org.h2.mvstore.tx

Class Transaction

java.lang.Object

org.h2.mvstore.tx.Transaction

public class Transaction
extends java.lang.Object

A transaction.

Field Summary

Fields

Modifier and Type	Field and Description
static int	STATUS_CLOSED The status of a closed transaction (committed or rolled back).
static int	STATUS_COMMITTED The status of a transaction that has been logically committed or rather marked as committed, because it might be still listed among prepared, if it was prepared for commit.
static int	STATUS_OPEN The status of an open transaction.
static int	STATUS_PREPARED The status of a prepared transaction.

Method Summary

Methods

Modifier and Type	Method and Description
void	commit() Commit the transaction.
int	getBlockerId()
java.util.Iterator<TransactionStore.Change>	getChanges(long savepointId) Get the list of changes, starting with the latest change, up to the given savepoint (in reverse order than they occurred).
int	getId()
java.lang.String	getName()
long	getSequenceNum()
int	getStatus()
boolean	hasChanges() Determine if any database changes were made as part of this transaction.
void	markStatementEnd() Mark an exit from SQL statement execution within this transaction.
void	markStatementStart() Mark an entry into a new SQL statement execution within this transaction.
<K,V> TransactionMap<K,V>	openMap(MVMap<K,VersionedValue> map) Open the transactional version of the given map.
<K,V> TransactionMap<K,V>	openMap(java.lang.String name) Open a data map.
<K,V> TransactionMap<K,V>	openMap(java.lang.String name, DataType keyType, DataType valueType) Open the map to store the data.
void	prepare() Prepare the transaction.
<K,V> void	removeMap(TransactionMap<K,V> map) Remove the map.
void	rollback() Roll the transaction back.
void	rollbackToSavepoint(long savepointId) Roll back to the given savepoint.
void	setName(java.lang.String name)
long	setSavepoint() Create a new savepoint.
java.lang.String	toString()
boolean	waitFor(Transaction toWaitFor, MVMap<?,VersionedValue> map, java.lang.Object key) Make this transaction to wait for the specified transaction to be closed, because both of them try to modify the same map entry.

Methods inherited from class java.lang.Object

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

Field Detail

STATUS_CLOSED

public static final int STATUS_CLOSED

The status of a closed transaction (committed or rolled back).

See Also:

Constant Field Values

STATUS_OPEN

public static final int STATUS_OPEN

The status of an open transaction.

See Also:

Constant Field Values

STATUS_PREPARED

public static final int STATUS_PREPARED

The status of a prepared transaction.

See Also:

Constant Field Values

STATUS_COMMITTED

public static final int STATUS_COMMITTED

The status of a transaction that has been logically committed or rather marked as committed, because it might be still listed among prepared, if it was prepared for commit. Undo log entries might still exists for it and not all of it's changes within map's are re-written as committed yet. Nevertheless, those changes should be already viewed by other transactions as committed. This transaction's id can not be re-used until all of the above is completed and transaction is closed. A transactions can be observed in this state when the store was closed while the transaction was not closed yet. When opening a store, such transactions will automatically be processed and closed as committed.

See Also:

Constant Field Values

Method Detail

getId

public int getId()

getSequenceNum

public long getSequenceNum()

getStatus

public int getStatus()

hasChanges

public boolean hasChanges()

Determine if any database changes were made as part of this transaction.

Returns:

true if there are changes to commit, false otherwise

setName

public void setName(java.lang.String name)

getName

public java.lang.String getName()

getBlockerId

public int getBlockerId()

setSavepoint

public long setSavepoint()

Create a new savepoint.

Returns:

the savepoint id

markStatementStart

public void markStatementStart()

Mark an entry into a new SQL statement execution within this transaction.

markStatementEnd

public void markStatementEnd()

Mark an exit from SQL statement execution within this transaction.

openMap

public <K,V> TransactionMap<K,V> openMap(java.lang.String name)

Open a data map.

Type Parameters:

K - the key type

V - the value type

Parameters:

name - the name of the map

Returns:

the transaction map

openMap

public <K,V> TransactionMap<K,V> openMap(java.lang.String name,
                                DataType keyType,
                                DataType valueType)

Open the map to store the data.

Type Parameters:

K - the key type

V - the value type

Parameters:

name - the name of the map

keyType - the key data type

valueType - the value data type

Returns:

the transaction map

openMap

public <K,V> TransactionMap<K,V> openMap(MVMap<K,VersionedValue> map)

Open the transactional version of the given map.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the base map

Returns:

the transactional map

prepare

public void prepare()

Prepare the transaction. Afterwards, the transaction can only be committed or completely rolled back.

commit

public void commit()

Commit the transaction. Afterwards, this transaction is closed.

rollbackToSavepoint

public void rollbackToSavepoint(long savepointId)

Roll back to the given savepoint. This is only allowed if the transaction is open.

Parameters:

savepointId - the savepoint id

rollback

public void rollback()

Roll the transaction back. Afterwards, this transaction is closed.

getChanges

public java.util.Iterator<TransactionStore.Change> getChanges(long savepointId)

Get the list of changes, starting with the latest change, up to the given savepoint (in reverse order than they occurred). The value of the change is the value before the change was applied.

Parameters:

savepointId - the savepoint id, 0 meaning the beginning of the transaction

Returns:

the changes

waitFor

public boolean waitFor(Transaction toWaitFor,
              MVMap<?,VersionedValue> map,
              java.lang.Object key)

Make this transaction to wait for the specified transaction to be closed, because both of them try to modify the same map entry.

Parameters:

toWaitFor - transaction to wait for

map - containing blocking entry

key - of the blocking entry

Returns:

true if other transaction was closed and this one can proceed, false if timed out

removeMap

public <K,V> void removeMap(TransactionMap<K,V> map)

Remove the map.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object