com.jivesoftware.forum.database
Class DbTreeWalker

java.lang.Object
  com.jivesoftware.forum.database.DbTreeWalker

All Implemented Interfaces:

TreeWalker, com.tangosol.io.ExternalizableLite, java.io.Serializable

public class DbTreeWalker
extends java.lang.Object
implements TreeWalker, java.io.Serializable, com.tangosol.io.ExternalizableLite

Database implementation of the TreeWalker interface. It caches the tree structure in memory for fastest access.

One important caveat is the following: we assumes that no child message will have a creation date that is earlier in time than its parent message. The assumption lets us make some big optimization gains and is safe as long as all the data is created in Jive Forums. The only possible problem is if data is imported from other forum apps that don't follow this behavior (not very likely).

See Also:

Serialized Form

Constructor Summary

DbTreeWalker()
Constructor for internal use only.

DbTreeWalker(DbForumThread thread)
Creates a new TreeWalker instance.

Method Summary

void	addChild(ForumMessage parent, ForumMessage child) Adds a child message to an existing parent.
ForumMessage	getChild(ForumMessage message, int index) Returns the child of parent at index index in the parent's child array.
int	getChildCount(ForumMessage parent) Returns the number of children of parent.
java.util.Iterator	getChildren(ForumMessage parent) Returns an Iterator for all the child messages of the parent.
int	getIndexOfChild(ForumMessage parent, ForumMessage child) Returns the index of child in parent.
int	getMessageDepth(ForumMessage message) Returns the depth of a message in the message tree hierarchy.
ForumMessage	getParent(ForumMessage message) Returns the parent of the child ForumMessage.
int	getRecursiveChildCount(ForumMessage parent) Returns the total number of recursive children of a parent.
java.util.Iterator	getRecursiveChildren(ForumMessage parent) Returns an Iterator for all child messages (and sub-children, etc) of the parent.
java.util.Iterator	getRecursiveMessages() Returns an Iterator for all messages in the thread in depth-first order.
ForumMessage	getRoot() Returns the root of the tree.
int	getSize()
boolean	hasParent(ForumMessage message) Returns true if the child message has a parent message.
boolean	isLeaf(ForumMessage message) Returns true if node is a leaf.
void	readExternal(java.io.DataInput in)
void	writeExternal(java.io.DataOutput out)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DbTreeWalker

public DbTreeWalker(DbForumThread thread)

Creates a new TreeWalker instance.

DbTreeWalker

public DbTreeWalker()

Constructor for internal use only.

Method Detail

getRoot

public ForumMessage getRoot()

Description copied from interface: TreeWalker

Returns the root of the tree. Returns null only if the tree has no nodes.

Specified by:

getRoot in interface TreeWalker

Returns:

the root of the tree

getChildCount

public int getChildCount(ForumMessage parent)

Description copied from interface: TreeWalker

Returns the number of children of parent. Returns 0 if the node is a leaf or if it has no children.

Specified by:

getChildCount in interface TreeWalker

Parameters:

parent - a node in the tree, obtained from this data source.

Returns:

the number of children of the node parent.

hasParent

public boolean hasParent(ForumMessage message)

Description copied from interface: TreeWalker

Returns true if the child message has a parent message.

Specified by:

hasParent in interface TreeWalker

Parameters:

message - the message.

Returns:

true if the message has a parent.

getParent

public ForumMessage getParent(ForumMessage message)
                       throws ForumMessageNotFoundException

Description copied from interface: TreeWalker

Returns the parent of the child ForumMessage.

Specified by:

getParent in interface TreeWalker

Returns:

the parent message of child.

Throws:

ForumMessageNotFoundException - if child does not have a parent, or if the parent message could not be loaded for any other reason.

getChild

public ForumMessage getChild(ForumMessage message,
                             int index)
                      throws ForumMessageNotFoundException

Description copied from interface: TreeWalker

Returns the child of parent at index index in the parent's child array. The index must be a valid one, that is: index >= 0, and index < getChildCount(parent). If the index is not valid, or if the child could not be loaded for any other reason, a ForumMessageNotFoundException will be thrown.

Specified by:

getChild in interface TreeWalker

Parameters:

message - the parent message.

index - the index of the child.

Returns:

the child of parent at index.

Throws:

ForumMessageNotFoundException - if the index was invalid or the child could not be loaded for any other reason.

getChildren

public java.util.Iterator getChildren(ForumMessage parent)

Description copied from interface: TreeWalker

Returns an Iterator for all the child messages of the parent. This method only considers direct descendants of the parent message and not sub-children. To get an iterator for the full hierarchy of children for a parent message, use the TreeWalker.getRecursiveChildren(ForumMessage) method.

