Package org.dizitart.no2.mvstore.compat.v1.mvstore

Class Page

java.lang.Object
org.dizitart.no2.mvstore.compat.v1.mvstore.Page
All Implemented Interfaces:
Cloneable
public abstract class Page extends Object implements Cloneable
A page (a node or a leaf).

For b-tree nodes, the key at a given index is larger than the largest key of the child at the same index.

File format: page length (including length): int check value: short map id: varInt number of keys: varInt type: byte (0: leaf, 1: node; +2: compressed) compressed: bytes saved (varInt) keys leaf: values (one for each key) node: children (1 more than keys)

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static final class 
    Page.PageReference
    A pointer to a page, either in-memory or using a page position.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    final MVMap<?,?>
    map
    Map this page belongs to

  • Method Summary

    Modifier and Type
    Method
    Description
    final Page
    copy()
    Create a copy of this page.
    static Page
    createNode(MVMap<?,?> map, Object[] keys, Page.PageReference[] children, long totalCount, int memory)
    Create a new non-leaf page.
    final boolean
    equals(Object other)
     
    abstract CursorPos
    getAppendCursorPos(CursorPos cursorPos)
    Extend path from a given CursorPos chain to "append point" in a B-tree, rooted at this Page.
    abstract Page
    getChildPage(int index)
    Get the child page at the given index.
    abstract long
    getChildPagePos(int index)
    Get the position of the child.
    long
    getDiskSpaceUsed()
    Amount of used disk space in persistent case including child pages.
    Object
    getKey(int index)
    Get the key at the given index.
    final int
    getKeyCount()
    Get the number of keys in this page.
    final int
    getMapId()
    Get the id of the page's owner map
    final int
    getMemory()
     
    abstract int
    getNodeType()
     
    final long
    getPos()
    Get the position of the page
    abstract CursorPos
    getPrependCursorPos(CursorPos cursorPos)
    Extend path from a given CursorPos chain to "prepend point" in a B-tree, rooted at this Page.
    abstract int
    getRawChildPageCount()
     
    abstract long
    getTotalCount()
    Get the total number of key-value pairs, including child pages.
    abstract Object
    getValue(int index)
    Get the value at the given index.
    final int
    hashCode()
     
    abstract void
    insertLeaf(int index, Object key, Object value)
    Insert a key-value pair into this leaf.
    abstract void
    insertNode(int index, Object key, Page childPage)
    Insert a child page into this node.
    boolean
    isComplete()
     
    final boolean
    isLeaf()
    Check whether this is a leaf page.
    final boolean
    isRemoved()
     
    final boolean
    isSaved()
     
    void
    remove(int index)
    Remove the key and value (or child) at the given index.
    abstract int
    removeAllRecursive(long version)
    Remove all page data recursively.
    final int
    removePage(long version)
    Make accounting changes (chunk occupancy or "unsaved" RAM), related to this page removal.
    abstract void
    setChild(int index, Page c)
    Replace the child page.
    void
    setComplete()
    Called when done with copying page.
    final void
    setKey(int index, Object key)
    Replace the key at an index in this page.
    abstract Object
    setValue(int index, Object value)
    Replace the value at an index in this page.
    String
    toString()
     

    Methods inherited from class java.lang.Object

    getClass, notify, notifyAll, wait, wait, wait

  • Field Details

    • map

      public final MVMap<?,?> map
      Map this page belongs to

  • Method Details

    • createNode

      public static Page createNode(MVMap<?,?> map, Object[] keys, Page.PageReference[] children, long totalCount, int memory)
      Create a new non-leaf page. The arrays are not cloned.
      Parameters:
      map - the map
      keys - the keys
      children - the child page positions
      totalCount - the total number of keys
      memory - the memory used in bytes
      Returns:
      the page

    • getMapId

      public final int getMapId()
      Get the id of the page's owner map
      Returns:
      id

    • getKey

      public Object getKey(int index)
      Get the key at the given index.
      Parameters:
      index - the index
      Returns:
      the key

