includes/utils/UIDGenerator.php

   1 <?php
   2 /**
   3  * This file deals with UID generation.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @author Aaron Schulz
  22  */
  23 use Wikimedia\Assert\Assert;
  24 use MediaWiki\MediaWikiServices;
  25
  26 /**
  27  * Class for getting statistically unique IDs
  28  *
  29  * @since 1.21
  30  */
  31 class UIDGenerator {
  32         /** @var UIDGenerator */
  33         protected static $instance = null;
  34
  35         protected $nodeIdFile; // string; local file path
  36         protected $nodeId32; // string; node ID in binary (32 bits)
  37         protected $nodeId48; // string; node ID in binary (48 bits)
  38
  39         protected $lockFile88; // string; local file path
  40         protected $lockFile128; // string; local file path
  41         protected $lockFileUUID; // string; local file path
  42
  43         /** @var array */
  44         protected $fileHandles = []; // cache file handles
  45
  46         const QUICK_RAND = 1; // get randomness from fast and insecure sources
  47         const QUICK_VOLATILE = 2; // use an APC like in-memory counter if available
  48
  49         protected function __construct() {
  50                 $this->nodeIdFile = wfTempDir() . '/mw-' . __CLASS__ . '-UID-nodeid';
  51                 $nodeId = '';
  52                 if ( is_file( $this->nodeIdFile ) ) {
  53                         $nodeId = file_get_contents( $this->nodeIdFile );
  54                 }
  55                 // Try to get some ID that uniquely identifies this machine (RFC 4122)...
  56                 if ( !preg_match( '/^[0-9a-f]{12}$/i', $nodeId ) ) {
  57                         MediaWiki\suppressWarnings();
  58                         if ( wfIsWindows() ) {
  59                                 // https://technet.microsoft.com/en-us/library/bb490913.aspx
  60                                 $csv = trim( wfShellExec( 'getmac /NH /FO CSV' ) );
  61                                 $line = substr( $csv, 0, strcspn( $csv, "\n" ) );
  62                                 $info = str_getcsv( $line );
  63                                 $nodeId = isset( $info[0] ) ? str_replace( '-', '', $info[0] ) : '';
  64                         } elseif ( is_executable( '/sbin/ifconfig' ) ) { // Linux/BSD/Solaris/OS X
  65                                 // See https://linux.die.net/man/8/ifconfig
  66                                 $m = [];
  67                                 preg_match( '/\s([0-9a-f]{2}(:[0-9a-f]{2}){5})\s/',
  68                                         wfShellExec( '/sbin/ifconfig -a' ), $m );
  69                                 $nodeId = isset( $m[1] ) ? str_replace( ':', '', $m[1] ) : '';
  70                         }
  71                         MediaWiki\restoreWarnings();
  72                         if ( !preg_match( '/^[0-9a-f]{12}$/i', $nodeId ) ) {
  73                                 $nodeId = MWCryptRand::generateHex( 12, true );
  74                                 $nodeId[1] = dechex( hexdec( $nodeId[1] ) | 0x1 ); // set multicast bit
  75                         }
  76                         file_put_contents( $this->nodeIdFile, $nodeId ); // cache
  77                 }
  78                 $this->nodeId32 = Wikimedia\base_convert( substr( sha1( $nodeId ), 0, 8 ), 16, 2, 32 );
  79                 $this->nodeId48 = Wikimedia\base_convert( $nodeId, 16, 2, 48 );
  80                 // If different processes run as different users, they may have different temp dirs.
  81                 // This is dealt with by initializing the clock sequence number and counters randomly.
  82                 $this->lockFile88 = wfTempDir() . '/mw-' . __CLASS__ . '-UID-88';
  83                 $this->lockFile128 = wfTempDir() . '/mw-' . __CLASS__ . '-UID-128';
  84                 $this->lockFileUUID = wfTempDir() . '/mw-' . __CLASS__ . '-UUID-128';
  85         }
  86
  87         /**
  88          * @todo: move to MW-specific factory class and inject temp dir
  89          * @return UIDGenerator
  90          */
  91         protected static function singleton() {
  92                 if ( self::$instance === null ) {
  93                         self::$instance = new self();
  94                 }
  95
  96                 return self::$instance;
  97         }
  98
  99         /**
 100          * Get a statistically unique 88-bit unsigned integer ID string.
 101          * The bits of the UID are prefixed with the time (down to the millisecond).
