ZooKeeperConfig::compareMachineInfo() - Code Metrics - Inspection of "Added process ID to zookeeper confguration to allo..." - Gendoria/cruftflake - Measure and Improve Code Quality continuously with Scrutinizer

Completed

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by Tomasz

created 2016-02-05 10:54 UTC

ZooKeeperConfig::compareMachineInfo() A

↳ Parent: ZooKeeperConfig

Complexity

Conditions	4
Paths	3

Size

Total Lines	7
Code Lines	4

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	1

Metric	Value
c	1
b	0
f	1
dl	0
loc	7
rs	9.2
cc	4
eloc	4
nc	3
nop	2

<?php

/**
 * ZooKeeper-based configuration.
 *
 * Couple of points:
 *
 *  1. We coordinate via ZK on launch - hence ZK must be available at launch
 *     time
 *  2. We create permanent nodes (not ephmeral) so that if we get disconnected
 *     ZK still knows about us running
 *  3. There is a danger that point 2 will mean that we run out of machine IDs
 *     if Mac Addresses change and we don't manually clean up
 *  4. This is assuming we don't run > 1 server on the same box - which we
 *     won't be able to do anyway since we bind to a ZeroMQ TCP port (which
 *     we can only do once)
 *
 * @author @davegardnerisme
 */

namespace Gendoria\CruftFlake\Config;

use BadMethodCallException;
use Psr\Log\LoggerAwareInterface;
use Psr\Log\LoggerInterface;
use Psr\Log\NullLogger;
use RuntimeException;

class ZooKeeperConfig implements ConfigInterface, LoggerAwareInterface
{
    /**
     * Parent path.
     *
     * @var string
     */
    private $parentPath;

    /**
     * ZK.
     *
     * @var \Zookeeper
     */
    private $zk;
    
    /**
     * Process ID for a multi-process-single-machine setup.
     * 
     * @var integer
     */
    private $procesId = 1;    

    /**
     * Logger.
     * 
     * @var LoggerInterface
     */
    private $logger;

    /**
     * Constructor.
     *
     * @param string          $hostnames A comma separated list of hostnames (including
     *                                   port)
     * @param integer           $processId If you want to run multiple server processes on a single machine, 
     *                                     you have to provide each one an unique ID,
     *                                     so the zookeeper knows, which machine ID belongs to which process.
     * @param string          $zkPath    The ZK path we look to find other machines under
     * @param LoggerInterface $logger    Logger class
     */
    public function __construct($hostnames, $processId = 1, $zkPath = '/cruftflake', LoggerInterface $logger = null)
    {
        if (!class_exists('\Zookeeper')) {
            $this->logger->critical('Zookeeper not present');
            throw new BadMethodCallException(
            'ZooKeeper extension not installed. Try hitting PECL.'
            );
        }
        $this->procesId = $processId;
        $this->zk = new \Zookeeper($hostnames);
        $this->parentPath = $zkPath;
        if ($logger) {
            $this->logger = $logger;
        } else {
            $this->logger = new NullLogger();
        }
    }

    /**
     * Get machine identifier.
     *
     * @return int Should be a 10-bit int (decimal 0 to 1023)
     * @throws RuntimeException Thrown, when obtaining machine ID has failed.
     */
    public function getMachine()
    {
        $machineId = null;

        $this->createParentIfNeeded($this->parentPath);

        // get info about _this_ machine
        $machineInfo = $this->getMachineInfo();

        // get current machine list
        $children = $this->zk->getChildren($this->parentPath);
        
        //Find existing machine info
        foreach ($children as $child) {
            $info = $this->zk->get("{$this->parentPath}/$child");
            $info = json_decode($info, true);
            if ($this->compareMachineInfo($info, $machineInfo)) {
                $machineId = (int) $child;
                break; //We don't have to check further
            }
        }
        
        //Machine info not found, attempt to create one
        if ($machineId === null) {
            $machineId = $this->createMachineInfo($children, $machineInfo);
        }

        $this->logger->debug('Obtained machine ID '.$machineId.' through ZooKeeper configuration');

        return (int) $machineId;
    }
    
    /**
     * Compare found machine information with expected values.
     * 
     * @param array $found
     * @param array $expected
     * @return boolean
     */
    private function compareMachineInfo(array $found, array $expected)
    {
        if (!isset($found['macAddress']) || !isset($found['processId'])) {
            return false;
        }
        return ($found['macAddress'] === $expected['macAddress'] && $found['processId'] === $expected['processId']);
    }
    
    /**
     * Attempt to claim and create new machine ID in Zookeeper.
     * 
     * @param array $children
     * @param array $machineInfo
     * @return integer Machine ID.
     * @throws RuntimeException Thrown, when creation of machine ID has failed.
     */
    private function createMachineInfo(array $children, array $machineInfo)
    {
        // find an unused machine number
        for ($i = 0; $i < 1024; ++$i) {
            $machineNode = $this->machineToNode($i);
            if (in_array($machineNode, $children)) {
                continue; // already used
            }

