Author: elecharny
Date: Thu Jun 21 21:42:35 2012
New Revision: 1352707
URL: http://svn.apache.org/viewvc?rev=1352707&view=rev
Log:
Added the Cursor, Tuple and Transaction classes
Added:
labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Cursor.java
labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Transaction.java
labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Tuple.java
Added:
labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Cursor.java
URL:
http://svn.apache.org/viewvc/labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Cursor.java?rev=1352707&view=auto
==============================================================================
---
labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Cursor.java
(added)
+++
labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Cursor.java
Thu Jun 21 21:42:35 2012
@@ -0,0 +1,194 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+package org.apache.mavibot.btree;
+
+/**
+ * A Cursor is used to fetch elements in a BTree and is returned by the
+ * @see BTree#browse method. The cursor <strng>must</strong> be closed
+ * when the user is done with it.
+ *
+ * @author <a href="mailto:[email protected]";>Mavibot labs Project</a>
+ *
+ * @param <K> The type for the Key
+ * @param <V> The type for the stored value
+ */
+public class Cursor<K, V>
+{
+ /** The transaction used for this cursor */
+ private Transaction<K, V> transaction;
+
+ /** The current leaf */
+ private Leaf<K, V> leaf;
+
+ /** The current position in the leaf */
+ private int pos;
+
+ /** The Tuple used to return the results */
+ private Tuple<K, V> tuple = new Tuple<K, V>();
+
+
+ /**
+ * Creates a new instance of Cursor, starting on a page at a given
position.
+ *
+ * @param transaction The transaction this operation is protected by
+ * @param leaf The page in which the first element is present
+ * @param pos The position of the first element
+ */
+ public Cursor( Transaction<K, V> transaction, Leaf<K, V> leaf, int pos )
+ {
+ this.transaction = transaction;
+ this.leaf = leaf;
+ this.pos = pos;
+ }
+
+
+ /**
+ * Find the next key/value
+ *
+ * @return A Tuple containing the found key and value
+ */
+ public Tuple<K, V> next()
+ {
+ if ( leaf == null )
+ {
+ return new Tuple<K, V>();
+ }
+
+ if ( pos == leaf.nbElems )
+ {
+ if ( leaf.nextPage == null )
+ {
+ // This is the end : no more value
+ return null;
+ }
+ else
+ {
+ leaf = leaf.nextPage;
+ pos = 0;
+ }
+ }
+
+ tuple.setKey( leaf.keys[pos] );
+ tuple.setValue( leaf.values[pos] );
+
+ pos++;
+
+ return tuple;
+ }
+
+
+ /**
+ * Find the previous key/value
+ *
+ * @return A Tuple containing the found key and value
+ */
+ public Tuple<K, V> prev()
+ {
+ if ( pos == 0 )
+ {
+ if ( leaf.prevPage == null )
+ {
+ // This is the end : no more value
+ return null;
+ }
+ else
+ {
+ leaf = leaf.prevPage;
+ pos = leaf.getNbElems();
+ }
+ }
+
+ pos--;
+
+ tuple.setKey( leaf.keys[pos] );
+ tuple.setValue( leaf.values[pos] );
+
+ return tuple;
+ }
+
+
+ /**
+ * Tells if the cursor can return a next element
+ * @return true if there are some more elements
+ */
+ public boolean hasNext()
+ {
+ if ( leaf == null )
+ {
+ return false;
+ }
+
+ if ( pos < leaf.nbElems )
+ {
+ return true;
+ }
+ else
+ {
+ if ( leaf.nextPage == null )
+ {
+ // This is the end : no more value
+ return false;
+ }
+ else
+ {
+ return true;
+ }
+ }
+ }
+
+
+ /**
+ * Tells if the cursor can return a previous element
+ * @return true if there are some more elements
+ */
+ public boolean hasPrev()
+ {
+ if ( leaf == null )
+ {
+ return false;
+ }
+
+ if ( pos > 0 )
+ {
+ return true;
+ }
+ else
+ {
+ if ( leaf.prevPage == null )
+ {
+ // This is the end : no more value
+ return false;
+ }
+ else
+ {
+ return true;
+ }
+ }
+ }
+
+
+ /**
+ * Closes the cursor, thus releases the associated transaction
+ */
+ public void close()
+ {
+ transaction.close();
+ }
+}
Added:
labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Transaction.java
URL:
http://svn.apache.org/viewvc/labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Transaction.java?rev=1352707&view=auto
==============================================================================
---
labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Transaction.java
(added)
+++
labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Transaction.java
Thu Jun 21 21:42:35 2012
@@ -0,0 +1,100 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+package org.apache.mavibot.btree;
+
+import java.util.Date;
+
+/**
+ * The Transaction is used to protect the BTree against concurrent modifcation,
+ * and insure that a read is always done against one single revision. It's also
+ * used to gather many modifications under one single revision, if needed.