 102          *
 103          * These IDs are suitable as values for the shard key of distributed data.
 104          * If a column uses these as values, it should be declared UNIQUE to handle collisions.
 105          * New rows almost always have higher UIDs, which makes B-TREE updates on INSERT fast.
 106          * They can also be stored "DECIMAL(27) UNSIGNED" or BINARY(11) in MySQL.
 107          *
 108          * UID generation is serialized on each server (as the node ID is for the whole machine).
 109          *
 110          * @param int $base Specifies a base other than 10
 111          * @return string Number
 112          * @throws RuntimeException
 113          */
 114         public static function newTimestampedUID88( $base = 10 ) {
 115                 Assert::parameterType( 'integer', $base, '$base' );
 116                 Assert::parameter( $base <= 36, '$base', 'must be <= 36' );
 117                 Assert::parameter( $base >= 2, '$base', 'must be >= 2' );
 118
 119                 $gen = self::singleton();
 120                 $info = $gen->getTimeAndDelay( 'lockFile88', 1, 1024, 1024 );
 121                 $info['offsetCounter'] = $info['offsetCounter'] % 1024;
 122                 return Wikimedia\base_convert( $gen->getTimestampedID88( $info ), 2, $base );
 123         }
 124
 125         /**
 126          * @param array $info The result of UIDGenerator::getTimeAndDelay() or
 127          *  a plain (UIDGenerator::millitime(), counter, clock sequence) array.
 128          * @return string 88 bits
 129          * @throws RuntimeException
 130          */
 131         protected function getTimestampedID88( array $info ) {
 132                 if ( isset( $info['time'] ) ) {
 133                         $time = $info['time'];
 134                         $counter = $info['offsetCounter'];
 135                 } else {
 136                         $time = $info[0];
 137                         $counter = $info[1];
 138                 }
 139                 // Take the 46 LSBs of "milliseconds since epoch"
 140                 $id_bin = $this->millisecondsSinceEpochBinary( $time );
 141                 // Add a 10 bit counter resulting in 56 bits total
 142                 $id_bin .= str_pad( decbin( $counter ), 10, '0', STR_PAD_LEFT );
 143                 // Add the 32 bit node ID resulting in 88 bits total
 144                 $id_bin .= $this->nodeId32;
 145                 // Convert to a 1-27 digit integer string
 146                 if ( strlen( $id_bin ) !== 88 ) {
 147                         throw new RuntimeException( "Detected overflow for millisecond timestamp." );
 148                 }
 149
 150                 return $id_bin;
 151         }
 152
 153         /**
 154          * Get a statistically unique 128-bit unsigned integer ID string.
 155          * The bits of the UID are prefixed with the time (down to the millisecond).
 156          *
 157          * These IDs are suitable as globally unique IDs, without any enforced uniqueness.
 158          * New rows almost always have higher UIDs, which makes B-TREE updates on INSERT fast.
 159          * They can also be stored as "DECIMAL(39) UNSIGNED" or BINARY(16) in MySQL.
 160          *
 161          * UID generation is serialized on each server (as the node ID is for the whole machine).
 162          *
 163          * @param int $base Specifies a base other than 10
 164          * @return string Number
 165          * @throws RuntimeException
 166          */
 167         public static function newTimestampedUID128( $base = 10 ) {
 168                 Assert::parameterType( 'integer', $base, '$base' );
 169                 Assert::parameter( $base <= 36, '$base', 'must be <= 36' );
 170                 Assert::parameter( $base >= 2, '$base', 'must be >= 2' );
 171
 172                 $gen = self::singleton();
 173                 $info = $gen->getTimeAndDelay( 'lockFile128', 16384, 1048576, 1048576 );
 174                 $info['offsetCounter'] = $info['offsetCounter'] % 1048576;
 175
 176                 return Wikimedia\base_convert( $gen->getTimestampedID128( $info ), 2, $base );
 177         }
 178
 179         /**
 180          * @param array $info The result of UIDGenerator::getTimeAndDelay() or
 181          *  a plain (UIDGenerator::millitime(), counter, clock sequence) array.
