com.sleepycat.je

Class TransactionConfig

java.lang.Object

com.sleepycat.je.TransactionConfig

All Implemented Interfaces:

java.lang.Cloneable

public class TransactionConfig
extends java.lang.Object
implements java.lang.Cloneable

Specifies the attributes of a database environment transaction.

Field Summary

Fields

Modifier and Type	Field and Description
static TransactionConfig	DEFAULT Default configuration used if null is passed to methods that create a transaction.

Constructor Summary

Constructors

Constructor and Description
TransactionConfig() An instance created using the default constructor is initialized with the system's default settings.

Method Summary

Modifier and Type	Method and Description
TransactionConfig	clone() Returns a copy of this configuration object.
ReplicaConsistencyPolicy	getConsistencyPolicy() Returns the consistency policy associated with the configuration.
Durability	getDurability() Returns the durability associated with the configuration.
boolean	getLocalWrite() Returns whether local-write is configured for this transaction.
boolean	getNoSync() Deprecated. replaced by getDurability()
boolean	getNoWait() Returns true if the transaction is configured to not wait if a lock request cannot be immediately granted.
boolean	getReadCommitted() Returns true if the transaction is configured for read committed isolation.
boolean	getReadOnly() Returns whether read-only is configured for this transaction.
boolean	getReadUncommitted() Returns true if read operations performed by the transaction are configured to return modified but not yet committed data.
boolean	getSerializableIsolation() Returns true if the transaction has been explicitly configured to have serializable (degree 3) isolation.
boolean	getSync() Returns true if the transaction is configured to write and synchronously flush the log it when commits.
boolean	getWriteNoSync() Deprecated. replaced by getDurability()
TransactionConfig	setConsistencyPolicy(ReplicaConsistencyPolicy consistencyPolicy) Associates a consistency policy with this configuration.
TransactionConfig	setDurability(Durability durability) Configures the durability associated with a transaction when it commits.
TransactionConfig	setLocalWrite(boolean localWrite) Configures this transaction to allow writing to non-replicated Databases in a ReplicatedEnvironment.
TransactionConfig	setNoSync(boolean noSync) Deprecated. replaced by setDurability(com.sleepycat.je.Durability)
TransactionConfig	setNoWait(boolean noWait) Configures the transaction to not wait if a lock request cannot be immediately granted.
TransactionConfig	setReadCommitted(boolean readCommitted) Configures the transaction for read committed isolation.
TransactionConfig	setReadOnly(boolean readOnly) Configures this transaction to disallow write operations, regardless of whether writes are allowed for the Environment or the Databases that are accessed.
TransactionConfig	setReadUncommitted(boolean readUncommitted) Configures read operations performed by the transaction to return modified but not yet committed data.
TransactionConfig	setSerializableIsolation(boolean serializableIsolation) Configures this transaction to have serializable (degree 3) isolation.
TransactionConfig	setSync(boolean sync) Configures the transaction to write and synchronously flush the log it when commits.
TransactionConfig	setWriteNoSync(boolean writeNoSync) Deprecated. replaced by setDurability(com.sleepycat.je.Durability)
java.lang.String	toString() Returns the values for each configuration attribute.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT

public static final TransactionConfig DEFAULT

Default configuration used if null is passed to methods that create a transaction.

Constructor Detail

TransactionConfig

public TransactionConfig()

An instance created using the default constructor is initialized with the system's default settings.

Method Detail

setSync

public TransactionConfig setSync(boolean sync)

Configures the transaction to write and synchronously flush the log it when commits.

This behavior may be set for a database environment using the Environment.setMutableConfig method. Any value specified to this method overrides that setting.

The default is false for this class and true for the database environment.

If true is passed to both setSync and setNoSync, setSync will take precedence.

Parameters:

sync - If true, transactions exhibit all the ACID (atomicity, consistency, isolation, and durability) properties.

Returns:

this

getSync

public boolean getSync()

Returns true if the transaction is configured to write and synchronously flush the log it when commits.

