Package org.apache.lucene.store
Class Directory
- java.lang.Object
-
- org.apache.lucene.store.Directory
-
- All Implemented Interfaces:
Closeable
,AutoCloseable
- Direct Known Subclasses:
FileSwitchDirectory
,FSDirectory
,MockDirectoryWrapper
,NRTCachingDirectory
,RAMDirectory
public abstract class Directory extends Object implements Closeable
A Directory is a flat list of files. Files may be written once, when they are created. Once a file is created it may only be opened for read, or deleted. Random access is permitted both when reading and writing.Java's i/o APIs not used directly, but rather all i/o is through this API. This permits things such as:
- implementation of RAM-based indices;
- implementation indices stored in a database, via JDBC;
- implementation of an index as a single file;
LockFactory
, and can be changed for each Directory instance usingsetLockFactory(org.apache.lucene.store.LockFactory)
.
-
-
Field Summary
Fields Modifier and Type Field Description protected boolean
isOpen
protected LockFactory
lockFactory
Holds the LockFactory instance (implements locking for this Directory instance).
-
Constructor Summary
Constructors Constructor Description Directory()
-
Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods Modifier and Type Method Description void
clearLock(String name)
Attempt to clear (forcefully unlock and remove) the specified lock.abstract void
close()
Closes the store.void
copy(Directory to, String src, String dest)
Copies the file src toDirectory
to under the new file name dest.static void
copy(Directory src, Directory dest, boolean closeDirSrc)
Deprecated.should be replaced with calls tocopy(Directory, String, String)
for every file that needs copying.abstract IndexOutput
createOutput(String name)
Creates a new, empty file in the directory with the given name.abstract void
deleteFile(String name)
Removes an existing file in the directory.protected void
ensureOpen()
abstract boolean
fileExists(String name)
Returns true iff a file with the given name exists.abstract long
fileLength(String name)
Returns the length of a file in the directory.abstract long
fileModified(String name)
Deprecated.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.abstract String[]
listAll()
Returns an array of strings, one for each file in the directory.Lock
makeLock(String name)
Construct aLock
.abstract IndexInput
openInput(String name)
Returns a stream reading an existing file.IndexInput
openInput(String name, int bufferSize)
Returns a stream reading an existing file, with the specified read buffer size.void
setLockFactory(LockFactory lockFactory)
Set the LockFactory that this Directory instance should use for its locking implementation.void
sync(String name)
Deprecated.usesync(Collection)
instead.void
sync(Collection<String> names)
Ensure that any writes to these files are moved to stable storage.String
toString()
abstract void
touchFile(String name)
Deprecated.Lucene never uses this API; it will be removed in 4.0.
-
-
-
Field Detail
-
isOpen
protected volatile boolean isOpen
-
lockFactory
protected LockFactory lockFactory
Holds the LockFactory instance (implements locking for this Directory instance).
-
-
Method Detail
-
listAll
public abstract String[] listAll() throws IOException
Returns an array of strings, one for each file in the directory.- Throws:
NoSuchDirectoryException
- if the directory is not prepared for any write operations (such ascreateOutput(String)
).IOException
- in case of other IO errors
-
fileExists
public abstract boolean fileExists(String name) throws IOException
Returns true iff a file with the given name exists.- Throws:
IOException
-
fileModified
@Deprecated public abstract long fileModified(String name) throws IOException
Deprecated.Returns the time the named file was last modified.- Throws:
IOException
-
touchFile
@Deprecated public abstract void touchFile(String name) throws IOException
Deprecated.Lucene never uses this API; it will be removed in 4.0.Set the modified time of an existing file to now.- Throws:
IOException
-
deleteFile
public abstract void deleteFile(String name) throws IOException
Removes an existing file in the directory.- Throws:
IOException
-
fileLength
public abstract long fileLength(String name) throws IOException
Returns the length of a file in the directory. This method follows the following contract:- Throws
FileNotFoundException
if the file does not exist - Returns a value ≥0 if the file exists, which specifies its length.
- Parameters:
name
- the name of the file for which to return the length.- Throws:
FileNotFoundException
- if the file does not exist.IOException
- if there was an IO error while retrieving the file's length.
