com.thinkaurelius.titan.diskstorage.keycolumnvalue.cache

Class KCVSCache

java.lang.Object

com.thinkaurelius.titan.diskstorage.keycolumnvalue.cache.KCVSCache

All Implemented Interfaces:

KeyColumnValueStore

Direct Known Subclasses:

ExpirationKCVSCache, NoKCVSCache

public abstract class KCVSCache
extends Object
implements KeyColumnValueStore

Author:

Matthias Broecheler (me@matthiasb.com)

Field Summary

Fields

Modifier and Type	Field and Description
static List<Entry>	NO_DELETIONS
protected KeyColumnValueStore	store

Fields inherited from interface com.thinkaurelius.titan.diskstorage.keycolumnvalue.KeyColumnValueStore

NO_ADDITIONS

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	KCVSCache(KeyColumnValueStore store, String metricsName)

Method Summary

Methods

Modifier and Type	Method and Description
void	acquireLock(StaticBuffer key, StaticBuffer column, StaticBuffer expectedValue, StoreTransaction txh) Attempts to claim a lock on the value at the specified key and column pair.
abstract void	clearCache()
void	close() Closes this store
KeyIterator	getKeys(KeyRangeQuery keyQuery, StoreTransaction txh) Returns a KeyIterator over all keys that fall within the key-range specified by the given query and have one or more columns matching the column-range.
KeyIterator	getKeys(SliceQuery columnQuery, StoreTransaction txh) Returns a KeyIterator over all keys in the store that have one or more columns matching the column-range.
String	getName() Returns the name of this store.
protected StoreTransaction	getTx(StoreTransaction txh)
protected boolean	hasValidateKeysOnly()
protected void	incActionBy(int by, CacheMetricsAction action, StoreTransaction txh)
protected abstract void	invalidate(StaticBuffer key, List<CachableStaticBuffer> entries)
void	mutate(StaticBuffer key, List<Entry> additions, List<StaticBuffer> deletions, StoreTransaction txh) Verifies acquisition of locks txh from previous calls to KeyColumnValueStore.acquireLock(StaticBuffer, StaticBuffer, StaticBuffer, StoreTransaction) , then writes supplied additions and/or deletions to key in the underlying data store.
void	mutateEntries(StaticBuffer key, List<Entry> additions, List<Entry> deletions, StoreTransaction txh)

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.thinkaurelius.titan.diskstorage.keycolumnvalue.KeyColumnValueStore

getSlice, getSlice

Field Detail

NO_DELETIONS

public static final List<Entry> NO_DELETIONS

store

protected final KeyColumnValueStore store

Constructor Detail

KCVSCache

protected KCVSCache(KeyColumnValueStore store,
         String metricsName)

Method Detail

hasValidateKeysOnly

protected boolean hasValidateKeysOnly()

incActionBy

protected void incActionBy(int by,
               CacheMetricsAction action,
               StoreTransaction txh)

clearCache

public abstract void clearCache()

invalidate

protected abstract void invalidate(StaticBuffer key,
              List<CachableStaticBuffer> entries)

mutate

public void mutate(StaticBuffer key,
          List<Entry> additions,
          List<StaticBuffer> deletions,
          StoreTransaction txh)
            throws StorageException

Description copied from interface: KeyColumnValueStore

Verifies acquisition of locks txh from previous calls to KeyColumnValueStore.acquireLock(StaticBuffer, StaticBuffer, StaticBuffer, StoreTransaction) , then writes supplied additions and/or deletions to key in the underlying data store. Deletions are applied strictly before additions. In other words, if both an addition and deletion are supplied for the same column, then the column will first be deleted and then the supplied Entry for the column will be added.

Implementations which don't support locking should skip the initial lock verification step but otherwise behave as described above.

Specified by:

mutate in interface KeyColumnValueStore

Parameters:

key - the key under which the columns in additions and deletions will be written

additions - the list of Entry instances representing column-value pairs to create under key, or null to add no column-value pairs

deletions - the list of columns to delete from key, or null to delete no columns

txh - the transaction to use

Throws:

PermanentLockingException - if locking is supported by the implementation and at least one lock acquisition attempted by KeyColumnValueStore.acquireLock(StaticBuffer, StaticBuffer, StaticBuffer, StoreTransaction) has failed

StorageException

mutateEntries

public void mutateEntries(StaticBuffer key,
                 List<Entry> additions,
                 List<Entry> deletions,
                 StoreTransaction txh)
                   throws StorageException

Throws:

StorageException

getTx

protected final StoreTransaction getTx(StoreTransaction txh)

acquireLock

public void acquireLock(StaticBuffer key,
               StaticBuffer column,
               StaticBuffer expectedValue,
               StoreTransaction txh)
                 throws StorageException

Description copied from interface: KeyColumnValueStore

Attempts to claim a lock on the value at the specified key and column pair. These locks are discretionary.

If locking fails, implementations of this method may, but are not required to, throw PermanentLockingException. This method is not required to determine whether locking actually succeeded and may return without throwing an exception even when the lock can't be acquired. Lock acquisition is only only guaranteed to be verified by the first call to KeyColumnValueStore.mutate(StaticBuffer, List, List, StoreTransaction) on any given txh.

The expectedValue must match the actual value present at the key and column pair. If the true value does not match the expectedValue, the lock attempt fails and LockingException is thrown. This method may check expectedValue. The mutate() mutate is required to check it.

When this method is called multiple times on the same key, column, and txh, calls after the first have no effect.

Locks acquired by this method must be automatically released on transaction commit() or rollback().

Implementations which don't support locking should throw UnsupportedOperationException.

Specified by:

acquireLock in interface KeyColumnValueStore

Parameters:

key - the key on which to lock

column - the column on which to lock

expectedValue - the expected value for the specified key-column pair on which to lock (null means the pair must have no value)

txh - the transaction to use

Throws:

PermanentLockingException - the lock could not be acquired due to contention with other transactions or a locking-specific storage problem

StorageException

getKeys

public KeyIterator getKeys(KeyRangeQuery keyQuery,
                  StoreTransaction txh)
                    throws StorageException

Description copied from interface: KeyColumnValueStore

Returns a KeyIterator over all keys that fall within the key-range specified by the given query and have one or more columns matching the column-range. Calling KeyIterator.getEntries() returns the list of all entries that match the column-range specified by the given query.

This method is only supported by stores which keep keys in byte-order.

Specified by:

getKeys in interface KeyColumnValueStore

Returns:

Throws:

StorageException

getKeys

public KeyIterator getKeys(SliceQuery columnQuery,
                  StoreTransaction txh)
                    throws StorageException

Description copied from interface: KeyColumnValueStore

Returns a KeyIterator over all keys in the store that have one or more columns matching the column-range. Calling KeyIterator.getEntries() returns the list of all entries that match the column-range specified by the given query.

This method is only supported by stores which do not keep keys in byte-order.

Specified by:

getKeys in interface KeyColumnValueStore

Returns:

Throws:

StorageException

getName

public String getName()

Description copied from interface: KeyColumnValueStore

Returns the name of this store. Each store has a unique name which is used to open it.

Specified by:

getName in interface KeyColumnValueStore

Returns:

store name

See Also:

KeyColumnValueStoreManager.openDatabase(String)

close

public void close()
           throws StorageException

Description copied from interface: KeyColumnValueStore

Closes this store

Specified by:

close in interface KeyColumnValueStore

Throws:

StorageException