public class RAMDirectory extends BaseDirectory implements Accountable
Directory implementation. Locking
implementation is by default the SingleInstanceLockFactory.
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.
| 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(FSDirectory dir,
IOContext context)
Creates a new
RAMDirectory instance from a different
Directory implementation. |
RAMDirectory(LockFactory lockFactory)
Constructs an empty
Directory with the given LockFactory. |
| 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.
|
IndexOutput |
createTempOutput(String prefix,
String suffix,
IOContext context)
Creates a new, empty file for writing in the directory, with a
temporary file name including prefix and suffix, ending with the
reserved extension
.tmp. |
void |
deleteFile(String name)
Removes an existing file in the directory.
|
long |
fileLength(String name)
Returns the length in bytes of a file in the directory.
|
boolean |
fileNameExists(String name) |
Collection<Accountable> |
getChildResources()
Returns nested resources of this class.
|
String[] |
listAll()
Returns an array of strings, one for each entry in the directory, in sorted (UTF16, java's String.compare) order.
|
protected RAMFile |
newRAMFile()
Returns a new
RAMFile for storing data. |
IndexInput |
openInput(String name,
IOContext context)
Returns a stream reading an existing file.
|
long |
ramBytesUsed()
Return total size in bytes of all files in this directory.
|
void |
rename(String source,
String dest)
Renames
source to dest as an atomic operation,
where dest does not yet exist in the directory. |
void |
sync(Collection<String> names)
Ensure that any writes to these files are moved to
stable storage.
|
void |
syncMetaData()
Ensure that directory metadata, such as recent file renames, are made
durable.
|
ensureOpen, obtainLock, toStringcopyFrom, openChecksumInputprotected final AtomicLong sizeInBytes
public RAMDirectory()
Directory.public RAMDirectory(LockFactory lockFactory)
Directory with the given LockFactory.public RAMDirectory(FSDirectory 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 final String[] listAll()
Directorypublic final boolean fileNameExists(String name)
public 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 ramBytesUsed()
ramBytesUsed in interface Accountablepublic Collection<Accountable> getChildResources()
AccountablegetChildResources in interface AccountableAccountablespublic void deleteFile(String name) throws IOException
DirectorydeleteFile in class DirectoryIOExceptionpublic IndexOutput createOutput(String name, IOContext context) throws IOException
DirectorycreateOutput in class DirectoryIOExceptionpublic IndexOutput createTempOutput(String prefix, String suffix, IOContext context) throws IOException
Directory.tmp. Use
IndexOutput.getName() to see what name was used.createTempOutput 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 void rename(String source, String dest) throws IOException
Directorysource to dest as an atomic operation,
where dest does not yet exist in the directory.
Notes: This method is used by IndexWriter to publish commits.
It is ok if this operation is not truly atomic, for example
both source and dest can be visible temporarily.
It is just important that the contents of dest appear
atomically, or an exception is thrown.
rename in class DirectoryIOExceptionpublic void syncMetaData()
throws IOException
DirectorysyncMetaData in class DirectoryIOExceptionpublic IndexInput openInput(String name, IOContext context) throws IOException
openInput in class DirectoryIOExceptionCopyright © 2000-2018 Apache Software Foundation. All Rights Reserved.