Class FSDirectory

Base class for Directory implementations that store index files in the file system.

There are currently three core subclasses:

• SimpleFSDirectory is a straightforward implementation using System.IO.FileStream, which is ideal for writing without using much RAM. However, it has poor concurrent performance (multiple threads will bottleneck) as it synchronizes when multiple threads read from the same file.
• NIOFSDirectory uses System.IO.FileStream's positional seeking, which makes it slightly less efficient than using SimpleFSDirectory during reading, with similar write performance.
• MMapDirectory uses memory-mapped IO when reading. This is a good choice if you have plenty of virtual memory relative to your index size, eg if you are running on a 64 bit runtime, or you are running on a 32 bit runtime but your index sizes are small enough to fit into the virtual memory space.

Unfortunately, because of system peculiarities, there is no single overall best implementation. Therefore, we've added the Open(String) method (or one of its overloads), to allow Lucene to choose the best FSDirectory implementation given your environment, and the known limitations of each implementation. For users who have no reason to prefer a specific implementation, it's best to simply use Open(String) (or one of its overloads). For all others, you should instantiate the desired implementation directly.

The locking implementation is by default NativeFSLockFactory, but can be changed by passing in a custom LockFactory instance.

NOTE: Unlike in Java, it is not recommended to use System.Threading.Thread.Interrupt in .NET in conjunction with an open FSDirectory because it is not guaranteed to exit atomically. Any lock statement or System.Threading.Monitor.Enter(System.Object) call can throw a System.Threading.ThreadInterruptedException, which makes shutting down unpredictable. To exit parallel tasks safely, we recommend using System.Threading.Tasks.Tasks and "interrupt" them with System.Threading.CancellationTokens.

Inheritance

System.Object

Directory

BaseDirectory

FSDirectory

MMapDirectory

NIOFSDirectory

SimpleFSDirectory

Implements

System.IDisposable

Inherited Members

BaseDirectory.IsOpen

BaseDirectory.m_lockFactory

BaseDirectory.MakeLock(String)

BaseDirectory.ClearLock(String)

BaseDirectory.LockFactory

BaseDirectory.EnsureOpen()

Directory.OpenInput(String, IOContext)

Directory.OpenChecksumInput(String, IOContext)

Directory.Dispose()

Directory.Copy(Directory, String, String, IOContext)

Directory.CreateSlicer(String, IOContext)

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

System.Object.ReferenceEquals(System.Object, System.Object)

Namespace: Lucene.Net.Store

Assembly: Lucene.Net.dll

Syntax

public abstract class FSDirectory : BaseDirectory, IDisposable

Constructors

FSDirectory(DirectoryInfo)

Declaration

protected FSDirectory(DirectoryInfo dir)

Parameters

Type	Name	Description
System.IO.DirectoryInfo	dir

FSDirectory(DirectoryInfo, LockFactory)

Create a new FSDirectory for the named location (ctor for subclasses).

Declaration

protected FSDirectory(DirectoryInfo path, LockFactory lockFactory)

Parameters

Type	Name	Description
System.IO.DirectoryInfo	path	the path of the directory
LockFactory	lockFactory	the lock factory to use, or null for the default (NativeFSLockFactory);

Exceptions

Type	Condition
System.IO.IOException	if there is a low-level I/O error

Fields

DEFAULT_READ_CHUNK_SIZE

Default read chunk size: 8192 bytes (this is the size up to which the runtime does not allocate additional arrays while reading/writing)

Declaration

[Obsolete("this constant is no longer used since Lucene 4.5.")]
public const int DEFAULT_READ_CHUNK_SIZE = 8192

Field Value

Type	Description
System.Int32

m_directory

Declaration

protected readonly DirectoryInfo m_directory

Field Value

Type	Description
System.IO.DirectoryInfo

Properties

Directory

the underlying filesystem directory

Declaration

public virtual DirectoryInfo Directory { get; }

Property Value

Type	Description
System.IO.DirectoryInfo

ReadChunkSize

this setting has no effect anymore.

Declaration

[Obsolete("this is no longer used since Lucene 4.5.")]
public int ReadChunkSize { get; set; }

Property Value

Type	Description
System.Int32

Methods

CreateOutput(String, IOContext)

Creates an IndexOutput for the file with the given name.

Declaration

public override IndexOutput CreateOutput(string name, IOContext context)

Parameters

Type	Name	Description
System.String	name
IOContext	context

Returns

Type	Description
IndexOutput

Overrides

Directory.CreateOutput(String, IOContext)

DeleteFile(String)

Removes an existing file in the directory.

Declaration

public override void DeleteFile(string name)

Parameters

Type	Name	Description
System.String	name

Overrides

Directory.DeleteFile(String)

Dispose(Boolean)

Closes the store to future operations.

