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135 lines
4.8 KiB
135 lines
4.8 KiB
// BufferedIndex.java
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// -----------------------------
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// (C) 2009 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
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// first published 15.3.2009 on http://yacy.net
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//
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// This is a part of YaCy, a peer-to-peer based web search engine
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//
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// $LastChangedDate: 2006-04-02 22:40:07 +0200 (So, 02 Apr 2006) $
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// $LastChangedRevision: 1986 $
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// $LastChangedBy: orbiter $
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//
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// LICENSE
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package net.yacy.kelondro.rwi;
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import java.io.IOException;
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import java.util.TreeSet;
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import net.yacy.kelondro.order.CloneableIterator;
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/*
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* a BufferedIndex is an integration of different index types, i.e.
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* - ReferenceContainerArray
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* - ReferenceContainerCache
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* - IndexCache (which is a wrapper of a ReferenceContainerCache)
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* - IndexCollection
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* This interface was created from the methods that are used in CachedIndexCollection
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* (which integrates IndexCache and IndexCollection)
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* and is applied to the new index integration class IndexCell
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* (which integrates ReferenceContainerArray and ReferenceContainerCache)
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* to make it possible to switch between the old and new index data structure
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*/
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public interface BufferedIndex<ReferenceType extends Reference> extends Index<ReferenceType> {
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/*
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* methods for monitoring of the buffer
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*/
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/**
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* set the size of the buffer, which can be defined with a given maximum number
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* of words that shall be stored. Because an arbitrary number of references can
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* be stored at each word entry, this does not limit the memory that the buffer
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* takes. It is possible to monitor the memory occupation of the buffer with the
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* getBufferSizeBytes() method, and then adopt the buffer size with a new word number
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* limit.
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*/
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public void setBufferMaxWordCount(final int maxWords);
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/**
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* return the maximum number of references, that one buffer entry has stored
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* @return
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*/
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public int getBufferMaxReferences();
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/**
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* return the date of the oldest buffer entry
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* @return a time as milliseconds from epoch
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*/
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public long getBufferMinAge();
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/**
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* return the date of the most recent buffer entry
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* @return a time as milliseconds from epoch
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*/
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public long getBufferMaxAge();
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/**
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* calculate the memory that is taken by the buffer.
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* This does not simply return a variable content. it is necessary
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* to iterate over all entries to get the whole size.
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* please use this method with great care
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* @return number of bytes that the buffer has allocated
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*/
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public long getBufferSizeBytes();
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/**
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* get the size of the buffer content
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* @return number of word references
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*/
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public int getBufferSize();
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/**
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* iterate over entries in index. this method differs from the iterator in an Index
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* object in such a way that it has the additional 'buffer' flag. When using this method,
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* the iteration goes only over the buffer content, or over the backend-content, but
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* not over a merged content.
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* @param startHash
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* @param rot
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* @param buffer
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* @return
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* @throws IOException
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*/
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public CloneableIterator<ReferenceContainer<ReferenceType>> references(
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byte[] startHash,
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boolean rot,
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boolean buffer
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) throws IOException;
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/**
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* collect reference container in index. this method differs from the collector in an Index
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* object in such a way that it has the additional 'buffer' flag. When using this method,
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* the collection goes only over the buffer content, or over the backend-content, but
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* not over a merged content.
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* @param startHash
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* @param rot
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* @param count
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* @param buffer
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* @return
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* @throws IOException
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*/
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public TreeSet<ReferenceContainer<ReferenceType>> references(
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byte[] startHash,
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boolean rot,
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int count,
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boolean buffer
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) throws IOException;
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}
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