FileDescriptorActivity.cpp

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/***************************************************************************
  tag: Peter Soetens  Thu Oct 22 11:59:08 CEST 2009  FileDescriptorActivity.cpp

                        FileDescriptorActivity.cpp -  description
                           -------------------
    begin                : Thu October 22 2009
    copyright            : (C) 2009 Peter Soetens
    email                : peter@thesourcworks.com

 ***************************************************************************
 *   This library is free software; you can redistribute it and/or         *
 *   modify it under the terms of the GNU General Public                   *
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 *   version 2 of the License.                                             *
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 *   software library without restriction.  Specifically, if other files   *
 *   instantiate templates or use macros or inline functions from this     *
 *   file, or you compile this file and link it with other files to        *
 *   produce an executable, this file does not by itself cause the         *
 *   resulting executable to be covered by the GNU General Public          *
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#include "FileDescriptorActivity.hpp"
#include "../ExecutionEngine.hpp"
#include "../base/TaskCore.hpp"
#include "../Logger.hpp"


#include <algorithm>

#ifdef WIN32
  #include <io.h>
  #include <fcntl.h>
  #define pipe(X) _pipe((X), 1024, _O_BINARY)
  #define close _close
  #define write _write
  #undef max

#else
#include <sys/select.h>
#include <unistd.h>
#include <errno.h>
#endif

#include <boost/cstdint.hpp>

using namespace RTT;
using namespace extras;
using namespace base;
const char FileDescriptorActivity::CMD_BREAK_LOOP;
const char FileDescriptorActivity::CMD_TRIGGER;
const char FileDescriptorActivity::CMD_UPDATE_SETS;


FileDescriptorActivity::FileDescriptorActivity(int priority, RunnableInterface* _r, const std::string& name )
    : Activity(priority, 0.0, _r, name)
    , m_running(false)
    , m_timeout(0)
{
    FD_ZERO(&m_fd_set);
    m_interrupt_pipe[0] = m_interrupt_pipe[1] = -1;
}

FileDescriptorActivity::FileDescriptorActivity(int scheduler, int priority, RunnableInterface* _r, const std::string& name )
    : Activity(scheduler, priority, 0.0, _r, name)
    , m_running(false)
    , m_timeout(0)
{
    FD_ZERO(&m_fd_set);
    m_interrupt_pipe[0] = m_interrupt_pipe[1] = -1;
}

FileDescriptorActivity::~FileDescriptorActivity()
{
    stop();
}

bool FileDescriptorActivity::isRunning() const
{ return Activity::isRunning() && m_running; }
int FileDescriptorActivity::getTimeout() const
{ return m_timeout; }
void FileDescriptorActivity::setTimeout(int timeout)
{ m_timeout = timeout; }
void FileDescriptorActivity::watch(int fd)
{ RTT::os::MutexLock lock(m_lock);
    if (fd < 0)
    {
        log(Error) << "negative file descriptor given to FileDescriptorActivity::watch" << endlog();
        return;
    }

    m_watched_fds.insert(fd);
    FD_SET(fd, &m_fd_set);
    triggerUpdateSets();
}
void FileDescriptorActivity::unwatch(int fd)
{ RTT::os::MutexLock lock(m_lock);
    m_watched_fds.erase(fd);
    FD_CLR(fd, &m_fd_set);
    triggerUpdateSets();
}
void FileDescriptorActivity::clearAllWatches()
{ RTT::os::MutexLock lock(m_lock);
    m_watched_fds.clear();
    FD_ZERO(&m_fd_set);
    triggerUpdateSets();
}
void FileDescriptorActivity::triggerUpdateSets()
{
    // i works around warn_unused_result
    int i = write(m_interrupt_pipe[1], &CMD_UPDATE_SETS, 1);
    i = i;
}
bool FileDescriptorActivity::isUpdated(int fd) const
{ return FD_ISSET(fd, &m_fd_work); }
bool FileDescriptorActivity::hasError() const
{ return m_has_error; }
bool FileDescriptorActivity::hasTimeout() const
{ return m_has_timeout; }
bool FileDescriptorActivity::isWatched(int fd) const
{ RTT::os::MutexLock lock(m_lock);
    return FD_ISSET(fd, &m_fd_set); }