Specified by:

getChildren in interface TreeWalker

Parameters:

parent - the parent message.

Returns:

an Iterator for the children of parent.

getRecursiveMessages

public java.util.Iterator getRecursiveMessages()

Description copied from interface: TreeWalker

Returns an Iterator for all messages in the thread in depth-first order. For example, consider the following message tree:

   1
   |-- 3
   |-- |-- 4
   |-- |-- |-- 7
   |-- |-- |-- |-- 10
   |-- |-- 6
   |-- |-- 8
   |-- 5
 

Calling getRecursiveMessages() on the tree above would return the sequence 1, 3, 4, 7, 10, 6, 8, 5. This method is a powerful way to show the full tree of messages, especially in combination with the TreeWalker.getMessageDepth(ForumMessage) method.

Specified by:

getRecursiveMessages in interface TreeWalker

Returns:

an Iterator for all messages in the thread in depth-first order.

getRecursiveChildren

public java.util.Iterator getRecursiveChildren(ForumMessage parent)

Description copied from interface: TreeWalker

Returns an Iterator for all child messages (and sub-children, etc) of the parent. Messages will be returned depth-first. For example, consider the following message tree:

   1
   |-- 3
   |-- |-- 4
   |-- |-- |-- 7
   |-- |-- |-- |-- 10
   |-- |-- 6
   |-- |-- 8
   |-- 5
 

Calling getRecursiveChildren(3) on the tree above would return the sequence 4, 7, 10, 6, 8. This method is a powerful way to show all children of a message, especially in combination with the TreeWalker.getMessageDepth(ForumMessage) method.

Specified by:

getRecursiveChildren in interface TreeWalker

Parameters:

parent - the parent message.

Returns:

an Iterator for all the recursive children of the parent.

getMessageDepth

public int getMessageDepth(ForumMessage message)

Description copied from interface: TreeWalker

Returns the depth of a message in the message tree hierarchy. The root message is always at depth 0. For example, consider the following message tree:

   1
   |-- 3
   |-- |-- 4
   |-- |-- |-- 7
 

The depth of message 4 is 2, the depth of message 7 is 3, etc. This method is useful in combination with the TreeWalker.getRecursiveChildren(ForumMessage) Iterator to build a UI of hierarchical messages.

Specified by:

getMessageDepth in interface TreeWalker

Parameters:

message - the message to determine the depth of.

Returns:

the depth of the message in the message tree hiearchy.

getRecursiveChildCount

public int getRecursiveChildCount(ForumMessage parent)

Description copied from interface: TreeWalker

Returns the total number of recursive children of a parent. Returns 0 if there are no children. This method is not intended to aid in navigation of a Thread but is included as an added utility.

Specified by:

getRecursiveChildCount in interface TreeWalker

Returns:

the recursive count of the children of parent.

getIndexOfChild

public int getIndexOfChild(ForumMessage parent,
                           ForumMessage child)

Description copied from interface: TreeWalker

Returns the index of child in parent. This method does not deal with the indexes of sub-children of parents. For example, take the following tree:

   4
   |-- 2
   |-- |-- 1
   |-- |-- 6
   |-- |-- 8
   |-- 5
 

In this example, getIndexOfChild(4, 2) would return 0, getIndexOfChild(4, 5) would return 1, and getIndexOfChild(2, 8) would return 2. getIndexOfChild(4, 8) -- NOT VALID

Specified by:

getIndexOfChild in interface TreeWalker

Parameters:

parent - the parent message.

child - the child message to get the index for.

Returns:

the index of child in the list of siblings under parent.

isLeaf

public boolean isLeaf(ForumMessage message)

Description copied from interface: TreeWalker

Returns true if node is a leaf. A node is a leaf when it has no children messages.

Specified by:

isLeaf in interface TreeWalker

Parameters:

message - a node in the tree, obtained from this data source

Returns:

true if node is a leaf

readExternal

public void readExternal(java.io.DataInput in)
                  throws java.io.IOException

Specified by:

readExternal in interface com.tangosol.io.ExternalizableLite

Throws:

java.io.IOException

writeExternal

public void writeExternal(java.io.DataOutput out)
                   throws java.io.IOException

Specified by:

writeExternal in interface com.tangosol.io.ExternalizableLite

Throws:

java.io.IOException

addChild

public void addChild(ForumMessage parent,
                     ForumMessage child)

Adds a child message to an existing parent.

Parameters:

parent - the parent message.

child - the new child message.

getSize

public int getSize()