org.h2.mvstore

Class MVMap.DecisionMaker<V>

java.lang.Object

org.h2.mvstore.MVMap.DecisionMaker<V>

Type Parameters:

V - value type of the map

Enclosing class:

MVMap<K,V>

public abstract static class MVMap.DecisionMaker<V>
extends java.lang.Object

Class DecisionMaker provides callback interface (and should become a such in Java 8) for MVMap.operate method. It provides control logic to make a decision about how to proceed with update at the point in execution when proper place and possible existing value for insert/update/delete key is found. Revised value for insert/update is also provided based on original input value and value currently existing in the map.

Field Summary

Fields

Modifier and Type	Field and Description
static MVMap.DecisionMaker<java.lang.Object>	DEFAULT Decision maker for transaction rollback.
static MVMap.DecisionMaker<java.lang.Object>	PUT Decision maker for put().
static MVMap.DecisionMaker<java.lang.Object>	REMOVE Decision maker for remove().

Constructor Summary

Constructors

Constructor and Description
DecisionMaker()

Method Summary

Modifier and Type	Method and Description
abstract MVMap.Decision	decide(V existingValue, V providedValue) Makes a decision about how to proceed with the update.
MVMap.Decision	decide(V existingValue, V providedValue, CursorPos<?,?> tip) Makes a decision about how to proceed with the update.
void	reset() Resets internal state (if any) of a this DecisionMaker to it's initial state.
<T extends V> T	selectValue(T existingValue, T providedValue) Provides revised value for insert/update based on original input value and value currently existing in the map.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT

public static final MVMap.DecisionMaker<java.lang.Object> DEFAULT

Decision maker for transaction rollback.

PUT

public static final MVMap.DecisionMaker<java.lang.Object> PUT

Decision maker for put().

REMOVE

public static final MVMap.DecisionMaker<java.lang.Object> REMOVE

Decision maker for remove().

Constructor Detail

DecisionMaker

public DecisionMaker()

Method Detail

decide

public MVMap.Decision decide(V existingValue,
                             V providedValue,
                             CursorPos<?,?> tip)

Makes a decision about how to proceed with the update.

Parameters:

existingValue - the old value

providedValue - the new value

tip - the cursor position

Returns:

the decision

decide

public abstract MVMap.Decision decide(V existingValue,
                                      V providedValue)

Makes a decision about how to proceed with the update.

Parameters:

existingValue - value currently exists in the map

providedValue - original input value

Returns:

PUT if a new value need to replace existing one or a new value to be inserted if there is none REMOVE if existing value should be deleted ABORT if update operation should be aborted or repeated later REPEAT if update operation should be repeated immediately

selectValue

public <T extends V> T selectValue(T existingValue,
                                   T providedValue)

Provides revised value for insert/update based on original input value and value currently existing in the map. This method is only invoked after call to decide(), if it returns PUT.

Type Parameters:

T - value type

Parameters:

existingValue - value currently exists in the map

providedValue - original input value

Returns:

value to be used by insert/update

reset

public void reset()

Resets internal state (if any) of a this DecisionMaker to it's initial state. This method is invoked whenever concurrent update failure is encountered, so we can re-start update process.