cpp/lib/broker/Daemon.h

#ifndef _broker_Daemon_h
#define _broker_Daemon_h

/*
 *
 * 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.
 *
 */

#include <string>
#include <boost/scoped_ptr.hpp>
#include <boost/function.hpp>
#include <boost/noncopyable.hpp>

namespace qpid {
namespace broker {

/**
 * Tools for forking and managing a daemon process.
 * NB: Only one Daemon instance is allowed in a process.
 */
class Daemon : private boost::noncopyable
{
  public:
    /** Check daemon is running on port, throw exception if not */
    static pid_t getPid(uint16_t port);

    Daemon();

    virtual ~Daemon();

    /**
     * Fork a daemon process.
     * Call parent() in the parent process, child() in the child.
     */
    void fork();

  protected:

    /** Called in parent process */
    virtual void parent() = 0;

    /** Called in child process */
    virtual void child() = 0;

    /** Call from parent(): wait for child to indicate it is ready.
     * @timeout in seconds to wait for response.
     * @return port passed by child to ready().
     */
    uint16_t wait(int timeout);

    /** Call from child(): Notify the parent we are ready and write the
     * PID file.
     *@param port returned by parent call to wait().
     */
    void ready(uint16_t port);
    
  private:
    static std::string dir();
    static std::string pidFile(uint16_t port);

    pid_t pid;
    int pipeFds[2];
    std::string lockFile;
};

}} // namespace qpid::broker

#endif  /*!_broker_Daemon_h*/