summaryrefslogtreecommitdiff
path: root/lib/parallelizingdaemon.php
blob: 8e09a3a411a3e25cbf9f75b2445aec159378b1f2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
<?php
/**
 * StatusNet, the distributed open-source microblogging tool
 *
 * Base class for making daemons that can do several tasks in parallel.
 *
 * PHP version 5
 *
 * LICENCE: This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @category  Daemon
 * @package   StatusNet
 * @author    Zach Copley <zach@controlyourself.ca>
 * @author    Evan Prodromou <evan@controlyourself.ca>
 * @copyright 2009 StatusNet, Inc.
 * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
 * @link      http://laconi.ca/
 */

if (!defined('LACONICA')) {
    exit(1);
}

declare(ticks = 1);

/**
 * Daemon able to spawn multiple child processes to do work in parallel
 *
 * @category Daemon
 * @package  StatusNet
 * @author   Zach Copley <zach@controlyourself.ca>
 * @author   Evan Prodromou <evan@controlyourself.ca>
 * @license  http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
 * @link     http://laconi.ca/
 */

class ParallelizingDaemon extends Daemon
{
    private $_children     = array();
    private $_interval     = 0; // seconds
    private $_max_children = 0; // maximum number of children
    private $_debug        = false;

    /**
     *  Constructor
     *
     * @param string  $id           the name/id of this daemon
     * @param int     $interval     sleep this long before doing everything again
     * @param int     $max_children maximum number of child processes at a time
     * @param boolean $debug        debug output flag
     *
     * @return void
     *
     **/

    function __construct($id = null, $interval = 60, $max_children = 2,
                         $debug = null)
    {
        parent::__construct(true); // daemonize

        $this->_interval     = $interval;
        $this->_max_children = $max_children;
        $this->_debug        = $debug;

        if (isset($id)) {
            $this->set_id($id);
        }
    }

    /**
     * Run the daemon
     *
     * @return void
     */

    function run()
    {
        if (isset($this->_debug)) {
            echo $this->name() . " - Debugging output enabled.\n";
        }

        do {

            $objects = $this->getObjects();

            foreach ($objects as $o) {

                // Fork a child for each object

                $pid = pcntl_fork();

                if ($pid == -1) {
                    die ($this->name() . ' - Couldn\'t fork!');
                }

                if ($pid) {

                    // Parent

                    if (isset($this->_debug)) {
                        echo $this->name() .
                          " - Forked new child - pid $pid.\n";

                    }

                    $this->_children[] = $pid;

                } else {

                    // Child

                    // Do something with each object

                    $this->childTask($o);

                    exit();
                }

                // Remove child from ps list as it finishes

                while (($c = pcntl_wait($status, WNOHANG OR WUNTRACED)) > 0) {

                    if (isset($this->_debug)) {
                        echo $this->name() . " - Child $c finished.\n";
                    }

                    $this->removePs($this->_children, $c);
                }

                // Wait! We have too many damn kids.

                if (sizeof($this->_children) >= $this->_max_children) {

                    if (isset($this->_debug)) {
                        echo $this->name() . " - Too many children. Waiting...\n";
                    }

                    if (($c = pcntl_wait($status, WUNTRACED)) > 0) {

                        if (isset($this->_debug)) {
                            echo $this->name() .
                              " - Finished waiting for child $c.\n";
                        }

                        $this->removePs($this->_children, $c);
                    }
                }
            }

            // Remove all children from the process list before restarting
            while (($c = pcntl_wait($status, WUNTRACED)) > 0) {

                if (isset($this->_debug)) {
                    echo $this->name() . " - Child $c finished.\n";
                }

                $this->removePs($this->_children, $c);
            }

            // Rest for a bit

            if (isset($this->_debug)) {
                echo $this->name() . ' - Waiting ' . $this->_interval .
                  " secs before running again.\n";
            }

            if ($this->_interval > 0) {
                sleep($this->_interval);
            }

        } while (true);
    }

    /**
     * Remove a child process from the list of children
     *
     * @param array &$plist array of processes
     * @param int   $ps     process id
     *
     * @return void
     */

    function removePs(&$plist, $ps)
    {
        for ($i = 0; $i < sizeof($plist); $i++) {
            if ($plist[$i] == $ps) {
                unset($plist[$i]);
                $plist = array_values($plist);
                break;
            }
        }
    }

    /**
     * Get a list of objects to work on in parallel
     *
     * @return array An array of objects to work on
     */

    function getObjects()
    {
        die('Implement ParallelizingDaemon::getObjects().');
    }

    /**
     * Do something with each object in parallel
     *
     * @param mixed $object data to work on
     *
     * @return void
     */

    function childTask($object)
    {
        die("Implement ParallelizingDaemon::childTask($object).");
    }

}