voldemort.store.configuration
Class FileBackedCachingStorageEngine

java.lang.Object
  voldemort.store.configuration.FileBackedCachingStorageEngine

All Implemented Interfaces:

StorageEngine<ByteArray,byte[],byte[]>, Store<ByteArray,byte[],byte[]>

public class FileBackedCachingStorageEngine
extends java.lang.Object
implements StorageEngine<ByteArray,byte[],byte[]>

A Storage Engine used to persist the keys and values in a human readable format on disk. The data is primarily served off of the cache. After each put, the entire cache state is flushed to the backing file. The data is UTF-8 serialized when writing to the file in order to make it human readable. The primary purpose of this storage engine is for maintaining the cluster metadata which is characterized by low QPS and not latency sensitive.

Author:

csoman

Constructor Summary

FileBackedCachingStorageEngine(java.lang.String name, java.lang.String inputDirectory)

Method Summary

boolean	beginBatchModifications() A lot of storage engines support efficient methods for performing large number of writes (puts/deletes) against the data source.
void	close() Close the store.
boolean	delete(ByteArray key, Version version) Delete all entries prior to the given version
boolean	endBatchModifications()
ClosableIterator<Pair<ByteArray,Versioned<byte[]>>>	entries() Get an iterator over pairs of entries in the store.
ClosableIterator<Pair<ByteArray,Versioned<byte[]>>>	entries(int partition) Get an iterator over pairs of entries in a store's partition.
java.util.List<Versioned<byte[]>>	get(ByteArray key, byte[] transforms) Get the value associated with the given key
java.util.Map<ByteArray,java.util.List<Versioned<byte[]>>>	getAll(java.lang.Iterable<ByteArray> keys, java.util.Map<ByteArray,byte[]> transforms) Get the values associated with the given keys and returns them in a Map of keys to a list of versioned values.
java.lang.Object	getCapability(StoreCapabilityType capability) Get some capability of the store.
java.lang.String	getName()
java.util.List<Version>	getVersions(ByteArray key)
boolean	isPartitionAware() Is the data persistence aware of partitions? In other words is the data internally stored on a per partition basis or together
boolean	isPartitionScanSupported() Does the storage engine support efficient scanning of a single partition
ClosableIterator<ByteArray>	keys() Get an iterator over keys in the store.
ClosableIterator<ByteArray>	keys(int partition) Get an iterator over keys in the store's partition Note that the iterator need not be threadsafe, and that it must be manually closed after use.
void	put(ByteArray key, Versioned<byte[]> value, byte[] transforms) Associate the value with the key and version in this store
void	truncate() Truncate all entries in the store

Methods inherited from class java.lang.Object

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

Constructor Detail

FileBackedCachingStorageEngine

public FileBackedCachingStorageEngine(java.lang.String name,
                                      java.lang.String inputDirectory)

Method Detail

getName

public java.lang.String getName()

Specified by:

getName in interface Store<ByteArray,byte[],byte[]>

Returns:

The name of the store.

close

public void close()
           throws VoldemortException

Description copied from interface: Store

Close the store.

Specified by:

close in interface Store<ByteArray,byte[],byte[]>

Throws:

VoldemortException - If closing fails.

getCapability

public java.lang.Object getCapability(StoreCapabilityType capability)

Description copied from interface: Store

Get some capability of the store. Examples would be the serializer used, or the routing strategy. This provides a mechanism to verify that the store hierarchy has some set of capabilities without knowing the precise layering.

Specified by:

getCapability in interface Store<ByteArray,byte[],byte[]>

Parameters:

capability - The capability type to retrieve

Returns:

The given capaiblity

entries

public ClosableIterator<Pair<ByteArray,Versioned<byte[]>>> entries()

Description copied from interface: StorageEngine

Get an iterator over pairs of entries in the store. The key is the first element in the pair and the versioned value is the second element. Note that the iterator need not be threadsafe, and that it must be manually closed after use.

Specified by:

entries in interface StorageEngine<ByteArray,byte[],byte[]>

Returns:

An iterator over the entries in this StorageEngine.

keys

public ClosableIterator<ByteArray> keys()

Description copied from interface: StorageEngine

Get an iterator over keys in the store. Note that the iterator need not be threadsafe, and that it must be manually closed after use.