Declaration

protected override void Dispose(bool disposing)

Parameters

Type	Name	Description
System.Boolean	disposing

Overrides

Directory.Dispose(Boolean)

EnsureCanWrite(String)

Declaration

protected virtual void EnsureCanWrite(string name)

Parameters

Type	Name	Description
System.String	name

FileExists(String)

Returns true iff a file with the given name exists.

Declaration

[Obsolete("this method will be removed in 5.0")]
public override bool FileExists(string name)

Parameters

Type	Name	Description
System.String	name

Returns

Type	Description
System.Boolean

Overrides

Directory.FileExists(String)

FileLength(String)

Returns the length in bytes of a file in the directory.

Declaration

public override long FileLength(string name)

Parameters

Type	Name	Description
System.String	name

Returns

Type	Description
System.Int64

Overrides

Directory.FileLength(String)

GetLockID()

Declaration

public override string GetLockID()

Returns

Type	Description
System.String

Overrides

Directory.GetLockID()

ListAll()

Lists all files (not subdirectories) in the directory.

Declaration

public override string[] ListAll()

Returns

Type	Description
System.String[]

Overrides

Directory.ListAll()

See Also

ListAll(DirectoryInfo)

ListAll(DirectoryInfo)

Lists all files (not subdirectories) in the directory. This method never returns null (throws System.IO.IOException instead).

Declaration

public static string[] ListAll(DirectoryInfo dir)

Parameters

Type	Name	Description
System.IO.DirectoryInfo	dir

Returns

Type	Description
System.String[]

Exceptions

Type	Condition
System.IO.DirectoryNotFoundException	if the directory does not exist, or does exist but is not a directory or is invalid (for example, it is on an unmapped drive).
System.Security.SecurityException	The caller does not have the required permission.

OnIndexOutputClosed(FSDirectory.FSIndexOutput)

Declaration

protected virtual void OnIndexOutputClosed(FSDirectory.FSIndexOutput io)

Parameters

Type	Name	Description
FSDirectory.FSIndexOutput	io

Open(DirectoryInfo)

Creates an FSDirectory instance, trying to pick the best implementation given the current environment. The directory returned uses the NativeFSLockFactory.

Currently this returns MMapDirectory for most Solaris and Windows 64-bit runtimes, NIOFSDirectory for other non-Windows runtimes, and SimpleFSDirectory for other runtimes on Windows. It is highly recommended that you consult the implementation's documentation for your platform before using this method.

NOTE: this method may suddenly change which implementation is returned from release to release, in the event that higher performance defaults become possible; if the precise implementation is important to your application, please instantiate it directly, instead. For optimal performance you should consider using MMapDirectory on 64 bit runtimes.

See FSDirectory.

Declaration

public static FSDirectory Open(DirectoryInfo path)

Parameters

Type	Name	Description
System.IO.DirectoryInfo	path

Returns

Type	Description
FSDirectory

Open(DirectoryInfo, LockFactory)

Just like Open(DirectoryInfo), but allows you to also specify a custom LockFactory.

Declaration

public static FSDirectory Open(DirectoryInfo path, LockFactory lockFactory)

Parameters

Type	Name	Description
System.IO.DirectoryInfo	path
LockFactory	lockFactory

Returns

Type	Description
FSDirectory

Open(String)

Just like Open(DirectoryInfo), but allows you to specify the directory as a System.String.

Declaration

public static FSDirectory Open(string path)

Parameters

Type	Name	Description
System.String	path	The path (to a directory) to open

Returns

Type	Description
FSDirectory	An open FSDirectory

Open(String, LockFactory)

Just like Open(DirectoryInfo, LockFactory), but allows you to specify the directory as a System.String.

Declaration

public static FSDirectory Open(string path, LockFactory lockFactory)

Parameters

Type	Name	Description
System.String	path	The path (to a directory) to open
LockFactory	lockFactory

Returns

Type	Description
FSDirectory	An open FSDirectory

SetLockFactory(LockFactory)

Declaration

public override void SetLockFactory(LockFactory lockFactory)

Parameters

Type	Name	Description
LockFactory	lockFactory

Overrides

BaseDirectory.SetLockFactory(LockFactory)

Sync(ICollection<String>)

Declaration

public override void Sync(ICollection<string> names)

Parameters

Type	Name	Description
System.Collections.Generic.ICollection<System.String>	names

Overrides

Directory.Sync(ICollection<String>)

ToString()

For debug output.

Declaration

public override string ToString()

Returns

Type	Description
System.String

Overrides

Directory.ToString()

Implements

System.IDisposable

See Also

Directory