org.neo4j.io.pagecache.tracing.cursor.context

Interface VersionContext

All Known Implementing Classes:

EmptyVersionContext

public interface VersionContext

Context that contains state of ongoing versioned data read or write.
Context can be in one of two states:

• Read context: reading is performed for a version that context was initialised with. As soon as reader that associated with a context will observe data with version that it higher, context will be marked as dirty.
  For example, when context is initialised with last closed transaction id and if at the end of reading operation context is not marked as dirty its guarantee that context did not encounter any data from more recent transaction.
• Write context: context that performs data modifications. Any modifications will be tagged with some version that write context was initialised with.
  For example, commit will start write context that with a version that is equal to current committing transaction id.

By default non context will be initialised with last closed transaction id which is equal to Long.MAX_VALUE and transaction id that is equal to minimal possible transaction id: 1.

Method Summary

Modifier and Type	Method and Description
long	committingTransactionId() Context currently committing transaction id
void	initRead() Initialise read context with latest closed transaction id as it current version.
void	initWrite(long committingTxId) Initialise write context with committingTxId as modification version.
boolean	isDirty() Check whenever current context is dirty
long	lastClosedTransactionId() Last closed transaction id that read context was initialised with
void	markAsDirty() Mark current context as dirty

Method Detail

initRead

void initRead()

Initialise read context with latest closed transaction id as it current version.

initWrite

void initWrite(long committingTxId)

Initialise write context with committingTxId as modification version.

Parameters:

committingTxId - currently committing transaction id

committingTransactionId

long committingTransactionId()

Context currently committing transaction id

Returns:

committing transaction id

lastClosedTransactionId

long lastClosedTransactionId()

Last closed transaction id that read context was initialised with

Returns:

last closed transaction id

markAsDirty

void markAsDirty()

Mark current context as dirty

isDirty

boolean isDirty()

Check whenever current context is dirty

Returns:

true if context is dirty, false otherwise