+ * <p/>
+ * A Transaction should be closed when the user is done with it, otherwise the
+ * pages associated with the given revision, and all the referenced pages, will
+ * remain on the storage.
+ * <p/>
+ * A Transaction can be hold for quite a long time, for instance while doing
+ * a browse against a big BTree. At some point, transactions which are pending
+ * for too long will be closed by the transaction manager.
+ *
+ * @author <a href="mailto:[email protected]";>Mavibot labs Project</a>
+ *
+ * @param <K> The type for the Key
+ * @param <V> The type for the stored value
+ */
+public class Transaction<K, V>
+{
+ /** The associated revision */
+ private long revision;
+
+ /** The date of creation */
+ private long creationDate;
+
+ /** The BTree on which we are having a transaction */
+ private BTree<K, V> btree;
+
+ /**
+ * Creates a new transaction instance
+ * @param revision The revision this transaction is using
+ * @param creationDate The creation date for this transaction
+ */
+ public Transaction( BTree<K, V> btree, long revision, long creationDate )
+ {
+ this.revision = revision;
+ this.creationDate = creationDate;
+ this.btree = btree;
+ }
+
+
+ /**
+ * @return the revision
+ */
+ public long getRevision()
+ {
+ return revision;
+ }
+
+
+ /**
+ * @return the creationDate
+ */
+ public long getCreationDate()
+ {
+ return creationDate;
+ }
+
+
+ /**
+ * Close the transaction, releasing the revision it was using.
+ */
+ public void close()
+ {
+ btree.commitTransaction( this );
+ }
+
+
+ /**
+ * @see Object#toString()
+ */
+ public String toString()
+ {
+ return "Transaction[" + revision + ":" + new Date( creationDate ) +
"]";
+ }
+}
Added:
labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Tuple.java
URL:
http://svn.apache.org/viewvc/labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Tuple.java?rev=1352707&view=auto
==============================================================================
---
labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Tuple.java
(added)
+++
labs/mavibot/trunk/mavibot/src/main/java/org/apache/mavibot/btree/Tuple.java
Thu Jun 21 21:42:35 2012
@@ -0,0 +1,92 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+package org.apache.mavibot.btree;
+
+/**
+ * The Tuple class is used when we browse a btree, it will contain the results
+ * fetched from the btree.
+ *
+ * @author <a href="mailto:[email protected]";>Mavibot labs Project</a>
+ *
+ * @param <K> The type for the Key
+ * @param <V> The type for the stored value
+ */
+public class Tuple<K, V>
+{
+ /** The key */
+ private K key;
+
+ /** The value */
+ private V value;
+
+ /**
+ * Creates a Tuple containing a key and its associated value.
+ * @param key The key
+ * @param value The associated value
+ */
+ /* No qualifier */ Tuple()
+ {
+ }
+
+
+ /**
+ * @return the key
+ */
+ public K getKey()
+ {
+ return key;
+ }
+
+
+ /**
+ * @param key the key to set
+ */
+ /* No qualifier*/ void setKey( K key )
+ {
+ this.key = key;
+ }
+
+
+ /**
+ * @return the value
+ */
+ public V getValue()
+ {
+ return value;
+ }
+
+
+ /**
+ * @param value the value to set
+ */
+ /* No qualifier*/ void setValue( V value )
+ {
+ this.value = value;
+ }
+
+
+ /**
+ * @see Object#toString()
+ */
+ public String toString()
+ {
+ return "<" + key + "," + value + ">";
+ }
+}
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