Module lmdbjava

Package org.lmdbjava

Class Txn<T>

java.lang.Object

org.lmdbjava.Txn<T>

Type Parameters:

T - buffer type

All Implemented Interfaces:

AutoCloseable

public final class Txn<T>
extends Object
implements AutoCloseable

LMDB transaction.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	Txn.BadException	Transaction must abort, has a child, or is invalid.
static final class	Txn.BadReaderLockException	Invalid reuse of reader locktable slot.
static class	Txn.EnvIsReadOnly	The proposed R-W transaction is incompatible with a R-O Env.
static class	Txn.IncompatibleParent	The proposed transaction is incompatible with its parent transaction.
static final class	Txn.NotReadyException	Transaction is not in a READY state.
static class	Txn.NotResetException	The current transaction has not been reset.
static class	Txn.ReadOnlyRequiredException	The current transaction is not a read-only transaction.
static class	Txn.ReadWriteRequiredException	The current transaction is not a read-write transaction.
static class	Txn.ResetException	The current transaction has already been reset.
static enum	Txn.State	Transaction states.
static final class	Txn.TxFullException	Transaction has too many dirty pages.

Method Summary

Modifier and Type	Method	Description
void	abort()	Aborts this transaction.
void	checkReadOnly()
void	checkReady()
void	checkWritesAllowed()
void	close()	Closes this transaction by aborting if not already committed.
void	commit()	Commits this transaction.
long	getId()	Return the transaction's ID.
Txn<T>	getParent()	Obtains this transaction's parent.
Txn.State	getState()	Return the state of the transaction.
boolean	isReadOnly()	Whether this transaction is read-only.
T	key()	Fetch the buffer which holds a read-only view of the LMDI allocated memory.
void	renew()	Renews a read-only transaction previously released by reset().
void	reset()	Aborts this read-only transaction and resets the transaction handle so it can be reused upon calling renew().
T	val()	Fetch the buffer which holds a read-only view of the LMDI allocated memory.

Methods inherited from class java.lang.Object

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

Method Details

abort

public void abort()

Aborts this transaction.

close

public void close()

Closes this transaction by aborting if not already committed.

Closing the transaction will invoke BufferProxy.deallocate(java.lang.Object) for each read-only buffer (ie the key and value).

Specified by:

close in interface AutoCloseable

commit

public void commit()

Commits this transaction.

getId

public long getId()

Return the transaction's ID.

Returns:

A transaction ID, valid if input is an active transaction

getParent

public Txn<T> getParent()

Obtains this transaction's parent.

Returns:

the parent transaction (may be null)

isReadOnly

public boolean isReadOnly()

Whether this transaction is read-only.

Returns:

if read-only

key

public T key()

Fetch the buffer which holds a read-only view of the LMDI allocated memory. Any use of this buffer must comply with the standard LMDB C "mdb_get" contract (ie do not modify, do not attempt to release the memory, do not use once the transaction or cursor closes, do not use after a write etc).

Returns:

the key buffer (never null)

renew

public void renew()

Renews a read-only transaction previously released by reset().

reset

public void reset()

Aborts this read-only transaction and resets the transaction handle so it can be reused upon calling renew().

val

public T val()

Fetch the buffer which holds a read-only view of the LMDI allocated memory. Any use of this buffer must comply with the standard LMDB C "mdb_get" contract (ie do not modify, do not attempt to release the memory, do not use once the transaction or cursor closes, do not use after a write etc).

Returns:

the value buffer (never null)

checkReadOnly

public void checkReadOnly()

checkReady

public void checkReady()

checkWritesAllowed

public void checkWritesAllowed()

getState

public Txn.State getState()

Return the state of the transaction.

Returns:

the state