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ExecFuture.php
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Mon, Mar 10, 07:16

ExecFuture.php
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<?php
/*
* Copyright 2011 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Execute system commands in parallel using futures.
*
* // execx() API: synchronous, throws on nonzero exit code
* list($stdout, $stderr) = execx('wc -l %s', $file);
*
* // exec_manual() API: synchronous, returns exit code
* list($err, $stdout, $stderr) = exec_manual('wc -l %s', $file);
*
* // Raw ExecFuture API: asynchronous
* $future = new ExecFuture(
* csprintf('wc -l %s'),
* $file);
*
* list($err, $stdout, $stderr) = $future->resolve();
*
* // ...or, throw on nonzero exit with 'resolvex()'.
* list($stdout, $stderr) = $future->resolvex();
*
* @group exec
*/
class ExecFuture extends Future {
const TIMED_OUT_EXIT_CODE = 142;
protected $pipes = array();
protected $proc = null;
protected $start = null;
protected $timeout = null;
protected $pid;
protected $stdout = null;
protected $stderr = null;
protected $stdin = null;
protected $closePipe = false;
protected $stdoutPos = 0;
protected $stderrPos = 0;
protected $command = null;
protected $stdoutSizeLimit = PHP_INT_MAX;
protected $stderrSizeLimit = PHP_INT_MAX;
protected static $echoMode = array();
protected static $descriptorSpec = array(
0 => array('pipe', 'r'), // stdin
1 => array('pipe', 'w'), // stdout
2 => array('pipe', 'w'), // stderr
);
public static function pushEchoMode($mode) {
self::$echoMode[] = $mode;
}
public static function popEchoMode() {
array_pop(self::$echoMode);
}
public static function peekEchoMode() {
return end(self::$echoMode);
}
public function setStdoutSizeLimit($limit) {
$this->stdoutSizeLimit = $limit;
}
public function getStdoutSizeLimit() {
return $this->stdoutSizeLimit;
}
public function setStderrSizeLimit($limit) {
$this->stderrSizeLimit = $limit;
}
public function getStderrSizeLimit() {
return $this->stderrSizeLimit;
}
public function getPID() {
return $this->pid;
}
public function __construct($command) {
$argv = func_get_args();
$this->command = call_user_func_array('csprintf', $argv);
}
public function __destruct() {
foreach ($this->pipes as $pipe) {
if (isset($pipe)) {
@fclose($pipe);
}
}
$this->pipes = array(null, null, null);
if ($this->proc) {
@proc_close($this->proc);
$this->proc = null;
}
$this->stdin = null;
}
public function getCommand() {
return $this->command;
}
public function read() {
if ($this->start) {
$this->isReady(); // Sync
}
$result = array(
(string)substr($this->stdout, $this->stdoutPos),
(string)substr($this->stderr, $this->stderrPos),
);
$this->stdoutPos = strlen($this->stdout);
$this->stderrPos = strlen($this->stderr);
return $result;
}
public function write($data, $keep_pipe = false) {
$this->stdin .= $data;
if (!$keep_pipe) {
$this->closePipe = true;
}
if ($this->start) {
$this->isReady(); // Sync
}
return $this;
}
public function getReadSockets() {
list($stdin, $stdout, $stderr) = $this->pipes;
$sockets = array();
if (isset($stdout) && !feof($stdout)) {
$sockets[] = $stdout;
}
if (isset($stderr) && !feof($stderr)) {
$sockets[] = $stderr;
}
return $sockets;
}
/**
* Reads some bytes from a stream, discarding output once a certain amount
* has been accumulated.
*
* @param resource $stream
* Stream to read from.
* @param int $limit
* Maximum number of bytes to return from $stream. If additional bytes
* are available, they will be read and discarded.
* @param string $description
* Human-readable description of stream, for exception message.
* @return string
* The data read from the stream.
* @throws Exception
* The stream was not readable.
