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From elecha...@apache.org
Subject svn commit: r1234057 - /directory/sandbox/elecharny/shared-mvbt/src/main/java/org/apache/directory/btree/Page.java
Date Fri, 20 Jan 2012 18:38:00 GMT
Author: elecharny
Date: Fri Jan 20 18:37:59 2012
New Revision: 1234057

URL: http://svn.apache.org/viewvc?rev=1234057&view=rev
Log:
o Added the missing Javadoc
o A bit of cleanup

Modified:
    directory/sandbox/elecharny/shared-mvbt/src/main/java/org/apache/directory/btree/Page.java

Modified: directory/sandbox/elecharny/shared-mvbt/src/main/java/org/apache/directory/btree/Page.java
URL: http://svn.apache.org/viewvc/directory/sandbox/elecharny/shared-mvbt/src/main/java/org/apache/directory/btree/Page.java?rev=1234057&r1=1234056&r2=1234057&view=diff
==============================================================================
--- directory/sandbox/elecharny/shared-mvbt/src/main/java/org/apache/directory/btree/Page.java
(original)
+++ directory/sandbox/elecharny/shared-mvbt/src/main/java/org/apache/directory/btree/Page.java
Fri Jan 20 18:37:59 2012
@@ -21,6 +21,11 @@ package org.apache.directory.btree;
 
 
 /**
+ * A MVCC Page. It contains the keys and the values, plus references to the child pages.
+ * 
+ * @param <K> The type for the Key
+ * @param <V> The type for the stored value
+
  * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
  */
 public class Page<K, V> implements Cloneable
@@ -76,7 +81,7 @@ public class Page<K, V> implements Clone
      * @param revisio the current revision
      */
     @SuppressWarnings("unchecked") // Cannot create an array of generic objects
-    /** No qualifier */ Page( BTree<K,V> btree, K key, V value )
+    /* No qualifier */ Page( BTree<K,V> btree, K key, V value )
     {
         this.btree = btree;
         this.revision = btree.generateRevision();
@@ -99,8 +104,15 @@ public class Page<K, V> implements Clone
     }
 
 
+    /**
+     * Creates a new root page, when the root is not anymore a leaf, and has been split.
+     * 
+     * @param revision The new page revision
+     * @param btree The associated btree
+     * @param result The split Page
+     */
     @SuppressWarnings("unchecked")
-    /** No qualifier */ Page( long revision, BTree<K, V> btree, OverflowResult<K,
V> result )
+    /* No qualifier */ Page( long revision, BTree<K, V> btree, OverflowResult<K,
V> result )
     {
         this.revision = revision;
         this.btree = btree;
@@ -117,7 +129,13 @@ public class Page<K, V> implements Clone
     }
     
     
-    /** No qualifier */ V find( K key )
+    /**
+     * Find a value in the tree, using its key. If it's not found, this method returns null
+     * 
+     * @param key The key of the searched value
+     * @return The value, if its key is present in the tree
+     */
+    /* No qualifier */ V find( K key )
     {
         int index = findIndex( key );
         
@@ -144,40 +162,44 @@ public class Page<K, V> implements Clone
      * Get largest key under this BPage.  Null is considered to be the
      * greatest possible key.
      */
-    /** No qualifier */ K getLargestKey()
+    /* No qualifier */ K getLargestKey()
     {
         return keys[btree.pageSize - 1];
     }
     
     
     /**
-     * @return The record ID
+     * @return The record ID of this page
      */
-    /** No qualifier */ long getRecordId()
+    /* No qualifier */ long getRecordId()
     {
         return recordId;
     }
     
     
     /**
-     * @return The revision
+     * @return The page's revision
      */
-    /** No qualifier */ long getRevision()
+    /* No qualifier */ long getRevision()
     {
         return revision;
     }
     
     
     /**
-     * @return The number of elements
+     * @return The number of elements in this page
      */
-    /** No qualifier */ long getNbElems()
+    /* No qualifier */ long getNbElems()
     {
         return nbElems;
     }
     
