root/lang/c/mpio/trunk/mp/fdnotify_impl.h @ 19040

//
// mp::fdnotify
//
// Copyright (C) 2008 FURUHASHI Sadayuki
//
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
//
//        http://www.apache.org/licenses/LICENSE-2.0
//
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//

#ifndef MP_FDNOTIFY_IMPL_H__
#define MP_FDNOTIFY_IMPL_H__

#include <fcntl.h>
#include <errno.h>

namespace mp {


template <typename NotifyObject>
fdnotify<NotifyObject>::fdnotify() : m_head(m_buffer), m_tail(m_buffer)
{
        if( ::pipe(m_pipe) < 0 ) {
                throw fdnotify_exception("can't create pipe");
        }
        if( ::fcntl(m_pipe[0], F_SETFL, O_NONBLOCK) < 0 ) {
                close(m_pipe[0]);
                close(m_pipe[1]);
                throw fdnotify_exception("can't set non-blocking mode");
        }
}

template <typename NotifyObject>
fdnotify<NotifyObject>::~fdnotify()
{
        close(m_pipe[0]);
        close(m_pipe[1]);
}

template <typename NotifyObject>
inline bool fdnotify<NotifyObject>::try_receive(NotifyObject* result)
{
        if(m_tail - m_head >= static_cast<ptrdiff_t>(sizeof(NotifyObject))) {
                *result = *((NotifyObject*)m_head);
                m_head += sizeof(NotifyObject);
                return true;
        } else {
                return receive_next(result);
        }
}

template <typename NotifyObject>
inline void fdnotify<NotifyObject>::send(const NotifyObject& obj)
{
        ssize_t len;
        while(1) {
                len = ::write(m_pipe[1], (void*)&obj, sizeof(NotifyObject));
                if(len >= static_cast<ssize_t>(sizeof(NotifyObject))) {
                        return;
                }
                if(len < 0) {
                        if(errno != EAGAIN && errno != EINTR) {
                                throw fdnotify_exception("write-side pipe is broken");
                        }
                }
        }
}

template <typename NotifyObject>
bool fdnotify<NotifyObject>::receive_next(NotifyObject* result)
{
        size_t carry = m_tail - m_head;

        std::memcpy(m_buffer, m_head, carry);
        m_head = m_buffer;
        m_tail = m_buffer + carry;

        ssize_t len = ::read(m_pipe[0], m_tail, sizeof(m_buffer)-carry);
        if(len < 0) {
                if(errno == EAGAIN || errno == EINTR) {
                        return false;
                } else {
                        throw fdnotify_exception("read-side pipe is broken");
                }
        } else if(len == 0) {
                throw fdnotify_exception("read-side pipe is closed");
        }

        m_tail += len;
        if(m_tail - m_head >= static_cast<ptrdiff_t>(sizeof(NotifyObject))) {
                *result = *((NotifyObject*)m_head);
                m_head += sizeof(NotifyObject);
                return true;
        } else {
                return false;
        }
}


}  // namespace mp

#endif /* mp/fdnotify_impl.h */