io.permazen.kv.lmdb

Class LMDBKVStore<T>

java.lang.Object

io.permazen.kv.AbstractKVStore

io.permazen.kv.lmdb.LMDBKVStore<T>

Type Parameters:

T - buffer type

All Implemented Interfaces:

CloseableKVStore, KVStore, Closeable, AutoCloseable

Direct Known Subclasses:

ByteArrayLMDBKVStore

public abstract class LMDBKVStore<T>
extends AbstractKVStore
implements CloseableKVStore

Straightforward KVStore view of a LMDB transaction.

Instances must be close()'d when no longer needed to avoid leaking resources.

Field Summary

Fields

Modifier and Type	Field and Description
protected Logger	log

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	LMDBKVStore(org.lmdbjava.Dbi<T> db, org.lmdbjava.Txn<T> tx) Constructor.

Method Summary

Modifier and Type	Method and Description
void	close() Close this instance.
protected void	finalize() Finalize this instance.
byte[]	get(byte[] key) Get the value associated with the given key, if any.
org.lmdbjava.Dbi<T>	getDatabase() Get the Dbi associated with this instance.
org.lmdbjava.KeyRange<T>	getKeyRange(byte[] minKey, byte[] maxKey, boolean reverse) Get the KeyRange corresponding to the given parameters.
CloseableIterator<KVPair>	getRange(byte[] minKey, byte[] maxKey, boolean reverse) Iterate the key/value pairs in the specified range.
org.lmdbjava.Txn<T>	getTransaction() Get the Txn associated with this instance.
boolean	isClosed() Determine if this instance is closed.
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.
void	removeRange(byte[] minKey, byte[] maxKey) Remove all key/value pairs whose keys are in a given range.
String	toString()
protected abstract byte[]	unwrap(T buf, boolean copy) Unwrap the given buffer, returning its contents as a byte[] array.
protected abstract T	wrap(byte[] buf, boolean copy) Wrap the given byte[] array in a buffer appropriate for this instance.

Methods inherited from class io.permazen.kv.AbstractKVStore

adjustCounter, decodeCounter, encodeCounter, getAtLeast, getAtMost

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.permazen.kv.KVStore

adjustCounter, apply, decodeCounter, encodeCounter, getAtLeast, getAtMost, getRange, getRange, removeRange

Field Detail

log

protected final Logger log

Constructor Detail

LMDBKVStore

protected LMDBKVStore(org.lmdbjava.Dbi<T> db,
                      org.lmdbjava.Txn<T> tx)

Constructor.

Closing this instance does not close the underlying transaction.

Parameters:

db - LMDB database

tx - LMDB transaction

Throws:

IllegalArgumentException - if db or tx is null

Method Detail

getTransaction

public org.lmdbjava.Txn<T> getTransaction()

Get the Txn associated with this instance.

Returns:

associated transaction

getDatabase

public org.lmdbjava.Dbi<T> getDatabase()

Get the Dbi associated with this instance.

Returns:

associated database handle

isClosed

public boolean isClosed()

Determine if this instance is closed.

Returns:

true if closed, false if still open

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

getRange

public CloseableIterator<KVPair> getRange(byte[] minKey,
                                          byte[] maxKey,
                                          boolean reverse)

Description copied from interface: KVStore

Iterate the key/value pairs in the specified range. The returned Iterator'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 Iterator must not throw ConcurrentModificationException; however, whether or not a "live" Iterator reflects any modifications made after its creation is implementation dependent. Implementations that do make post-creation updates visible in the Iterator, even if the update occurs after some delay, must preserve the order in which the modifications actually occurred.

The returned Iterator itself is not guaranteed to be thread safe.

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.

Specified by:

getRange in interface KVStore

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

removeRange

public void removeRange(byte[] minKey,
                        byte[] maxKey)

Description copied from interface: KVStore

Remove all key/value pairs whose keys are in a given range.

The minKey must be less than or equal to maxKey; if they equal (and not null) then nothing happens; if they are both null then all entries are deleted.

If keys starting with 0xff are not supported by this instance, then:

• If minKey starts with 0xff, then no change occurs
• If maxKey starts with 0xff, then this method behaves as if maxKey were null

Specified by:

removeRange in interface KVStore

Overrides:

removeRange in class AbstractKVStore

Parameters:

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

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

getKeyRange

public org.lmdbjava.KeyRange<T> getKeyRange(byte[] minKey,
                                            byte[] maxKey,
                                            boolean reverse)

Get the KeyRange corresponding to the given parameters.

Parameters:

minKey - minimum key (inclusive), or null for none

maxKey - maximum key (exclusive), or null for none

reverse - true for reverse ordering, false for forward ordering

Returns:

KeyRange instance

wrap

protected abstract T wrap(byte[] buf,
                          boolean copy)

Wrap the given byte[] array in a buffer appropriate for this instance.

Parameters:

buf - byte array data, or possibly null

copy - if true, then changes to the data in either buf or the returned buffer must not affect the other

Returns:

null if buf is null, otherwise a buffer containing the data in buf

unwrap

protected abstract byte[] unwrap(T buf,
                                 boolean copy)

Unwrap the given buffer, returning its contents as a byte[] array.

Parameters:

buf - a buffer containing byte[] array data, or possibly null

copy - if true, then changes to the data in either buf or the returned array must not affect the other

Returns:

byte array data in buf, or null if buf is null

close

public void close()

Close this instance.

This closes any unclosed iterators; it does not close the underlying transaction.

Specified by:

close in interface CloseableKVStore

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

finalize

protected void finalize()
                 throws Throwable

Finalize this instance. Invokes close() to close any unclosed iterators.

Overrides:

finalize in class Object

Throws:

Throwable

toString

public String toString()

Overrides:

toString in class Object