 182          * @return string 128 bits
 183          * @throws RuntimeException
 184          */
 185         protected function getTimestampedID128( array $info ) {
 186                 if ( isset( $info['time'] ) ) {
 187                         $time = $info['time'];
 188                         $counter = $info['offsetCounter'];
 189                         $clkSeq = $info['clkSeq'];
 190                 } else {
 191                         $time = $info[0];
 192                         $counter = $info[1];
 193                         $clkSeq = $info[2];
 194                 }
 195                 // Take the 46 LSBs of "milliseconds since epoch"
 196                 $id_bin = $this->millisecondsSinceEpochBinary( $time );
 197                 // Add a 20 bit counter resulting in 66 bits total
 198                 $id_bin .= str_pad( decbin( $counter ), 20, '0', STR_PAD_LEFT );
 199                 // Add a 14 bit clock sequence number resulting in 80 bits total
 200                 $id_bin .= str_pad( decbin( $clkSeq ), 14, '0', STR_PAD_LEFT );
 201                 // Add the 48 bit node ID resulting in 128 bits total
 202                 $id_bin .= $this->nodeId48;
 203                 // Convert to a 1-39 digit integer string
 204                 if ( strlen( $id_bin ) !== 128 ) {
 205                         throw new RuntimeException( "Detected overflow for millisecond timestamp." );
 206                 }
 207
 208                 return $id_bin;
 209         }
 210
 211         /**
 212          * Return an RFC4122 compliant v1 UUID
 213          *
 214          * @return string
 215          * @throws RuntimeException
 216          * @since 1.27
 217          */
 218         public static function newUUIDv1() {
 219                 $gen = self::singleton();
 220                 // There can be up to 10000 intervals for the same millisecond timestamp.
 221                 // [0,4999] counter + [0,5000] offset is in [0,9999] for the offset counter.
 222                 // Add this onto the timestamp to allow making up to 5000 IDs per second.
 223                 return $gen->getUUIDv1( $gen->getTimeAndDelay( 'lockFileUUID', 16384, 5000, 5001 ) );
 224         }
 225
 226         /**
 227          * Return an RFC4122 compliant v1 UUID
 228          *
 229          * @return string 32 hex characters with no hyphens
 230          * @throws RuntimeException
 231          * @since 1.27
 232          */
 233         public static function newRawUUIDv1() {
 234                 return str_replace( '-', '', self::newUUIDv1() );
 235         }
 236
 237         /**
 238          * @param array $info Result of UIDGenerator::getTimeAndDelay()
 239          * @return string 128 bits
 240          */
 241         protected function getUUIDv1( array $info ) {
 242                 $clkSeq_bin = Wikimedia\base_convert( $info['clkSeq'], 10, 2, 14 );
 243                 $time_bin = $this->intervalsSinceGregorianBinary( $info['time'], $info['offsetCounter'] );
 244                 // Take the 32 bits of "time low"
 245                 $id_bin = substr( $time_bin, 28, 32 );
 246                 // Add 16 bits of "time mid" resulting in 48 bits total
 247                 $id_bin .= substr( $time_bin, 12, 16 );
 248                 // Add 4 bit version resulting in 52 bits total
 249                 $id_bin .= '0001';
 250                 // Add 12 bits of "time high" resulting in 64 bits total
 251                 $id_bin .= substr( $time_bin, 0, 12 );
 252                 // Add 2 bits of "variant" resulting in 66 bits total
 253                 $id_bin .= '10';
 254                 // Add 6 bits of "clock seq high" resulting in 72 bits total
 255                 $id_bin .= substr( $clkSeq_bin, 0, 6 );
 256                 // Add 8 bits of "clock seq low" resulting in 80 bits total
 257                 $id_bin .= substr( $clkSeq_bin, 6, 8 );
 258                 // Add the 48 bit node ID resulting in 128 bits total
 259                 $id_bin .= $this->nodeId48;
 260                 // Convert to a 32 char hex string with dashes
 261                 if ( strlen( $id_bin ) !== 128 ) {
 262                         throw new RuntimeException( "Detected overflow for millisecond timestamp." );
 263                 }
 264                 $hex = Wikimedia\base_convert( $id_bin, 2, 16, 32 );
 265                 return sprintf( '%s-%s-%s-%s-%s',
 266                         // "time_low" (32 bits)
 267                         substr( $hex, 0, 8 ),
 268                         // "time_mid" (16 bits)
 269                         substr( $hex, 8, 4 ),
 270                         // "time_hi_and_version" (16 bits)
 271                         substr( $hex, 12, 4 ),
 272                         // "clk_seq_hi_res" (8 bits) and "clk_seq_low" (8 bits)
 273                         substr( $hex, 16, 4 ),
