inc/classes/main/stacker/file/class_BaseFileStack.php

   1 <?php
   2 /**
   3  * A general file-based stack class
   4  *
   5  * @author              Roland Haeder <webmaster@ship-simu.org>
   6  * @version             0.0.0
   7  * @copyright   Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2013 Core Developer Team
   8  * @license             GNU GPL 3.0 or any newer version
   9  * @link                http://www.ship-simu.org
  10  *
  11  * This program is free software: you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation, either version 3 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  23  */
  24 class BaseFileStack extends BaseStacker {
  25         /**
  26          * Magic for this stack
  27          */
  28         const STACK_MAGIC = 'STACKv0.1';
  29
  30         /**
  31          * Separator for header data
  32          */
  33         const SEPARATOR_HEADER_DATA = 0x01;
  34
  35         /**
  36          * Separator header->entries
  37          */
  38         const SEPARATOR_HEADER_ENTRIES = 0x02;
  39
  40         /**
  41          * Separator hash->name
  42          */
  43         const SEPARATOR_HASH_NAME = 0x03;
  44
  45         /**
  46          * Length of name
  47          */
  48         const LENGTH_NAME = 10;
  49
  50         /**
  51          * Length of count
  52          */
  53         const LENGTH_COUNT = 20;
  54
  55         /**
  56          * Length of position
  57          */
  58         const LENGTH_POSITION = 20;
  59
  60         /**
  61          * Counter for total entries
  62          */
  63         private $totalEntries = 0;
  64
  65         /**
  66          * Current seek position
  67          */
  68         private $seekPosition = 0;
  69
  70         /**
  71          * Size of header
  72          */
  73         private $headerSize = 0;
  74
  75         /**
  76          * File header
  77          */
  78         private $header = array();
  79
  80         /**
  81          * Seek positions for gaps ("fragmentation")
  82          */
  83         private $gaps = array();
  84
  85         /**
  86          * Seek positions for damaged entries (e.g. mismatching hash sum, ...)
  87          */
  88         private $damagedEntries = array();
  89
  90         /**
  91          * Protected constructor
  92          *
  93          * @param       $className      Name of the class
  94          * @return      void
  95          */
  96         protected function __construct ($className) {
  97                 // Call parent constructor
  98                 parent::__construct($className);
  99
 100                 // Calculate header size
 101                 $this->headerSize = (
 102                         strlen(self::STACK_MAGIC) +
 103                         strlen(self::SEPARATOR_HEADER_DATA) +
 104                         self::LENGTH_COUNT +
 105                         strlen(self::SEPARATOR_HEADER_DATA) +
 106                         self::LENGTH_POSITION +
 107                         strlen(self::SEPARATOR_HEADER_ENTRIES)
 108                 );
 109
 110                 // Init counters and gaps array
 111                 $this->initCountersGapsArray();
 112         }
 113
 114         /**
 115          * Initializes counter for valid entries, arrays for damaged entries and
 116          * an array for gap seek positions. If you call this method on your own,
 117          * please re-analyze the file structure. So you are better to call
 118          * analyzeStackFile() instead of this method.
 119          *
 120          * @return      void
 121          */
 122         private function initCountersGapsArray () {
 123                 // Init counter and seek position
 124                 $this->setCounter(0);
 125                 $this->setSeekPosition(0);
 126
 127                 // Init arrays
 128                 $this->gaps = array();
 129                 $this->damagedEntries = array();
 130         }
 131
 132         /**
 133          * Getter for total entries
 134          *
 135          * @return      $totalEntries   Total entries in this stack
 136          */
 137         private final function getCounter () {
 138                 // Get it
 139                 return $this->totalEntries;
 140         }
 141
 142         /**
 143          * Setter for total entries
 144          *
 145          * @param       $totalEntries   Total entries in this stack
 146          * @return      void
 147          */
 148         private final function setCounter ($counter) {
 149                 // Set it
 150                 $this->totalEntries = $counter;
 151         }
 152
 153         /**
 154          * Increment counter
 155          *
 156          * @return      void
 157          */
 158         private final function incrementCounter () {
 159                 // Get it
 160                 $this->totalEntries++;
 161         }
 162
 163         /**
 164          * Getter for seek position
 165          *
 166          * @return      $seekPosition   Current seek position (stored here in object)
 167          */
 168         private final function getSeekPosition () {
 169                 // Get it
 170                 return $this->seekPosition;
 171         }
 172
 173         /**
 174          * Setter for seek position
 175          *
 176          * @param       $seekPosition   Current seek position (stored here in object)
 177          * @return      void
 178          */
 179         private final function setSeekPosition ($seekPosition) {
 180                 // And set it
 181                 $this->seekPosition = $seekPosition;
 182         }
 183
 184         /**
 185          * Updates seekPosition attribute from file to avoid to much access on file.
