Package org.h2.mvstore
Class MVMap.DecisionMaker<V>
java.lang.Object
org.h2.mvstore.MVMap.DecisionMaker<V>
- Type Parameters:
V
- value type of the map
- Direct Known Subclasses:
CommitDecisionMaker
,MVMap.EqualsDecisionMaker
,MVMap.RewriteDecisionMaker
,RollbackDecisionMaker
,TxDecisionMaker
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
FieldsModifier and TypeFieldDescriptionstatic final MVMap.DecisionMaker
<Object> Decision maker for transaction rollback.(package private) static final MVMap.DecisionMaker
<Object> Decision maker for putIfAbsent() key/value.(package private) static final MVMap.DecisionMaker
<Object> Decision maker for replace().static final MVMap.DecisionMaker
<Object> Decision maker for put().static final MVMap.DecisionMaker
<Object> Decision maker for remove(). -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionabstract MVMap.Decision
Makes a decision about how to proceed with the update.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>
TselectValue
(T existingValue, T providedValue) Provides revised value for insert/update based on original input value and value currently existing in the map.
-
Field Details
-
DEFAULT
Decision maker for transaction rollback. -
PUT
Decision maker for put(). -
REMOVE
Decision maker for remove(). -
IF_ABSENT
Decision maker for putIfAbsent() key/value. -
IF_PRESENT
Decision maker for replace().
-
-
Constructor Details
-
DecisionMaker
public DecisionMaker()
-
-
Method Details
-
decide
Makes a decision about how to proceed with the update.- Parameters:
existingValue
- the old valueprovidedValue
- the new valuetip
- the cursor position- Returns:
- the decision
-
decide
Makes a decision about how to proceed with the update.- Parameters:
existingValue
- value currently exists in the mapprovidedValue
- 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
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 mapprovidedValue
- 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.
-