yacy_search_server/source/de/anomic/kelondro/kelondroFlexSplitTable.java

// kelondroFlexSplitTable.java
// (C) 2006 by Michael Peter Christen; mc@anomic.de, Frankfurt a. M., Germany
// first published 12.10.2006 on http://www.anomic.de
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate: 2006-04-02 22:40:07 +0200 (So, 02 Apr 2006) $
// $LastChangedRevision: 1986 $
// $LastChangedBy: orbiter $
//
// LICENSE
// 
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

package de.anomic.kelondro;

import java.io.File;
import java.io.IOException;
import java.util.Calendar;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;

public class kelondroFlexSplitTable implements kelondroIndex {

    // this is a set of kelondroFlex tables
    // the set is divided into FlexTables with different entry date
    
    private HashMap tables;
    private kelondroOrder objectOrder;
    private kelondroRow rowdef;
    private File path;
    private String tablename;
    private long buffersize;
    
    public kelondroFlexSplitTable(File path, String tablename, long buffersize, long preloadTime, kelondroRow rowdef, kelondroOrder objectOrder) throws IOException {
        this.path = path;
        this.tablename = tablename;
        this.objectOrder = objectOrder;
        this.rowdef = rowdef;
        
        // initialized tables map
        this.tables = new HashMap();
        String[] dir = path.list();
        String date;
        
        // first pass: count tables
        int count = 0;
        for (int i = 0; i < dir.length; i++) if (dir[i].startsWith(tablename)) count++;
        
        // second pass: open tables
        for (int i = 0; i < dir.length; i++) {
            if ((dir[i].startsWith(tablename)) &&
                (dir[i].charAt(tablename.length()) == '.') &&
                (dir[i].length() == tablename.length() + 7)) {
                // open table
                date = dir[i].substring(tablename.length() + 1);
                this.tables.put(date, new kelondroFlexTable(path, dir[i], buffersize / count, preloadTime, rowdef, objectOrder));
            }
        }
    }
        
    private static final Calendar thisCalendar = Calendar.getInstance();
    public static final String dateSuffix(Date date) {
        int month, year;
        StringBuffer suffix = new StringBuffer(6);
        synchronized (thisCalendar) {
            thisCalendar.setTime(date);
            month = thisCalendar.get(Calendar.MONTH);
            year = thisCalendar.get(Calendar.YEAR);
        }
        if ((year < 1970) && (year >= 70)) suffix.append("19").append(Integer.toString(year));
        else if (year < 1970) suffix.append("20").append(Integer.toString(year));
        else if (year > 3000) return null;
        else suffix.append(Integer.toString(year));
        if (month < 10) suffix.append("0").append(Integer.toString(month)); else suffix.append(Integer.toString(month));
        return new String(suffix);    
    }
    
    public kelondroOrder order() {
        return this.objectOrder;
    }
    
    public synchronized int size() throws IOException {
        Iterator i = tables.values().iterator();
        int s = 0;
        while (i.hasNext()) {
            s += ((kelondroFlexTable) i.next()).size();
        }
        return s;
    }
    
    public kelondroRow row() throws IOException {
        return this.rowdef;
    }
    
    public synchronized kelondroRow.Entry get(byte[] key) throws IOException {
        Iterator i = tables.values().iterator();
        kelondroFlexTable table;
        kelondroRow.Entry entry;
        while (i.hasNext()) {
            table = (kelondroFlexTable) i.next();
            entry = table.get(key);
            if (entry != null) return entry;
        }
        return null;
    }
    
    public synchronized kelondroRow.Entry put(kelondroRow.Entry row) throws IOException {
        return put(row, new Date()); // entry for current date
    }
    
    public synchronized kelondroRow.Entry put(kelondroRow.Entry row, Date entryDate) throws IOException {
        kelondroRow.Entry r = remove(row.getColBytes(0));
        
        String suffix = dateSuffix(entryDate);
        if (suffix == null) return null;
        kelondroFlexTable table = (kelondroFlexTable) tables.get(suffix);
        if (table == null) {
            // make new table
            table = new kelondroFlexTable(path, tablename + "." + suffix, buffersize / (tables.size() + 1), -1, rowdef, objectOrder);
            tables.put(suffix, table);
        }
    
        table.put(row);
        return r;
    }
    
    public synchronized kelondroRow.Entry remove(byte[] key) throws IOException {
        Iterator i = tables.values().iterator();
        kelondroFlexTable table;
        kelondroRow.Entry entry;
        while (i.hasNext()) {
            table = (kelondroFlexTable) i.next();
            entry = table.remove(key);
            if (entry != null) return entry;
        }
        return null;
    }
    
    public synchronized Iterator rows(boolean up, boolean rotating, byte[] firstKey) throws IOException {
        return new rowIter();
    }

    public class rowIter implements Iterator {

        Iterator t, tt;
        
        public rowIter() {
            t = tables.values().iterator();
            tt = null;
        }
        
        public boolean hasNext() {
            return ((t.hasNext()) || ((tt != null) && (tt.hasNext())));
        }

        public Object next() {
            if (t.hasNext()) {
                if ((tt == null) || (!(tt.hasNext()))) {
                    try {
                        tt = ((kelondroFlexTable) t.next()).rows(true, false, null);
                    } catch (IOException e) {
                        return null;
                    }
                }
                if (tt.hasNext()) {
                    return tt.next();
                } else {
                    return null;
                }
            }
            return null;
        }

        public void remove() {
            if (tt != null) tt.remove();
        }
        
    }
    
    public synchronized void close() throws IOException {
        Iterator i = tables.values().iterator();
        while (i.hasNext()) ((kelondroFlexTable) i.next()).close();
        tables = null;
    }
    
    public static void main(String[] args) {
        System.out.println(dateSuffix(new Date()));
    }
    
}