Package org.jgroups

Class NioMessage

    • Field Detail

      • buf

        protected java.nio.ByteBuffer buf
        The payload

      • use_direct_memory_for_allocations

        protected boolean use_direct_memory_for_allocations
        If true, use direct memory when creating ByteBuffer payloads, e.g. on setArray(byte[], int, int), setArray(ByteArray), setObject(Object) or when getting read from the network (readPayload(DataInput)).
        Unless this flag is set to true, a direct ByteBuffer payload will become a heap-based payload by a receiver when sent over the network. This may be useful if we want to use off-heap (direct) memory only for sending, but not receiving of messages.
        If we want the receiver to create a direct-memory based message, set this flag to true before sending the message.

    • Constructor Detail

      • NioMessage

        public NioMessage()

      • NioMessage

        public NioMessage​(Address dest)
        Constructs a message given a destination address
        Parameters:
        dest - The Address of the receiver. If it is null, then the message is sent to all cluster members. Otherwise, it is sent to a single member.

      • NioMessage

        public NioMessage​(Address dest,
                  java.nio.ByteBuffer buf)
        Constructs a message given a destination and source address and the payload byte buffer
        Parameters:
        dest - The Address of the receiver. If it is null, then the message is sent to all cluster members. Otherwise, it is sent to a single member.
        buf - The payload. Note that this buffer must not be modified (e.g. buf[0]='x' is not allowed) since we don't copy the contents.

    • Method Detail

      • getBuf

        public java.nio.ByteBuffer getBuf()
        Returns the byte buffer. Do not read from/write to it, or else retransmissions will fail! Use ByteBuffer.duplicate() before, to create a copy, if the buffer needs to be read from

      • setBuf

        public NioMessage setBuf​(java.nio.ByteBuffer b)

      • create

        public java.util.function.Supplier<Message> create()
        Description copied from interface: Constructable
        Creates an instance of the class implementing this interface

      • getType

        public short getType()
        Description copied from interface: Message
        Returns the type of the message, e.g. BYTES_MSG, OBJ_MSG etc

      • useDirectMemory

        public boolean useDirectMemory()

      • useDirectMemory

        public NioMessage useDirectMemory​(boolean b)

      • hasPayload

        public boolean hasPayload()
        Description copied from interface: Message
        Returns true if the message has a payload, e.g. a byte[] array in a BytesMessage or an object in an ObjectMessage. This is more generic than Message.hasArray(), as it is not just applicable to a byte array.
        Returns:
        True if the message has a payload

      • hasArray

        public boolean hasArray()
        Description copied from interface: Message
        Returns true if this message has a byte[] array as payload (even if it's null!), false otherwise

      • isDirect

        public boolean isDirect()

      • getOffset

        public int getOffset()
        Description copied from interface: Message
        Returns the offset of the byte[] array at which user data starts. Throws an exception if the message does not have a byte[] array payload (if Message.hasArray() is false).
        Note that this is a convenience method, as most messages are of type BytesMessage.

      • getLength

        public int getLength()
        Description copied from interface: Message
        Returns the length of the byte[] array payload. If the message does not have a byte[] array payload (Message.hasArray() is false), then the serialized size may be returned, or an implementation may choose to throw an exception

      • getArray

        public byte[] getArray()
        Description copied from interface: Message
        Returns a reference to the payload (byte array). Note that this array should not be modified as we do not copy the array on copy() or clone(): the array of the copied message is simply a reference to the old array.
        Even if offset and length are used: we return the entire array, not a subset.
        Throws an exception if the message does not have a byte[] array payload (Message.hasArray() is false).
        Note that this is a convenience method, as most messages are of type BytesMessage. It is recommended to downcast a Message to the correct subtype and use the methods available there to get/set the payload.

      • setArray

        public NioMessage setArray​(byte[] b,
                           int offset,
                           int length)
        Sets the internal buffer to point to a subset of a given buffer.

        Note that the byte[] buffer passed as argument must not be modified. Reason: if we retransmit the message, it would still have a ref to the original byte[] buffer passed in as argument, and so we would retransmit a changed byte[] buffer !

        Parameters:
        b - The reference to a given buffer. If null, we'll reset the buffer to null
        offset - The initial position
        length - The number of bytes

      • setArray

        public NioMessage setArray​(ByteArray b)
        Sets the buffer

        Note that the byte[] buffer passed as argument must not be modified. Reason: if we retransmit the message, it would still have a ref to the original byte[] buffer passed in as argument, and so we would retransmit a changed byte[] buffer !

      • getObject

        public <T> T getObject()
        Description copied from interface: Message
        Gets an object from the payload. If the payload is a byte[] array (e.g. as in BytesMessage), an attempt to de-serialize the array into an object is made, and the object returned.
        If the payload is an object (e.g. as is the case in ObjectMessage), the object will be returned directly.

      • getObject

        public <T> T getObject​(java.lang.ClassLoader loader)
        Tries to unmarshal the byte buffer payload into an object
        Returns:
        The object

      • setObject

        public NioMessage setObject​(java.lang.Object obj)
        Takes an object and uses Java serialization to generate the byte[] buffer which is set in the message. Parameter 'obj' has to be serializable (e.g. implementing Serializable, Externalizable or Streamable, or be a basic type (e.g. Integer, Short etc)).

      • copy

        public NioMessage copy​(boolean copy_payload,
                       boolean copy_headers)
        Create a copy of the message.
        Note that for headers, only the arrays holding references to the headers are copied, not the headers themselves ! The consequence is that the headers array of the copy hold the *same* references as the original, so do *not* modify the headers ! If you want to change a header, copy it and call BaseMessage.putHeader(short,Header) again.
        Specified by:
        copy in interface Message
        Overrides:
        copy in class BaseMessage
        Parameters:
        copy_payload - Copy the buffer
        copy_headers - Copy the headers
        Returns:
        Message with specified data

      • writePayload

        public void writePayload​(java.io.DataOutput out)
                  throws java.io.IOException
        Throws:
        java.io.IOException

      • readPayload

        public void readPayload​(java.io.DataInput in)
                 throws java.io.IOException
        Throws:
        java.io.IOException

      • createBuffer

        protected java.nio.ByteBuffer createBuffer​(byte[] array,
                                           int offset,
                                           int length)