public class RAMDirectory extends BaseDirectory
Directory implementation. Locking
implementation is by default the SingleInstanceLockFactory
but can be changed with BaseDirectory.setLockFactory(org.apache.lucene.store.LockFactory).
Warning: This class is not intended to work with huge
indexes. Everything beyond several hundred megabytes will waste
resources (GC cycles), because it uses an internal buffer size
of 1024 bytes, producing millions of byte[1024] arrays.
This class is optimized for small memory-resident indexes.
It also has bad concurrency on multithreaded environments.
It is recommended to materialize large indexes on disk and use
MMapDirectory, which is a high-performance directory
implementation working directly on the file system cache of the
operating system, so copying data to Java heap space is not useful.
Directory.IndexInputSlicer| Modifier and Type | Field and Description |
|---|---|
protected Map<String,RAMFile> |
fileMap |
protected AtomicLong |
sizeInBytes |
isOpen, lockFactory| Constructor and Description |
|---|
RAMDirectory()
Constructs an empty
Directory. |
RAMDirectory(Directory dir,
IOContext context)
Creates a new
RAMDirectory instance from a different
Directory implementation. |
| Modifier and Type | Method and Description |
|---|---|
void |
close()
Closes the store to future operations, releasing associated memory.
|
IndexOutput |
createOutput(String name,
IOContext context)
Creates a new, empty file in the directory with the given name.
|
void |
deleteFile(String name)
Removes an existing file in the directory.
|
boolean |
fileExists(String name)
Returns true iff the named file exists in this directory.
|
long |
fileLength(String name)
Returns the length in bytes of a file in the directory.
|
String |
getLockID()
Return a string identifier that uniquely differentiates
this Directory instance from other Directory instances.
|
String[] |
listAll()
Returns an array of strings, one for each file in the directory.
|
protected RAMFile |
newRAMFile()
Returns a new
RAMFile for storing data. |
IndexInput |
openInput(String name,
IOContext context)
Returns a stream reading an existing file.
|
long |
sizeInBytes()
Return total size in bytes of all files in this directory.
|
void |
sync(Collection<String> names)
Ensure that any writes to these files are moved to
stable storage.
|
clearLock, ensureOpen, getLockFactory, makeLock, setLockFactorycopy, createSlicer, toStringprotected final AtomicLong sizeInBytes
public RAMDirectory()
Directory.public RAMDirectory(Directory dir, IOContext context) throws IOException
RAMDirectory instance from a different
Directory implementation. This can be used to load
a disk-based index into memory.
Warning: This class is not intended to work with huge
indexes. Everything beyond several hundred megabytes will waste
resources (GC cycles), because it uses an internal buffer size
of 1024 bytes, producing millions of byte[1024] arrays.
This class is optimized for small memory-resident indexes.
It also has bad concurrency on multithreaded environments.
For disk-based indexes it is recommended to use
MMapDirectory, which is a high-performance directory
implementation working directly on the file system cache of the
operating system, so copying data to Java heap space is not useful.
Note that the resulting RAMDirectory instance is fully
independent from the original Directory (it is a
complete copy). Any subsequent changes to the
original Directory will not be visible in the
RAMDirectory instance.
dir - a Directory valueIOException - if an error occurspublic String getLockID()
Directorypublic final String[] listAll()
Directorypublic final boolean fileExists(String name)
fileExists in class Directorypublic final long fileLength(String name) throws IOException
fileLength in class Directoryname - the name of the file for which to return the length.IOException - if the file does not existpublic final long sizeInBytes()
public void deleteFile(String name) throws IOException
deleteFile in class DirectoryIOException - if the file does not existpublic IndexOutput createOutput(String name, IOContext context) throws IOException
createOutput in class DirectoryIOExceptionprotected RAMFile newRAMFile()
RAMFile for storing data. This method can be
overridden to return different RAMFile impls, that e.g. override
RAMFile.newBuffer(int).public void sync(Collection<String> names) throws IOException
Directorysync in class DirectoryIOExceptionpublic IndexInput openInput(String name, IOContext context) throws IOException
openInput in class DirectoryIOExceptionCopyright © 2000-2014 Apache Software Foundation. All Rights Reserved.