Class AtomicSafeInitializer<T>
- Type Parameters:
T
- the type of the object managed by this initializer class
- All Implemented Interfaces:
ConcurrentInitializer<T>
,FailableSupplier<T,
ConcurrentException>
ConcurrentInitializer
implementation which is similar
to AtomicInitializer
, but ensures that the AbstractConcurrentInitializer.initialize()
method is called only once.
As AtomicInitializer
this class is based on atomic variables, so it
can create an object under concurrent access without synchronization.
However, it implements an additional check to guarantee that the
AbstractConcurrentInitializer.initialize()
method which actually creates the object cannot be
called multiple times.
Because of this additional check this implementation is slightly less
efficient than AtomicInitializer
, but if the object creation in the
initialize()
method is expensive or if multiple invocations of
initialize()
are problematic, it is the better alternative.
From its semantics this class has the same properties as
LazyInitializer
. It is a "save" implementation of the lazy
initializer pattern. Comparing both classes in terms of efficiency is
difficult because which one is faster depends on multiple factors. Because
AtomicSafeInitializer
does not use synchronization at all it probably
outruns LazyInitializer
, at least under low or moderate concurrent
access. Developers should run their own benchmarks on the expected target
platform to decide which implementation is suitable for their specific use
case.
- Since:
- 3.0
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
AtomicSafeInitializer.Builder<I extends AtomicSafeInitializer<T>,
T> Builds a new instance.Nested classes/interfaces inherited from class org.apache.commons.lang3.concurrent.AbstractConcurrentInitializer
AbstractConcurrentInitializer.AbstractBuilder<I extends AbstractConcurrentInitializer<T,
E>, T, B extends AbstractConcurrentInitializer.AbstractBuilder<I, T, B, E>, E extends Exception> -
Field Summary
FieldsModifier and TypeFieldDescriptionprivate final AtomicReference
<AtomicSafeInitializer<T>> A guard which ensures that initialize() is called only once.private static final Object
private final AtomicReference
<T> Holds the reference to the managed object.Fields inherited from interface org.apache.commons.lang3.function.FailableSupplier
NUL
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Constructor Summary
ConstructorsModifierConstructorDescriptionConstructs a new instance.private
AtomicSafeInitializer
(FailableSupplier<T, ConcurrentException> initializer, FailableConsumer<T, ConcurrentException> closer) Constructs a new instance. -
Method Summary
Modifier and TypeMethodDescriptionstatic <T> AtomicSafeInitializer.Builder
<AtomicSafeInitializer<T>, T> builder()
Creates a new builder.final T
get()
Gets (and initialize, if not initialized yet) the required objectprivate T
Gets the internal no-init object cast for this instance.protected ConcurrentException
Gets an Exception with a type of E as defined by a concrete subclass of this class.boolean
Tests whether this instance is initialized.Methods inherited from class org.apache.commons.lang3.concurrent.AbstractConcurrentInitializer
close, initialize
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Field Details
-
NO_INIT
-
factory
A guard which ensures that initialize() is called only once. -
reference
Holds the reference to the managed object.
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Constructor Details
-
AtomicSafeInitializer
public AtomicSafeInitializer()Constructs a new instance. -
AtomicSafeInitializer
private AtomicSafeInitializer(FailableSupplier<T, ConcurrentException> initializer, FailableConsumer<T, ConcurrentException> closer) Constructs a new instance.- Parameters:
initializer
- the initializer supplier called byAbstractConcurrentInitializer.initialize()
.closer
- the closer consumer called byAbstractConcurrentInitializer.close()
.
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Method Details
-
builder
Creates a new builder.- Type Parameters:
T
- the type of object to build.- Returns:
- a new builder.
- Since:
- 3.14.0
-
get
Gets (and initialize, if not initialized yet) the required object- Returns:
- lazily initialized object
- Throws:
ConcurrentException
- if the initialization of the object causes an exception
-
getNoInit
Gets the internal no-init object cast for this instance. -
getTypedException
Gets an Exception with a type of E as defined by a concrete subclass of this class.- Specified by:
getTypedException
in classAbstractConcurrentInitializer<T,
ConcurrentException> - Parameters:
e
- The actual exception that was thrown- Returns:
- a new exception with the actual type of E, that wraps e.
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isInitialized
public boolean isInitialized()Tests whether this instance is initialized. Once initialized, always returns true.- Specified by:
isInitialized
in classAbstractConcurrentInitializer<T,
ConcurrentException> - Returns:
- whether this instance is initialized. Once initialized, always returns true.
- Since:
- 3.14.0
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