Package io.permazen.kv.mvstore

Class MVMapKVStore

java.lang.Object

io.permazen.kv.AbstractKVStore

io.permazen.kv.mvstore.MVMapKVStore

All Implemented Interfaces:

KVStore

Direct Known Subclasses:

MVMapSnapshot, MVStoreAtomicKVStore

public class MVMapKVStore
extends AbstractKVStore

Straightforward KVStore view of an MVMap.

Field Summary

Fields

Modifier and Type	Field	Description
protected final Logger	log

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	MVMapKVStore()	Default constructor.
	MVMapKVStore(org.h2.mvstore.MVMap<byte[],byte[]> mvmap)	Constructor.

Method Summary

Modifier and Type	Method	Description
byte[]	get(byte[] key)	Get the value associated with the given key, if any.
KVPair	getAtLeast(byte[] minKey, byte[] maxKey)	Get the key/value pair having the smallest key greater than or equal to the given minimum, if any.
KVPair	getAtMost(byte[] maxKey, byte[] minKey)	Get the key/value pair having the largest key strictly less than the given maximum, if any.
org.h2.mvstore.MVMap<byte[],byte[]>	getMVMap()	Get the underlying MVMap associated with this instance.
CursorIterator	getRange(byte[] minKey, byte[] maxKey, boolean reverse)	Iterate the key/value pairs in the specified range.
void	put(byte[] key, byte[] value)	Set the value associated with the given key.
void	remove(byte[] key)	Remove the key/value pair with the given key, if it exists.
String	toString()

Methods inherited from class io.permazen.kv.AbstractKVStore

adjustCounter, decodeCounter, encodeCounter, removeRange

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.permazen.kv.KVStore

apply, getRange, getRange, removeRange

Field Details

log

protected final Logger log

Constructor Details

MVMapKVStore

protected MVMapKVStore()

Default constructor.

If this constructor is used, this class must be subclassed and getMVMap() overridden to supply the delegate MVMap.

Throws:

IllegalArgumentException - if mvmap is null

MVMapKVStore

public MVMapKVStore(org.h2.mvstore.MVMap<byte[],byte[]> mvmap)

Constructor.

Parameters:

mvmap - the underlying MVMap to use

Throws:

IllegalArgumentException - if mvmap is null

Method Details

getMVMap

public org.h2.mvstore.MVMap<byte[],byte[]> getMVMap()

Get the underlying MVMap associated with this instance.

The implementation in MVMapKVStore returns the MVMap passed to the constructor, if any. Subclasses that use this class' default constructor must override this method.

Returns:

underlying MVMap

get

public byte[] get(byte[] key)

Description copied from interface: KVStore

Get the value associated with the given key, if any.

Modifications to the returned byte[] array do not affect this instance.

Specified by:

get in interface KVStore

Overrides:

get in class AbstractKVStore

Parameters:

key - key

Returns:

value associated with key, or null if not found

getAtLeast

public KVPair getAtLeast(byte[] minKey,
 byte[] maxKey)

Description copied from interface: KVStore

Get the key/value pair having the smallest key greater than or equal to the given minimum, if any.

An optional (exclusive) maximum key may also be specified; if maxKey is null, there is no upper bound; if maxKey <= minKey, null is always returned.

If keys starting with 0xff are not supported by this instance, and minKey starts with 0xff, then this method returns null.

Modifications to the returned byte[] arrays do not affect this instance.

Specified by:

getAtLeast in interface KVStore

Overrides:

getAtLeast in class AbstractKVStore

Parameters:

minKey - minimum key (inclusive), or null for no minimum (get the smallest key)

maxKey - maximum key (exclusive), or null for no maximum (no upper bound)

Returns:

smallest key/value pair with key >= minKey and key < maxKey, or null if none exists

getAtMost

public KVPair getAtMost(byte[] maxKey,
 byte[] minKey)

Description copied from interface: KVStore

Get the key/value pair having the largest key strictly less than the given maximum, if any.

An optional (inclusive) minimum key may also be specified; if minKey is null, there is no lower bound (equivalent to a lower bound of the empty byte array); if minKey >= maxKey, null is always returned.

If keys starting with 0xff are not supported by this instance, and maxKey starts with 0xff, then this method behaves as if maxKey were null.

Modifications to the returned byte[] arrays do not affect this instance.

Specified by:

getAtMost in interface KVStore

Overrides:

getAtMost in class AbstractKVStore

Parameters:

maxKey - maximum key (exclusive), or null for no maximum (get the largest key)

minKey - minimum key (inclusive), or null for no minimum (no lower bound)

Returns:

largest key/value pair with key < maxKey and key >= minKey, or null if none exists

getRange

public CursorIterator getRange(byte[] minKey,
 byte[] maxKey,
 boolean reverse)

Description copied from interface: KVStore

Iterate the key/value pairs in the specified range. The returned CloseableIterator's remove() method must be supported and should have the same effect as invoking remove() on the corresponding key.

If keys starting with 0xff are not supported by this instance, and minKey starts with 0xff, then this method returns an empty iteration.

If keys starting with 0xff are not supported by this instance, and maxKey starts with 0xff, then this method behaves as if maxKey were null.

The returned CloseableIterator is weakly consistent (see java.util.concurrent). In short, the returned CloseableIterator must not throw ConcurrentModificationException; however, whether or not a "live" CloseableIterator reflects any modifications made after its creation is implementation dependent. Implementations that do make post-creation updates visible in the CloseableIterator, even if the update occurs after some delay, must preserve the order in which the modifications actually occurred.

The returned CloseableIterator itself is not guaranteed to be thread safe; is should only be used in the thread that created it.

Invokers of this method are encouraged to close() the returned iterators, though this is not required for correct behavior.

Modifications to the returned KVPair key and value byte[] arrays do not affect this instance.

Parameters:

minKey - minimum key (inclusive), or null for no minimum (start at the smallest key)

maxKey - maximum key (exclusive), or null for no maximum (end at the largest key)

reverse - true to return key/value pairs in reverse order (i.e., keys descending)

Returns:

iteration of key/value pairs in the range minKey (inclusive) to maxKey (exclusive)

put

public void put(byte[] key,
 byte[] value)

Description copied from interface: KVStore

Set the value associated with the given key.

Specified by:

put in interface KVStore

Overrides:

put in class AbstractKVStore

Parameters:

key - key

value - value

remove

public void remove(byte[] key)

Description copied from interface: KVStore

Remove the key/value pair with the given key, if it exists.

Specified by:

remove in interface KVStore

Overrides:

remove in class AbstractKVStore

Parameters:

key - key

toString

public String toString()

Overrides:

toString in class Object