/* -*-mode: C; fill-column: 78; c-basic-offset: 4; -*- */

/* 
 * Copyright 2005 by Eric House (fixin@peak.org).  All rights reserved.
 *
 * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include <assert.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/poll.h>
#include <errno.h>

#include "tpool.h"
#include "xwrelay_priv.h"
#include "xwrelay.h"
#include "mlock.h"

XWThreadPool* XWThreadPool::g_instance = NULL;

/* static */ XWThreadPool*
XWThreadPool::GetTPool()
{
    XWThreadPool* me = g_instance;
    if ( me == NULL ) {
        me = new XWThreadPool();
        g_instance = me;
    }
    return me;
}

XWThreadPool::XWThreadPool()
{
    pthread_rwlock_init( &m_activeSocketsRWLock, NULL );
    pthread_mutex_init ( &m_queueMutex, NULL );

    pthread_cond_init( &m_queueCondVar, NULL );

    int fd[2];
    if ( pipe( fd ) ) {
        logf( "pipe failed" );
    }
    m_pipeRead = fd[0];
    m_pipeWrite = fd[1];

    m_nThreads = 0;
}

void
XWThreadPool::Setup( int nThreads, packet_func pFunc )
{
    m_nThreads = nThreads;
    m_pFunc = pFunc;

    pthread_t thread;

    int i;
    for ( i = 0; i < nThreads; ++i ) {
        int result = pthread_create( &thread, NULL, tpool_main, this );
        assert( result == 0 );
    }

    int result = pthread_create( &thread, NULL, listener_main, this );
    assert( result == 0 );
}

void
XWThreadPool::AddSocket( int socket )
{
    logf( "AddSocket(%d)", socket );
    {
        RWWriteLock ml( &m_activeSocketsRWLock );
        m_activeSockets.push_back( socket );
    }
    interrupt_poll();
}

int
XWThreadPool::RemoveSocket( int socket )
{
    int found = 0;
    {
        RWWriteLock ml( &m_activeSocketsRWLock );

        vector<int>::iterator iter = m_activeSockets.begin();
        while ( iter != m_activeSockets.end() ) {
            if ( *iter == socket ) {
                m_activeSockets.erase( iter );
                found = 1;
                break;
            }
            ++iter;
        }
    }
    return found;
}


void
XWThreadPool::CloseSocket( int socket )
{
    int do_interrupt = 0;
    if ( !RemoveSocket( socket ) ) {
        RWWriteLock rwl( &m_activeSocketsRWLock );
        deque<int>::iterator iter = m_queue.begin();
        while ( iter != m_queue.end() ) {
            if ( *iter == socket ) {
                m_queue.erase( iter );
                do_interrupt = 1;
                break;
            }
            ++iter;
        }
    }
    close( socket );
    if ( do_interrupt ) {
        interrupt_poll();
    }
}

int
XWThreadPool::get_process_packet( int socket )
{
    short packetSize;
    assert( sizeof(packetSize) == 2 );

    ssize_t nRead = recv( socket, &packetSize, 
                          sizeof(packetSize), MSG_WAITALL );
    if ( nRead != 2 ) {
        killSocket( socket, "nRead != 2" );
        return 0;
    }

    packetSize = ntohs( packetSize );
    if ( packetSize < 0 || packetSize > MAX_MSG_LEN ) {
        killSocket( socket, "packetSize wrong" );
        return 0;
    }

    unsigned char buf[MAX_MSG_LEN];
    nRead = recv( socket, buf, packetSize, MSG_WAITALL );
    if ( nRead != packetSize ) {
        killSocket( socket, "nRead != packetSize" ); 
        return 0;
    }
    logf( "read %d bytes\n", nRead );

    logf( "calling m_pFunc" );
    (*m_pFunc)( buf, packetSize, socket );

    return 1;
} /* get_process_packet */

/* static */ void*
XWThreadPool::tpool_main( void* closure )
{
    XWThreadPool* me = (XWThreadPool*)closure;
    return me->real_tpool_main();
}

void*
XWThreadPool::real_tpool_main()
{
    logf( "worker thread starting" );
    for ( ; ; ) {

        pthread_mutex_lock( &m_queueMutex );
        while ( m_queue.size() == 0 ) {
            pthread_cond_wait( &m_queueCondVar, &m_queueMutex );
        }

        int socket = m_queue.front();
        m_queue.pop_front();
        pthread_mutex_unlock( &m_queueMutex );
        logf( "worker thread got socket %d from queue", socket );

        if ( get_process_packet( socket ) ) {
            AddSocket( socket );
        } /* else drop it: error */
    }
    logf( "worker thread exiting" );
    return NULL;
}

void
XWThreadPool::interrupt_poll()
{
    logf( "interrupt_poll" );
    unsigned char byt = 0;
    int nSent = write( m_pipeWrite, &byt, 1 );
    if ( nSent != 1 ) {
        logf( "errno = %d", errno );
    }
}

void*
XWThreadPool::real_listener()
{
    int flags = POLLIN | POLLERR | POLLHUP;

    for ( ; ; ) {

        pthread_rwlock_rdlock( &m_activeSocketsRWLock );
        int nSockets = m_activeSockets.size() + 1; /* for pipe */
        pollfd* fds = (pollfd*)malloc( sizeof(fds[0]) * nSockets );
        pollfd* curfd = fds;
        char* log = (char*)malloc( 4 * nSockets );
        log[0] = '\0';
        int len = 0;
        
        curfd->fd = m_pipeRead;
        curfd->events = flags;
        len += sprintf( log+len, "%d,", curfd->fd );
        ++curfd;

        vector<int>::iterator iter = m_activeSockets.begin();
        while ( iter != m_activeSockets.end() ) {
            curfd->fd = *iter++;
            curfd->events = flags;
            len += sprintf( log+len, "%d,", curfd->fd );
            ++curfd;
        }
        pthread_rwlock_unlock( &m_activeSocketsRWLock );

        logf( "calling poll on %s", log );
        int nEvents = poll( fds, nSockets, -1 ); /* -1: infinite timeout */
        logf( "back from  poll: %d", nEvents );
        if ( nEvents < 0 ) {
            logf( "errno: %d", errno );
        }

        if ( fds[0].revents != 0 ) {
            logf( "poll interrupted" );
            assert( fds[0].revents == POLLIN );
            unsigned char byt;
            read( fds[0].fd, &byt, 1 );
            --nEvents;
        }

        if ( nEvents > 0 ) {
            --nSockets;
            curfd = &fds[1];

            int i;
            for ( i = 0; i < nSockets && nEvents > 0; ++i ) {

                if ( curfd->revents != 0 ) {
                    int socket = curfd->fd;
                    RemoveSocket( socket );

                    if ( curfd->revents == POLLIN || curfd->revents == POLLPRI ) {
                        logf( "enqueuing %d", socket );
                        enqueue( socket );
                    } else {
                        logf( "odd revents: %d", curfd->revents );
                        killSocket( socket, "error/hup in poll()" ); 
                    }
                    --nEvents;
                }
                ++curfd;
            }
            assert( nEvents == 0 );
        }

        free( fds );
    }
    return NULL;
} /* real_listener */

/* static */ void*
XWThreadPool::listener_main( void* closure )
{
    XWThreadPool* me = (XWThreadPool*)closure;
    return me->real_listener();
}

void
XWThreadPool::enqueue( int socket ) 
{
    MutexLock ml( &m_queueMutex );
    m_queue.push_back( socket );

    logf( "calling pthread_cond_signal" );
    pthread_cond_signal( &m_queueCondVar );
    /* implicit unlock */
}