    • getChildPage

      public abstract Page getChildPage(int index)
      Get the child page at the given index.
      Parameters:
      index - the index
      Returns:
      the child page

    • getChildPagePos

      public abstract long getChildPagePos(int index)
      Get the position of the child.
      Parameters:
      index - the index
      Returns:
      the position

    • getValue

      public abstract Object getValue(int index)
      Get the value at the given index.
      Parameters:
      index - the index
      Returns:
      the value

    • getKeyCount

      public final int getKeyCount()
      Get the number of keys in this page.
      Returns:
      the number of keys

    • isLeaf

      public final boolean isLeaf()
      Check whether this is a leaf page.
      Returns:
      true if it is a leaf

    • getNodeType

      public abstract int getNodeType()

    • getPos

      public final long getPos()
      Get the position of the page
      Returns:
      the position

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • copy

      public final Page copy()
      Create a copy of this page.
      Returns:
      a mutable copy of this page

    • getTotalCount

      public abstract long getTotalCount()
      Get the total number of key-value pairs, including child pages.
      Returns:
      the number of key-value pairs

    • setChild

      public abstract void setChild(int index, Page c)
      Replace the child page.
      Parameters:
      index - the index
      c - the new child page

    • setKey

      public final void setKey(int index, Object key)
      Replace the key at an index in this page.
      Parameters:
      index - the index
      key - the new key

    • setValue

      public abstract Object setValue(int index, Object value)
      Replace the value at an index in this page.
      Parameters:
      index - the index
      value - the new value
      Returns:
      the old value

    • insertLeaf

      public abstract void insertLeaf(int index, Object key, Object value)
      Insert a key-value pair into this leaf.
      Parameters:
      index - the index
      key - the key
      value - the value

    • insertNode

      public abstract void insertNode(int index, Object key, Page childPage)
      Insert a child page into this node.
      Parameters:
      index - the index
      key - the key
      childPage - the child page

    • remove

      public void remove(int index)
      Remove the key and value (or child) at the given index.
      Parameters:
      index - the index

    • isSaved

      public final boolean isSaved()

    • isRemoved

      public final boolean isRemoved()

    • getRawChildPageCount

      public abstract int getRawChildPageCount()

    • equals

      public final boolean equals(Object other)
      Overrides:
      equals in class Object

    • hashCode

      public final int hashCode()
      Overrides:
      hashCode in class Object

    • getMemory

      public final int getMemory()

    • getDiskSpaceUsed

      public long getDiskSpaceUsed()
      Amount of used disk space in persistent case including child pages.
      Returns:
      amount of used disk space in persistent case

    • isComplete

      public boolean isComplete()

    • setComplete

      public void setComplete()
      Called when done with copying page.

    • removePage

      public final int removePage(long version)
      Make accounting changes (chunk occupancy or "unsaved" RAM), related to this page removal.
      Parameters:
      version - at which page was removed
      Returns:
      amount (negative), by which "unsaved memory" should be adjusted, if page is unsaved one, and 0 for page that was already saved, or in case of non-persistent map

    • getPrependCursorPos

      public abstract CursorPos getPrependCursorPos(CursorPos cursorPos)
      Extend path from a given CursorPos chain to "prepend point" in a B-tree, rooted at this Page.
      Parameters:
      cursorPos - presumably pointing to this Page (null if real root), to build upon
      Returns:
      new head of the CursorPos chain

    • getAppendCursorPos

      public abstract CursorPos getAppendCursorPos(CursorPos cursorPos)
      Extend path from a given CursorPos chain to "append point" in a B-tree, rooted at this Page.
      Parameters:
      cursorPos - presumably pointing to this Page (null if real root), to build upon
      Returns:
      new head of the CursorPos chain

    • removeAllRecursive

      public abstract int removeAllRecursive(long version)
      Remove all page data recursively.
      Parameters:
      version - at which page got removed
      Returns:
      adjustment for "unsaved memory" amount