Package org.jgroups.protocols

Class FRAG3

  • All Implemented Interfaces:
    Lifecycle
    public class FRAG3
extends Fragmentation
    Fragmentation protocol which uses less memory to store fragments than FRAG2.
    When a message is fragmented, all fragments carry the size of the original message, their offset and length with respect to the original message and a fragment ID (to identify the fragment).
    When the first fragment is received, the full message is created and each fragment copies its data into the full message at its offset and length. When all fragments have been received, the full message is passed up.
    Only the first fragment carries the headers and dest and src addresses. When received, its src/dest addresses and the headers will be set in the full message.
    For details see https://issues.redhat.com/browse/JGRP-2154
    Requirement: lossless delivery (e.g. NAKACK2 or UNICAST3). No requirement on ordering. Works for both unicast and multicast messages.
    Since:
    4.0
    Author:
    Bela Ban

    • Field Detail

      • fragment_list

        protected final java.util.concurrent.ConcurrentMap<Address,​java.util.concurrent.ConcurrentMap<java.lang.Integer,​FRAG3.FragEntry>> fragment_list

      • HAS_FRAG_HEADER

        protected final java.util.function.Predicate<Message> HAS_FRAG_HEADER

      • curr_id

        protected final java.util.concurrent.atomic.AtomicInteger curr_id

      • members

        protected final java.util.List<Address> members

    • Constructor Detail

      • FRAG3

        public FRAG3()

    • Method Detail

      • getAvgSizeDown

        public java.lang.String getAvgSizeDown()

      • getAvgSizeUp

        public java.lang.String getAvgSizeUp()

      • getNextId

        protected int getNextId()

      • init

        public void init()
          throws java.lang.Exception
        Description copied from class: Protocol
        Called after a protocol has been created and before the protocol is started. Attributes are already set. Other protocols are not yet connected and events cannot yet be sent.
        Specified by:
        init in interface Lifecycle
        Overrides:
        init in class Protocol
        Throws:
        java.lang.Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the the channel constructor will throw an exception

      • down

        public java.lang.Object down​(Event evt)
        Fragment a packet if larger than frag_size (add a header). Otherwise just pass down. Only add a header if fragmentation is needed !
        Overrides:
        down in class Protocol

      • down

        public java.lang.Object down​(Message msg)
        Description copied from class: Protocol
        A message is sent down the stack. Protocols may examine the message and do something (e.g. add a header) with it, before passing it down.
        Overrides:
        down in class Protocol

      • up

        public java.lang.Object up​(Event evt)
        If event is a message, if it is fragmented, re-assemble fragments into big message and pass up the stack.
        Overrides:
        up in class Protocol

      • up

        public java.lang.Object up​(Message msg)
        Description copied from class: Protocol
        A single message was received. Protocols may examine the message and do something (e.g. add a header) with it before passing it up.
        Overrides:
        up in class Protocol

      • up

        public void up​(MessageBatch batch)
        Description copied from class: Protocol
        Sends up a multiple messages in a MessageBatch. The sender of the batch is always the same, and so is the destination (null == multicast messages). Messages in a batch can be OOB messages, regular messages, or mixed messages, although the transport itself will create initial MessageBatches that contain only either OOB or regular messages.

        The default processing below sends messages up the stack individually, based on a matching criteria (calling Protocol.accept(Message)), and - if true - calls Protocol.up(org.jgroups.Event) for that message and removes the message. If the batch is not empty, it is passed up, or else it is dropped.

        Subclasses should check if there are any messages destined for them (e.g. using MessageBatch.iterator(Predicate)), then possibly remove and process them and finally pass the batch up to the next protocol. Protocols can also modify messages in place, e.g. ENCRYPT could decrypt all encrypted messages in the batch, not remove them, and pass the batch up when done.

        Overrides:
        up in class Protocol
        Parameters:
        batch - The message batch

      • handleViewChange

        protected void handleViewChange​(View view)

      • clearFragmentsFor

        public void clearFragmentsFor​(Address mbr)

      • clearAllFragments

        public void clearAllFragments()

      • fragment

        protected void fragment​(Message msg)
        Send all fragments as separate messages (with same ID !). Example: 
             Given the generated ID is 2344, number of fragments=3, message {dst,src,buf}
     would be fragmented into:

     [2344,3,0]{dst,src,buf1},
     [2344,3,1]{dst,src,buf2} and
     [2344,3,2]{dst,src,buf3}

      • unfragment

        protected Message unfragment​(Message msg,
                             Frag3Header hdr)
        1. Get all the fragment buffers 2. When all are received -> Assemble them into one big buffer 3. Read headers and byte buffer from big buffer 4. Set headers and buffer in msg 5. Return the message