/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
#ident "$Id$"
/*
COPYING CONDITIONS NOTICE:

  This program is free software; you can redistribute it and/or modify
  it under the terms of version 2 of the GNU General Public License as
  published by the Free Software Foundation, and provided that the
  following conditions are met:

      * Redistributions of source code must retain this COPYING
        CONDITIONS NOTICE, the COPYRIGHT NOTICE (below), the
        DISCLAIMER (below), the UNIVERSITY PATENT NOTICE (below), the
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        GRANT (below).

      * Redistributions in binary form must reproduce this COPYING
        CONDITIONS NOTICE, the COPYRIGHT NOTICE (below), the
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        GRANT (below) in the documentation and/or other materials
        provided with the distribution.

  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., 51 Franklin Street, Fifth Floor, Boston, MA
  02110-1301, USA.

COPYRIGHT NOTICE:

  TokuDB, Tokutek Fractal Tree Indexing Library.
  Copyright (C) 2007-2013 Tokutek, Inc.

DISCLAIMER:

  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.

UNIVERSITY PATENT NOTICE:

  The technology is licensed by the Massachusetts Institute of
  Technology, Rutgers State University of New Jersey, and the Research
  Foundation of State University of New York at Stony Brook under
  United States of America Serial No. 11/760379 and to the patents
  and/or patent applications resulting from it.

PATENT MARKING NOTICE:

  This software is covered by US Patent No. 8,185,551.
  This software is covered by US Patent No. 8,489,638.

PATENT RIGHTS GRANT:

  "THIS IMPLEMENTATION" means the copyrightable works distributed by
  Tokutek as part of the Fractal Tree project.

  "PATENT CLAIMS" means the claims of patents that are owned or
  licensable by Tokutek, both currently or in the future; and that in
  the absence of this license would be infringed by THIS
  IMPLEMENTATION or by using or running THIS IMPLEMENTATION.

  "PATENT CHALLENGE" shall mean a challenge to the validity,
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  IMPLEMENTATION.  If you or your agent or licensee institute or order
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  (including a cross-claim or counterclaim in a lawsuit) alleging that
  THIS IMPLEMENTATION constitutes direct or contributory patent
  infringement, or inducement of patent infringement, then any rights
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  such litigation is filed.  If you or your agent or exclusive
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*/

#ident "Copyright (c) 2007-2013 Tokutek Inc.  All rights reserved."
#ident "The technology is licensed by the Massachusetts Institute of Technology, Rutgers State University of New Jersey, and the Research Foundation of State University of New York at Stony Brook under United States of America Serial No. 11/760379 and to the patents and/or patent applications resulting from it."

#include <db.h>
#include <toku_assert.h>
#include <memory.h>
#include <string.h>

#include "txnid_set.h"
#include "wfg.h"

namespace toku {

// Create a lock request graph
void wfg::create(void) {
    m_nodes.create();
}

// Destroy the internals of the lock request graph
void wfg::destroy(void) {
    size_t n_nodes = m_nodes.size();
    for (size_t i = 0; i < n_nodes; i++) {
        node *n;
        int r = m_nodes.fetch(i, &n); 
        invariant_zero(r);
        invariant_notnull(n);
        node::free(n);
    }
    m_nodes.destroy();
}

// Add an edge (a_id, b_id) to the graph
void wfg::add_edge(TXNID a_txnid, TXNID b_txnid) {
    node *a_node = find_create_node(a_txnid);
    node *b_node = find_create_node(b_txnid);
    a_node->edges.add(b_node->txnid);
}

// Return true if a node with the given transaction id exists in the graph.
// Return false otherwise.
bool wfg::node_exists(TXNID txnid) {
    node *n = find_node(txnid);
    return n != NULL;
}

bool wfg::cycle_exists_from_node(node *target, node *head) {
    bool cycle_found = false;
    head->visited = true;
    size_t n_edges = head->edges.size();
    for (size_t i = 0; i < n_edges && !cycle_found; i++) {
        TXNID edge_id = head->edges.get(i);
        if (target->txnid == edge_id) { 
            cycle_found = true;
        } else {
            node *new_head = find_node(edge_id);
            if (new_head && !new_head->visited) {
                cycle_found = cycle_exists_from_node(target, new_head);
            }
        }
    }
    head->visited = false;
    return cycle_found;
}

// Return true if there exists a cycle from a given transaction id in the graph.
// Return false otherwise.
bool wfg::cycle_exists_from_txnid(TXNID txnid) {
    node *a_node = find_node(txnid);
    bool cycles_found = false;
    if (a_node) {
        cycles_found = cycle_exists_from_node(a_node, a_node);
    }
    return cycles_found;
}

// Apply a given function f to all of the nodes in the graph.  The apply function
// returns when the function f is called for all of the nodes in the graph, or the 
// function f returns non-zero.
void wfg::apply_nodes(int (*fn)(TXNID id, void *extra), void *extra) {
    int r = 0;
    size_t n_nodes = m_nodes.size();
    for (size_t i = 0; i < n_nodes && r == 0; i++) {
        node *n;
        r = m_nodes.fetch(i, &n);
        invariant_zero(r);
        r = fn(n->txnid, extra);
    }
}

// Apply a given function f to all of the edges whose origin is a given node id. 
// The apply function returns when the function f is called for all edges in the
// graph rooted at node id, or the function f returns non-zero.
void wfg::apply_edges(TXNID txnid,
        int (*fn)(TXNID txnid, TXNID edge_txnid, void *extra), void *extra) {
    node *n = find_node(txnid);
    if (n) {
        int r = 0;
        size_t n_edges = n->edges.size();
        for (size_t i = 0; i < n_edges && r == 0; i++) {
            r = fn(txnid, n->edges.get(i), extra);
        }
    }
}

// find node by id
wfg::node *wfg::find_node(TXNID txnid) {
    node *n = nullptr;
    int r = m_nodes.find_zero<TXNID, find_by_txnid>(txnid, &n, nullptr);
    invariant(r == 0 || r == DB_NOTFOUND);
    return n;
}

// this is the omt comparison function
// nodes are compared by their txnid.
int wfg::find_by_txnid(node *const &node_a, const TXNID &txnid_b) {
    TXNID txnid_a = node_a->txnid;
    if (txnid_a < txnid_b) {
        return -1;
    } else if (txnid_a == txnid_b) {
        return 0;
    } else {
        return 1;
    }
}

// insert a new node
wfg::node *wfg::find_create_node(TXNID txnid) {
    node *n;
    uint32_t idx;
    int r = m_nodes.find_zero<TXNID, find_by_txnid>(txnid, &n, &idx);
    if (r == DB_NOTFOUND) {
        n = node::alloc(txnid);
        r = m_nodes.insert_at(n, idx);
        invariant_zero(r);
    }
    invariant_notnull(n);
    return n;
}

wfg::node *wfg::node::alloc(TXNID txnid) {
    node *XCALLOC(n);
    n->txnid = txnid;
    n->visited = false;
    n->edges.create();
    return n;
}

void wfg::node::free(wfg::node *n) {
    n->edges.destroy();
    toku_free(n);
}

} /* namespace toku */