 274                         // "node" (48 bits)
 275                         substr( $hex, 20, 12 )
 276                 );
 277         }
 278
 279         /**
 280          * Return an RFC4122 compliant v4 UUID
 281          *
 282          * @param int $flags Bitfield (supports UIDGenerator::QUICK_RAND)
 283          * @return string
 284          * @throws RuntimeException
 285          */
 286         public static function newUUIDv4( $flags = 0 ) {
 287                 $hex = ( $flags & self::QUICK_RAND )
 288                         ? wfRandomString( 31 )
 289                         : MWCryptRand::generateHex( 31 );
 290
 291                 return sprintf( '%s-%s-%s-%s-%s',
 292                         // "time_low" (32 bits)
 293                         substr( $hex, 0, 8 ),
 294                         // "time_mid" (16 bits)
 295                         substr( $hex, 8, 4 ),
 296                         // "time_hi_and_version" (16 bits)
 297                         '4' . substr( $hex, 12, 3 ),
 298                         // "clk_seq_hi_res" (8 bits, variant is binary 10x) and "clk_seq_low" (8 bits)
 299                         dechex( 0x8 | ( hexdec( $hex[15] ) & 0x3 ) ) . $hex[16] . substr( $hex, 17, 2 ),
 300                         // "node" (48 bits)
 301                         substr( $hex, 19, 12 )
 302                 );
 303         }
 304
 305         /**
 306          * Return an RFC4122 compliant v4 UUID
 307          *
 308          * @param int $flags Bitfield (supports UIDGenerator::QUICK_RAND)
 309          * @return string 32 hex characters with no hyphens
 310          * @throws RuntimeException
 311          */
 312         public static function newRawUUIDv4( $flags = 0 ) {
 313                 return str_replace( '-', '', self::newUUIDv4( $flags ) );
 314         }
 315
 316         /**
 317          * Return an ID that is sequential *only* for this node and bucket
 318          *
 319          * These IDs are suitable for per-host sequence numbers, e.g. for some packet protocols.
 320          * If UIDGenerator::QUICK_VOLATILE is used the counter might reset on server restart.
 321          *
 322          * @param string $bucket Arbitrary bucket name (should be ASCII)
 323          * @param int $bits Bit size (<=48) of resulting numbers before wrap-around
 324          * @param int $flags (supports UIDGenerator::QUICK_VOLATILE)
 325          * @return float Integer value as float
 326          * @since 1.23
 327          */
 328         public static function newSequentialPerNodeID( $bucket, $bits = 48, $flags = 0 ) {
 329                 return current( self::newSequentialPerNodeIDs( $bucket, $bits, 1, $flags ) );
 330         }
 331
 332         /**
 333          * Return IDs that are sequential *only* for this node and bucket
 334          *
 335          * @see UIDGenerator::newSequentialPerNodeID()
 336          * @param string $bucket Arbitrary bucket name (should be ASCII)
 337          * @param int $bits Bit size (16 to 48) of resulting numbers before wrap-around
 338          * @param int $count Number of IDs to return
 339          * @param int $flags (supports UIDGenerator::QUICK_VOLATILE)
 340          * @return array Ordered list of float integer values
 341          * @since 1.23
 342          */
 343         public static function newSequentialPerNodeIDs( $bucket, $bits, $count, $flags = 0 ) {
 344                 $gen = self::singleton();
 345                 return $gen->getSequentialPerNodeIDs( $bucket, $bits, $count, $flags );
 346         }
 347
 348         /**
 349          * Return IDs that are sequential *only* for this node and bucket
 350          *
 351          * @see UIDGenerator::newSequentialPerNodeID()
 352          * @param string $bucket Arbitrary bucket name (should be ASCII)
 353          * @param int $bits Bit size (16 to 48) of resulting numbers before wrap-around
 354          * @param int $count Number of IDs to return
 355          * @param int $flags (supports UIDGenerator::QUICK_VOLATILE)
 356          * @return array Ordered list of float integer values
 357          * @throws RuntimeException
 358          */
 359         protected function getSequentialPerNodeIDs( $bucket, $bits, $count, $flags ) {
 360                 if ( $count <= 0 ) {
 361                         return []; // nothing to do
 362                 } elseif ( $bits < 16 || $bits > 48 ) {
 363                         throw new RuntimeException( "Requested bit size ($bits) is out of range." );
 364                 }
 365
 366                 $counter = null; // post-increment persistent counter value
 367
 368                 // Use APC/eAccelerator/xcache if requested, available, and not in CLI mode;
 369                 // Counter values would not survive accross script instances in CLI mode.
