org.apache.lucene.store

Class Directory

public abstract class Directory extends Object

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:

Directory locking is implemented by an instance of LockFactory, and can be changed for each Directory instance using Directory.

Author: Doug Cutting

Field Summary
protected LockFactorylockFactory
Holds the LockFactory instance (implements locking for this Directory instance).
Method Summary
voidclearLock(String name)
Attempt to clear (forcefully unlock and remove) the specified lock.
abstract voidclose()
Closes the store.
static voidcopy(Directory src, Directory dest, boolean closeDirSrc)
Copy contents of a directory src to a directory dest.
abstract IndexOutputcreateOutput(String name)
Creates a new, empty file in the directory with the given name.
abstract voiddeleteFile(String name)
Removes an existing file in the directory.
abstract booleanfileExists(String name)
Returns true iff a file with the given name exists.
abstract longfileLength(String name)
Returns the length of a file in the directory.
abstract longfileModified(String name)
Returns the time the named file was last modified.
LockFactorygetLockFactory()
Get the LockFactory that this Directory instance is using for its locking implementation.
StringgetLockID()
Return a string identifier that uniquely differentiates this Directory instance from other Directory instances.
abstract String[]list()
Returns an array of strings, one for each file in the directory.
LockmakeLock(String name)
Construct a Lock.
abstract IndexInputopenInput(String name)
Returns a stream reading an existing file.
IndexInputopenInput(String name, int bufferSize)
Returns a stream reading an existing file, with the specified read buffer size.
abstract voidrenameFile(String from, String to)
Renames an existing file in the directory.
voidsetLockFactory(LockFactory lockFactory)
Set the LockFactory that this Directory instance should use for its locking implementation.
abstract voidtouchFile(String name)
Set the modified time of an existing file to now.

Field Detail

lockFactory

protected LockFactory lockFactory
Holds the LockFactory instance (implements locking for this Directory instance).

Method Detail

clearLock

public void clearLock(String name)
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.

close

public abstract void close()
Closes the store.

copy

public static void copy(Directory src, Directory dest, boolean closeDirSrc)
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.

Parameters: src source directory dest destination directory closeDirSrc if true, call close method on source directory

Throws: IOException

createOutput

public abstract IndexOutput createOutput(String name)
Creates a new, empty file in the directory with the given name. Returns a stream writing this file.

deleteFile

public abstract void deleteFile(String name)
Removes an existing file in the directory.

fileExists

public abstract boolean fileExists(String name)
Returns true iff a file with the given name exists.

fileLength

public abstract long fileLength(String name)
Returns the length of a file in the directory.

fileModified

public abstract long fileModified(String name)
Returns the time the named file was last modified.

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.

list

public abstract String[] list()
Returns an array of strings, one for each file in the directory. This method may return null (for example for FSDirectory if the underlying directory doesn't exist in the filesystem or there are permissions problems).

makeLock

public Lock makeLock(String name)
Construct a Lock.

Parameters: name the name of the lock file

openInput

public abstract IndexInput openInput(String name)
Returns a stream reading an existing file.

openInput

public IndexInput openInput(String name, int bufferSize)
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 are FSDirectory and CompoundFileReader.

renameFile

public abstract void renameFile(String from, String to)

Deprecated:

Renames an existing file in the directory. If a file already exists with the new name, then it is replaced. This replacement is not guaranteed to be atomic.

setLockFactory

public void setLockFactory(LockFactory lockFactory)
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 of LockFactory.

touchFile

public abstract void touchFile(String name)
Set the modified time of an existing file to now.
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