com.palantir.giraffe.file.base

Class SystemCache<K,S>

java.lang.Object

com.palantir.giraffe.file.base.SystemCache<K,S>

Type Parameters:

K - the type of cache keys

S - the type of cached systems

public final class SystemCache<K,S>
extends Object

A thread-safe cache for file systems or similar I/O systems. Systems are initialized and cached atomically. Threads that try to get a system while it is being constructed block until construction is complete or an error occurs.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	SystemCache.Factory<S> Constructs new systems to be stored in the cache.

Constructor Summary

Constructors

Constructor and Description
SystemCache()

Method Summary

Modifier and Type	Method and Description
S	get(K key) Gets the system associated with key if it exists.
S	init(K key, SystemCache.Factory<S> factory) Atomically initializes a system associated with key if no such system exists.
void	remove(K key) Removes the initialized system associated with key from the cache.

Methods inherited from class java.lang.Object

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

Constructor Detail

SystemCache

public SystemCache()

Method Detail

get

public S get(K key)
      throws InterruptedException,
             ExecutionException

Gets the system associated with key if it exists. Returns null if there is no system associated with key.

If a thread calls this method concurrently with another thread that is initializing a system for the same key, this thread will block until initialization completes. If an error occurs in the initialization thread, it is also reported to this thread.

Throws:

InterruptedException - if this thread is interrupted while waiting for initialization

ExecutionException - if an error occurs while this thread is waiting for initialization

init

public S init(K key,
              SystemCache.Factory<S> factory)
       throws IOException

Atomically initializes a system associated with key if no such system exists. If this thread initialized the system, the system is returned. Otherwise, this method returns null.

Throws:

IOException - if an I/O error occurs while initializing the system

remove

public void remove(K key)

Removes the initialized system associated with key from the cache.

Throws:

IllegalStateException - if this method is called while initialization is in progress.