de.schlichtherle.truezip.fs
Class FsCachingController

java.lang.Object
  de.schlichtherle.truezip.fs.FsController<M>
      de.schlichtherle.truezip.fs.FsDecoratingController<FsConcurrentModel,FsController<? extends FsConcurrentModel>>
          de.schlichtherle.truezip.fs.FsCachingController

@NotThreadSafe
@DefaultAnnotation(value=edu.umd.cs.findbugs.annotations.NonNull.class)
public final class FsCachingController
extends FsDecoratingController<FsConcurrentModel,FsController<? extends FsConcurrentModel>>

A content caching file system controller implements a combined caching and buffering strategy for entry data. Decorating a concurrent file system controller with this class has the following effects:

• Caching and buffering needs to be activated by using the method input socket with the input option FsInputOption.CACHE or the method output socket with the output option FsOutputOption.CACHE.
• Unless a write operation succeeds, upon each read operation the entry data gets copied from the backing store for buffering purposes only.
• Upon a successful write operation, the entry data gets cached for subsequent read operations until the file system gets synced.
• Entry data written to the cache is not written to the backing store until the file system gets synced - this is a write back strategy.
• As a side effect, caching decouples the underlying storage from its clients, allowing it to create, read, update or delete the entry data while some clients are still busy on reading or writing the copied entry data.

Author:

Christian Schlichtherle

STRATEGY

private static final IOCache.Strategy STRATEGY

pool

private final IOPool<?> pool

caches

private final Map<FsEntryName,FsCachingController.EntryCache> caches

FsCachingController

public FsCachingController(FsController<? extends FsConcurrentModel> controller,
                           IOPool<?> pool)

Constructs a new content caching file system controller.

Parameters:

controller - the decorated file system controller.

pool - the pool of temporary entries to hold the copied entry data.

getEntry

public FsEntry getEntry(FsEntryName name)
                 throws IOException

Overrides:

getEntry in class FsDecoratingController<FsConcurrentModel,FsController<? extends FsConcurrentModel>>

Throws:

IOException

getInputSocket

public InputSocket<?> getInputSocket(FsEntryName name,
                                     BitField<FsInputOption> options)

Description copied from class: FsController

Returns an input socket for reading the contents of the entry addressed by the given name from the file system.

Overrides:

getInputSocket in class FsDecoratingController<FsConcurrentModel,FsController<? extends FsConcurrentModel>>

Parameters:

name - a file system entry name.

Returns:

An InputSocket.

getOutputSocket

public OutputSocket<?> getOutputSocket(FsEntryName name,
                                       BitField<FsOutputOption> options,
                                       Entry template)

Description copied from class: FsController

Returns an output socket for writing the contents of the entry addressed by the given name to the file system. If template is not null, then the output entry shall have as many of its properties copied as reasonable, e.g. the last modification time.

Overrides:

getOutputSocket in class FsDecoratingController<FsConcurrentModel,FsController<? extends FsConcurrentModel>>

Parameters:

name - a file system entry name.

template - a nullable template for the properties of the output entry.

Returns:

An OutputSocket.

mknod

public void mknod(FsEntryName name,
                  Entry.Type type,
                  BitField<FsOutputOption> options,
                  Entry template)
           throws IOException

Description copied from class: FsController

Creates or replaces and finally links a chain of one or more entries for the given entry name into the file system.

Overrides:

mknod in class FsDecoratingController<FsConcurrentModel,FsController<? extends FsConcurrentModel>>

Parameters:

name - the file system entry name.

type - the file system entry type.

options - the file system output options. If CREATE_PARENTS is set, any missing parent directories will be created and linked into this file system with its last modification time set to the system's current time.

template - if not null, then the file system entry at the end of the chain shall inherit as much properties from this entry as possible - with the exception of its name and type.

Throws:

IOException - for some other I/O related reason, including but not exclusively upon one or more of the following conditions:

• The file system is read only.
• name contains characters which are not supported by the file system.
• The entry already exists and either the option FsOutputOption.EXCLUSIVE is set or the entry is a directory.
• The entry exists as a different type.
• A parent entry exists but is not a directory.
• A parent entry is missing and createParents is false.

unlink

public void unlink(FsEntryName name)
            throws IOException

Overrides:

unlink in class FsDecoratingController<FsConcurrentModel,FsController<? extends FsConcurrentModel>>

Throws:

IOException

sync

public <X extends IOException> void sync(BitField<FsSyncOption> options,
                                         ExceptionHandler<? super FsSyncException,X> handler)
          throws X extends IOException

Description copied from class: FsController

Commits all unsynchronized changes to the contents of this file system to its parent file system. If this is not a federated file system, i.e. if its not a member of a parent file system, then nothing happens. Otherwise, the state of this file system controller is reset.

Overrides:

sync in class FsDecoratingController<FsConcurrentModel,FsController<? extends FsConcurrentModel>>

Type Parameters:

X - the type of the IOException to throw at the discretion of the exception handler.

Parameters:

options - the synchronization options.

handler - the exception handling strategy for dealing with one or more input FsSyncExceptions which may trigger an X.

Throws:

X extends IOException

beforeSync

private <X extends IOException> void beforeSync(BitField<FsSyncOption> options,
                                                ExceptionHandler<? super FsSyncException,X> handler)
                 throws X extends IOException

Throws:

X extends IOException