 186          *
 187          * @return      void
 188          */
 189         private function updateSeekPosition () {
 190                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 191
 192                 // Get key (= seek position)
 193                 $seekPosition = $this->getIteratorInstance()->key();
 194                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Setting seekPosition=%s', __METHOD__, __LINE__, $seekPosition));
 195
 196                 // And set it here
 197                 $this->setSeekPosition($seekPosition);
 198
 199                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 200         }
 201
 202         /**
 203          * Reads the file header
 204          *
 205          * @return      void
 206          */
 207         private function readFileHeader () {
 208                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 209
 210                 // First rewind to beginning as the header sits at the beginning ...
 211                 $this->getIteratorInstance()->rewind();
 212
 213                 // Then read it (see constructor for calculation)
 214                 $data = $this->getIteratorInstance()->read($this->headerSize);
 215                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Read %d bytes (%d wanted).', __METHOD__, __LINE__, strlen($data), $this->headerSize));
 216
 217                 // Have all requested bytes been read?
 218                 assert(strlen($data) == $this->headerSize);
 219                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Passed assert().', __METHOD__, __LINE__));
 220
 221                 // Last character must be the separator
 222                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] data(-1)=%s', __METHOD__, __LINE__, dechex(ord(substr($data, -1, 1)))));
 223                 assert(substr($data, -1, 1) == chr(self::SEPARATOR_HEADER_ENTRIES));
 224                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Passed assert().', __METHOD__, __LINE__));
 225
 226                 // Okay, then remove it
 227                 $data = substr($data, 0, -1);
 228
 229                 // And update seek position
 230                 $this->updateSeekPosition();
 231
 232                 /*
 233                  * Now split it:
 234                  *
 235                  * 0 => Magic
 236                  * 1 => Total entries
 237                  * 2 => Current seek position
 238                  */
 239                 $this->header = explode(chr(self::SEPARATOR_HEADER_DATA), $data);
 240
 241                 // Check if the array has only 3 elements
 242                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] header(%d)=%s', __METHOD__, __LINE__, count($this->header), print_r($this->header, TRUE)));
 243                 assert(count($this->header) == 3);
 244                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Passed assert().', __METHOD__, __LINE__));
 245
 246                 // Check magic
 247                 assert($this->header[0] == self::STACK_MAGIC);
 248                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Passed assert().', __METHOD__, __LINE__));
 249
 250                 // Check length of count and seek position
 251                 assert(strlen($this->header[1]) == self::LENGTH_COUNT);
 252                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Passed assert().', __METHOD__, __LINE__));
 253                 assert(strlen($this->header[2]) == self::LENGTH_POSITION);
 254                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Passed assert().', __METHOD__, __LINE__));
 255
 256                 // Decode count and seek position
 257                 $this->header[1] = hex2bin($this->header[1]);
 258                 $this->header[2] = hex2bin($this->header[2]);
 259
 260                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 261         }
 262
 263         /**
 264          * Checks whether the file header is initialized
 265          *
 266          * @return      $isInitialized  Whether the file header is initialized
 267          */
 268         private function isFileHeaderInitialized () {
 269                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 270                 // Default is not initialized
 271                 $isInitialized = FALSE;
 272
 273                 // Is the file initialized?
 274                 if ($this->isFileInitialized()) {
 275                         // Some bytes has been written, so rewind to start of it.
 276                         $rewindStatus = $this->getIteratorInstance()->rewind();
 277                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] rewindStatus=%s', __METHOD__, __LINE__, $rewindStatus));
 278
 279                         // Is the rewind() call successfull?