Specified by:

keys in interface StorageEngine<ByteArray,byte[],byte[]>

Returns:

An iterator over the keys in this StorageEngine.

truncate

public void truncate()

Description copied from interface: StorageEngine

Truncate all entries in the store

Specified by:

truncate in interface StorageEngine<ByteArray,byte[],byte[]>

isPartitionAware

public boolean isPartitionAware()

Description copied from interface: StorageEngine

Is the data persistence aware of partitions? In other words is the data internally stored on a per partition basis or together

Specified by:

isPartitionAware in interface StorageEngine<ByteArray,byte[],byte[]>

Returns:

Boolean indicating if the data persistence is partition aware

get

public java.util.List<Versioned<byte[]>> get(ByteArray key,
                                             byte[] transforms)
                                      throws VoldemortException

Description copied from interface: Store

Get the value associated with the given key

Specified by:

get in interface Store<ByteArray,byte[],byte[]>

Parameters:

key - The key to check for

Returns:

The value associated with the key or an empty list if no values are found.

Throws:

VoldemortException

getAll

public java.util.Map<ByteArray,java.util.List<Versioned<byte[]>>> getAll(java.lang.Iterable<ByteArray> keys,
                                                                         java.util.Map<ByteArray,byte[]> transforms)
                                                                  throws VoldemortException

Description copied from interface: Store

Get the values associated with the given keys and returns them in a Map of keys to a list of versioned values. Note that the returned map will only contain entries for the keys which have a value associated with them.

Specified by:

getAll in interface Store<ByteArray,byte[],byte[]>

Parameters:

keys - The keys to check for.

Returns:

A Map of keys to a list of versioned values.

Throws:

VoldemortException

getVersions

public java.util.List<Version> getVersions(ByteArray key)

Specified by:

getVersions in interface Store<ByteArray,byte[],byte[]>

put

public void put(ByteArray key,
                Versioned<byte[]> value,
                byte[] transforms)
         throws VoldemortException

Description copied from interface: Store

Associate the value with the key and version in this store

Specified by:

put in interface Store<ByteArray,byte[],byte[]>

Parameters:

key - The key to use

value - The value to store and its version.

Throws:

VoldemortException

delete

public boolean delete(ByteArray key,
                      Version version)
               throws VoldemortException

Description copied from interface: Store

Delete all entries prior to the given version

Specified by:

delete in interface Store<ByteArray,byte[],byte[]>

Parameters:

key - The key to delete

version - The current value of the key

Returns:

True if anything was deleted

Throws:

VoldemortException

entries

public ClosableIterator<Pair<ByteArray,Versioned<byte[]>>> entries(int partition)

Description copied from interface: StorageEngine

Get an iterator over pairs of entries in a store's partition. The key is the first element in the pair and the versioned value is the second element. Note that the iterator need not be threadsafe, and that it must be manually closed after use.

Specified by:

entries in interface StorageEngine<ByteArray,byte[],byte[]>

Parameters:

partition - partition whose entries are to be fetched

Returns:

An iterator over the entries in this StorageEngine.

keys

public ClosableIterator<ByteArray> keys(int partition)

Description copied from interface: StorageEngine

Get an iterator over keys in the store's partition Note that the iterator need not be threadsafe, and that it must be manually closed after use.

Specified by:

keys in interface StorageEngine<ByteArray,byte[],byte[]>

Parameters:

partition - partition whose keys are to be fetched

Returns:

An iterator over the keys in this StorageEngine.

isPartitionScanSupported

public boolean isPartitionScanSupported()

Description copied from interface: StorageEngine

Does the storage engine support efficient scanning of a single partition

Specified by:

isPartitionScanSupported in interface StorageEngine<ByteArray,byte[],byte[]>

Returns:

true if the storage engine implements the capability. false otherwise

beginBatchModifications

public boolean beginBatchModifications()

Description copied from interface: StorageEngine

A lot of storage engines support efficient methods for performing large number of writes (puts/deletes) against the data source. This method puts the storage engine in this batch write mode

Specified by:

beginBatchModifications in interface StorageEngine<ByteArray,byte[],byte[]>

Returns:

true if the storage engine took successful action to switch to 'batch-write' mode

endBatchModifications

public boolean endBatchModifications()

Specified by:

endBatchModifications in interface StorageEngine<ByteArray,byte[],byte[]>

Returns:

true if the storage engine successfully returned to normal mode