com.atlassian.confluence.impl.journal
Interface JournalManager

All Known Implementing Classes:
DefaultJournalManager

public interface JournalManager

This manager is an entry point to the journal subsystem.

Typical way to use journal subsystem is to call enqueue(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
 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(JournalIdentifier, int, com.google.common.base.Function).
 

Method Detail

enqueue

long enqueue(@Nonnull
             JournalEntry entry)
             throws org.springframework.dao.DataAccessException
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:
org.springframework.dao.DataAccessException - 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 org.springframework.dao.DataAccessException
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:
org.springframework.dao.DataAccessException - 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(JournalIdentifier, int, com.google.common.base.Function).

Throws:
InterruptedException - if the thread got interrupted

peek

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

reset

void reset(@Nonnull
           JournalIdentifier journalId)
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

countEntries

int countEntries(@Nonnull
                 JournalIdentifier journalId)
Counts the number of entries in a journal.

Parameters:
journalId - identifier of the journal


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