Class AtomicSafeInitializer<T>
- Type Parameters:
T
- the type of the object managed by this initializer class
- All Implemented Interfaces:
ConcurrentInitializer<T>
A specialized ConcurrentInitializer
implementation which is similar
to AtomicInitializer
, but ensures that the 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
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
-
Constructor Details
-
AtomicSafeInitializer
public AtomicSafeInitializer()
-
-
Method Details
-
get
Gets (and initialize, if not initialized yet) the required object- Specified by:
get
in interfaceConcurrentInitializer<T>
- Returns:
- lazily initialized object
- Throws:
ConcurrentException
- if the initialization of the object causes an exception
-
initialize
Creates and initializes the object managed by thisAtomicInitializer
. This method is called byget()
when the managed object is not available yet. An implementation can focus on the creation of the object. No synchronization is needed, as this is already handled byget()
. This method is guaranteed to be called only once.- Returns:
- the managed data object
- Throws:
ConcurrentException
- if an error occurs during object creation
-