MediaWiki  1.23.8
UIDGenerator.php
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1 <?php
29 class UIDGenerator {
31  protected static $instance = null;
32 
33  protected $nodeIdFile; // string; local file path
34  protected $nodeId32; // string; node ID in binary (32 bits)
35  protected $nodeId48; // string; node ID in binary (48 bits)
36 
37  protected $lockFile88; // string; local file path
38  protected $lockFile128; // string; local file path
39 
41  protected $fileHandles = array(); // cache file handles
42 
43  const QUICK_RAND = 1; // get randomness from fast and insecure sources
44  const QUICK_VOLATILE = 2; // use an APC like in-memory counter if available
45 
46  protected function __construct() {
47  $this->nodeIdFile = wfTempDir() . '/mw-' . __CLASS__ . '-UID-nodeid';
48  $nodeId = '';
49  if ( is_file( $this->nodeIdFile ) ) {
50  $nodeId = file_get_contents( $this->nodeIdFile );
51  }
52  // Try to get some ID that uniquely identifies this machine (RFC 4122)...
53  if ( !preg_match( '/^[0-9a-f]{12}$/i', $nodeId ) ) {
55  if ( wfIsWindows() ) {
56  // http://technet.microsoft.com/en-us/library/bb490913.aspx
57  $csv = trim( wfShellExec( 'getmac /NH /FO CSV' ) );
58  $line = substr( $csv, 0, strcspn( $csv, "\n" ) );
59  $info = str_getcsv( $line );
60  $nodeId = isset( $info[0] ) ? str_replace( '-', '', $info[0] ) : '';
61  } elseif ( is_executable( '/sbin/ifconfig' ) ) { // Linux/BSD/Solaris/OS X
62  // See http://linux.die.net/man/8/ifconfig
63  $m = array();
64  preg_match( '/\s([0-9a-f]{2}(:[0-9a-f]{2}){5})\s/',
65  wfShellExec( '/sbin/ifconfig -a' ), $m );
66  $nodeId = isset( $m[1] ) ? str_replace( ':', '', $m[1] ) : '';
67  }
69  if ( !preg_match( '/^[0-9a-f]{12}$/i', $nodeId ) ) {
70  $nodeId = MWCryptRand::generateHex( 12, true );
71  $nodeId[1] = dechex( hexdec( $nodeId[1] ) | 0x1 ); // set multicast bit
72  }
73  file_put_contents( $this->nodeIdFile, $nodeId ); // cache
74  }
75  $this->nodeId32 = wfBaseConvert( substr( sha1( $nodeId ), 0, 8 ), 16, 2, 32 );
76  $this->nodeId48 = wfBaseConvert( $nodeId, 16, 2, 48 );
77  // If different processes run as different users, they may have different temp dirs.
78  // This is dealt with by initializing the clock sequence number and counters randomly.
79  $this->lockFile88 = wfTempDir() . '/mw-' . __CLASS__ . '-UID-88';
80  $this->lockFile128 = wfTempDir() . '/mw-' . __CLASS__ . '-UID-128';
81  }
82 
86  protected static function singleton() {
87  if ( self::$instance === null ) {
88  self::$instance = new self();
89  }
90 
91  return self::$instance;
92  }
93 
109  public static function newTimestampedUID88( $base = 10 ) {
110  if ( !is_integer( $base ) || $base > 36 || $base < 2 ) {
111  throw new MWException( "Base must an integer be between 2 and 36" );
112  }
113  $gen = self::singleton();
114  $time = $gen->getTimestampAndDelay( 'lockFile88', 1, 1024 );
115 
116  return wfBaseConvert( $gen->getTimestampedID88( $time ), 2, $base );
117  }
118 
123  protected function getTimestampedID88( array $info ) {
124  list( $time, $counter ) = $info;
125  // Take the 46 MSBs of "milliseconds since epoch"
126  $id_bin = $this->millisecondsSinceEpochBinary( $time );
127  // Add a 10 bit counter resulting in 56 bits total
128  $id_bin .= str_pad( decbin( $counter ), 10, '0', STR_PAD_LEFT );
129  // Add the 32 bit node ID resulting in 88 bits total
130  $id_bin .= $this->nodeId32;
131  // Convert to a 1-27 digit integer string
132  if ( strlen( $id_bin ) !== 88 ) {
133  throw new MWException( "Detected overflow for millisecond timestamp." );
134  }
135 
136  return $id_bin;
137  }
138 
153  public static function newTimestampedUID128( $base = 10 ) {
154  if ( !is_integer( $base ) || $base > 36 || $base < 2 ) {
155  throw new MWException( "Base must be an integer between 2 and 36" );
156  }
157  $gen = self::singleton();
158  $time = $gen->getTimestampAndDelay( 'lockFile128', 16384, 1048576 );
