/* vim:set ts=4 sw=4 sts=4 et cindent: */
/*
 * nanodc - The ncurses DC++ client
 * Copyright © 2005-2006 Markus Lindqvist <nanodc.developer@gmail.com>
 *
 * This program 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 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Contributor(s):
 *  
 */

#ifndef _MUTEX_H_
#define _MUTEX_H_

#include <pthread.h>
#include <utils/stacktrace.h>
#include <sstream>
#include <iterator>

#define DEBUG_MUTEX 1

#if DEBUG_MUTEX
/** gettid() system call number */
const unsigned int SYS_gettid = 224;

/** Returns thread id of the calling thread.
 *  * Implemented only if \c __i386__ is defined. */
inline static pid_t __gettid() {
    pid_t tid = 0;
#ifdef __i386__
    __asm__("int $0x80" :
    "=a" (tid) :
    "0" (SYS_gettid));
#endif
    return tid;
}

template<class T>
std::string __to_string(T s)
{
    std::ostringstream oss;
    oss << s;
    return oss.str();
}
#endif // DEBUG_MUTEX


namespace utils {

/** A wrapper for <code>pthread_mutex_t</code> */
class Mutex {
public:
    /** Initializes the mutex. */
    Mutex() {
        #if DEBUG_MUTEX
        m_tid = 0;
        #endif
        pthread_mutex_init(&m_lock, 0);
    }
    /** Locks the mutex. */
    void lock() {
        #if DEBUG_MUTEX
        if(m_tid != 0 && m_tid == __gettid()) {
            std::string message = ("Mutex already locked by the same thread: " + __to_string(m_tid));
            if(cow::StackTrace::is_enabled()) {
                std::ostringstream oss;
                cow::StackTrace trace;
                trace.generate_frames();
                std::copy(trace.begin(), trace.end(),
                std::ostream_iterator<cow::StackFrame>(oss, "\n"));
                message += "\n" + oss.str();
            }
            else {
                message += ("\nStack not available");
            }
            message = "echo '" + message + "' >> MUTEX_ERRORS";
            system(message.c_str());
            return;
        }
        m_tid = __gettid();
        #endif
        pthread_mutex_lock(&m_lock);
    }
    /** Releases the mutex. */
    void unlock() {
        pthread_mutex_unlock(&m_lock);
        #if DEBUG_MUTEX
        m_tid = 0;
        #endif
    }

    /** Get the internal pthread mutex handle. */
    pthread_mutex_t *get_mutex() {
        return &m_lock;
    }

    /** Deletes the mutex. */
    ~Mutex() {
        pthread_mutex_destroy(&m_lock);
    }
private:
    pthread_mutex_t m_lock;
    #if DEBUG_MUTEX
    int m_tid;
    #endif
};

} // namespace utils

#endif // _MUTEX_H_