Returns:

true if the transaction is configured to write and synchronously flush the log it when commits.

setNoSync

public TransactionConfig setNoSync(boolean noSync)

Deprecated. replaced by setDurability(com.sleepycat.je.Durability)

Configures the transaction to not write or synchronously flush the log it when commits.

This behavior may be set for a database environment using the Environment.setMutableConfig method. Any value specified to this method overrides that setting.

The default is false for this class and the database environment.

Parameters:

noSync - If true, transactions exhibit the ACI (atomicity, consistency, and isolation) properties, but not D (durability); that is, database integrity will be maintained, but if the application or system fails, it is possible some number of the most recently committed transactions may be undone during recovery. The number of transactions at risk is governed by how many log updates can fit into the log buffer, how often the operating system flushes dirty buffers to disk, and how often the log is checkpointed.

Returns:

this

getNoSync

public boolean getNoSync()

Deprecated. replaced by getDurability()

Returns true if the transaction is configured to not write or synchronously flush the log it when commits.

Returns:

true if the transaction is configured to not write or synchronously flush the log it when commits.

setWriteNoSync

public TransactionConfig setWriteNoSync(boolean writeNoSync)

Deprecated. replaced by setDurability(com.sleepycat.je.Durability)

Configures the transaction to write but not synchronously flush the log it when commits.

This behavior may be set for a database environment using the Environment.setMutableConfig method. Any value specified to this method overrides that setting.

The default is false for this class and the database environment.

Parameters:

writeNoSync - If true, transactions exhibit the ACI (atomicity, consistency, and isolation) properties, but not D (durability); that is, database integrity will be maintained, but if the operating system fails, it is possible some number of the most recently committed transactions may be undone during recovery. The number of transactions at risk is governed by how often the operating system flushes dirty buffers to disk, and how often the log is checkpointed.

Returns:

this

getWriteNoSync

public boolean getWriteNoSync()

Deprecated. replaced by getDurability()

Returns true if the transaction is configured to write but not synchronously flush the log it when commits.

Returns:

true if the transaction is configured to not write or synchronously flush the log it when commits.

setDurability

public TransactionConfig setDurability(Durability durability)

Configures the durability associated with a transaction when it commits. Changes to durability are not reflected back to the "sync" booleans -- there isn't a one to one mapping. Note that you should not use both the durability and the XXXSync() apis on the same config object.

Parameters:

durability - the durability definition

Returns:

this

getDurability

public Durability getDurability()

Returns the durability associated with the configuration. If setDurability(com.sleepycat.je.Durability) has not been called, this method returns null. When no durability settings have been specified using the TransactionConfig, the default durability is applied to the Transaction by Environment.beginTransaction(com.sleepycat.je.Transaction, com.sleepycat.je.TransactionConfig) using EnvironmentConfig settings.

Returns:

the durability setting currently associated with this config.

setConsistencyPolicy

public TransactionConfig setConsistencyPolicy(ReplicaConsistencyPolicy consistencyPolicy)

Associates a consistency policy with this configuration.

Parameters:

consistencyPolicy - the consistency definition

Returns:

this

getConsistencyPolicy

public ReplicaConsistencyPolicy getConsistencyPolicy()

Returns the consistency policy associated with the configuration.

Returns:

the consistency policy currently associated with this config.

setNoWait

public TransactionConfig setNoWait(boolean noWait)

Configures the transaction to not wait if a lock request cannot be immediately granted.

The default is false for this class and the database environment.

Parameters:

noWait - If true, transactions will not wait if a lock request cannot be immediately granted, instead LockNotAvailableException will be thrown.

Returns:

this

getNoWait

public boolean getNoWait()

Returns true if the transaction is configured to not wait if a lock request cannot be immediately granted.

Returns:

true if the transaction is configured to not wait if a lock request cannot be immediately granted.

setReadUncommitted

public TransactionConfig setReadUncommitted(boolean readUncommitted)

Configures read operations performed by the transaction to return modified but not yet committed data.

Parameters:

readUncommitted - If true, configure read operations performed by the transaction to return modified but not yet committed data.