 370                 $cache = null;
 371                 if ( ( $flags & self::QUICK_VOLATILE ) && PHP_SAPI !== 'cli' ) {
 372                         $cache = MediaWikiServices::getInstance()->getLocalServerObjectCache();
 373                 }
 374                 if ( $cache ) {
 375                         $counter = $cache->incrWithInit( $bucket, $cache::TTL_INDEFINITE, $count, $count );
 376                         if ( $counter === false ) {
 377                                 throw new RuntimeException( 'Unable to set value to ' . get_class( $cache ) );
 378                         }
 379                 }
 380
 381                 // Note: use of fmod() avoids "division by zero" on 32 bit machines
 382                 if ( $counter === null ) {
 383                         $path = wfTempDir() . '/mw-' . __CLASS__ . '-' . rawurlencode( $bucket ) . '-48';
 384                         // Get the UID lock file handle
 385                         if ( isset( $this->fileHandles[$path] ) ) {
 386                                 $handle = $this->fileHandles[$path];
 387                         } else {
 388                                 $handle = fopen( $path, 'cb+' );
 389                                 $this->fileHandles[$path] = $handle ?: null; // cache
 390                         }
 391                         // Acquire the UID lock file
 392                         if ( $handle === false ) {
 393                                 throw new RuntimeException( "Could not open '{$path}'." );
 394                         } elseif ( !flock( $handle, LOCK_EX ) ) {
 395                                 fclose( $handle );
 396                                 throw new RuntimeException( "Could not acquire '{$path}'." );
 397                         }
 398                         // Fetch the counter value and increment it...
 399                         rewind( $handle );
 400                         $counter = floor( trim( fgets( $handle ) ) ) + $count; // fetch as float
 401                         // Write back the new counter value
 402                         ftruncate( $handle, 0 );
 403                         rewind( $handle );
 404                         fwrite( $handle, fmod( $counter, pow( 2, 48 ) ) ); // warp-around as needed
 405                         fflush( $handle );
 406                         // Release the UID lock file
 407                         flock( $handle, LOCK_UN );
 408                 }
 409
 410                 $ids = [];
 411                 $divisor = pow( 2, $bits );
 412                 $currentId = floor( $counter - $count ); // pre-increment counter value
 413                 for ( $i = 0; $i < $count; ++$i ) {
 414                         $ids[] = fmod( ++$currentId, $divisor );
 415                 }
 416
 417                 return $ids;
 418         }
 419
 420         /**
 421          * Get a (time,counter,clock sequence) where (time,counter) is higher
 422          * than any previous (time,counter) value for the given clock sequence.
 423          * This is useful for making UIDs sequential on a per-node bases.
 424          *
 425          * @param string $lockFile Name of a local lock file
 426          * @param int $clockSeqSize The number of possible clock sequence values
 427          * @param int $counterSize The number of possible counter values
 428          * @param int $offsetSize The number of possible offset values
 429          * @return array (result of UIDGenerator::millitime(), counter, clock sequence)
 430          * @throws RuntimeException
 431          */
 432         protected function getTimeAndDelay( $lockFile, $clockSeqSize, $counterSize, $offsetSize ) {
 433                 // Get the UID lock file handle
 434                 if ( isset( $this->fileHandles[$lockFile] ) ) {
 435                         $handle = $this->fileHandles[$lockFile];
 436                 } else {
 437                         $handle = fopen( $this->$lockFile, 'cb+' );
 438                         $this->fileHandles[$lockFile] = $handle ?: null; // cache
 439                 }
 440                 // Acquire the UID lock file
 441                 if ( $handle === false ) {
 442                         throw new RuntimeException( "Could not open '{$this->$lockFile}'." );
 443                 } elseif ( !flock( $handle, LOCK_EX ) ) {
 444                         fclose( $handle );
 445                         throw new RuntimeException( "Could not acquire '{$this->$lockFile}'." );
 446                 }
 447                 // Get the current timestamp, clock sequence number, last time, and counter
 448                 rewind( $handle );
 449                 $data = explode( ' ', fgets( $handle ) ); // "<clk seq> <sec> <msec> <counter> <offset>"
 450                 $clockChanged = false; // clock set back significantly?