159 
160  return wfBaseConvert( $gen->getTimestampedID128( $time ), 2, $base );
161  }
162 
167  protected function getTimestampedID128( array $info ) {
168  list( $time, $counter, $clkSeq ) = $info;
169  // Take the 46 MSBs of "milliseconds since epoch"
170  $id_bin = $this->millisecondsSinceEpochBinary( $time );
171  // Add a 20 bit counter resulting in 66 bits total
172  $id_bin .= str_pad( decbin( $counter ), 20, '0', STR_PAD_LEFT );
173  // Add a 14 bit clock sequence number resulting in 80 bits total
174  $id_bin .= str_pad( decbin( $clkSeq ), 14, '0', STR_PAD_LEFT );
175  // Add the 48 bit node ID resulting in 128 bits total
176  $id_bin .= $this->nodeId48;
177  // Convert to a 1-39 digit integer string
178  if ( strlen( $id_bin ) !== 128 ) {
179  throw new MWException( "Detected overflow for millisecond timestamp." );
180  }
181 
182  return $id_bin;
183  }
184 
192  public static function newUUIDv4( $flags = 0 ) {
193  $hex = ( $flags & self::QUICK_RAND )
194  ? wfRandomString( 31 )
195  : MWCryptRand::generateHex( 31 );
196 
197  return sprintf( '%s-%s-%s-%s-%s',
198  // "time_low" (32 bits)
199  substr( $hex, 0, 8 ),
200  // "time_mid" (16 bits)
201  substr( $hex, 8, 4 ),
202  // "time_hi_and_version" (16 bits)
203  '4' . substr( $hex, 12, 3 ),
204  // "clk_seq_hi_res (8 bits, variant is binary 10x) and "clk_seq_low" (8 bits)
205  dechex( 0x8 | ( hexdec( $hex[15] ) & 0x3 ) ) . $hex[16] . substr( $hex, 17, 2 ),
206  // "node" (48 bits)
207  substr( $hex, 19, 12 )
208  );
209  }
210 
218  public static function newRawUUIDv4( $flags = 0 ) {
219  return str_replace( '-', '', self::newUUIDv4( $flags ) );
220  }
221 
234  public static function newSequentialPerNodeID( $bucket, $bits = 48, $flags = 0 ) {
235  return current( self::newSequentialPerNodeIDs( $bucket, $bits, 1, $flags ) );
236  }
237 
249  public static function newSequentialPerNodeIDs( $bucket, $bits, $count, $flags = 0 ) {
250  $gen = self::singleton();
251  return $gen->getSequentialPerNodeIDs( $bucket, $bits, $count, $flags );
252  }
253 
264  protected function getSequentialPerNodeIDs( $bucket, $bits, $count, $flags ) {
265  if ( $count <= 0 ) {
266  return array(); // nothing to do
267  } elseif ( $count > 10000 ) {
268  throw new MWException( "Number of requested IDs ($count) is too high." );
269  } elseif ( $bits < 16 || $bits > 48 ) {
270  throw new MWException( "Requested bit size ($bits) is out of range." );
271  }
272 
273  $counter = null; // post-increment persistent counter value
274 
275  // Use APC/eAccelerator/xcache if requested, available, and not in CLI mode;
276  // Counter values would not survive accross script instances in CLI mode.
277  $cache = null;
278  if ( ( $flags & self::QUICK_VOLATILE ) && PHP_SAPI !== 'cli' ) {
279  try {
281  } catch ( MWException $e ) {} // not supported
282  }
283  if ( $cache ) {
284  $counter = $cache->incr( $bucket, $count );
285  if ( $counter === false ) {
286  if ( !$cache->add( $bucket, $count ) ) {
287  throw new MWException( 'Unable to set value to ' . get_class( $cache ) );
288  }
289  $counter = $count;
290  }
291  }
292 
293  // Note: use of fmod() avoids "division by zero" on 32 bit machines
294  if ( $counter === null ) {
295  $path = wfTempDir() . '/mw-' . __CLASS__ . '-' . rawurlencode( $bucket ) . '-48';
296  // Get the UID lock file handle
297  if ( isset( $this->fileHandles[$path] ) ) {
298  $handle = $this->fileHandles[$path];
299  } else {
300  $handle = fopen( $path, 'cb+' );
301  $this->fileHandles[$path] = $handle ?: null; // cache
302  }
303  // Acquire the UID lock file
304  if ( $handle === false ) {
305  throw new MWException( "Could not open '{$path}'." );
306  } elseif ( !flock( $handle, LOCK_EX ) ) {
307  fclose( $handle );
308  throw new MWException( "Could not acquire '{$path}'." );
309  }
310  // Fetch the counter value and increment it...
