com.atlassian.confluence.api.service.journal

Interface JournalService

All Known Implementing Classes:

DefaultJournalService

@PublicApi
public interface JournalService

This service is an entry point to the journal subsystem.

Typical way to use journal subsystem is to call enqueue(com.atlassian.confluence.api.model.journal.JournalEntry) to queue new entries that should be actioned on each cluster node. Later on queued entries can be processed by calling processEntries(com.atlassian.confluence.api.model.journal.JournalIdentifier, int, com.google.common.base.Function) on each cluster node. Subsequent calls to processEntries will be passed only entries that were added since the last call on that cluster node.

Since:

5.6

Method Summary

Modifier and Type	Method and Description
int	countEntries(JournalIdentifier journalId) Counts the number of entries in a journal.
long	enqueue(JournalEntry entry) Adds the given entry to a journal.
Iterable<JournalEntry>	peek(JournalIdentifier journalId, int maxEntries) Return a copy of journal entries that are waiting to be processed.
<V> V	processEntries(JournalIdentifier journalId, int maxEntries, com.google.common.base.Function<Iterable<JournalEntry>,EntryProcessorResult<V>> entryProcessor) Processes journal entries that were added since the last time this method was called for this journal on this cluster node.
void	reset(JournalIdentifier journalId) Resets the state of the journal so that all entries currently in the journal will be skipped.
void	waitForRecentEntriesToBecomeVisible() Waits long enough to ensure that entries added before calling this method will be available to subsequent call to processEntries(com.atlassian.confluence.api.model.journal.JournalIdentifier, int, com.google.common.base.Function).

Method Detail

enqueue

long enqueue(@Nonnull
             JournalEntry entry)
      throws ServiceException

Adds the given entry to a journal.

New journal is automatically created if a journal with the given name does not exists.

Parameters:

entry - entry to persist

Returns:

id generated for the entry

Throws:

ServiceException - if the entry could not be persisted

processEntries

<V> V processEntries(@Nonnull
                     JournalIdentifier journalId,
                     int maxEntries,
                     @Nonnull
                     com.google.common.base.Function<Iterable<JournalEntry>,EntryProcessorResult<V>> entryProcessor)
              throws ServiceException

Processes journal entries that were added since the last time this method was called for this journal on this cluster node.

This method does not return entries that were added immediately before calling this method. Use waitForRecentEntriesToBecomeVisible() for ensuring these entries will be included.

This method can miss some entries due to identifier assignment and entry insertion not being an atomic operation. The risk of missed entries can be reduced by creating new entries as close to transaction commit as possible.

If entryProcessor throws an exception, the same entries will be returned again when this method is next called for this journal on this cluster node.

New journal is automatically created if a journal with the given name does not exists.

Parameters:

journalId - only entries with this journal id will be returned

maxEntries - maximum number of entries to process

entryProcessor - function that will process entries that were added since the last time

Returns:

result of entryProcessor

Throws:

ServiceException - if entries could not be fetched or the journal state could not be saved

waitForRecentEntriesToBecomeVisible

void waitForRecentEntriesToBecomeVisible()
                                  throws InterruptedException

Waits long enough to ensure that entries added before calling this method will be available to subsequent call to processEntries(com.atlassian.confluence.api.model.journal.JournalIdentifier, int, com.google.common.base.Function).

Throws:

InterruptedException - if the thread got interrupted

peek

Iterable<JournalEntry> peek(@Nonnull
                            JournalIdentifier journalId,
                            int maxEntries)
                     throws ServiceException

Return a copy of journal entries that are waiting to be processed.

Parameters:

journalId - only entries with this journal id will be returned

maxEntries - maximum number of entries to return

Returns:

a copy of journal entries that are waiting to be processed

Throws:

ServiceException - if entries could not be fetched

reset

void reset(@Nonnull
           JournalIdentifier journalId)
    throws ServiceException

Resets the state of the journal so that all entries currently in the journal will be skipped.

Parameters:

journalId - identifier of the journal to reset

Throws:

ServiceException - if the reset fails

countEntries

int countEntries(@Nonnull
                 JournalIdentifier journalId)
          throws ServiceException

Counts the number of entries in a journal.

Parameters:

journalId - identifier of the journal

Throws:

ServiceException - if entries could not be counted