Package org.jgroups.blocks

Class ReplicatedTree

  • All Implemented Interfaces:
    Receiver
    public class ReplicatedTree
extends java.lang.Object
implements Receiver
    A tree-like structure that is replicated across several members. Updates will be multicast to all group members reliably and in the same order.

    • Field Detail

      • groupname

        java.lang.String groupname

      • members

        final java.util.List<Address> members

      • state_fetch_timeout

        long state_fetch_timeout

      • jmx

        boolean jmx

      • log

        protected final Log log

      • remote_calls

        boolean remote_calls
        Whether or not to use remote calls. If false, all methods will be invoked directly on this instance rather than sending a message to all replicas and only then invoking the method. Useful for testing

      • props

        java.lang.String props

      • send_message

        private boolean send_message
        Determines when the updates have to be sent across the network, avoids sending unnecessary messages when there are no member in the group

    • Constructor Detail

      • ReplicatedTree

        public ReplicatedTree​(java.lang.String groupname,
                      java.lang.String props,
                      long state_fetch_timeout)
               throws java.lang.Exception
        Creates a channel with the given properties. Connects to the channel, then creates a PullPushAdapter and starts it
        Throws:
        java.lang.Exception

      • ReplicatedTree

        public ReplicatedTree​(java.lang.String groupname,
                      java.lang.String props,
                      long state_fetch_timeout,
                      boolean jmx)
               throws java.lang.Exception
        Throws:
        java.lang.Exception

      • ReplicatedTree

        public ReplicatedTree()

      • ReplicatedTree

        public ReplicatedTree​(JChannel channel)
               throws java.lang.Exception
        Expects an already connected channel. Creates a PullPushAdapter and starts it
        Throws:
        java.lang.Exception

    • Method Detail

      • setRemoteCalls

        public void setRemoteCalls​(boolean flag)

      • getLocalAddress

        public Address getLocalAddress()

      • getMembers

        public java.util.List<Address> getMembers()

      • fetchState

        public void fetchState​(long timeout)
                throws java.lang.Exception
        Fetch the group state from the current coordinator. If successful, this will trigger setState().
        Throws:
        java.lang.Exception

      • start

        public final void start()
                 throws java.lang.Exception
        Throws:
        java.lang.Exception

      • stop

        public void stop()

      • put

        public void put​(java.lang.String fqn,
                java.util.HashMap data)
        Adds a new node to the tree and sets its data. If the node doesn not yet exist, it will be created. Also, parent nodes will be created if not existent. If the node already has data, then the new data will override the old one. If the node already existed, a nodeModified() notification will be generated. Otherwise a nodeCreated() motification will be emitted.
        Parameters:
        fqn - The fully qualified name of the new node
        data - The new data. May be null if no data should be set in the node.

      • put

        public void put​(java.lang.String fqn,
                java.lang.String key,
                java.lang.Object value)
        Adds a key and value to a given node. If the node doesn't exist, it will be created. If the node already existed, a nodeModified() notification will be generated. Otherwise a nodeCreated() motification will be emitted.
        Parameters:
        fqn - The fully qualified name of the node
        key - The key
        value - The value

      • remove

        public void remove​(java.lang.String fqn)
        Removes the node from the tree.
        Parameters:
        fqn - The fully qualified name of the node.

      • remove

        public void remove​(java.lang.String fqn,
                   java.lang.String key)
        Removes key from the node's hashmap
        Parameters:
        fqn - The fullly qualified name of the node
        key - The key to be removed

      • exists

        public boolean exists​(java.lang.String fqn)
        Checks whether a given node exists in the tree
        Parameters:
        fqn - The fully qualified name of the node
        Returns:
        boolean Whether or not the node exists

      • getKeys

        public java.util.Set getKeys​(java.lang.String fqn)
        Gets the keys of the data map. Returns all keys as Strings. Returns null if node does not exist.
        Parameters:
        fqn - The fully qualified name of the node
        Returns:
        Set A set of keys (as Strings)

      • get

        public java.lang.Object get​(java.lang.String fqn,
                            java.lang.String key)
        Finds a node given its name and returns the value associated with a given key in its data map. Returns null if the node was not found in the tree or the key was not found in the hashmap.
        Parameters:
        fqn - The fully qualified name of the node.
        key - The key.

      • get

        java.util.Map<java.lang.String,​java.lang.Object> get​(java.lang.String fqn)
        Returns the data hashmap for a given node. This method can only be used by callers that are inside the same package. The reason is that callers must not modify the return value, as these modifications would not be replicated, thus rendering the replicas inconsistent.
        Parameters:
        fqn - The fully qualified name of the node
        Returns:
        HashMap The data hashmap for the given node

      • print

        public java.lang.String print​(java.lang.String fqn)
        Prints a representation of the node defined by fqn. Output includes name, fqn and data.