311  rewind( $handle );
312  $counter = floor( trim( fgets( $handle ) ) ) + $count; // fetch as float
313  // Write back the new counter value
314  ftruncate( $handle, 0 );
315  rewind( $handle );
316  fwrite( $handle, fmod( $counter, pow( 2, 48 ) ) ); // warp-around as needed
317  fflush( $handle );
318  // Release the UID lock file
319  flock( $handle, LOCK_UN );
320  }
321 
322  $ids = array();
323  $divisor = pow( 2, $bits );
324  $currentId = floor( $counter - $count ); // pre-increment counter value
325  for ( $i = 0; $i < $count; ++$i ) {
326  $ids[] = fmod( ++$currentId, $divisor );
327  }
328 
329  return $ids;
330  }
331 
343  protected function getTimestampAndDelay( $lockFile, $clockSeqSize, $counterSize ) {
344  // Get the UID lock file handle
345  $path = $this->$lockFile;
346  if ( isset( $this->fileHandles[$path] ) ) {
347  $handle = $this->fileHandles[$path];
348  } else {
349  $handle = fopen( $path, 'cb+' );
350  $this->fileHandles[$path] = $handle ?: null; // cache
351  }
352  // Acquire the UID lock file
353  if ( $handle === false ) {
354  throw new MWException( "Could not open '{$this->$lockFile}'." );
355  } elseif ( !flock( $handle, LOCK_EX ) ) {
356  fclose( $handle );
357  throw new MWException( "Could not acquire '{$this->$lockFile}'." );
358  }
359  // Get the current timestamp, clock sequence number, last time, and counter
360  rewind( $handle );
361  $data = explode( ' ', fgets( $handle ) ); // "<clk seq> <sec> <msec> <counter> <offset>"
362  $clockChanged = false; // clock set back significantly?
363  if ( count( $data ) == 5 ) { // last UID info already initialized
364  $clkSeq = (int)$data[0] % $clockSeqSize;
365  $prevTime = array( (int)$data[1], (int)$data[2] );
366  $offset = (int)$data[4] % $counterSize; // random counter offset
367  $counter = 0; // counter for UIDs with the same timestamp
368  // Delay until the clock reaches the time of the last ID.
369  // This detects any microtime() drift among processes.
370  $time = $this->timeWaitUntil( $prevTime );
371  if ( !$time ) { // too long to delay?
372  $clockChanged = true; // bump clock sequence number
374  } elseif ( $time == $prevTime ) {
375  // Bump the counter if there are timestamp collisions
376  $counter = (int)$data[3] % $counterSize;
377  if ( ++$counter >= $counterSize ) { // sanity (starts at 0)
378  flock( $handle, LOCK_UN ); // abort
379  throw new MWException( "Counter overflow for timestamp value." );
380  }
381  }
382  } else { // last UID info not initialized
383  $clkSeq = mt_rand( 0, $clockSeqSize - 1 );
384  $counter = 0;
385  $offset = mt_rand( 0, $counterSize - 1 );
387  }
388  // microtime() and gettimeofday() can drift from time() at least on Windows.
389  // The drift is immediate for processes running while the system clock changes.
390  // time() does not have this problem. See https://bugs.php.net/bug.php?id=42659.
391  if ( abs( time() - $time[0] ) >= 2 ) {
392  // We don't want processes using too high or low timestamps to avoid duplicate
393  // UIDs and clock sequence number churn. This process should just be restarted.
394  flock( $handle, LOCK_UN ); // abort
395  throw new MWException( "Process clock is outdated or drifted." );
396  }
397  // If microtime() is synced and a clock change was detected, then the clock went back
398  if ( $clockChanged ) {
399  // Bump the clock sequence number and also randomize the counter offset,
400  // which is useful for UIDs that do not include the clock sequence number.