 280                         if ($rewindStatus != 1) {
 281                                 // Something bad happened
 282                                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Could not rewind().', __METHOD__, __LINE__));
 283                         } // END - if
 284
 285                         // Read file header
 286                         $this->readFileHeader();
 287
 288                         // The above method does already check the header
 289                         $isInitialized = TRUE;
 290                 } // END - if
 291
 292                 // Return result
 293                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] isInitialized=%d - EXIT!', __METHOD__, __LINE__, intval($isInitialized)));
 294                 return $isInitialized;
 295         }
 296
 297         /**
 298          * Checks whether the file-based stack has been initialized
 299          *
 300          * @return      $isInitialized          Whether the file's size is zero
 301          */
 302         private function isFileInitialized () {
 303                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 304
 305                 // Get it from iterator which holds the pointer instance. If FALSE is returned
 306                 $fileSize = $this->getIteratorInstance()->size();
 307                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] fileSize=%s', __METHOD__, __LINE__, $fileSize));
 308
 309                 /*
 310                  * The returned file size should not be FALSE or NULL as this means
 311                  * that the pointer class does not work correctly.
 312                  */
 313                 assert(is_int($fileSize));
 314
 315                 // Is more than 0 returned?
 316                 $isInitialized = ($fileSize > 0);
 317
 318                 // Return result
 319                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] isInitialized=%d - EXIT!', __METHOD__, __LINE__, intval($isInitialized)));
 320                 return $isInitialized;
 321         }
 322
 323         /**
 324          * Creates the file-stack's header
 325          *
 326          * @return      void
 327          */
 328         private function createFileHeader () {
 329                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 330                 // The file's header should not be initialized here
 331                 assert(!$this->isFileHeaderInitialized());
 332
 333                 // Simple flush file header which will create it.
 334                 $this->flushFileHeader();
 335
 336                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!!', __METHOD__, __LINE__));
 337         }
 338
 339         /**
 340          * Flushes the file header
 341          *
 342          * @return      void
 343          */
 344         private function flushFileHeader () {
 345                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 346
 347                 // Put all informations together
 348                 $header = sprintf('%s%s%s%s%s%s',
 349                         // Magic
 350                         self::STACK_MAGIC,
 351
 352                         // Separator magic<->count
 353                         chr(self::SEPARATOR_HEADER_DATA),
 354
 355                         // Total entries (will be zero) and pad it to 20 chars
 356                         str_pad($this->dec2hex($this->getCounter()), self::LENGTH_COUNT, '0', STR_PAD_LEFT),
 357
 358                         // Separator count<->seek position
 359                         chr(self::SEPARATOR_HEADER_DATA),
 360
 361                         // Position (will be zero)
 362                         str_pad($this->dec2hex($this->getSeekPosition(), 2), self::LENGTH_POSITION, '0', STR_PAD_LEFT),
 363
 364                         // Separator position<->entries
 365                         chr(self::SEPARATOR_HEADER_ENTRIES)
 366                 );
 367
 368                 // Write it to disk (header is always at seek position 0)
 369                 $this->writeData(0, $header);
 370
 371                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 372         }
 373
 374         /**
 375          * Writes data at given position
 376          *
 377          * @param       $seekPosition   Seek position
 378          * @param       $data                   Data to be written
 379          * @return      void
 380          */
 381         private function writeData ($seekPosition, $data) {
 382                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] seekPosition=%s,data()=%s - CALLED!', __METHOD__, __LINE__, $seekPosition, strlen($data)));
 383
 384                 // Write data at given position
 385                 $this->getIteratorInstance()->writeAtPosition($seekPosition, $data);
 386
 387                 // Update seek position
 388                 $this->updateSeekPosition();
 389
 390                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 391         }
 392
 393         /**
 394          * Pre-allocates file (if enabled) with some space for later faster write access.
 395          *
 396          * @return      void
 397          */
 398         private function preAllocateFile () {
 399                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 400
 401                 // Is it enabled?
 402                 if ($this->getConfigInstance()->getConfigEntry('file_stack_pre_allocate_enabled') != 'Y') {
 403                         // Not enabled
 404                         self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Not pre-allocating stack file.', __METHOD__, __LINE__));
 405
 406                         // Don't continue here.
 407                         return;
 408                 } // END - if
 409
 410                 // Message to user
 411                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Pre-allocating stack file ...', __METHOD__, __LINE__));
 412
 413                 /*
 414                  * Calculate minimum length for one entry:
 415                  * minimum length = hash length + separator + name + minimum entry size = ?? + 1 + 10 + 1 = ??
