kfsdecls.h

nandflash文件系统源代码

//---------------------------------------------------------- -*- Mode: C++ -*-
// $Id: kfsdecls.h 188 2008-10-15 19:54:42Z sriramsrao $ 
//
// \brief Common declarations of KFS structures
//
// Created 2006/10/20
// Author: Sriram Rao
//
// Copyright 2008 Quantcast Corp.
// Copyright 2006-2008 Kosmix Corp.
//
// This file is part of Kosmos File System (KFS).
//
// Licensed 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.
//
//----------------------------------------------------------------------------

#ifndef COMMON_KFSDECLS_H
#define COMMON_KFSDECLS_H

#include <cassert>
#include <cerrno>
#include <string>
#include <sstream>
#include <stdlib.h>

namespace KFS {
///
/// Define a server process' location: hostname and the port at which
/// it is listening for incoming connections
///
struct ServerLocation {
    ServerLocation(): hostname(""), port(-1) { }
    ServerLocation(const ServerLocation &other):
	hostname(other.hostname), port(other.port) { }
    ServerLocation(const std::string &h, int p): hostname(h), port(p) { }
    ServerLocation & operator = (const ServerLocation &other) {
	hostname = other.hostname;
	port = other.port;
	return *this;
    }
    void Reset(const char *h, int p) {
	hostname = h;
	port = p;
    }
    bool operator == (const ServerLocation &other) const {
	return hostname == other.hostname && port == other.port;
    }
    bool operator != (const ServerLocation &other) const {
	return hostname != other.hostname || port != other.port;
    }
    bool IsValid() const {
	// Hostname better be non-null and port better
	// be a positive number
	return hostname.compare("") != 0 && port > 0;
    }

    // a proxy for distance between two hosts: take the difference
    // between their hostnames.  this will mostly work as long as all
    // machines in the cluster are named as nodeXXX, where XXX is a number
    int Distance(const std::string &otherhost) {
        int len = (int) std::min(hostname.size(), otherhost.size());
        int hosta = 0, hostb = 0;
        int scalefactor = 1;

        for (int i = len - 1; i >= 0; --i) {
            if (isdigit(hostname[i]))
                hosta += (hostname[i] - '0') * scalefactor;
            if (isdigit(otherhost[i]))
                hostb += (otherhost[i] - '0') * scalefactor;
            scalefactor *= 10;
        }
        return abs(hosta - hostb);
    }
    std::string ToString() const {
	std::ostringstream os;

	os << hostname << ' ' << port;
	return os.str();
    }
    void FromString(const std::string &s) {
	std::istringstream is(s);

	is >> hostname;
	is >> port;
    }

    std::string hostname; //!< Location of the server: machine name/IP addr
    int port; //!< Location of the server: port to connect to
};

}

#endif // COMMON_KFSDECLS_H