kea/src/lib/util/pid.h

// Copyright (C) 2015 Internet Systems Consortium, Inc. ("ISC")
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

#ifndef PID_H
#define PID_H

#include <exceptions/exceptions.h>
#include <boost/lexical_cast.hpp>
#include <boost/shared_ptr.hpp>
#include <fstream>
#include <ostream>
#include <string>

namespace isc {
namespace util {

/// @brief Exception thrown when an error occurs during PID file processing.
class pidFileError : public Exception {
public:
    pidFileError(const char* file, size_t line, const char* what) :
    isc::Exception(file, line, what) { };
};

/// @brief Class to help with processing PID files
///
/// This is a utility class to manipulate PID files.  It provides
/// functiosn for writing and deleting a file containing a PID as
/// well as for extracting a PID from a file and checking if the
/// process is still running.

class pidFile {
public:
    /// @brief Constructor
    ///
    /// @param filename PID filename.
    pidFile(const std::string& filename);

    /// @brief Destructor
    ~pidFile();

    /// @brief Read the PID in from the file and check it.
    ///
    /// Read the PID in from the file then use it to see if
    /// a process with that PID exists.  If the file doesn't
    /// exist treat it as the process not being there.
    /// If the file exists but can't be read or it doesn't
    /// the proper format treat it as the process existing.
    ///
    /// @return true if the PID is in use, false otherwise
    bool check();

    /// @brief Write the PID to the file.
    void write(int);

    /// @brief Get PID of the proces and write it to the file.
    void write();

    /// @brief Delete the file.
    void deleteFile();

    /// @brief Returns the path to the PID file.
    std::string getFilename() const {
        return (filename_);
    }

private:
    /// @brief PID filename
    std::string filename_;
};

} // namespace isc::util
} // namespace isc

#endif // PID_H