org.apache.lucene.codecs

## Class CompoundDirectory

- java.lang.Object
- - org.apache.lucene.store.Directory
  - - org.apache.lucene.codecs.CompoundDirectory

- All Implemented Interfaces:
    Closeable, AutoCloseable

      public abstract class CompoundDirectory
      extends Directory

  A read-only `Directory` that consists of a view over a compound file.
  See Also:
    `CompoundFormat`
  WARNING: This API is experimental and might change in incompatible ways in the next release.

- - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `CompoundDirectory()` Sole constructor.

  - ### Method Summary

    All Methods Instance Methods Abstract Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `abstract void` | `checkIntegrity()` Checks consistency of this directory.
    `IndexOutput` | `createOutput(String name, IOContext context)` Creates a new, empty file in the directory and returns an `IndexOutput` instance for appending data to this file.
    `IndexOutput` | `createTempOutput(String prefix, String suffix, IOContext context)` Creates a new, empty, temporary file in the directory and returns an `IndexOutput` instance for appending data to this file.
    `void` | `deleteFile(String name)` Not implemented
    `Lock` | `obtainLock(String name)` Acquires and returns a `Lock` for a file with the given name.
    `void` | `rename(String from, String to)` Not implemented
    `void` | `sync(Collection<String> names)` Ensures that any writes to these files are moved to stable storage (made durable).
    `void` | `syncMetaData()` Ensures that directory metadata, such as recent file renames, are moved to stable storage.

    - ### Methods inherited from class org.apache.lucene.store.Directory

      `close, copyFrom, ensureOpen, fileLength, getPendingDeletions, getTempFileName, listAll, openChecksumInput, openInput, toString`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### CompoundDirectory

          protected CompoundDirectory()

      Sole constructor.

  - ### Method Detail

    - #### checkIntegrity

          public abstract void checkIntegrity()
                                       throws IOException

      Checks consistency of this directory.

      Note that this may be costly in terms of I/O, e.g. may involve computing a checksum value against large data files.

      Throws:
        `IOException`

    - #### deleteFile

          public final void deleteFile(String name)

      Not implemented
      Specified by:
        `deleteFile` in class `Directory`
      Parameters:
        `name` - the name of an existing file.
      Throws:
        `UnsupportedOperationException` - always: not supported by CFS

    - #### rename

          public final void rename(String from,
                                   String to)

      Not implemented
      Specified by:
        `rename` in class `Directory`
      Throws:
        `UnsupportedOperationException` - always: not supported by CFS

    - #### syncMetaData

          public final void syncMetaData()

      Description copied from class: `Directory`
      Ensures that directory metadata, such as recent file renames, are moved to stable storage.
      Specified by:
        `syncMetaData` in class `Directory`
      See Also:
        `Directory.sync(Collection)`

    - #### createOutput

          public final IndexOutput createOutput(String name,
                                                IOContext context)
                                         throws IOException

      Description copied from class: `Directory`
      Creates a new, empty file in the directory and returns an `IndexOutput` instance for appending data to this file. This method must throw `FileAlreadyExistsException` if the file already exists.
      Specified by:
        `createOutput` in class `Directory`
      Parameters:
        `name` - the name of the file to create.
      Throws:
        `IOException` - in case of I/O error

    - #### createTempOutput

          public final IndexOutput createTempOutput(String prefix,
                                                    String suffix,
                                                    IOContext context)
                                             throws IOException

      Description copied from class: `Directory`
      Creates a new, empty, temporary file in the directory and returns an `IndexOutput` instance for appending data to this file. The temporary file name (accessible via `IndexOutput.getName()`) will start with `prefix`, end with `suffix` and have a reserved file extension `.tmp`.
      Specified by:
        `createTempOutput` in class `Directory`
      Throws:
        `IOException`

    - #### sync

          public final void sync(Collection<String> names)

      Description copied from class: `Directory`
      Ensures that any writes to these files are moved to stable storage (made durable). Lucene uses this to properly commit changes to the index, to prevent a machine/OS crash from corrupting the index.
      Specified by:
        `sync` in class `Directory`
      See Also:
        `Directory.syncMetaData()`

    - #### obtainLock

          public final Lock obtainLock(String name)

      Description copied from class: `Directory`
      Acquires and returns a `Lock` for a file with the given name.
      Specified by:
        `obtainLock` in class `Directory`
      Parameters:
        `name` - the name of the lock file

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