source: sandbox/expresso-solr/expressoMail1_2/solrclient/library/Solarium/Plugin/Loadbalancer/WeightedRandomChoice.php @ 7588

Revision 7588, 4.0 KB checked in by adir, 11 years ago (diff)

Ticket #000 - Adicionando a integracao de buscas com Solr na base a ser isnerida na comunidade

Line 
1<?php
2/**
3 * Copyright 2011 Bas de Nooijer. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice,
9 *    this list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 *    this listof conditions and the following disclaimer in the documentation
13 *    and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
19 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
20 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
21 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
22 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
23 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
24 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
25 * POSSIBILITY OF SUCH DAMAGE.
26 *
27 * The views and conclusions contained in the software and documentation are
28 * those of the authors and should not be interpreted as representing official
29 * policies, either expressed or implied, of the copyright holder.
30 *
31 * @copyright Copyright 2011 Bas de Nooijer <solarium@raspberry.nl>
32 * @license http://github.com/basdenooijer/solarium/raw/master/COPYING
33 * @link http://www.solarium-project.org/
34 *
35 * @package Solarium
36 */
37
38/**
39 * Weighted random choice class
40 *
41 * For use in the loadbalancer plugin
42 *
43 * @package Solarium
44 * @subpackage Plugin
45 */
46class Solarium_Plugin_Loadbalancer_WeightedRandomChoice
47{
48
49    /**
50     * Total weight of all choices
51     *
52     * @var int
53     */
54    protected $_totalWeight = 0;
55
56    /**
57     * Choices total lookup array
58     *
59     * @var array
60     */
61    protected $_lookup = array();
62
63    /**
64     * Values lookup array
65     *
66     * @var array
67     */
68    protected $_values = array();
69
70    /**
71     * Constructor
72     *
73     * @param array $choices
74     */
75    public function __construct($choices)
76    {
77        $i = 0;
78        foreach ($choices AS $key => $weight) {
79            if ($weight <=0) throw new Solarium_Exception('Weight must be greater than zero');
80
81            $this->_totalWeight += $weight;
82            $this->_lookup[$i] = $this->_totalWeight;
83            $this->_values[$i] = $key;
84
85            $i++;
86        }
87    }
88
89    /**
90     * Get a (weighted) random entry
91     *
92     * @param array $excludes Keys to exclude
93     * @return string
94     */
95    public function getRandom($excludes = array())
96    {
97        if (count($excludes) == count($this->_values)) {
98            throw new Solarium_Exception('No more server entries available');
99        }
100
101        // continue until a non-excluded value is found
102        // @todo optimize?
103        $result = null;
104        while (1) {
105            $result = $this->_values[$this->_getKey()];
106            if(!in_array($result, $excludes)) break;
107        }
108
109        return $result;
110    }
111
112    /**
113     * Get a (weighted) random entry key
114     *
115     * @return int
116     */
117    protected function _getKey()
118    {
119        $random = mt_rand(1, $this->_totalWeight);
120        $high = count($this->_lookup)-1;
121        $low = 0;
122
123        while ( $low < $high ) {
124            $probe = (int)(($high + $low) / 2);
125            if ($this->_lookup[$probe] < $random) {
126                $low = $probe + 1;
127            } else if ($this->_lookup[$probe] > $random) {
128                $high = $probe - 1;
129            } else {
130                return $probe;
131            }
132        }
133
134        if ($this->_lookup[$low] >= $random) {
135            return $low;
136        } else {
137            return $low+1;
138        }
139
140    }
141
142}
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