401  $clkSeq = ( $clkSeq + 1 ) % $clockSeqSize;
402  $offset = mt_rand( 0, $counterSize - 1 );
403  trigger_error( "Clock was set back; sequence number incremented." );
404  }
405  // Update the (clock sequence number, timestamp, counter)
406  ftruncate( $handle, 0 );
407  rewind( $handle );
408  fwrite( $handle, "{$clkSeq} {$time[0]} {$time[1]} {$counter} {$offset}" );
409  fflush( $handle );
410  // Release the UID lock file
411  flock( $handle, LOCK_UN );
412 
413  return array( $time, ( $counter + $offset ) % $counterSize, $clkSeq );
414  }
415 
423  protected function timeWaitUntil( array $time ) {
424  do {
425  $ct = self::millitime();
426  if ( $ct >= $time ) { // http://php.net/manual/en/language.operators.comparison.php
427  return $ct; // current timestamp is higher than $time
428  }
429  } while ( ( ( $time[0] - $ct[0] ) * 1000 + ( $time[1] - $ct[1] ) ) <= 10 );
430 
431  return false;
432  }
433 
438  protected function millisecondsSinceEpochBinary( array $time ) {
439  list( $sec, $msec ) = $time;
440  $ts = 1000 * $sec + $msec;
441  if ( $ts > pow( 2, 52 ) ) {
442  throw new MWException( __METHOD__ .
443  ': sorry, this function doesn\'t work after the year 144680' );
444  }
445 
446  return substr( wfBaseConvert( $ts, 10, 2, 46 ), -46 );
447  }
448 
452  protected static function millitime() {
453  list( $msec, $sec ) = explode( ' ', microtime() );
454 
455  return array( (int)$sec, (int)( $msec * 1000 ) );
456  }
457 
469  protected function deleteCacheFiles() {
470  // Bug: 44850
471  foreach ( $this->fileHandles as $path => $handle ) {
472  if ( $handle !== null ) {
473  fclose( $handle );
474  }
475  if ( is_file( $path ) ) {
476  unlink( $path );
477  }
478  unset( $this->fileHandles[$path] );
479  }
480  if ( is_file( $this->nodeIdFile ) ) {
481  unlink( $this->nodeIdFile );
482  }
483  }
484 
496  public static function unitTestTearDown() {
497  // Bug: 44850
498  $gen = self::singleton();
499  $gen->deleteCacheFiles();
500  }
501 
502  function __destruct() {
503  array_map( 'fclose', array_filter( $this->fileHandles ) );
504  }
505 }
UIDGenerator\$nodeId32
$nodeId32
Definition: UIDGenerator.php:34
UIDGenerator\newTimestampedUID128
static newTimestampedUID128( $base=10)
Get a statistically unique 128-bit unsigned integer ID string.
Definition: UIDGenerator.php:152
$time
see documentation in includes Linker php for Linker::makeImageLink & $time
Definition: hooks.txt:1358
UIDGenerator\QUICK_RAND
const QUICK_RAND
Definition: UIDGenerator.php:42
wfShellExec
wfShellExec( $cmd, &$retval=null, $environ=array(), $limits=array(), $options=array())
Execute a shell command, with time and memory limits mirrored from the PHP configuration if supported...
Definition: GlobalFunctions.php:2804
php
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Definition: skin.txt:62
UIDGenerator\getTimestampedID128
getTimestampedID128(array $info)
Definition: UIDGenerator.php:166
UIDGenerator\getTimestampAndDelay
getTimestampAndDelay( $lockFile, $clockSeqSize, $counterSize)
Get a (time,counter,clock sequence) where (time,counter) is higher than any previous (time,...
Definition: UIDGenerator.php:342
UIDGenerator\$instance
static $instance
Definition: UIDGenerator.php:31
wfSuppressWarnings
wfSuppressWarnings( $end=false)
Reference-counted warning suppression.
Definition: GlobalFunctions.php:2387
UIDGenerator\$fileHandles
Array $fileHandles
Definition: UIDGenerator.php:40
MWCryptRand\generateHex
static generateHex( $chars, $forceStrong=false)
Generate a run of (ideally) cryptographically random data and return it in hexadecimal string format.
Definition: MWCryptRand.php:514
UIDGenerator
Class for getting statistically unique IDs.