            // attempt to claim
            $created = $this->zk->create(
                "{$this->parentPath}/{$machineNode}", json_encode($machineInfo),
                array(array(// acl
                    'perms' => \Zookeeper::PERM_ALL,
                    'scheme' => 'world',
                    'id' => 'anyone',
                ))
            );
            if ($created !== null) {
                return $i;
            }
        }
        
        //Creating machine ID failed, throw an error
        $this->logger->critical('Cannot locate and claim a free machine ID via ZK', array($this));
        throw new RuntimeException('Cannot locate and claim a free machine ID via ZK');
    }

    /**
     * Get mac address and hostname.
     *
     * @return array "macAddress", "hostname" keys
     */
    private function getMachineInfo()
    {
        $info = array();
        $output = array();
        // Possible responses are: HWaddr 12:31:3c:01:65:b8, ether 00:1c:42:00:00:08
        exec('ifconfig', $output);
        if ($output == null) {
            $output = array();
        }
        foreach ($output as $o) {
            $matched = array();
            if (preg_match('/(HWaddr|ether) ([a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2})/i',
                    $o, $matched)) {
                $info['macAddress'] = $matched[2];
                break;
            }
        }
        $info['hostname'] = exec('hostname');

        if (empty($info['hostname']) || empty($info['macAddress'])) {
            $this->logger->critical('Unable to identify machine mac address and hostname',
                array($this));
            throw new RuntimeException(
            'Unable to identify machine mac address and hostname'
            );
        }
        $info['processId'] = $this->procesId;

        return $info;
    }

    /**
     * Create parent node, if needed.
     *
     * @param string $nodePath
     */
    private function createParentIfNeeded($nodePath)
    {
        if (!$this->zk->exists($nodePath)) {
            $this->zk->create(
                $nodePath, 'Cruftflake machines',
                array(array(// acl
                    'perms' => \Zookeeper::PERM_ALL,
                    'scheme' => 'world',
                    'id' => 'anyone',
                ))
            );
        }
    }

    /**
     * Machine ID to ZK node.
     *
     * @param int $id
     *
     * @return string The node path to use in ZK
     */
    private function machineToNode($id)
    {
        return str_pad($id, 4, '0', STR_PAD_LEFT);
    }

    /**
     * Set logger.
     * 
     * @param LoggerInterface $logger
     */
    public function setLogger(LoggerInterface $logger)
    {
        $this->logger = $logger;
    }
}