      • getChildrenNames

        public java.util.Set getChildrenNames​(java.lang.String fqn)
        Returns all children of a given node
        Parameters:
        fqn - The fully qualified name of the node
        Returns:
        Set A list of child names (as Strings)

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object

      • getGroupName

        public java.lang.String getGroupName()
        Returns the name of the group that the DistributedTree is connected to
        Returns:
        String

      • getChannel

        public JChannel getChannel()
        Returns the Channel the DistributedTree is connected to
        Returns:
        Channel

      • getGroupMembersNumber

        public int getGroupMembersNumber()
        Returns the number of current members joined to the group
        Returns:
        int

      • _put

        public void _put​(java.lang.String fqn,
                 java.util.HashMap data)

      • _put

        public void _put​(java.lang.String fqn,
                 java.lang.String key,
                 java.lang.Object value)

      • _remove

        public void _remove​(java.lang.String fqn)

      • _remove

        public void _remove​(java.lang.String fqn,
                    java.lang.String key)

      • _removeData

        public void _removeData​(java.lang.String fqn)

      • receive

        public void receive​(Message msg)
        Callback. Process the contents of the message; typically an _add() or _set() request
        Specified by:
        receive in interface Receiver
        Parameters:
        msg - The message

      • getState

        public void getState​(java.io.OutputStream ostream)
              throws java.lang.Exception
        Description copied from interface: Receiver
        Allows an application to write the state to an OutputStream. After the state has been written, the OutputStream doesn't need to be closed as stream closing is automatically done when a calling thread returns from this callback.
        Specified by:
        getState in interface Receiver
        Parameters:
        ostream - The OutputStream
        Throws:
        java.lang.Exception - If the streaming fails, any exceptions should be thrown so that the state requester can re-throw them and let the caller know what happened

      • setState

        public void setState​(java.io.InputStream istream)
              throws java.lang.Exception
        Description copied from interface: Receiver
        Allows an application to read the state from an InputStream. After the state has been read, the InputStream doesn't need to be closed as stream closing is automatically done when a calling thread returns from this callback.
        Specified by:
        setState in interface Receiver
        Parameters:
        istream - The InputStream
        Throws:
        java.lang.Exception - If the streaming fails, any exceptions should be thrown so that the state requester can catch them and thus know what happened

      • viewAccepted

        public void viewAccepted​(View new_view)
        Description copied from interface: Receiver
        Called when a change in membership has occurred. No long running actions, sending of messages or anything that could block should be done in this callback. If some long running action needs to be performed, it should be done in a separate thread.
        Note that on reception of the first view (a new member just joined), the channel will not yet be in the connected state. This only happens when JChannel.connect(String) returns.
        Specified by:
        viewAccepted in interface Receiver

      • findParentNode

        ReplicatedTree.Node findParentNode​(java.lang.String fqn,
                                   ReplicatedTree.StringHolder child_name,
                                   boolean create_if_not_exists)
        Find the node just above the one indicated by fqn. This is needed in many cases, e.g. to add a new node or remove an existing node.
        Parameters:
        fqn - The fully qualified name of the node.
        child_name - Will be filled with the name of the child when this method returns. The child name is the last relative name of the fqn, e.g. in "/a/b/c" it would be "c".
        create_if_not_exists - Create parent nodes along the way if they don't exist. Otherwise, this method will return when a node cannot be found.

      • findNode

        ReplicatedTree.Node findNode​(java.lang.String fqn)
        Returns the node at fqn. This method should not be used by clients (therefore it is package-private): it is only used internally (for navigation). C++ 'friend' would come in handy here...
        Parameters:
        fqn - The fully qualified name of the node
        Returns:
        Node The node at fqn

      • notifyNodeAdded

        void notifyNodeAdded​(java.lang.String fqn)

      • notifyNodeRemoved

        void notifyNodeRemoved​(java.lang.String fqn)

      • notifyNodeModified

        void notifyNodeModified​(java.lang.String fqn)

      • notifyViewChange

        void notifyViewChange​(View v)

      • notifyAllNodesCreated

        void notifyAllNodesCreated​(ReplicatedTree.Node curr)
        Generates NodeAdded notifications for all nodes of the tree. This is called whenever the tree is initially retrieved (state transfer)

      • main

        public static void main​(java.lang.String[] args)