 451                 if ( count( $data ) == 5 ) { // last UID info already initialized
 452                         $clkSeq = (int)$data[0] % $clockSeqSize;
 453                         $prevTime = [ (int)$data[1], (int)$data[2] ];
 454                         $offset = (int)$data[4] % $counterSize; // random counter offset
 455                         $counter = 0; // counter for UIDs with the same timestamp
 456                         // Delay until the clock reaches the time of the last ID.
 457                         // This detects any microtime() drift among processes.
 458                         $time = $this->timeWaitUntil( $prevTime );
 459                         if ( !$time ) { // too long to delay?
 460                                 $clockChanged = true; // bump clock sequence number
 461                                 $time = self::millitime();
 462                         } elseif ( $time == $prevTime ) {
 463                                 // Bump the counter if there are timestamp collisions
 464                                 $counter = (int)$data[3] % $counterSize;
 465                                 if ( ++$counter >= $counterSize ) { // sanity (starts at 0)
 466                                         flock( $handle, LOCK_UN ); // abort
 467                                         throw new RuntimeException( "Counter overflow for timestamp value." );
 468                                 }
 469                         }
 470                 } else { // last UID info not initialized
 471                         $clkSeq = mt_rand( 0, $clockSeqSize - 1 );
 472                         $counter = 0;
 473                         $offset = mt_rand( 0, $offsetSize - 1 );
 474                         $time = self::millitime();
 475                 }
 476                 // microtime() and gettimeofday() can drift from time() at least on Windows.
 477                 // The drift is immediate for processes running while the system clock changes.
 478                 // time() does not have this problem. See https://bugs.php.net/bug.php?id=42659.
 479                 if ( abs( time() - $time[0] ) >= 2 ) {
 480                         // We don't want processes using too high or low timestamps to avoid duplicate
 481                         // UIDs and clock sequence number churn. This process should just be restarted.
 482                         flock( $handle, LOCK_UN ); // abort
 483                         throw new RuntimeException( "Process clock is outdated or drifted." );
 484                 }
 485                 // If microtime() is synced and a clock change was detected, then the clock went back
 486                 if ( $clockChanged ) {
 487                         // Bump the clock sequence number and also randomize the counter offset,
 488                         // which is useful for UIDs that do not include the clock sequence number.
 489                         $clkSeq = ( $clkSeq + 1 ) % $clockSeqSize;
 490                         $offset = mt_rand( 0, $offsetSize - 1 );
 491                         trigger_error( "Clock was set back; sequence number incremented." );
 492                 }
 493                 // Update the (clock sequence number, timestamp, counter)
 494                 ftruncate( $handle, 0 );
 495                 rewind( $handle );
 496                 fwrite( $handle, "{$clkSeq} {$time[0]} {$time[1]} {$counter} {$offset}" );
 497                 fflush( $handle );
 498                 // Release the UID lock file
 499                 flock( $handle, LOCK_UN );
 500
 501                 return [
 502                         'time'          => $time,
 503                         'counter'       => $counter,
 504                         'clkSeq'        => $clkSeq,
 505                         'offset'        => $offset,
 506                         'offsetCounter' => $counter + $offset
 507                 ];
 508         }
 509
 510         /**
 511          * Wait till the current timestamp reaches $time and return the current
 512          * timestamp. This returns false if it would have to wait more than 10ms.
 513          *
 514          * @param array $time Result of UIDGenerator::millitime()
 515          * @return array|bool UIDGenerator::millitime() result or false
 516          */
 517         protected function timeWaitUntil( array $time ) {
 518                 do {
 519                         $ct = self::millitime();
 520                         if ( $ct >= $time ) { // https://secure.php.net/manual/en/language.operators.comparison.php
 521                                 return $ct; // current timestamp is higher than $time
 522                         }
 523                 } while ( ( ( $time[0] - $ct[0] ) * 1000 + ( $time[1] - $ct[1] ) ) <= 10 );
 524
 525                 return false;
 526         }
 527
 528         /**
 529          * @param array $time Result of UIDGenerator::millitime()
 530          * @return string 46 LSBs of "milliseconds since epoch" in binary (rolls over in 4201)
 531          * @throws RuntimeException
 532          */
 533         protected function millisecondsSinceEpochBinary( array $time ) {
 534                 list( $sec, $msec ) = $time;
 535                 $ts = 1000 * $sec + $msec;
 536                 if ( $ts > pow( 2, 52 ) ) {
 537                         throw new RuntimeException( __METHOD__ .
