Package org.opends.server.backends.pluggable.spi

Interface Storage

All Superinterfaces:

AutoCloseable, Closeable

All Known Implementing Classes:

CASStorage, JDBCStorage, JEStorage, PDBStorage

public interface Storage
extends Closeable

This interface abstracts the underlying storage engine, isolating the pluggable backend generic code from a particular storage engine implementation.

Method Summary

Modifier and Type	Method	Description
void	close()
void	createBackup(BackupConfig backupConfig)	Creates a backup for this storage.
StorageStatus	getStorageStatus()	Returns the current status of the storage.
Set<TreeName>	listTrees()	Lists the trees that exist in this storage.
void	open(AccessMode accessMode)	Opens the storage engine to allow executing operations on it.
<T> T	read(ReadOperation<T> readOperation)	Executes a read operation.
void	removeBackup(BackupDirectory backupDirectory, String backupID)	Removes a backup for this storage.
void	removeStorageFiles()	Remove all files for a backend of this storage.
void	restoreBackup(RestoreConfig restoreConfig)	Restores a backup for this storage.
Importer	startImport()	Starts the import operation.
boolean	supportsBackupAndRestore()	Returns true if this storage supports backup and restore.
void	write(WriteOperation writeOperation)	Executes a write operation.

Method Detail

startImport

Importer startImport()
              throws ConfigException,
                     StorageRuntimeException

Starts the import operation.

Returns:

a new Importer object which must be closed to release all resources

Throws:

ConfigException - if there is a problem with the configuration

StorageRuntimeException - if a problem occurs with the underlying storage engine

See Also:

to release all resources once import is finished

open

void open(AccessMode accessMode)
   throws Exception

Opens the storage engine to allow executing operations on it.

Parameters:

accessMode - Specify the access mode to this storage.

Throws:

NullPointerException - if accessMode is null.

Exception - if a problem occurs with the underlying storage engine

See Also:

to release all resources once import is finished

read

<T> T read(ReadOperation<T> readOperation)
    throws Exception

Executes a read operation. In case of a read operation rollback, implementations must propagate the failure to the caller rather than replay the operation: unlike WriteOperation, a ReadOperation is not required to be idempotent, and several of them are not - they write to a stream, print, or accumulate state that a second attempt would double.

Type Parameters:

T - type of the value returned

Parameters:

readOperation - the read operation to execute

Returns:

the value read by the read operation

Throws:

Exception - if a problem occurs with the underlying storage engine

write

void write(WriteOperation writeOperation)
    throws Exception

Executes a write operation. In case of a write operation rollback, implementations may replay the write operation rather than propagate the failure: a WriteOperation is required to be idempotent for exactly that reason. A replay may be bounded - by a number of attempts, by a window of time, or by both - so that a conflict which does not clear reaches the caller, or may go on for as long as the conflict lasts, the way a writer of a lock based engine waits for a lock; an engine which resolves every conflict by a rollback should bound it by time only, since a healthy write under concurrent load loses several in a row. The pluggable backend holds locks across this method, up to the exclusive lock of an entry container, and every thread waiting on one of those locks waits for as long as this method does.

A caller that mutates state around this method must handle that bound being spent. Removing an entry from an in-memory map before the write so that a replay still finds the work to do, or reading configuration back out of the operation once it returns, both assume the write is applied; when it is not, this method throws with that state already changed and the transaction not applied, and the caller is the only place that can reconcile the two.

Parameters:

writeOperation - the write operation to execute

Throws:

Exception - if a problem occurs with the underlying storage engine, including a conflict that outlasted the replays the implementation makes

removeStorageFiles

void removeStorageFiles()
                 throws StorageRuntimeException

Remove all files for a backend of this storage.

Throws:

StorageRuntimeException - if removal fails

getStorageStatus

StorageStatus getStorageStatus()

Returns the current status of the storage.

Returns:

the current status of the storage

supportsBackupAndRestore

boolean supportsBackupAndRestore()

Returns true if this storage supports backup and restore.

Returns:

true if this storage supports backup and restore.

createBackup

void createBackup(BackupConfig backupConfig)
           throws DirectoryException

Creates a backup for this storage.

Parameters:

backupConfig - The configuration to use when performing the backup.

Throws:

DirectoryException - If a Directory Server error occurs.

removeBackup

void removeBackup(BackupDirectory backupDirectory,
                  String backupID)
           throws DirectoryException

Removes a backup for this storage.

Parameters:

backupDirectory - The backup directory structure with which the specified backup is associated.

backupID - The backup ID for the backup to be removed.

Throws:

DirectoryException - If it is not possible to remove the specified backup.

restoreBackup

void restoreBackup(RestoreConfig restoreConfig)
            throws DirectoryException

Restores a backup for this storage.

Parameters:

restoreConfig - The configuration to use when performing the restore.

Throws:

DirectoryException - If a Directory Server error occurs.

listTrees

Set<TreeName> listTrees()

Lists the trees that exist in this storage.

Returns:

a set of TreeNames representing the trees that exist in this storage

close

void close()

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable