org.iids.aos.kernel.ac
Class PersistentStore

java.lang.Object
  org.iids.aos.kernel.ac.PersistentStore

Direct Known Subclasses:

PersistentStoreFS

public abstract class PersistentStore
extends java.lang.Object

Defines an abstract interface to acces persistent storage. A PersistentStore allows (key, value) pairs to be stored on persistent storage. Currently, only regular files are used as the actual persistent storage.

Author:

Michel Oey

Constructor Summary

PersistentStore()

Method Summary

abstract void	close() Close the persistent store.
abstract void	delete(java.lang.String key) Deletes a (key, value) pair from the persistent storage.
abstract boolean	exists(java.lang.String key) Checks whether a key is stored in the persistent storage.
abstract byte[]	get(java.lang.String key) Retrieves value associated with key from the persistent storage.
abstract byte[]	get(java.lang.String key, int offset, int length) Retrieves part of the value associated with key from the persistent storage.
static PersistentStore	getInstance()
abstract void	put(java.lang.String key, byte[] value) Stores (key, value) pair in the persistent storage.
abstract void	put(java.lang.String key, byte[] value, int length) Stores (key, value) pair in the persistent storage.
abstract void	put(java.lang.String key, int offset, byte[] value, int length) Overwrite any (key, value) pair in the persistent storage by overwriting the stored value starting at offset with the byte array given as parameter.
abstract void	put(java.lang.String key, int offset, byte[] value, int length, boolean sync) Overwrite any (key, value) pair in the persistent storage by overwriting the stored value starting at offset with the byte array given as parameter.
static void	setup(java.io.File directory)

Methods inherited from class java.lang.Object

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

Constructor Detail

PersistentStore

public PersistentStore()

Method Detail

setup

public static void setup(java.io.File directory)

getInstance

public static PersistentStore getInstance()
                                   throws InputOutputException

Throws:

InputOutputException

put

public abstract void put(java.lang.String key,
                         byte[] value)
                  throws InputOutputException

Stores (key, value) pair in the persistent storage.

Throws:

InputOutputException

put

public abstract void put(java.lang.String key,
                         byte[] value,
                         int length)
                  throws InputOutputException

Stores (key, value) pair in the persistent storage.

Throws:

InputOutputException

put

public abstract void put(java.lang.String key,
                         int offset,
                         byte[] value,
                         int length)
                  throws InputOutputException

Overwrite any (key, value) pair in the persistent storage by overwriting the stored value starting at offset with the byte array given as parameter. Only length bytes are copied.

Throws:

InputOutputException

put

public abstract void put(java.lang.String key,
                         int offset,
                         byte[] value,
                         int length,
                         boolean sync)
                  throws InputOutputException

Overwrite any (key, value) pair in the persistent storage by overwriting the stored value starting at offset with the byte array given as parameter. Only length bytes are copied. Sync indicates whether the write should be made persistent immediately.

Throws:

InputOutputException

get

public abstract byte[] get(java.lang.String key)
                    throws InputOutputException

Retrieves value associated with key from the persistent storage. If the data cannot be found, null is returned.

Throws:

InputOutputException

get

public abstract byte[] get(java.lang.String key,
                           int offset,
                           int length)
                    throws InputOutputException

Retrieves part of the value associated with key from the persistent storage. Which part of the value is returned is specified by the offset and length parameters. No more bytes than are available in the value will be returned. If the data cannot be found, null is returned.

Throws:

InputOutputException

delete

public abstract void delete(java.lang.String key)
                     throws InputOutputException

Deletes a (key, value) pair from the persistent storage.

Throws:

InputOutputException

exists

public abstract boolean exists(java.lang.String key)
                        throws InputOutputException

Checks whether a key is stored in the persistent storage.

Throws:

InputOutputException

close

public abstract void close()
                    throws InputOutputException

Close the persistent store. Allows the implementation to do some cleanup.

Throws:

InputOutputException