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. However, it has poor concurrent performance (multiple threads will bottleneck) as it synchronizes when multiple threads read from the same file.
  • NIOFSDirectory uses java.nio's FileChannel's positional io when reading to avoid synchronization when reading from the same file. Unfortunately, due to a Windows-only Sun JRE bug this is a poor choice for Windows, but on all other platforms this is the preferred choice. Applications using or System.Threading.Tasks.Task<TResult> should use SimpleFSDirectory instead. See NIOFSDirectory java doc for details.
  • 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.

    Applications using or System.Threading.Tasks.Task should use SimpleFSDirectory instead. See MMapDirectory doc for details.

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.

Inheritance
System.Object
Directory
BaseDirectory
FSDirectory
MMapDirectory
NIOFSDirectory
SimpleFSDirectory
Implements
System.IDisposable
Inherited Members
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

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FSDirectory(DirectoryInfo)

Declaration
protected FSDirectory(DirectoryInfo dir)
Parameters
Type Name Description
System.IO.DirectoryInfo dir
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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

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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
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m_directory

Declaration
protected readonly DirectoryInfo m_directory
Field Value
Type Description
System.IO.DirectoryInfo

Properties

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Directory

the underlying filesystem directory

Declaration
public virtual DirectoryInfo Directory { get; }
Property Value
Type Description
System.IO.DirectoryInfo
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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

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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
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DeleteFile(String)

Removes an existing file in the directory.

Declaration
public override void DeleteFile(string name)
Parameters
Type Name Description
System.String name
Overrides
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Dispose(Boolean)

Closes the store to future operations.

Declaration
protected override void Dispose(bool disposing)
Parameters
Type Name Description
System.Boolean disposing
Overrides
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EnsureCanWrite(String)

Declaration
protected virtual void EnsureCanWrite(string name)
Parameters
Type Name Description
System.String name
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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
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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
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GetLockID()

Declaration
public override string GetLockID()
Returns
Type Description
System.String
Overrides
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ListAll()

Lists all files (not subdirectories) in the directory.

Declaration
public override string[] ListAll()
Returns
Type Description
System.String[]
Overrides
See Also
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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.
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OnIndexOutputClosed(FSDirectory.FSIndexOutput)

Declaration
protected virtual void OnIndexOutputClosed(FSDirectory.FSIndexOutput io)
Parameters
Type Name Description
FSDirectory.FSIndexOutput io
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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
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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
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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
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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
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SetLockFactory(LockFactory)

Declaration
public override void SetLockFactory(LockFactory lockFactory)
Parameters
Type Name Description
LockFactory lockFactory
Overrides
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Sync(ICollection<String>)

Declaration
public override void Sync(ICollection<string> names)
Parameters
Type Name Description
System.Collections.Generic.ICollection<System.String> names
Overrides
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ToString()

For debug output.

Declaration
public override string ToString()
Returns
Type Description
System.String
Overrides

Implements

System.IDisposable

Extension Methods

See Also