buffer.h

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// -*- mode: c++; tab-width: 4; indent-tabs-mode: t; eval: (progn (c-set-style "stroustrup") (c-set-offset 'innamespace 0)); -*-
// vi:set ts=4 sts=4 sw=4 noet :
// Copyright 2012, The TPIE development team
// 
// This file is part of TPIE.
// 
// TPIE 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 3 of the License, or (at your
// option) any later version.
// 
// TPIE 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 TPIE.  If not, see <http://www.gnu.org/licenses/>


#ifndef __TPIE_PIPELINING_BUFFER_H__
#define __TPIE_PIPELINING_BUFFER_H__

#include <tpie/pipelining/node.h>
#include <tpie/pipelining/factory_helpers.h>
#include <tpie/pipelining/pipe_base.h>
#include <tpie/file_stream.h>
#include <tpie/maybe.h>
#include <memory>

namespace tpie {

namespace pipelining {

namespace bits {

template <typename T>
class buffer_pull_output_t: public node {
    tpie::maybe<file_stream<T> > * m_queue_ptr;
    file_stream<T> * m_queue;
public:
    typedef T item_type;

    buffer_pull_output_t(const node_token & input_token) {
        add_dependency(input_token);
        set_name("Fetching items", PRIORITY_SIGNIFICANT);
        set_minimum_memory(file_stream<T>::memory_usage());
        set_minimum_resource_usage(FILES, 1);
        set_plot_options(PLOT_BUFFERED);
    }

    virtual void propagate() override {
        m_queue_ptr = fetch<tpie::maybe<file_stream<T> > *>("queue");
        m_queue = &**m_queue_ptr;
        m_queue->seek(0);
        forward("items", m_queue->size());
        set_steps(m_queue->size());
    }

    bool can_pull() const {
        return m_queue->can_read();
    }

    T pull() {
        step();
        return m_queue->read();
    }

    virtual void end() override {
        (*m_queue_ptr).destruct();
    }
};


template <typename T>
class buffer_input_t: public node {
public:
    typedef T item_type;

    buffer_input_t(const node_token & token, std::shared_ptr<node> output=std::shared_ptr<node>())
        : node(token)
        , m_output(output)
    {
        set_name("Storing items", PRIORITY_INSIGNIFICANT);
        set_minimum_memory(tpie::file_stream<item_type>::memory_usage());
        set_minimum_resource_usage(FILES, 1);
        set_plot_options(PLOT_BUFFERED | PLOT_SIMPLIFIED_HIDE);
    }
    
    void begin() override {
        m_queue.construct();
        m_queue->open(static_cast<memory_size_type>(0), access_sequential, compression_normal);
    }

    void push(const T & item) {
        m_queue->write(item);
    }

    void end() override {
        forward("queue", &m_queue, 1);
    }

private:
    tpie::maybe< file_stream<T> > m_queue;
    std::shared_ptr<node> m_output;
};

template <typename dest_t>
class buffer_output_t: public node {
public:
    typedef typename push_type<dest_t>::type item_type;

    buffer_output_t(dest_t dest, const node_token & input_token)
        : dest(std::move(dest))
    {
        add_dependency(input_token);
        add_push_destination(this->dest);
        set_minimum_memory(tpie::file_stream<item_type>::memory_usage());
        set_minimum_resource_usage(FILES, 1);
        set_name("Buffer", PRIORITY_INSIGNIFICANT);
        set_plot_options(PLOT_BUFFERED);
    }


    void propagate() override {
        m_queue_ptr = fetch<tpie::maybe<file_stream<item_type> > *>("queue");
        m_queue = &**m_queue_ptr;
        forward("items", m_queue->size());
        set_steps(m_queue->size());
    }

    void go() override {
        m_queue->seek(0);
        while (m_queue->can_read()) {
            dest.push(m_queue->read());
            step();
        }
    }

    void end() override {
        m_queue_ptr->destruct();
    }
private:
    tpie::maybe<file_stream<item_type> > * m_queue_ptr;
    file_stream<item_type> * m_queue;
    dest_t dest;
};

} // namespace bits

template <typename T>
class passive_buffer {
public:
    typedef T item_type;
    typedef bits::buffer_input_t<T> input_t;
    typedef bits::buffer_pull_output_t<T> output_t;
private:
    typedef termfactory<input_t,  const node_token &> inputfact_t;
    typedef termfactory<output_t, const node_token &> outputfact_t;
public:
    typedef pipe_end      <inputfact_t>  inputpipe_t;
    typedef pullpipe_begin<outputfact_t> outputpipe_t;


    passive_buffer() {}

    inline input_t raw_input() {
        return input_t(input_token);
    }

    inline output_t raw_output() {
        return output_t(input_token);
    }

    inline inputpipe_t input() {
        return inputfact_t(input_token);
    }

    inline outputpipe_t output() {
        return outputfact_t(input_token);
    }

private:
    node_token input_token;

    passive_buffer(const passive_buffer &);
    passive_buffer & operator=(const passive_buffer &);
};

typedef pipe_middle<split_factory<bits::buffer_input_t, node, bits::buffer_output_t> > buffer;

} // namespace pipelining

} // namespace tpie

#endif // __TPIE_PIPELINING_BUFFER_H__