 416                  */
 417                 $minLengthEntry = self::getHashLength() + strlen(self::SEPARATOR_HASH_NAME) + self::LENGTH_NAME + 1;
 418                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] minLengthEntry=%s', __METHOD__, __LINE__, $minLengthEntry));
 419
 420                 // Calulcate seek position
 421                 $seekPosition = $minLengthEntry * $this->getConfigInstance()->getConfigEntry('file_stack_pre_allocate_count');
 422                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] seekPosition=%s', __METHOD__, __LINE__, $seekPosition));
 423
 424                 // Now simply write a NUL there. This will pre-allocate the file.
 425                 $this->writeData($seekPosition, chr(0));
 426
 427                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 428         }
 429
 430         /**
 431          * Analyzes entries in stack file. This will count all found (and valid)
 432          * entries, mark invalid as damaged and count gaps ("fragmentation"). If
 433          * only gaps are found, the file is considered as "virgin" (no entries).
 434          *
 435          * @return      void
 436          */
 437         private function analyzeStackFile () {
 438                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 439
 440                 // Make sure the file is initialized
 441                 assert($this->isFileInitialized());
 442
 443                 // Init counters and gaps array
 444                 $this->initCountersGapsArray();
 445
 446                 // Output message (as this may take some time)
 447                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Analyzing file structure ... (this may take some time)', __METHOD__, __LINE__));
 448
 449                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 450         }
 451
 452         /**
 453          * Initializes this file-based stack.
 454          *
 455          * @param       $fileName       File name of this stack
 456          * @param       $type           Type of this stack (e.g. url_source for URL sources)
 457          * @return      void
 458          */
 459         protected function initFileStack ($fileName, $type) {
 460                 // Get a file i/o pointer instance for stack file
 461                 $pointerInstance = ObjectFactory::createObjectByConfiguredName('file_raw_input_output_class', array($fileName));
 462
 463                 // Get iterator instance
 464                 $iteratorInstance = ObjectFactory::createObjectByConfiguredName('file_io_iterator_class', array($pointerInstance));
 465
 466                 // Is the instance implementing the right interface?
 467                 assert($iteratorInstance instanceof SeekableWritableFileIterator);
 468
 469                 // Set iterator here
 470                 $this->setIteratorInstance($iteratorInstance);
 471
 472                 // Is the file's header initialized?
 473                 if (!$this->isFileHeaderInitialized()) {
 474                         // No, then create it (which may pre-allocate the stack)
 475                         $this->createFileHeader();
 476
 477                         // And pre-allocate a bit
 478                         $this->preAllocateFile();
 479                 } // END - if
 480
 481                 // Load the file header
 482                 $this->readFileHeader();
 483
 484                 // Count all entries in file
 485                 $this->analyzeStackFile();
 486
 487                 /*
 488                  * Get stack index instance. This can be used for faster
 489                  * "defragmentation" and startup.
 490                  */
 491                 $indexInstance = FileStackIndexFactory::createFileStackIndexInstance($fileName, $type);
 492
 493                 // And set it here
 494                 $this->setIndexInstance($indexInstance);
 495         }
 496
 497         /**
 498          * Adds a value to given stack
 499          *
 500          * @param       $stackerName    Name of the stack
 501          * @param       $value                  Value to add to this stacker
 502          * @return      void
 503          * @throws      FullStackerException    If the stack is full
 504          */
 505         protected function addValue ($stackerName, $value) {
 506                 // Do some tests
 507                 if ($this->isStackFull($stackerName)) {
 508                         // Stacker is full
 509                         throw new FullStackerException(array($this, $stackerName, $value), self::EXCEPTION_STACKER_IS_FULL);
 510                 } // END - if
 511
 512                 // Now add the value to the stack
 513                 $this->partialStub('stackerName=' . $stackerName . ',value[]=' . gettype($value));
 514         }
 515
 516         /**
 517          * Get last value from named stacker
 518          *
 519          * @param       $stackerName    Name of the stack
 520          * @return      $value                  Value of last added value
 521          * @throws      EmptyStackerException   If the stack is empty
 522          */
 523         protected function getLastValue ($stackerName) {
 524                 // Is the stack not yet initialized or full?
