Package org.apache.lucene.store

Class RAMDirectory

  • All Implemented Interfaces:
    Closeable, AutoCloseable, Accountable
    @Deprecated
public class RAMDirectory
extends BaseDirectory
implements Accountable
    Deprecated.
    This class uses inefficient synchronization and is discouraged in favor of MMapDirectory. It will be removed in future versions of Lucene.
    A memory-resident 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.

    • Field Detail

      • sizeInBytes

        protected final AtomicLong sizeInBytes
        Deprecated.

    • Constructor Detail

      • RAMDirectory

        public RAMDirectory()
        Deprecated.
        Constructs an empty Directory.

      • RAMDirectory

        public RAMDirectory​(FSDirectory dir,
                    IOContext context)
             throws IOException
        Deprecated.
        Creates a new 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.

        Parameters:
        dir - a Directory value
        Throws:
        IOException - if an error occurs

    • Method Detail

      • fileNameExists

        public final boolean fileNameExists​(String name)
        Deprecated.

      • fileLength

        public final long fileLength​(String name)
                      throws IOException
        Deprecated.
        Returns the length in bytes of a file in the directory.
        Specified by:
        fileLength in class Directory
        Parameters:
        name - the name of an existing file.
        Throws:
        IOException - if the file does not exist

      • ramBytesUsed

        public final long ramBytesUsed()
        Deprecated.
        Return total size in bytes of all files in this directory. This is currently quantized to RAMOutputStream.BUFFER_SIZE.
        Specified by:
        ramBytesUsed in interface Accountable

      • sync

        public void sync​(Collection<String> names)
          throws IOException
        Deprecated.
        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
        Throws:
        IOException
        See Also:
        Directory.syncMetaData()

      • rename

        public void rename​(String source,
                   String dest)
            throws IOException
        Deprecated.
        Description copied from class: Directory
        Renames source file to dest file where dest must not already exist in the directory. It is permitted for this operation to not be truly atomic, for example both source and dest can be visible temporarily in Directory.listAll(). However, the implementation of this method must ensure the content of dest appears as the entire source atomically. So once dest is visible for readers, the entire content of previous source is visible. This method is used by IndexWriter to publish commits.
        Specified by:
        rename in class Directory
        Throws:
        IOException

      • close

        public void close()
        Deprecated.
        Closes the store to future operations, releasing associated memory.
        Specified by:
        close in interface AutoCloseable
        Specified by:
        close in interface Closeable
        Specified by:
        close in class Directory

      • getPendingDeletions

        public Set<String> getPendingDeletions()
        Deprecated.
        Description copied from class: Directory
        Returns a set of files currently pending deletion in this directory.
        Specified by:
        getPendingDeletions in class Directory