- Throws
-
createOutput
public abstract IndexOutput createOutput(String name) throws IOException
Creates a new, empty file in the directory with the given name. Returns a stream writing this file.- Throws:
IOException
-
sync
@Deprecated public void sync(String name) throws IOException
Deprecated.usesync(Collection)
instead. For easy migration you can change your code to call sync(Collections.singleton(name))Ensure that any writes to this file are moved to stable storage. Lucene uses this to properly commit changes to the index, to prevent a machine/OS crash from corrupting the index.- Throws:
IOException
-
sync
public void sync(Collection<String> names) throws IOException
Ensure that any writes to these files are moved to stable storage. Lucene uses this to properly commit changes to the index, to prevent a machine/OS crash from corrupting the index.
NOTE: Clients may call this method for same files over and over again, so some impls might optimize for that. For other impls the operation can be a noop, for various reasons.- Throws:
IOException
-
openInput
public abstract IndexInput openInput(String name) throws IOException
Returns a stream reading an existing file.- Throws:
IOException
-
openInput
public IndexInput openInput(String name, int bufferSize) throws IOException
Returns a stream reading an existing file, with the specified read buffer size. The particular Directory implementation may ignore the buffer size. Currently the only Directory implementations that respect this parameter areFSDirectory
andCompoundFileReader
.- Throws:
IOException
-
makeLock
public Lock makeLock(String name)
Construct aLock
.- Parameters:
name
- the name of the lock file
-
clearLock
public void clearLock(String name) throws IOException
Attempt to clear (forcefully unlock and remove) the specified lock. Only call this at a time when you are certain this lock is no longer in use.- Parameters:
name
- name of the lock to be cleared.- Throws:
IOException
-
close
public abstract void close() throws IOException
Closes the store.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Throws:
IOException
-
setLockFactory
public void setLockFactory(LockFactory lockFactory) throws IOException
Set the LockFactory that this Directory instance should use for its locking implementation. Each * instance of LockFactory should only be used for one directory (ie, do not share a single instance across multiple Directories).- Parameters:
lockFactory
- instance ofLockFactory
.- Throws:
IOException
-
getLockFactory
public LockFactory getLockFactory()
Get the LockFactory that this Directory instance is using for its locking implementation. Note that this may be null for Directory implementations that provide their own locking implementation.
-
getLockID
public String getLockID()
Return a string identifier that uniquely differentiates this Directory instance from other Directory instances. This ID should be the same if two Directory instances (even in different JVMs and/or on different machines) are considered "the same index". This is how locking "scopes" to the right index.
-
copy
public void copy(Directory to, String src, String dest) throws IOException
Copies the file src toDirectory
to under the new file name dest.If you want to copy the entire source directory to the destination one, you can do so like this:
Directory to; // the directory to copy to for (String file : dir.listAll()) { dir.copy(to, file, newFile); // newFile can be either file, or a new name }
NOTE: this method does not check whether dest exist and will overwrite it if it does.
- Throws:
IOException
-
copy
@Deprecated public static void copy(Directory src, Directory dest, boolean closeDirSrc) throws IOException
Deprecated.should be replaced with calls tocopy(Directory, String, String)
for every file that needs copying. You can use the following code:IndexFileNameFilter filter = IndexFileNameFilter.getFilter(); for (String file : src.listAll()) { if (filter.accept(null, file)) { src.copy(dest, file, file); } }
Copy contents of a directory src to a directory dest. If a file in src already exists in dest then the one in dest will be blindly overwritten.NOTE: the source directory cannot change while this method is running. Otherwise the results are undefined and you could easily hit a FileNotFoundException.
NOTE: this method only copies files that look like index files (ie, have extensions matching the known extensions of index files).
- Parameters:
src
- source directorydest
- destination directorycloseDirSrc
- iftrue
, callclose()
method on source directory- Throws:
IOException
-
ensureOpen
protected final void ensureOpen() throws AlreadyClosedException
- Throws:
AlreadyClosedException
- if this Directory is closed
-
-