MarshallerThread.h

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// -*- mode: c++; c-basic-offset:4 -*-
 
// This file is part of libdap, A C++ implementation of the OPeNDAP Data
// Access Protocol.
 
// Copyright (c) 2015 OPeNDAP, Inc.
// Author: James Gallagher <jgallagher@opendap.org>
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//
// You can contact OPeNDAP, Inc. at PO Box 112, Saunderstown, RI. 02874-0112.
 
/*
 * MarshallerThread.h
 *
 *  Created on: Aug 27, 2015
 *      Author: jimg
 */
 
#ifndef MARSHALLERTHREAD_H_
#define MARSHALLERTHREAD_H_
 
#include <pthread.h>
 
#include <iostream>
#include <ostream>
#include <string>
 
namespace libdap {

class Locker {
public:
    Locker() = delete;
    Locker(pthread_mutex_t &lock, pthread_cond_t &cond, int &count);
    virtual ~Locker();
 
private:
    pthread_mutex_t &m_mutex;
 
    Locker(const Locker &rhs);
};

class ChildLocker {
public:
    ChildLocker() = delete;
    ChildLocker(const Locker &rhs) = delete;
    ChildLocker(pthread_mutex_t &lock, pthread_cond_t &cond, int &count);
    virtual ~ChildLocker();
 
private:
    pthread_mutex_t &m_mutex;
    pthread_cond_t &m_cond;
    int &m_count;
};

class MarshallerThread {
private:
    pthread_t d_thread = 0;
    pthread_attr_t d_thread_attr;
 
    pthread_mutex_t d_out_mutex;
    pthread_cond_t d_out_cond;
 
    int d_child_thread_count = 0; // 0 or 1
    std::string d_thread_error;   // non-null indicates an error

    struct write_args {
        pthread_mutex_t &d_mutex;
        pthread_cond_t &d_cond;
        int &d_count;
        std::string &d_error;
        std::ostream &d_out;   // The output stream protected by the mutex, ...
        int d_out_file;        // file descriptor; if not -1, use this.
        char *d_buf;           // The data to write to the stream
        std::streamsize d_num; // The size of d_buf

        write_args(pthread_mutex_t &m, pthread_cond_t &c, int &count, std::string &e, std::ostream &s, char *vals,
                   std::streamsize num)
            : d_mutex(m), d_cond(c), d_count(count), d_error(e), d_out(s), d_out_file(-1), d_buf(vals), d_num(num) {}

        write_args(pthread_mutex_t &m, pthread_cond_t &c, int &count, std::string &e, int fd, char *vals,
                   std::streamsize num)
            : d_mutex(m), d_cond(c), d_count(count), d_error(e), d_out(std::cerr), d_out_file(fd), d_buf(vals),
              d_num(num) {}
    };
 
public:
    MarshallerThread();
    virtual ~MarshallerThread();
 
    pthread_mutex_t &get_mutex() { return d_out_mutex; }
    pthread_cond_t &get_cond() { return d_out_cond; }
 
    int &get_child_thread_count() { return d_child_thread_count; }
    void increment_child_thread_count() { ++d_child_thread_count; }
 
    void start_thread(void *(*thread)(void *arg), std::ostream &out, char *byte_buf, std::streamsize bytes_written);
    void start_thread(void *(*thread)(void *arg), int fd, char *byte_buf, std::streamsize bytes_written);
 
    // These are static so they will have c-linkage - required because they
    // are passed to pthread_create()
    static void *write_thread(void *arg);
    static void *write_thread_part(void *arg);
};
 
} // namespace libdap
 
#endif /* MARSHALLERTHREAD_H_ */