Class MMapDirectory

File-based Directory implementation that uses System.IO.MemoryMappedFiles.MemoryMappedFile for reading, and FSDirectory.FSIndexOutput for writing.

NOTE: memory mapping uses up a portion of the virtual memory address space in your process equal to the size of the file being mapped. Before using this class, be sure your have plenty of virtual address space, e.g. by using a 64 bit runtime, or a 32 bit runtime with indexes that are guaranteed to fit within the address space. On 32 bit platforms also consult MMapDirectory(DirectoryInfo, LockFactory, Int32) if you have problems with mmap failing because of fragmented address space. If you get an System.OutOfMemoryException, it is recommended to reduce the chunk size, until it works.

NOTE: Accessing this class either directly or indirectly from a thread while it's interrupted can close the underlying channel immediately if at the same time the thread is blocked on IO. The channel will remain closed and subsequent access to MMapDirectory will throw a System.ObjectDisposedException.

Inheritance

System.Object

Directory

BaseDirectory

FSDirectory

MMapDirectory

Implements

System.IDisposable

Inherited Members

FSDirectory.DEFAULT_READ_CHUNK_SIZE

FSDirectory.m_directory

FSDirectory.Open(DirectoryInfo)

FSDirectory.Open(String)

FSDirectory.Open(DirectoryInfo, LockFactory)

FSDirectory.Open(String, LockFactory)

FSDirectory.SetLockFactory(LockFactory)

FSDirectory.ListAll(DirectoryInfo)

FSDirectory.ListAll()

FSDirectory.FileExists(String)

FSDirectory.FileLength(String)

FSDirectory.DeleteFile(String)

FSDirectory.CreateOutput(String, IOContext)

FSDirectory.EnsureCanWrite(String)

FSDirectory.OnIndexOutputClosed(FSDirectory.FSIndexOutput)

FSDirectory.Sync(ICollection<String>)

FSDirectory.GetLockID()

FSDirectory.Dispose(Boolean)

FSDirectory.Directory

FSDirectory.ToString()

FSDirectory.ReadChunkSize

BaseDirectory.IsOpen

BaseDirectory.m_lockFactory

BaseDirectory.MakeLock(String)

BaseDirectory.ClearLock(String)

BaseDirectory.LockFactory

BaseDirectory.EnsureOpen()

Directory.OpenChecksumInput(String, IOContext)

Directory.Dispose()

Directory.Copy(Directory, String, 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 class MMapDirectory : FSDirectory, IDisposable

Constructors

MMapDirectory(DirectoryInfo)

Create a new MMapDirectory for the named location and NativeFSLockFactory.

Declaration

public MMapDirectory(DirectoryInfo path)

Parameters

Type	Name	Description
System.IO.DirectoryInfo	path	the path of the directory

Exceptions

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

MMapDirectory(DirectoryInfo, LockFactory)

Create a new MMapDirectory for the named location.

Declaration

public MMapDirectory(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

MMapDirectory(DirectoryInfo, LockFactory, Int32)

Create a new MMapDirectory for the named location, specifying the maximum chunk size used for memory mapping.

Declaration

public MMapDirectory(DirectoryInfo path, LockFactory lockFactory, int maxChunkSize)

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);
System.Int32	maxChunkSize	maximum chunk size (default is 1 GiBytes for 64 bit runtimes and 256 MiBytes for 32 bit runtimes) used for memory mapping. Especially on 32 bit platform, the address space can be very fragmented, so large index files cannot be mapped. Using a lower chunk size makes the directory implementation a little bit slower (as the correct chunk may be resolved on lots of seeks) but the chance is higher that mmap does not fail. On 64 bit platforms, this parameter should always be 1 << 30, as the address space is big enough. Please note: The chunk size is always rounded down to a power of 2.

Exceptions

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

MMapDirectory(String)

Create a new MMapDirectory for the named location and NativeFSLockFactory.

LUCENENET specific overload for convenience using string instead of System.IO.DirectoryInfo.

Declaration

public MMapDirectory(string path)

Parameters

Type	Name	Description
System.String	path	the path of the directory

Exceptions

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

MMapDirectory(String, LockFactory)

Create a new MMapDirectory for the named location.

LUCENENET specific overload for convenience using string instead of System.IO.DirectoryInfo.

Declaration

public MMapDirectory(string path, LockFactory lockFactory)

Parameters

Type	Name	Description
System.String	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

MMapDirectory(String, LockFactory, Int32)

Create a new MMapDirectory for the named location, specifying the maximum chunk size used for memory mapping.

LUCENENET specific overload for convenience using string instead of System.IO.DirectoryInfo.

Declaration

public MMapDirectory(string path, LockFactory lockFactory, int maxChunkSize)

Parameters

Type	Name	Description
System.String	path	the path of the directory
LockFactory	lockFactory	the lock factory to use, or null for the default (NativeFSLockFactory);
System.Int32	maxChunkSize	maximum chunk size (default is 1 GiBytes for 64 bit runtimes and 256 MiBytes for 32 bit runtimes) used for memory mapping. Especially on 32 bit platform, the address space can be very fragmented, so large index files cannot be mapped. Using a lower chunk size makes the directory implementation a little bit slower (as the correct chunk may be resolved on lots of seeks) but the chance is higher that mmap does not fail. On 64 bit platforms, this parameter should always be 1 << 30, as the address space is big enough. Please note: The chunk size is always rounded down to a power of 2.

Exceptions

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

Fields

DEFAULT_MAX_BUFF

Default max chunk size.

Declaration

public static readonly int DEFAULT_MAX_BUFF

Field Value

Type	Description
System.Int32

See Also

MMapDirectory(DirectoryInfo, LockFactory, Int32)

Properties

MaxChunkSize

Returns the current mmap chunk size.

Declaration

public int MaxChunkSize { get; }

Property Value

Type	Description
System.Int32

See Also

MMapDirectory(DirectoryInfo, LockFactory, Int32)

Methods

CreateSlicer(String, IOContext)

Declaration

public override Directory.IndexInputSlicer CreateSlicer(string name, IOContext context)

Parameters

Type	Name	Description
System.String	name
IOContext	context

Returns

Type	Description
Directory.IndexInputSlicer

Overrides

Directory.CreateSlicer(String, IOContext)

OpenInput(String, IOContext)

Creates an IndexInput for the file with the given name.

Declaration

public override IndexInput OpenInput(string name, IOContext context)

Parameters

Type	Name	Description
System.String	name
IOContext	context

Returns

Type	Description
IndexInput

Overrides

Directory.OpenInput(String, IOContext)

Implements

System.IDisposable