public class NRTCachingDirectory extends Directory
RAMDirectory
around any provided delegate directory, to
be used during NRT search.
This class is likely only useful in a near-real-time context, where indexing rate is lowish but reopen rate is highish, resulting in many tiny files being written. This directory keeps such segments (as well as the segments produced by merging them, as long as they are small enough), in RAM.
This is safe to use: when your app calls {IndexWriter#commit}, all cached files will be flushed from the cached and sync'd.
Here's a simple example usage:
Directory fsDir = FSDirectory.open(new File("/path/to/index")); NRTCachingDirectory cachedFSDir = new NRTCachingDirectory(fsDir, 5.0, 60.0); IndexWriterConfig conf = new IndexWriterConfig(Version.LUCENE_32, analyzer); IndexWriter writer = new IndexWriter(cachedFSDir, conf);
This will cache all newly flushed segments, all merges whose expected segment size is <= 5 MB, unless the net cached bytes exceeds 60 MB at which point all writes will not be cached (until the net bytes falls below 60 MB).
Directory.IndexInputSlicer
isOpen, lockFactory
Constructor and Description |
---|
NRTCachingDirectory(Directory delegate,
double maxMergeSizeMB,
double maxCachedMB)
We will cache a newly created output if 1) it's a
flush or a merge and the estimated size of the merged segment is <=
maxMergeSizeMB, and 2) the total cached bytes is <=
maxCachedMB
|
Modifier and Type | Method and Description |
---|---|
void |
clearLock(String name)
Attempt to clear (forcefully unlock and remove) the
specified lock.
|
void |
close()
Close this directory, which flushes any cached files
to the delegate and then closes the delegate.
|
IndexOutput |
createOutput(String name,
IOContext context)
Creates a new, empty file in the directory with the given name.
|
Directory.IndexInputSlicer |
createSlicer(String name,
IOContext context)
Creates an
Directory.IndexInputSlicer for the given file name. |
void |
deleteFile(String name)
Removes an existing file in the directory.
|
protected boolean |
doCacheWrite(String name,
IOContext context)
Subclass can override this to customize logic; return
true if this file should be written to the RAMDirectory.
|
boolean |
fileExists(String name)
Returns true iff a file with the given name exists.
|
long |
fileLength(String name)
Returns the length of a file in the directory.
|
Directory |
getDelegate() |
LockFactory |
getLockFactory()
Get the LockFactory that this Directory instance is
using for its locking implementation.
|
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.
|
String[] |
listCachedFiles() |
Lock |
makeLock(String name)
Construct a
Lock . |
IndexInput |
openInput(String name,
IOContext context)
Returns a stream reading an existing file, with the
specified read buffer size.
|
void |
setLockFactory(LockFactory lf)
Set the LockFactory that this Directory instance should
use for its locking implementation.
|
long |
sizeInBytes()
Returns how many bytes are being used by the
RAMDirectory cache
|
void |
sync(Collection<String> fileNames)
Ensure that any writes to these files are moved to
stable storage.
|
String |
toString() |
copy, ensureOpen
public NRTCachingDirectory(Directory delegate, double maxMergeSizeMB, double maxCachedMB)
public Directory getDelegate()
public LockFactory getLockFactory()
Directory
getLockFactory
in class Directory
public void setLockFactory(LockFactory lf) throws IOException
Directory
setLockFactory
in class Directory
lf
- instance of LockFactory
.IOException
public String getLockID()
Directory
public Lock makeLock(String name)
Directory
Lock
.public void clearLock(String name) throws IOException
Directory
clearLock
in class Directory
name
- name of the lock to be cleared.IOException
public String[] listAll() throws IOException
Directory
listAll
in class Directory
NoSuchDirectoryException
- if the directory is not prepared for any
write operations (such as Directory.createOutput(String, IOContext)
).IOException
- in case of other IO errorspublic long sizeInBytes()
public boolean fileExists(String name) throws IOException
Directory
fileExists
in class Directory
IOException
public void deleteFile(String name) throws IOException
Directory
deleteFile
in class Directory
IOException
public long fileLength(String name) throws IOException
Directory
FileNotFoundException
if the file does not exist
fileLength
in class Directory
name
- the name of the file for which to return the length.FileNotFoundException
- if the file does not exist.IOException
- if there was an IO error while retrieving the file's
length.public String[] listCachedFiles()
public IndexOutput createOutput(String name, IOContext context) throws IOException
Directory
createOutput
in class Directory
IOException
public void sync(Collection<String> fileNames) throws IOException
Directory
sync
in class Directory
IOException
public IndexInput openInput(String name, IOContext context) throws IOException
Directory
FSDirectory
and CompoundFileDirectory
.openInput
in class Directory
IOException
public Directory.IndexInputSlicer createSlicer(String name, IOContext context) throws IOException
Directory
Directory.IndexInputSlicer
for the given file name.
IndexInputSlicer allows other Directory
implementations to
efficiently open one or more sliced IndexInput
instances from a
single file handle. The underlying file handle is kept open until the
Directory.IndexInputSlicer
is closed.createSlicer
in class Directory
IOException
- if an IOException
occurspublic void close() throws IOException
close
in interface Closeable
close
in class Directory
IOException
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