Definition: UIDGenerator.php:29
$flags
it s the revision text itself In either if gzip is the revision text is gzipped $flags
Definition: hooks.txt:2113
UIDGenerator\$nodeId48
$nodeId48
Definition: UIDGenerator.php:35
UIDGenerator\getSequentialPerNodeIDs
getSequentialPerNodeIDs( $bucket, $bits, $count, $flags)
Return IDs that are sequential only for this node and bucket.
Definition: UIDGenerator.php:263
UIDGenerator\newRawUUIDv4
static newRawUUIDv4( $flags=0)
Return an RFC4122 compliant v4 UUID.
Definition: UIDGenerator.php:217
UIDGenerator\newSequentialPerNodeID
static newSequentialPerNodeID( $bucket, $bits=48, $flags=0)
Return an ID that is sequential only for this node and bucket.
Definition: UIDGenerator.php:233
UIDGenerator\millisecondsSinceEpochBinary
millisecondsSinceEpochBinary(array $time)
Definition: UIDGenerator.php:437
MWException
MediaWiki exception.
Definition: MWException.php:26
wfRestoreWarnings
wfRestoreWarnings()
Restore error level to previous value.
Definition: GlobalFunctions.php:2417
UIDGenerator\deleteCacheFiles
deleteCacheFiles()
Delete all cache files that have been created.
Definition: UIDGenerator.php:468
UIDGenerator\$lockFile128
$lockFile128
Definition: UIDGenerator.php:38
array
the array() calling protocol came about after MediaWiki 1.4rc1.
List of Api Query prop modules.
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Definition: deferred.txt:11
$line
$line
Definition: cdb.php:57
UIDGenerator\millitime
static millitime()
Definition: UIDGenerator.php:451
UIDGenerator\newTimestampedUID88
static newTimestampedUID88( $base=10)
Get a statistically unique 88-bit unsigned integer ID string.
Definition: UIDGenerator.php:108
UIDGenerator\newUUIDv4
static newUUIDv4( $flags=0)
Return an RFC4122 compliant v4 UUID.
Definition: UIDGenerator.php:191
UIDGenerator\unitTestTearDown
static unitTestTearDown()
Cleanup resources when tearing down after a unit test.
Definition: UIDGenerator.php:495
wfIsWindows
wfIsWindows()
Check if the operating system is Windows.
Definition: GlobalFunctions.php:2524
UIDGenerator\singleton
static singleton()
Definition: UIDGenerator.php:85
UIDGenerator\__construct
__construct()
Definition: UIDGenerator.php:45
UIDGenerator\$lockFile88
$lockFile88
Definition: UIDGenerator.php:37
ObjectCache\newAccelerator
static newAccelerator( $params)
Factory function referenced from DefaultSettings.php for CACHE_ACCEL.
Definition: ObjectCache.php:125
UIDGenerator\getTimestampedID88
getTimestampedID88(array $info)
Definition: UIDGenerator.php:122
$count
$count
Definition: UtfNormalTest2.php:96
wfTempDir
wfTempDir()
Tries to get the system directory for temporary files.
Definition: GlobalFunctions.php:2564
$cache
$cache
Definition: mcc.php:32
wfBaseConvert
wfBaseConvert( $input, $sourceBase, $destBase, $pad=1, $lowercase=true, $engine='auto')
Convert an arbitrarily-long digit string from one numeric base to another, optionally zero-padding to...
Definition: GlobalFunctions.php:3377
$path
$path
Definition: NoLocalSettings.php:35
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Definition: distributors.txt:9
UIDGenerator\QUICK_VOLATILE
const QUICK_VOLATILE
Definition: UIDGenerator.php:43
UIDGenerator\newSequentialPerNodeIDs
static newSequentialPerNodeIDs( $bucket, $bits, $count, $flags=0)
Return IDs that are sequential only for this node and bucket.
Definition: UIDGenerator.php:248
$e
if( $useReadline) $e
Definition: eval.php:66
UIDGenerator\$nodeIdFile
$nodeIdFile
Definition: UIDGenerator.php:33
UIDGenerator\timeWaitUntil
timeWaitUntil(array $time)
Wait till the current timestamp reaches $time and return the current timestamp.
Definition: UIDGenerator.php:422
UIDGenerator\__destruct
__destruct()
Definition: UIDGenerator.php:501
wfRandomString
wfRandomString( $length=32)
Get a random string containing a number of pseudo-random hex characters.
Definition: GlobalFunctions.php:300