tokens.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_TOKENS_H__
#define __TPIE_PIPELINING_TOKENS_H__

#include <tpie/exception.h>
#include <tpie/pipelining/exception.h>
#include <tpie/pipelining/predeclare.h>
#include <tpie/types.h>
#include <tpie/tpie_assert.h>
#include <map>
#include <iostream>
#include <boost/shared_ptr.hpp>
#include <boost/weak_ptr.hpp>

namespace tpie {

namespace pipelining {

namespace bits {

enum node_relation {
    pushes,
    pulls,
    depends
};

class node_map {
public:
    typedef uint64_t id_t;
    typedef node * val_t;

    typedef std::map<id_t, val_t> map_t;
    typedef map_t::const_iterator mapit;

    typedef std::multimap<id_t, std::pair<id_t, node_relation> > relmap_t;
    typedef relmap_t::const_iterator relmapit;

    typedef boost::shared_ptr<node_map> ptr;
    typedef boost::weak_ptr<node_map> wptr;

    static inline ptr create() {
        ptr result(new node_map);
        result->self = wptr(result);
        return result;
    }

    inline id_t add_token(val_t token) {
        id_t id = nextId++;
        set_token(id, token);
        return id;
    }

    inline void set_token(id_t id, val_t token) {
        assert_authoritative();
        m_tokens[id] = token;
    }

    // union-find link
    void link(ptr target);

    inline void union_set(ptr target) {
        find_authority()->link(target->find_authority());
    }

    inline val_t get(id_t id) const {
        mapit i = m_tokens.find(id);
        if (i == m_tokens.end()) return 0;
        return i->second;
    }

    inline mapit begin() const {
        return m_tokens.begin();
    }

    inline mapit end() const {
        return m_tokens.end();
    }

    // union-find
    ptr find_authority();

    inline void add_relation(id_t from, id_t to, node_relation rel) {
        m_relations.insert(std::make_pair(from, std::make_pair(to, rel)));
        m_relationsInv.insert(std::make_pair(to, std::make_pair(from, rel)));
    }

    inline const relmap_t & get_relations() const {
        return m_relations;
    }

    inline size_t in_degree(id_t from, node_relation rel) const {
        return out_degree(m_relationsInv, from, rel);
    }

    inline size_t out_degree(id_t from, node_relation rel) const {
        return out_degree(m_relations, from, rel);
    }

    void assert_authoritative() const {
        if (m_authority) throw non_authoritative_node_map();
    }

    void dump(std::ostream & os = std::cout) const;

    void send_successors() const;

private:
    map_t m_tokens;
    relmap_t m_relations;
    relmap_t m_relationsInv;

    size_t out_degree(const relmap_t & map, id_t from, node_relation rel) const;

    wptr self;

    // union rank structure
    ptr m_authority;
    size_t m_rank;

    inline node_map()
        : m_rank(0)
    {
    }

    inline node_map(const node_map &);
    inline node_map & operator=(const node_map &);

    static id_t nextId;
};

} // namespace bits

class node_token {
public:
    typedef bits::node_map::id_t id_t;
    typedef bits::node_map::val_t val_t;

    // Use for the simple case in which a node owns its own token
    inline node_token(val_t owner)
        : m_tokens(bits::node_map::create())
        , m_id(m_tokens->add_token(owner))
        , m_free(false)
    {
    }

    // This copy constructor has two uses:
    // 1. Simple case when a node is copied (freshToken = false)
    // 2. Advanced case when a node is being constructed with a specific token (freshToken = true)
    inline node_token(const node_token & other, val_t newOwner, bool freshToken = false)
        : m_tokens(other.m_tokens->find_authority())
        , m_id(other.id())
        , m_free(false)
    {
        if (freshToken) {
            if (!other.m_free)
                throw exception("Trying to take ownership of a non-free token");
            if (m_tokens->get(m_id) != 0)
                throw exception("A token already has an owner, but m_free is true - contradiction");
        } else {
            if (other.m_free)
                throw exception("Trying to copy a free token");
        }
        m_tokens->set_token(m_id, newOwner);
    }

    // Use for the advanced case when a node_token is allocated before the node
    inline node_token()
        : m_tokens(bits::node_map::create())
        , m_id(m_tokens->add_token(0))
        , m_free(true)
    {
    }

    inline id_t id() const { return m_id; }

    inline bits::node_map::ptr map_union(const node_token & with) {
        if (m_tokens == with.m_tokens) return m_tokens;
        m_tokens->union_set(with.m_tokens);
        return m_tokens = m_tokens->find_authority();
    }

    inline bits::node_map::ptr get_map() const {
        return m_tokens;
    }

    inline val_t get() const {
        return m_tokens->get(m_id);
    }

private:
    bits::node_map::ptr m_tokens;
    id_t m_id;
    bool m_free;
};

} // namespace pipelining

} // namespace tpie

#endif // __TPIE_PIPELINING_TOKENS_H__