bool FileDescriptorActivity::start()
{
    if (pipe(m_interrupt_pipe) == -1)
    {
        log(Error) << "FileDescriptorActivity: cannot create control pipe" << endlog();
        return false;
    }

    if (!Activity::start())
    {
        close(m_interrupt_pipe[0]);
        close(m_interrupt_pipe[1]);
        m_interrupt_pipe[0] = m_interrupt_pipe[1] = -1;
        return false;
    }
    return true;
}

bool FileDescriptorActivity::trigger()
{ return write(m_interrupt_pipe[1], &CMD_TRIGGER, 1) == 1; }

struct fd_watch {
    int& fd;
    fd_watch(int& fd) : fd(fd) {}
    ~fd_watch()
    {
        close(fd);
        fd = -1;
    };
};

void FileDescriptorActivity::loop()
{
    int pipe = m_interrupt_pipe[0];
    fd_watch watch_pipe_0(m_interrupt_pipe[0]);
    fd_watch watch_pipe_1(m_interrupt_pipe[1]);

    while(true)
    {
        int max_fd;
        { RTT::os::MutexLock lock(m_lock);
            if (m_watched_fds.empty())
                max_fd = pipe;
            else
                max_fd = std::max(pipe, *m_watched_fds.rbegin());

            m_fd_work = m_fd_set;
        }
        FD_SET(pipe, &m_fd_work);

        int ret;
        m_running = false;
        if (m_timeout == 0)
        {
            ret = select(max_fd + 1, &m_fd_work, NULL, NULL, NULL);
        }
        else
        {
            timeval timeout = { m_timeout / 1000, (m_timeout % 1000) * 1000 };
            ret = select(max_fd + 1, &m_fd_work, NULL, NULL, &timeout);
        }

        m_has_error   = false;
        m_has_timeout = false;
        if (ret == -1)
        {
            log(Error) << "FileDescriptorActivity: error in select(), errno = " << errno << endlog();
            m_has_error = true;
        }
        else if (ret == 0)
        {
            log(Error) << "FileDescriptorActivity: timeout in select()" << endlog();
            m_has_timeout = true;
        }

        bool do_break = false, do_trigger = true;
        if (ret > 0 && FD_ISSET(pipe, &m_fd_work)) // breakLoop or trigger requests
        { // Empty all commands queued in the pipe

            // These variables are used in order to loop with select(). See the
            // while() condition below.
            fd_set watch_pipe;
            timeval timeout;

            do_trigger = false;
            do
            {
                boost::uint8_t code;
                if (read(pipe, &code, 1) == 1)
                {
                    if (code == CMD_BREAK_LOOP)
                    {
                        do_break = true;
                    }
                    else if (code == CMD_UPDATE_SETS){}
                    else
                        do_trigger = true;
                }

                // Initialize the values for the next select() call
                FD_ZERO(&watch_pipe);
                FD_SET(pipe, &watch_pipe);
                timeout.tv_sec  = 0;
                timeout.tv_usec = 0;
            }
            while(select(pipe + 1, &watch_pipe, NULL, NULL, &timeout) > 0);

            if (do_break)
                break;
        }

        if (do_trigger)
        {
            try
            {
                m_running = true;
                step();
                m_running = false;
            }
            catch(...)
            {
                m_running = false;
                throw;
            }
        }
    }
}

bool FileDescriptorActivity::breakLoop()
{
    if (write(m_interrupt_pipe[1], &CMD_BREAK_LOOP, 1) != 1)
        return false;

    // either OS::SingleThread properly waits for loop() to return, or we are
    // called from within loop() [for instance because updateHook() called
    // fatal()]. In both cases, just return.
    return true;
}

void FileDescriptorActivity::step()
{
    m_running = true;
    if (runner != 0)
        runner->step();
    m_running = false;
}

bool FileDescriptorActivity::stop()
{
    // If fatal() is called from the updateHook(), stop() will be called from
    // within the context and loop() will still run after this command has quit.
    //
    // This is bad and will have to be fixed in RTT 2.0 by having delayed stops
    // (i.e. setting the task context's state to FATAL only when loop() has
    // quit)
    return Activity::stop();
}