 538                                 ': sorry, this function doesn\'t work after the year 144680' );
 539                 }
 540
 541                 return substr( Wikimedia\base_convert( $ts, 10, 2, 46 ), -46 );
 542         }
 543
 544         /**
 545          * @param array $time Result of UIDGenerator::millitime()
 546          * @param integer $delta Number of intervals to add on to the timestamp
 547          * @return string 60 bits of "100ns intervals since 15 October 1582" (rolls over in 3400)
 548          * @throws RuntimeException
 549          */
 550         protected function intervalsSinceGregorianBinary( array $time, $delta = 0 ) {
 551                 list( $sec, $msec ) = $time;
 552                 $offset = '122192928000000000';
 553                 if ( PHP_INT_SIZE >= 8 ) { // 64 bit integers
 554                         $ts = ( 1000 * $sec + $msec ) * 10000 + (int)$offset + $delta;
 555                         $id_bin = str_pad( decbin( $ts % pow( 2, 60 ) ), 60, '0', STR_PAD_LEFT );
 556                 } elseif ( extension_loaded( 'gmp' ) ) {
 557                         $ts = gmp_add( gmp_mul( (string)$sec, '1000' ), (string)$msec ); // ms
 558                         $ts = gmp_add( gmp_mul( $ts, '10000' ), $offset ); // 100ns intervals
 559                         $ts = gmp_add( $ts, (string)$delta );
 560                         $ts = gmp_mod( $ts, gmp_pow( '2', '60' ) ); // wrap around
 561                         $id_bin = str_pad( gmp_strval( $ts, 2 ), 60, '0', STR_PAD_LEFT );
 562                 } elseif ( extension_loaded( 'bcmath' ) ) {
 563                         $ts = bcadd( bcmul( $sec, 1000 ), $msec ); // ms
 564                         $ts = bcadd( bcmul( $ts, 10000 ), $offset ); // 100ns intervals
 565                         $ts = bcadd( $ts, $delta );
 566                         $ts = bcmod( $ts, bcpow( 2, 60 ) ); // wrap around
 567                         $id_bin = Wikimedia\base_convert( $ts, 10, 2, 60 );
 568                 } else {
 569                         throw new RuntimeException( 'bcmath or gmp extension required for 32 bit machines.' );
 570                 }
 571                 return $id_bin;
 572         }
 573
 574         /**
 575          * @return array (current time in seconds, milliseconds since then)
 576          */
 577         protected static function millitime() {
 578                 list( $msec, $sec ) = explode( ' ', microtime() );
 579
 580                 return [ (int)$sec, (int)( $msec * 1000 ) ];
 581         }
 582
 583         /**
 584          * Delete all cache files that have been created.
 585          *
 586          * This is a cleanup method primarily meant to be used from unit tests to
 587          * avoid poluting the local filesystem. If used outside of a unit test
 588          * environment it should be used with caution as it may destroy state saved
 589          * in the files.
 590          *
 591          * @see unitTestTearDown
 592          * @since 1.23
 593          */
 594         protected function deleteCacheFiles() {
 595                 // Bug: 44850
 596                 foreach ( $this->fileHandles as $path => $handle ) {
 597                         if ( $handle !== null ) {
 598                                 fclose( $handle );
 599                         }
 600                         if ( is_file( $path ) ) {
 601                                 unlink( $path );
 602                         }
 603                         unset( $this->fileHandles[$path] );
 604                 }
 605                 if ( is_file( $this->nodeIdFile ) ) {
 606                         unlink( $this->nodeIdFile );
 607                 }
 608         }
 609
 610         /**
 611          * Cleanup resources when tearing down after a unit test.
 612          *
 613          * This is a cleanup method primarily meant to be used from unit tests to
 614          * avoid poluting the local filesystem. If used outside of a unit test
 615          * environment it should be used with caution as it may destroy state saved
 616          * in the files.
 617          *
 618          * @see deleteCacheFiles
 619          * @since 1.23
 620          */
 621         public static function unitTestTearDown() {
 622                 // Bug: 44850
 623                 $gen = self::singleton();
 624                 $gen->deleteCacheFiles();
 625         }
 626
 627         function __destruct() {
 628                 array_map( 'fclose', array_filter( $this->fileHandles ) );
 629         }
 630 }