*/
protected function readAndDiscard($stream, $limit, $description) {
$output = '';
do {
$data = fread($stream, 4096);
if (false === $data) {
throw new Exception('Failed to read from '.$description);
}
$read_bytes = strlen($data);
if ($read_bytes > 0 && $limit > 0) {
if ($read_bytes > $limit) {
$data = substr($data, 0, $limit);
}
$output .= $data;
$limit -= strlen($data);
}
} while ($read_bytes > 0);
return $output;
}
public function getWriteSockets() {
list($stdin, $stdout, $stderr) = $this->pipes;
$sockets = array();
if (isset($stdin) && strlen($this->stdin) && !feof($stdin)) {
$sockets[] = $stdin;
}
return $sockets;
}
public function isReady() {
if (!$this->pipes) {
if (self::peekEchoMode()) {
echo " >>> \$ {$this->command}\n";
}
$pipes = array();
$proc = proc_open($this->command, self::$descriptorSpec, $pipes);
if (!is_resource($proc)) {
throw new Exception('Failed to open process.');
}
$status = proc_get_status($proc);
if (!$status) {
throw new Exception('Failed to get process status.');
}
$this->pid = $status['pid'];
$this->start = time();
$this->pipes = $pipes;
$this->proc = $proc;
list($stdin, $stdout, $stderr) = $pipes;
if ((!stream_set_blocking($stdout, false)) ||
(!stream_set_blocking($stderr, false)) ||
(!stream_set_blocking($stdin, false))) {
$this->__destruct();
throw new Exception('Failed to set streams nonblocking.');
}
return false;
}
if (!$this->proc) {
return true;
}
list($stdin, $stdout, $stderr) = $this->pipes;
if (isset($this->stdin) && strlen($this->stdin)) {
$bytes = fwrite($stdin, $this->stdin);
if ($bytes === false) {
throw new Exception('Unable to write to stdin!');
} else if ($bytes) {
$this->stdin = substr($this->stdin, $bytes);
}
if (!strlen($this->stdin) && $this->closePipe) {
@fclose($stdin);
$this->pipes[0] = null;
}
} else {
// make sure to remove any references to the pipe in the case when stdin
// length was zero. avoid the overhead of calling fclose() as it is not
// necessary.
$this->pipes[0] = null;
}
// Read status before reading pipes so that we can never miss data that
// arrives between our last read and the process exiting.
$status = proc_get_status($this->proc);
$this->stdout .= $this->readAndDiscard(
$stdout,
$this->getStdoutSizeLimit() - strlen($this->stdout),
'stdout');
$this->stderr .= $this->readAndDiscard(
$stderr,
$this->getStderrSizeLimit() - strlen($this->stderr),
'stderr');
if (!$status['running']) {
$this->result = array(
$status['exitcode'],
$this->stdout,
$this->stderr,
);
$this->__destruct();
return true;
}
if ($this->timeout && ((time() - $this->start) >= $this->timeout)) {
if (defined('SIGKILL')) {
$signal = SIGKILL;
} else {
$signal = 9;
}
proc_terminate($this->proc, $signal);
$this->result = array(
self::TIMED_OUT_EXIT_CODE,
$this->stdout,
$this->stderr."\n".
"(This process was prematurely terminated by timeout.)");
$this->__destruct();
return true;
}
}
public function setTimeout($seconds) {
$this->timeout = $seconds;
return $this;
}
public function resolve($timeout = null) {
if (null === $timeout) {
$timeout = $this->timeout;
}
return parent::resolve($timeout);
}
public function resolvex($timeout = null) {
list($err, $stdout, $stderr) = $this->resolve($timeout);
if ($err) {
$cmd = $this->command;
throw new CommandException(
"Command '{$cmd}' failed with error #{$err}:\n".
"stdout:\n{$stdout}\n".
"stderr:\n{$stderr}\n",
$cmd,
$err,
$stdout,
$stderr);
}
return array($stdout, $stderr);
}
public function resolveJSON($timeout = null) {
list($stdout, $stderr) = $this->resolvex($timeout);
if (strlen($stderr)) {
$cmd = $this->command;
throw new CommandException(
"JSON command '{$cmd}' emitted text to stderr when none was expected: ".
$stderr,
$cmd,
0,
$stdout,
$stderr);
}
$object = json_decode($stdout, true);
if (!is_array($object)) {
$cmd = $this->command;
throw new CommandException(
"JSON command '{$cmd}' did not produce a valid JSON object on stdout: ".
$stdout,
$cmd,
0,
$stdout,
$stderr);
}
return $object;
}
}

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