immediately fail if value is not available.
static <V> V	lookupOrFail(io.dropwizard.setup.Environment environment, java.lang.Class<?> key, java.lang.String message, java.lang.Object... args) Shortcut for lookup(Environment, Class) to immediately fail if value is not available.
void	put(java.lang.Class<?> key, java.lang.Object value) Assumed to be used to store some configuration during startup.
static int	statesCount() Could be useful only in tests in order to validate possibly stale applications.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

CONTEXT_APPLICATION_PROPERTY

public static final java.lang.String CONTEXT_APPLICATION_PROPERTY

Attribute name used to store application instance in application context attributes.

See Also:

Constant Field Values

Constructor Detail

SharedConfigurationState

public SharedConfigurationState()

Method Detail

get

public <V> V get(java.lang.Class<?> key)

Note: in spite of fact that class is used for key, actual value is stored with full class name string. So classes, loaded from different class loaders will lead to the same value.

Type Parameters:

V - shared object type

Parameters:

key - shared object key

Returns:

value or null

get

public <V> V get(java.lang.Class<?> key,
                 java.util.function.Supplier<V> defaultValue)

Get value or declare default if value not set yet.

Type Parameters:

V - shared object type

Parameters:

key - shared object key

defaultValue - default shared object provider

Returns:

stored or default (just stored) value

getOrFail

public <V> V getOrFail(java.lang.Class<?> key,
                       java.lang.String message,
                       java.lang.Object... args)

Shortcut for get(Class) to immediately fail if value not set. Supposed to be used by shared state consumers (to validate situations when value must exists for sure).

Type Parameters:

V - shared object type

Parameters:

key - shared object key

message - exception message (could use String.format(String, Object...) placeholders)

args - placeholder arguments for error message

Returns:

stored object (never null)

Throws:

java.lang.IllegalStateException - if value not set

put

public void put(java.lang.Class<?> key,
                java.lang.Object value)

Assumed to be used to store some configuration during startup. For example, if multiple bundle instances should know of each other - they could use shared state to communicate.

Class is used for key to avoid dummy mistakes with strings (in most cases bundle class would be key). But internally string class name is used in order to unify classes from different class loaders.

Note: warning will be printed if existing state value is overridden because it is assumed that some global configuration object would be shared once and later all participants will work with the same object.

Parameters:

key - shared object key

value - shared value (usually configuration object)

getKeys

public java.util.Set<java.lang.String> getKeys()

Note: each key is a full name of registration class.

Returns:

all available keys

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

assignTo

protected void assignTo(io.dropwizard.Application application)

Called on initialization phase to assign registry instance to application (to be able to statically reference registry).

Parameters:

application - application instance

listen

protected void listen(io.dropwizard.setup.Environment environment)

Called on run phase to assign to application lifecycle and listen for shutdown.

Parameters:

environment - environment object

lookup

public static <V> java.util.Optional<V> lookup(io.dropwizard.Application application,
                                               java.lang.Class<?> key)

Static lookup for registry value.

Type Parameters:

V - shared object key

Parameters:

application - application instance

key - shared object key

Returns:

value optional

lookup

public static <V> java.util.Optional<V> lookup(io.dropwizard.setup.Environment environment,
                                               java.lang.Class<?> key)

Static lookup for registry value by environment instance.

Type Parameters:

V - shared object key

Parameters:

environment - dropwizard environment object

key - shared object key

Returns:

value optional

lookupOrFail

public static <V> V lookupOrFail(io.dropwizard.Application application,
                                 java.lang.Class<?> key,
                                 java.lang.String message,
                                 java.lang.Object... args)

Shortcut for lookup(Application, Class) to immediately fail if value is not available.

Type Parameters:

V - shared object type

Parameters:

application - application instance

key - shared object key

message - exception message (could use String.format(String, Object...) placeholders)

args - placeholder arguments for error message

Returns:

value (never null)

Throws:

java.lang.IllegalStateException - if value not available

lookupOrFail

public static <V> V lookupOrFail(io.dropwizard.setup.Environment environment,
                                 java.lang.Class<?> key,
                                 java.lang.String message,
                                 java.lang.Object... args)

Shortcut for lookup(Environment, Class) to immediately fail if value is not available.

Type Parameters:

V - shared object type

Parameters:

environment - environment instance

key - shared object key

message - exception message (could use String.format(String, Object...) placeholders)

args - placeholder arguments for error message

Returns:

value (never null)

Throws:

java.lang.IllegalStateException - if value not available

get

public static java.util.Optional<SharedConfigurationState> get(io.dropwizard.Application application)

Static lookup for entire application registry.

Parameters:

application - application instance

Returns:

optional of application registry (may be empty if called too early or too late)

get

public static java.util.Optional<SharedConfigurationState> get(io.dropwizard.setup.Environment environment)

Static lookup for entire application registry by environment instance.

Parameters:

environment - environment instance

Returns:

optional of application registry (may be empty if called too early or too late)

getOrFail

public static SharedConfigurationState getOrFail(io.dropwizard.Application application,
                                                 java.lang.String message,
                                                 java.lang.Object... args)

Shortcut for get(Application) to immediately fail if registry is not available.

Parameters:

application - application instance

message - exception message (could use String.format(String, Object...) placeholders)

args - placeholder arguments for error message

Returns:

registry (never null)

Throws:

java.lang.IllegalStateException - if no state is associated with application yet

getOrFail

public static SharedConfigurationState getOrFail(io.dropwizard.setup.Environment environment,
                                                 java.lang.String message,
                                                 java.lang.Object... args)

Shortcut for get(Environment) to immediately fail if registry is not available.

Parameters:

environment - environment instance

message - exception message (could use String.format(String, Object...) placeholders)

args - placeholder arguments for error message

Returns:

registry (never null)

Throws:

java.lang.IllegalStateException - if no state is associated with application yet

clear

public static void clear()

Clears stored injectors references. Normally shouldn't be used at all, because managed object will detect application shutdown and remove assigned state (for example, when used DropwizardAppRule or GuiceyAppRule).

May be useful in tests, when application was not shut down properly (but just to clear memory).

WARNING: calling this method while application is working may cause incorrect behaviour.

statesCount

public static int statesCount()

Could be useful only in tests in order to validate possibly stale applications.

Returns:

number of registered contexts