/*
 * Copyright 2012-2017 Red Hat, Inc.
 *
 * This file is part of Thermostat.
 *
 * Thermostat 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, or (at your
 * option) any later version.
 *
 * Thermostat 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 Thermostat; see the file COPYING.  If not see
 * <http://www.gnu.org/licenses/>.
 *
 * Linking this code with other modules is making a combined work
 * based on this code.  Thus, the terms and conditions of the GNU
 * General Public License cover the whole combination.
 *
 * As a special exception, the copyright holders of this code give
 * you permission to link this code with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also
 * meet, for each linked independent module, the terms and conditions
 * of the license of that module.  An independent module is a module
 * which is not derived from or based on this code.  If you modify
 * this code, you may extend this exception to your version of the
 * library, but you are not obligated to do so.  If you do not wish
 * to do so, delete this exception statement from your version.
 */

package com.redhat.thermostat.vm.numa.agent.internal;

import com.redhat.thermostat.common.portability.SysConf;
import com.redhat.thermostat.common.portability.linux.ProcDataSource;

import java.io.BufferedReader;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

class PageSizeProviderImpl implements PageSizeProvider {

    private static final Pattern HUGE_PAGESIZE_PATTERN = Pattern.compile("Hugepagesize:[\\s]+([\\d]+) kB");
    private long pagesize = 4L * 1024L;
    private long hugePagesize = 2048L * 1024L;

    PageSizeProviderImpl() throws IOException {
        pagesize = SysConf.getPageSize();

        try (BufferedReader br = new BufferedReader(new ProcDataSource().getMemInfoReader())) {
            for (String line = br.readLine(); line != null; line = br.readLine()) {
                Matcher matcher = HUGE_PAGESIZE_PATTERN.matcher(line);
                if (matcher.matches()) {
                    hugePagesize = Long.parseLong(matcher.group(1)) * 1024;
                    break;
                }
            }
        }
    }

    @Override
    public long getPageSize() {
        return pagesize;
    }

    @Override
    public long getHugePageSize() {
        return hugePagesize;
    }
}