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
|
<?php
/**
* Reads lines of work from an input stream and farms them out to multiple
* child streams. Each child has exactly one piece of work in flight at a given
* moment. Writes the result of child's work to an output stream. If numProcs
* <= zero the work will be performed in process.
*
* This class amends ForkController with the requirement that the output is
* produced in the same exact order as input values were.
*
* Currently used by CirrusSearch extension to implement CLI search script.
*
* @ingroup Maintenance
* @since 1.30
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 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 General Public License for more details.
*
* 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.
* http://www.gnu.org/copyleft/gpl.html
*/
class OrderedStreamingForkController extends ForkController {
/** @var callable */
protected $workCallback;
/** @var resource */
protected $input;
/** @var resource */
protected $output;
/** @var int */
protected $nextOutputId;
/** @var string[] Int key indicates order, value is data */
protected $delayedOutputData = [];
/**
* @param int $numProcs The number of worker processes to fork
* @param callable $workCallback A callback to call in the child process
* once for each line of work to process.
* @param resource $input A socket to read work lines from
* @param resource $output A socket to write the result of work to.
*/
public function __construct( $numProcs, $workCallback, $input, $output ) {
parent::__construct( $numProcs );
$this->workCallback = $workCallback;
$this->input = $input;
$this->output = $output;
}
/**
* @inheritDoc
*/
public function start() {
if ( $this->procsToStart > 0 ) {
$status = parent::start();
if ( $status === 'child' ) {
$this->consume();
}
} else {
$status = 'parent';
$this->consumeNoFork();
}
return $status;
}
/**
* @param int $numProcs
* @return string
*/
protected function forkWorkers( $numProcs ) {
$this->prepareEnvironment();
$childSockets = [];
// Create the child processes
for ( $i = 0; $i < $numProcs; $i++ ) {
$sockets = stream_socket_pair( STREAM_PF_UNIX, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP );
// Do the fork
$pid = pcntl_fork();
if ( $pid === -1 || $pid === false ) {
echo "Error creating child processes\n";
exit( 1 );
}
if ( !$pid ) {
$this->initChild();
$this->childNumber = $i;
$this->input = $sockets[0];
$this->output = $sockets[0];
fclose( $sockets[1] );
return 'child';
} else {
// This is the parent process
$this->children[$pid] = true;
fclose( $sockets[0] );
$childSockets[] = $sockets[1];
}
}
$this->feedChildren( $childSockets );
foreach ( $childSockets as $socket ) {
// if a child has already shutdown the sockets will be closed,
// closing a second time would raise a warning.
if ( is_resource( $socket ) ) {
fclose( $socket );
}
}
return 'parent';
}
/**
* Child worker process. Reads work from $this->input and writes the
* result of that work to $this->output when completed.
*/
protected function consume() {
while ( !feof( $this->input ) ) {
$line = trim( fgets( $this->input ) );
if ( $line ) {
list( $id, $data ) = json_decode( $line );
$result = call_user_func( $this->workCallback, $data );
fwrite( $this->output, json_encode( [ $id, $result ] ) . "\n" );
}
}
}
/**
* Special cased version of self::consume() when no forking occurs
*/
protected function consumeNoFork() {
while ( !feof( $this->input ) ) {
$line = trim( fgets( $this->input ) );
if ( $line ) {
$result = call_user_func( $this->workCallback, $line );
fwrite( $this->output, "$result\n" );
}
}
}
/**
* Reads lines of work from $this->input and farms them out to
* the provided socket.
*
* @param resource[] $sockets
*/
protected function feedChildren( array $sockets ) {
$used = [];
$id = 0;
$this->nextOutputId = 0;
while ( !feof( $this->input ) ) {
$data = fgets( $this->input );
if ( $used ) {
do {
$this->updateAvailableSockets( $sockets, $used, $sockets ? 0 : 5 );
} while ( !$sockets );
}
$data = trim( $data );
if ( !$data ) {
continue;
}
$socket = array_pop( $sockets );
fwrite( $socket, json_encode( [ $id++, $data ] ) . "\n" );
$used[] = $socket;
}
while ( $used ) {
$this->updateAvailableSockets( $sockets, $used, 5 );
}
}
/**
* Moves sockets from $used to $sockets when they are available
* for more work
*
* @param resource[] &$sockets List of sockets that are waiting for work
* @param resource[] &$used List of sockets currently performing work
* @param int $timeout The number of seconds to block waiting. 0 for
* non-blocking operation.
*/
protected function updateAvailableSockets( &$sockets, &$used, $timeout ) {
$read = $used;
$write = $except = [];
stream_select( $read, $write, $except, $timeout );
foreach ( $read as $socket ) {
$line = fgets( $socket );
list( $id, $data ) = json_decode( trim( $line ) );
$this->receive( (int)$id, $data );
$sockets[] = $socket;
$idx = array_search( $socket, $used );
unset( $used[$idx] );
}
}
/**
* @param int $id
* @param string $data
*/
protected function receive( $id, $data ) {
if ( $id !== $this->nextOutputId ) {
$this->delayedOutputData[$id] = $data;
return;
}
fwrite( $this->output, $data . "\n" );
$this->nextOutputId = $id + 1;
while ( isset( $this->delayedOutputData[$this->nextOutputId] ) ) {
fwrite( $this->output, $this->delayedOutputData[$this->nextOutputId] . "\n" );
unset( $this->delayedOutputData[$this->nextOutputId] );
$this->nextOutputId++;
}
}
}
|
