com.exonum.binding.core.storage.database

Interface ModificationCounter

All Known Implementing Classes:

IncrementalModificationCounter

public interface ModificationCounter

A counter of modification events of some objects (e.g., a collection, or a database view). It is updated each time the object notifies of an event. The clients that need to detect modifications must save the current value of the counter, and check if it has changed to determine if the corresponding source object is modified.

Implementations must reliably detect up to 4 billion modifications (2^32-1).

Implementations are not required to be thread-safe.

Method Summary

Modifier and Type	Method and Description
int	getCurrentValue() Returns the current value of the counter.
boolean	isModifiedSince(int lastValue) Returns true if the counter was modified since the given value (if notifyModified() has been invoked); false — otherwise.
void	notifyModified() Notifies this counter that the source object is modified, updating its current value.

Method Detail

isModifiedSince

boolean isModifiedSince(int lastValue)

Returns true if the counter was modified since the given value (if notifyModified() has been invoked); false — otherwise.

Parameters:

lastValue - the last value of the counter

getCurrentValue

int getCurrentValue()

Returns the current value of the counter. No assumptions must be made on how it changes when a notification is received.

notifyModified

void notifyModified()

Notifies this counter that the source object is modified, updating its current value.

Throws:

IllegalStateException - if this counter corresponds to a read-only (immutable) object, i.e., must reject any modification events