1			<?php
2
3			/**
4			* ZooKeeper-based configuration.
5			*
6			* Couple of points:
7			*
8			* 1. We coordinate via ZK on launch - hence ZK must be available at launch
9			* time
10			* 2. We create permanent nodes (not ephmeral) so that if we get disconnected
11			* ZK still knows about us running
12			* 3. There is a danger that point 2 will mean that we run out of machine IDs
13			* if Mac Addresses change and we don't manually clean up
14			* 4. This is assuming we don't run > 1 server on the same box - which we
15			* won't be able to do anyway since we bind to a ZeroMQ TCP port (which
16			* we can only do once)
17			*
18			* @author @davegardnerisme
19			*/
20
21			namespace Gendoria\CruftFlake\Config;
22
23			use BadMethodCallException;
24			use Psr\Log\LoggerAwareInterface;
25			use Psr\Log\LoggerInterface;
26			use Psr\Log\NullLogger;
27			use RuntimeException;
28
29			class ZooKeeperConfig implements ConfigInterface, LoggerAwareInterface
30			{
31			/**
32			* Parent path.
33			*
34			* @var string
35			*/
36			private $parentPath;
37
38			/**
39			* ZK.
40			*
41			* @var \Zookeeper
42			*/
43			private $zk;
44
45			/**
46			* Process ID for a multi-process-single-machine setup.
47			*
48			* @var integer
49			*/
50			private $procesId = 1;
51
52			/**
53			* Logger.
54			*
55			* @var LoggerInterface
56			*/
57			private $logger;
58
59			/**
60			* Constructor.
61			*
62			* @param string $hostnames A comma separated list of hostnames (including
63			* port)
64			* @param integer $processId If you want to run multiple server processes on a single machine,
65			* you have to provide each one an unique ID,
66			* so the zookeeper knows, which machine ID belongs to which process.
67			* @param string $zkPath The ZK path we look to find other machines under
68			* @param LoggerInterface $logger Logger class
69			*/
70			public function __construct($hostnames, $processId = 1, $zkPath = '/cruftflake', LoggerInterface $logger = null)
71			{
72			if (!class_exists('\Zookeeper')) {
73			$this->logger->critical('Zookeeper not present');
74			throw new BadMethodCallException(
75			'ZooKeeper extension not installed. Try hitting PECL.'
76			);
77			}
78			$this->procesId = $processId;
79			$this->zk = new \Zookeeper($hostnames);
80			$this->parentPath = $zkPath;
81			if ($logger) {
82			$this->logger = $logger;
83			} else {
84			$this->logger = new NullLogger();
85			}
86			}
87
88			/**
89			* Get machine identifier.
90			*
91			* @return int Should be a 10-bit int (decimal 0 to 1023)
92			* @throws RuntimeException Thrown, when obtaining machine ID has failed.
93			*/
94			public function getMachine()
95			{
96			$machineId = null;
97
98			$this->createParentIfNeeded($this->parentPath);
99
100			// get info about _this_ machine
101			$machineInfo = $this->getMachineInfo();
102
103			// get current machine list
104			$children = $this->zk->getChildren($this->parentPath);
105
106			//Find existing machine info
107			foreach ($children as $child) {
108			$info = $this->zk->get("{$this->parentPath}/$child");
109			$info = json_decode($info, true);
110			if ($this->compareMachineInfo($info, $machineInfo)) {
111			$machineId = (int) $child;
112			break; //We don't have to check further
113			}
114			}
115
116			//Machine info not found, attempt to create one
117			if ($machineId === null) {
118			$machineId = $this->createMachineInfo($children, $machineInfo);
119			}
120
121			$this->logger->debug('Obtained machine ID '.$machineId.' through ZooKeeper configuration');
122
123			return (int) $machineId;
124			}
125
126			/**
127			* Compare found machine information with expected values.
128			*
129			* @param array $found
130			* @param array $expected
131			* @return boolean
132			*/
133			private function compareMachineInfo(array $found, array $expected)
134			{
135			if (!isset($found['macAddress']) \|\| !isset($found['processId'])) {
136			return false;
137			}
138			return ($found['macAddress'] === $expected['macAddress'] && $found['processId'] === $expected['processId']);
139			}
140
141			/**
142			* Attempt to claim and create new machine ID in Zookeeper.
143			*
144			* @param array $children
145			* @param array $machineInfo
146			* @return integer Machine ID.
147			* @throws RuntimeException Thrown, when creation of machine ID has failed.
148			*/
149			private function createMachineInfo(array $children, array $machineInfo)
150			{
151			// find an unused machine number
152			for ($i = 0; $i < 1024; ++$i) {
153			$machineNode = $this->machineToNode($i);
154			if (in_array($machineNode, $children)) {
155			continue; // already used
156			}
157
158			// attempt to claim
159			$created = $this->zk->create(
160			"{$this->parentPath}/{$machineNode}", json_encode($machineInfo),
161			array(array(// acl
162			'perms' => \Zookeeper::PERM_ALL,
163			'scheme' => 'world',
164			'id' => 'anyone',
165			))
166			);
167			if ($created !== null) {
168			return $i;
169			}
170			}
171
172			//Creating machine ID failed, throw an error
173			$this->logger->critical('Cannot locate and claim a free machine ID via ZK', array($this));
174			throw new RuntimeException('Cannot locate and claim a free machine ID via ZK');
175			}
176
177			/**
178			* Get mac address and hostname.
179			*
180			* @return array "macAddress", "hostname" keys
181			*/
182			private function getMachineInfo()
183			{
184			$info = array();
185			$output = array();
186			// Possible responses are: HWaddr 12:31:3c:01:65:b8, ether 00:1c:42:00:00:08
187			exec('ifconfig', $output);
188			if ($output == null) {
189			$output = array();
190			}
191			foreach ($output as $o) {
192			$matched = array();
193			if (preg_match('/(HWaddr\|ether) ([a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2}:[a-f0-9]{2})/i',
194			$o, $matched)) {
195			$info['macAddress'] = $matched[2];
196			break;
197			}
198			}
199			$info['hostname'] = exec('hostname');
200
201			if (empty($info['hostname']) \|\| empty($info['macAddress'])) {
202			$this->logger->critical('Unable to identify machine mac address and hostname',
203			array($this));
204			throw new RuntimeException(
205			'Unable to identify machine mac address and hostname'
206			);
207			}
208			$info['processId'] = $this->procesId;
209
210			return $info;
211			}
212
213			/**
214			* Create parent node, if needed.
215			*
216			* @param string $nodePath
217			*/
218			private function createParentIfNeeded($nodePath)
219			{
220			if (!$this->zk->exists($nodePath)) {
221			$this->zk->create(
222			$nodePath, 'Cruftflake machines',
223			array(array(// acl
224			'perms' => \Zookeeper::PERM_ALL,
225			'scheme' => 'world',
226			'id' => 'anyone',
227			))
228			);
229			}
230			}
231
232			/**
233			* Machine ID to ZK node.
234			*
235			* @param int $id
236			*
237			* @return string The node path to use in ZK
238			*/
239			private function machineToNode($id)
240			{
241			return str_pad($id, 4, '0', STR_PAD_LEFT);
242			}
243
244			/**
245			* Set logger.
246			*
247			* @param LoggerInterface $logger
248			*/
249			public function setLogger(LoggerInterface $logger)
250			{
251			$this->logger = $logger;
252			}
253			}
254

Gendoria / cruftflake

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ZooKeeperConfig::compareMachineInfo() A

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