Class InMemoryRepository.ByteArrayReadableChannel

java.lang.Object
org.eclipse.jgit.internal.storage.dfs.InMemoryRepository.ByteArrayReadableChannel
All Implemented Interfaces:
Closeable, AutoCloseable, Channel, ReadableByteChannel, ReadableChannel
Enclosing class:
InMemoryRepository

private static class InMemoryRepository.ByteArrayReadableChannel extends Object implements ReadableChannel
  • Field Details

    • data

      private final byte[] data
    • blockSize

      private final int blockSize
    • position

      private int position
    • open

      private boolean open
  • Constructor Details

    • ByteArrayReadableChannel

      ByteArrayReadableChannel(byte[] buf, int blockSize)
  • Method Details

    • read

      public int read(ByteBuffer dst)
      Specified by:
      read in interface ReadableByteChannel
    • close

      public void close()
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Channel
      Specified by:
      close in interface Closeable
    • isOpen

      public boolean isOpen()
      Specified by:
      isOpen in interface Channel
    • position

      public long position()
      Description copied from interface: ReadableChannel
      Get the current position of the channel.
      Specified by:
      position in interface ReadableChannel
      Returns:
      r current offset.
    • position

      public void position(long newPosition)
      Description copied from interface: ReadableChannel
      Seek the current position of the channel to a new offset.
      Specified by:
      position in interface ReadableChannel
      Parameters:
      newPosition - position to move the channel to. The next read will start from here. This should be a multiple of the ReadableChannel.blockSize().
    • size

      public long size()
      Description copied from interface: ReadableChannel
      Get the total size of the channel.

      Prior to reading from a channel the size might not yet be known. Implementors may return -1 until after the first read method call. Once a read has been completed, the underlying file size should be available.

      Specified by:
      size in interface ReadableChannel
      Returns:
      r total size of the channel; -1 if not yet available.
    • blockSize

      public int blockSize()
      Description copied from interface: ReadableChannel
      Get the recommended alignment for reads.

      Starting a read at multiples of the blockSize is more efficient than starting a read at any other position. If 0 or -1 the channel does not have any specific block size recommendation.

      Channels should not recommend large block sizes. Sizes up to 1-4 MiB may be reasonable, but sizes above that may be horribly inefficient. The DfsBlockCache favors the alignment suggested by the channel rather than the configured size under the assumption that reads are very expensive and the channel knows what size is best to access it with.

      Specified by:
      blockSize in interface ReadableChannel
      Returns:
      recommended alignment size for randomly positioned reads. Does not need to be a power of 2.
    • setReadAheadBytes

      public void setReadAheadBytes(int b)
      Description copied from interface: ReadableChannel
      Recommend the channel maintain a read-ahead buffer.

      A read-ahead buffer of approximately bufferSize in bytes may be allocated and used by the channel to smooth out latency for read.

      Callers can continue to read in smaller than bufferSize chunks. With read-ahead buffering enabled read latency may fluctuate in a pattern of one slower read followed by (bufferSize / readSize) - 1 fast reads satisfied by the read-ahead buffer. When summed up overall time to read the same contiguous range should be lower than if read-ahead was not enabled, as the implementation can combine reads to increase throughput.

      To avoid unnecessary IO callers should only enable read-ahead if the majority of the channel will be accessed in order.

      Implementations may chose to read-ahead using asynchronous APIs or background threads, or may simply aggregate reads using a buffer.

      This read ahead stays in effect until the channel is closed or the buffer size is set to 0.

      Specified by:
      setReadAheadBytes in interface ReadableChannel
      Parameters:
      b - requested size of the read ahead buffer, in bytes.