Returns:

this

See Also:

LockMode.READ_UNCOMMITTED

getReadUncommitted

public boolean getReadUncommitted()

Returns true if read operations performed by the transaction are configured to return modified but not yet committed data.

Returns:

true if read operations performed by the transaction are configured to return modified but not yet committed data.

See Also:

LockMode.READ_UNCOMMITTED

setReadCommitted

public TransactionConfig setReadCommitted(boolean readCommitted)

Configures the transaction for read committed isolation.

This ensures the stability of the current data item read by the cursor but permits data read by this transaction to be modified or deleted prior to the commit of the transaction.

Parameters:

readCommitted - If true, configure the transaction for read committed isolation.

Returns:

this

See Also:

LockMode.READ_COMMITTED

getReadCommitted

public boolean getReadCommitted()

Returns true if the transaction is configured for read committed isolation.

Returns:

true if the transaction is configured for read committed isolation.

See Also:

LockMode.READ_COMMITTED

setSerializableIsolation

public TransactionConfig setSerializableIsolation(boolean serializableIsolation)

Configures this transaction to have serializable (degree 3) isolation. By setting serializable isolation, phantoms will be prevented.

By default a transaction provides Repeatable Read isolation; EnvironmentConfig.setTxnSerializableIsolation(boolean) may be called to override the default. If the environment is configured for serializable isolation, all transactions will be serializable regardless of whether this method is called; calling setSerializableIsolation(boolean) with a false parameter will not disable serializable isolation.

The default is false for this class and the database environment.

Returns:

this

See Also:

LockMode

getSerializableIsolation

public boolean getSerializableIsolation()

Returns true if the transaction has been explicitly configured to have serializable (degree 3) isolation.

Returns:

true if the transaction has been configured to have serializable isolation.

See Also:

LockMode

setReadOnly

public TransactionConfig setReadOnly(boolean readOnly)

Configures this transaction to disallow write operations, regardless of whether writes are allowed for the Environment or the Databases that are accessed.

If a write operation is attempted using a read-only transaction, an UnsupportedOperationException will be thrown.

For a read-only transaction, the transaction's Durability is ignored, even when it is explicitly specified using setDurability(Durability).

In a ReplicatedEnvironment, a read-only transaction implicitly uses Durability.ReplicaAckPolicy.NONE. A read-only transaction on a Master will thus not be held up, or throw InsufficientReplicasException, if the Master is not in contact with a sufficient number of Replicas at the time the transaction is initiated.

The default setting is false (writes are allowed).

Returns:

this

getReadOnly

public boolean getReadOnly()

Returns whether read-only is configured for this transaction.

setLocalWrite

public TransactionConfig setLocalWrite(boolean localWrite)

Configures this transaction to allow writing to non-replicated Databases in a ReplicatedEnvironment.

In a replicated environment, a given transaction may be used to write to either replicated databases or non-replicated databases, but not both. If a write operation to a replicated database is attempted when local-write is true, or to a non-replicated database when local-write is false, an UnsupportedOperationException will be thrown.

Note that for auto-commit transactions (when the Transaction parameter is null), the local-write setting is automatically set to correspond to whether the database is replicated. With auto-commit, local-write is always true for a non-replicated database, and always false for a replicated database.

In a replicated environment, a local-write transaction implicitly uses Durability.ReplicaAckPolicy.NONE. A local-write transaction on a Master will thus not be held up, or throw InsufficientReplicasException, if the Master is not in contact with a sufficient number of Replicas at the time the transaction is initiated.

By default the local-write setting is false, meaning that the transaction may only write to replicated Databases in a replicated environment.

This configuration setting is ignored in a non-replicated Environment since no databases are replicated.

Returns:

this

See Also:

getLocalWrite

public boolean getLocalWrite()

Returns whether local-write is configured for this transaction.

clone

public TransactionConfig clone()

Returns a copy of this configuration object.

Overrides:

clone in class java.lang.Object

toString

public java.lang.String toString()

Returns the values for each configuration attribute.

Overrides:

toString in class java.lang.Object

Returns:

the values for each configuration attribute.