Alexey Goncharuk created IGNITE-4337:
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Summary: Introduce persistence interface to allow build reliable
persistence plugins
Key: IGNITE-4337
URL: https://issues.apache.org/jira/browse/IGNITE-4337
Project: Ignite
Issue Type: Sub-task
Components: general
Reporter: Alexey Goncharuk
Fix For: 2.0
If page memory interface is introduced, it may be possible to build a
persistence layer around this architecture. I think we should add some form of
persistence logging to allow us build a crash-resistant system in future.
Something like
{code}
public interface IgniteWriteAheadLogManager extends GridCacheSharedManager {
/**
* @return {@code true} If we have to always write full pages.
*/
public boolean isAlwaysWriteFullPages();
/**
* @return {@code true} if WAL will perform fair syncs on fsync call.
*/
public boolean isFullSync();
/**
* Resumes logging after start. When WAL manager is started, it will skip
logging any updates until this
* method is called to avoid logging changes induced by the state restore
procedure.
*/
public void resumeLogging(WALPointer lastWrittenPtr) throws
IgniteCheckedException;
/**
* Appends the given log entry to the write-ahead log.
*
* @param entry entry to log.
* @return WALPointer that may be passed to {@link #fsync(WALPointer)}
method to make sure the record is
* written to the log.
* @throws IgniteCheckedException If failed to construct log entry.
* @throws StorageException If IO error occurred while writing log entry.
*/
public WALPointer log(WALRecord entry) throws IgniteCheckedException,
StorageException;
/**
* Makes sure that all log entries written to the log up until the
specified pointer are actually persisted to
* the underlying storage.
*
* @param ptr Optional pointer to sync. If {@code null}, will sync up to
the latest record.
* @throws IgniteCheckedException If
* @throws StorageException
*/
public void fsync(WALPointer ptr) throws IgniteCheckedException,
StorageException;
/**
* Invoke this method to iterate over the written log entries.
*
* @param start Optional WAL pointer from which to start iteration.
* @return Records iterator.
* @throws IgniteException If failed to start iteration.
* @throws StorageException If IO error occurred while reading WAL entries.
*/
public WALIterator replay(WALPointer start) throws IgniteCheckedException,
StorageException;
/**
* Gives a hint to WAL manager to clear entries logged before the given
pointer. Some entries before the
* the given pointer will be kept because there is a configurable WAL
history size. Those entries may be used
* for partial partition rebalancing.
*
* @param ptr Pointer for which it is safe to clear the log.
* @return Number of deleted WAL segments.
*/
public int truncate(WALPointer ptr);
}
{code}
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