Package org.apache.flink.runtime.io.network.buffer

Class FileRegionBuffer

  • All Implemented Interfaces:
    Buffer, org.apache.flink.shaded.netty4.io.netty.channel.FileRegion, org.apache.flink.shaded.netty4.io.netty.util.ReferenceCounted
    public class FileRegionBuffer
extends org.apache.flink.shaded.netty4.io.netty.channel.DefaultFileRegion
implements Buffer
    This class represents a chunk of data in a file channel. Its purpose is to be passed to the netty code and to be written to the socket via the zero-copy direct transfer capabilities of FileChannel.transferTo(long, long, WritableByteChannel).

    This class implements Buffer mainly for compatible with existing usages. It can be thought of as a "lazy buffer" that does not hold the data directly, although the data can be fetches as a read-only ByteBuffer when needed, for example in local input channels. See readInto(MemorySegment) and getNioBufferReadable(). Because this buffer is read-only, the modification methods (and methods that give a writable buffer) throw UnsupportedOperationException.

    This class extends from Netty's DefaultFileRegion, similar as the NetworkBuffer extends from Netty's ByteBuf. That way we can pass both of them to Netty in the same way, and Netty will internally treat them appropriately.

    • Constructor Detail

      • FileRegionBuffer

        public FileRegionBuffer​(FileChannel fileChannel,
                        long fileChannelPosition,
                        int bufferSize,
                        Buffer.DataType dataType,
                        boolean isCompressed)

    • Method Detail

      • isBuffer

        public boolean isBuffer()
        Description copied from interface: Buffer
        Returns whether this buffer represents a buffer or an event.
        Specified by:
        isBuffer in interface Buffer
        Returns:
        true if this is a real buffer, false if this is an event

      • getMemorySegment

        public org.apache.flink.core.memory.MemorySegment getMemorySegment()
        Description copied from interface: Buffer
        Returns the underlying memory segment. This method is dangerous since it ignores read only protections and omits slices. Use it only along the Buffer.getMemorySegmentOffset().

        This method will be removed in the future. For writing use BufferBuilder.

        Specified by:
        getMemorySegment in interface Buffer
        Returns:
        the memory segment backing this buffer

      • getMemorySegmentOffset

        public int getMemorySegmentOffset()
        Description copied from interface: Buffer
        This method will be removed in the future. For writing use BufferBuilder.
        Specified by:
        getMemorySegmentOffset in interface Buffer
        Returns:
        the offset where this (potential slice) Buffer's data start in the underlying memory segment.

      • readOnlySlice

        public ReadOnlySlicedNetworkBuffer readOnlySlice​(int index,
                                                 int length)
        Description copied from interface: Buffer
        Returns a read-only slice of this buffer.

        Reader and writer indices as well as markers are not shared. Reference counters are shared but the slice is not retained automatically.

        Specified by:
        readOnlySlice in interface Buffer
        Parameters:
        index - the index to start from
        length - the length of the slice
        Returns:
        a read-only sliced buffer

      • getMaxCapacity

        public int getMaxCapacity()
        Description copied from interface: Buffer
        Returns the maximum size of the buffer, i.e. the capacity of the underlying MemorySegment.
        Specified by:
        getMaxCapacity in interface Buffer
        Returns:
        size of the buffer

      • getReaderIndex

        public int getReaderIndex()
        Description copied from interface: Buffer
        Returns the reader index of this buffer.

        This is where readable (unconsumed) bytes start in the backing memory segment.

        Specified by:
        getReaderIndex in interface Buffer
        Returns:
        reader index (from 0 (inclusive) to the size of the backing MemorySegment (inclusive))

      • getNioBufferReadable

        public ByteBuffer getNioBufferReadable()
        This method is only called by tests and by event-deserialization, like checkpoint barriers. Because such events are not used for bounded intermediate results, this method currently executes only in tests.
        Specified by:
        getNioBufferReadable in interface Buffer
        Returns:
        byte buffer sharing the contents of the underlying memory segment

      • asByteBuf

        public org.apache.flink.shaded.netty4.io.netty.buffer.ByteBuf asByteBuf()
        Specified by:
        asByteBuf in interface Buffer
        Returns:
        self as ByteBuf implementation.

      • setSize

        public void setSize​(int writerIndex)
        Description copied from interface: Buffer
        Sets the size of the written data, i.e. the writer index, of this buffer.
        Specified by:
        setSize in interface Buffer

      • getSize

        public int getSize()
        Description copied from interface: Buffer
        Returns the size of the written data, i.e. the writer index, of this buffer.

        This is where writable bytes start in the backing memory segment.

        Specified by:
        getSize in interface Buffer
        Returns:
        writer index (from 0 (inclusive) to the size of the backing MemorySegment (inclusive))

      • setAllocator

        public void setAllocator​(org.apache.flink.shaded.netty4.io.netty.buffer.ByteBufAllocator allocator)
        Description copied from interface: Buffer
        Sets the buffer allocator for use in netty.
        Specified by:
        setAllocator in interface Buffer
        Parameters:
        allocator - netty buffer allocator

      • getRecycler

        public BufferRecycler getRecycler()
        Description copied from interface: Buffer
        Gets the buffer's recycler.
        Specified by:
        getRecycler in interface Buffer
        Returns:
        buffer recycler

      • setRecycler

        public void setRecycler​(BufferRecycler bufferRecycler)
        Description copied from interface: Buffer
        Sets the buffer's recycler.

        Note that updating the recycler is an unsafe operation and this method cannot guarantee thread safety. It is important for the caller to fully understand the consequences of calling this method. Incorrectly updating the buffer recycler can result in a leak of the buffer due to using a wrong recycler to recycle buffer. Therefore, be careful when calling this method.

        Specified by:
        setRecycler in interface Buffer
        Parameters:
        bufferRecycler - the new buffer recycler

      • recycleBuffer

        public void recycleBuffer()
        Description copied from interface: Buffer
        Releases this buffer once, i.e. reduces the reference count and recycles the buffer if the reference count reaches 0.
        Specified by:
        recycleBuffer in interface Buffer
        See Also:
        Buffer.retainBuffer()

      • isRecycled

        public boolean isRecycled()
        Description copied from interface: Buffer
        Returns whether this buffer has been recycled or not.
        Specified by:
        isRecycled in interface Buffer
        Returns:
        true if already recycled, false otherwise

      • isCompressed

        public boolean isCompressed()
        Specified by:
        isCompressed in interface Buffer
        Returns:
        whether the buffer is compressed or not.

      • setCompressed

        public void setCompressed​(boolean isCompressed)
        Description copied from interface: Buffer
        Tags the buffer as compressed or uncompressed.
        Specified by:
        setCompressed in interface Buffer

      • setDataType

        public void setDataType​(Buffer.DataType dataType)
        Description copied from interface: Buffer
        Sets the type of data this buffer represents.
        Specified by:
        setDataType in interface Buffer

      • deallocate

        public void deallocate()
        Overrides:
        deallocate in class org.apache.flink.shaded.netty4.io.netty.channel.DefaultFileRegion