Package org.apache.hadoop.fs.impl.prefetch

Class FilePosition

java.lang.Object
org.apache.hadoop.fs.impl.prefetch.FilePosition
public final class FilePosition extends Object
Provides functionality related to tracking the position within a file. The file is accessed through an in memory buffer. The absolute position within the file is the sum of start offset of the buffer within the file and the relative offset of the current access location within the buffer. A file is made up of equal sized blocks. The last block may be of a smaller size. The size of a buffer associated with this file is typically the same as block size.

  • Constructor Details

    • FilePosition

      public FilePosition(long fileSize, int blockSize)
      Constructs an instance of FilePosition.
      Parameters:
      fileSize - size of the associated file.
      blockSize - size of each block within the file.
      Throws:
      IllegalArgumentException - if fileSize is negative.
      IllegalArgumentException - if blockSize is zero or negative.

  • Method Details

    • setData

      public void setData(BufferData bufferData, long startOffset, long readOffset)
      Associates a buffer with this file.
      Parameters:
      bufferData - the buffer associated with this file.
      startOffset - Start offset of the buffer relative to the start of a file.
      readOffset - Offset where reading starts relative to the start of a file.
      Throws:
      IllegalArgumentException - if bufferData is null.
      IllegalArgumentException - if startOffset is negative.
      IllegalArgumentException - if readOffset is negative.
      IllegalArgumentException - if readOffset is outside the range [startOffset, buffer end].

    • buffer

      public ByteBuffer buffer()

    • data

      public BufferData data()

    • absolute

      public long absolute()
      Gets the current absolute position within this file.
      Returns:
      the current absolute position within this file.

    • setAbsolute

      public boolean setAbsolute(long pos)
      If the given pos lies within the current buffer, updates the current position to the specified value and returns true; otherwise returns false without changing the position.
      Parameters:
      pos - the absolute position to change the current position to if possible.
      Returns:
      true if the given current position was updated, false otherwise.

    • relative

      public int relative()
      Gets the current position within this file relative to the start of the associated buffer.
      Returns:
      the current position within this file relative to the start of the associated buffer.

    • isWithinCurrentBuffer

      public boolean isWithinCurrentBuffer(long pos)
      Determines whether the given absolute position lies within the current buffer.
      Parameters:
      pos - the position to check.
      Returns:
      true if the given absolute position lies within the current buffer, false otherwise.

    • blockNumber

      public int blockNumber()
      Gets the id of the current block.
      Returns:
      the id of the current block.

    • isLastBlock

      public boolean isLastBlock()
      Determines whether the current block is the last block in this file.
      Returns:
      true if the current block is the last block in this file, false otherwise.

    • isValid

      public boolean isValid()
      Determines if the current position is valid.
      Returns:
      true if the current position is valid, false otherwise.

    • invalidate

      public void invalidate()
      Marks the current position as invalid.

    • bufferStartOffset

      public long bufferStartOffset()
      Gets the start of the current block's absolute offset.
      Returns:
      the start of the current block's absolute offset.

    • bufferFullyRead

      public boolean bufferFullyRead()
      Determines whether the current buffer has been fully read.
      Returns:
      true if the current buffer has been fully read, false otherwise.

    • incrementBytesRead

      public void incrementBytesRead(int n)

    • numBytesRead

      public int numBytesRead()

    • numSingleByteReads

      public int numSingleByteReads()

    • numBufferReads

      public int numBufferReads()

    • toString

      public String toString()
      Overrides:
      toString in class Object