     
-    /** No qualifier */ boolean isLeaf()
+    /**
+     * Tells if this page has children or not
+     * @return true if the page has no children
+     */
+    /* No qualifier */ boolean isLeaf()
     {
         return isLeaf;
     }
@@ -335,7 +357,6 @@ public class Page<K, V> implements Clone
                         OverflowResult<K, V> overflow = (OverflowResult<K, V>)result;
                         
                         return addAndSplit( revision, index, overflow.pivotKey, overflow.pivotValue,
overflow.leftPage, overflow.rightPage );
-                        //return split( revision, (OverflowResult<K, V>)result, index
);
                     }
                 }
             }
@@ -397,6 +418,15 @@ public class Page<K, V> implements Clone
     }
     
     
+    /**
+     * Inject an element from a split page into the current page, which can contain it without
+     * being split itself.
+     * 
+     * @param revision The new revision
+     * @param result The overflow element
+     * @param index The position of the overflow element in the current page
+     * @return The modified page containing the overflow element
+     */
     @SuppressWarnings("unchecked")
     private InsertResult<K, V> insertOverflow( long revision, OverflowResult<K,
V> result, int index )
     {
@@ -543,6 +573,12 @@ public class Page<K, V> implements Clone
         return newPage;
     }
     
+    
+    /**
+     * Private method used to print an array, for debug purposes.
+     * 
+     * @param array The array to dump
+     */
     private void dump( Object[] array )
     {
         boolean isFirst = true;
@@ -567,6 +603,10 @@ public class Page<K, V> implements Clone
     }
     
     
+    /**
+     * Copy an array into a new one, with a dump if we get an OOBE. this method is
+     * only used for debug purposes.
+     */
     void arrayCopy( Object[] src, int srcPos, Object[] dest, int destPos, int length )
     {
         try
@@ -748,37 +788,48 @@ public class Page<K, V> implements Clone
     }
     
     
-    private final int compare( K value1, K value2 )
+    /**
+     * Compare two keys
+     * @param key1 The first key
+     * @param key2 The second key
+     * @return -1 if the first key is above the second one, 1 if it's below, and 0
+     * if the two keys are equal
+     */
+    private final int compare( K key1, K key2 )
     {
-        if ( value1 == value2 )
+        if ( key1 == key2 )
         {
             return 0;
         }
         
-        if ( value1 == null )
+        if ( key1 == null )
         {
             return 1;
         }
         
-        if ( value2 == null )
+        if ( key2 == null )
         {
             return -1;
         }
         
-        return btree.getComparator().compare( value1, value2 );
+        return btree.getComparator().compare( key1, key2 );
     }
 
 
-    /** STATIC INNER CLASS
+    /**
      *  Result from insert() method call. If the insertion has created
      *  a new page, it will be contained in the overflow field.
      *  If the inserted element already exist, then we will store
      *  the existing element.
      */
-    interface InsertResult<K, V>
+    /* No qualifier */ interface InsertResult<K, V>
     {
     }
     
+    /**
+     * A inner class used to store a split page. It has a pivot element
+     * and a left and right page.
+     */
     static class OverflowResult<K, V> implements InsertResult<K, V>
     {
         /** The Left page if it has been split, or the new page containing the new value
*/
@@ -793,6 +844,9 @@ public class Page<K, V> implements Clone
         /** The Value that must be copied in the parent page if the page was full */
         V pivotValue;
         
+        /**
+         * @see Object#toString()
+         */
         public String toString()
         {
             // This is a split page
@@ -801,15 +855,27 @@ public class Page<K, V> implements Clone
         }
     }
     
+    
+    /**
+     * An inner class used to store a modified page.
+     */
     static class PageResult<K, V> implements InsertResult<K, V>
     {
+        /** The modified page */
         Page<K, V> page;
         
+        /**
+         * Create the instance of a PageResult
+         * @param page The modified page
+         */
         private PageResult( Page<K, V> page )
         {
             this.page = page;
         }
         
+        /**
+         * @see Object#toString()
+         */
         public String toString()
         {
             return "Modified Page [" + page.recordId + ", r" + page.revision + "]";



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