 525                 if ($this->isStackEmpty($stackerName)) {
 526                         // Throw an exception
 527                         throw new EmptyStackerException(array($this, $stackerName), self::EXCEPTION_STACKER_IS_EMPTY);
 528                 } // END - if
 529
 530                 // Now get the last value
 531                 $this->partialStub('stackerName=' . $stackerName);
 532                 $value = NULL;
 533
 534                 // Return it
 535                 return $value;
 536         }
 537
 538         /**
 539          * Get first value from named stacker
 540          *
 541          * @param       $stackerName    Name of the stack
 542          * @return      $value                  Value of last added value
 543          * @throws      EmptyStackerException   If the stack is empty
 544          */
 545         protected function getFirstValue ($stackerName) {
 546                 // Is the stack not yet initialized or full?
 547                 if ($this->isStackEmpty($stackerName)) {
 548                         // Throw an exception
 549                         throw new EmptyStackerException(array($this, $stackerName), self::EXCEPTION_STACKER_IS_EMPTY);
 550                 } // END - if
 551
 552                 // Now get the first value
 553                 $this->partialStub('stackerName=' . $stackerName);
 554                 $value = NULL;
 555
 556                 // Return it
 557                 return $value;
 558         }
 559
 560         /**
 561          * "Pops" last entry from stack
 562          *
 563          * @param       $stackerName    Name of the stack
 564          * @return      $value                  Value "poped" from array
 565          * @throws      EmptyStackerException   If the stack is empty
 566          */
 567         protected function popLast ($stackerName) {
 568                 // Is the stack not yet initialized or full?
 569                 if ($this->isStackEmpty($stackerName)) {
 570                         // Throw an exception
 571                         throw new EmptyStackerException(array($this, $stackerName), self::EXCEPTION_STACKER_IS_EMPTY);
 572                 } // END - if
 573
 574                 // Now, remove the last entry, we don't care about the return value here, see elseif() block above
 575                 $this->partialStub('stackerName=' . $stackerName);
 576                 return NULL;
 577         }
 578
 579         /**
 580          * "Pops" first entry from stack
 581          *
 582          * @param       $stackerName    Name of the stack
 583          * @return      $value                  Value "shifted" from array
 584          * @throws      EmptyStackerException   If the named stacker is empty
 585          */
 586         protected function popFirst ($stackerName) {
 587                 // Is the stack not yet initialized or full?
 588                 if ($this->isStackEmpty($stackerName)) {
 589                         // Throw an exception
 590                         throw new EmptyStackerException(array($this, $stackerName), self::EXCEPTION_STACKER_IS_EMPTY);
 591                 } // END - if
 592
 593                 // Now, remove the last entry, we don't care about the return value here, see elseif() block above
 594                 $this->partialStub('stackerName=' . $stackerName);
 595                 return NULL;
 596         }
 597
 598         /**
 599          * Checks whether the given stack is full
 600          *
 601          * @param       $stackerName    Name of the stack
 602          * @return      $isFull                 Whether the stack is full
 603          */
 604         protected function isStackFull ($stackerName) {
 605                 // File-based stacks will only run full if the disk space is low.
 606                 // @TODO Please implement this, returning FALSE
 607                 $isFull = FALSE;
 608
 609                 // Return result
 610                 return $isFull;
 611         }
 612
 613         /**
 614          * Checks whether the given stack is empty
 615          *
 616          * @param       $stackerName            Name of the stack
 617          * @return      $isEmpty                        Whether the stack is empty
 618          * @throws      NoStackerException      If given stack is missing
 619          */
 620         public function isStackEmpty ($stackerName) {
 621                 // So, is the stack empty?
 622                 $isEmpty = (($this->getStackCount($stackerName)) == 0);
 623
 624                 // Return result
 625                 return $isEmpty;
 626         }
 627
 628         /**
 629          * Initializes given stacker
 630          *
 631          * @param       $stackerName    Name of the stack
 632          * @param       $forceReInit    Force re-initialization
 633          * @return      void
 634          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 635          */
 636         public function initStack ($stackerName, $forceReInit = FALSE) {
 637                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 638         }
 639
 640         /**
 641          * Initializes all stacks
 642          *
 643          * @return      void
 644          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 645          */
 646         public function initStacks (array $stacks, $forceReInit = FALSE) {
 647                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 648         }
 649
 650         /**
 651          * Checks whether the given stack is initialized (set in array $stackers)
 652          *
 653          * @param       $stackerName    Name of the stack
 654          * @return      $isInitialized  Whether the stack is initialized
 655          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 656          */
 657         public function isStackInitialized ($stackerName) {
 658                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 659         }
 660
 661         /**
 662          * Getter for size of given stack (array count)
 663          *
 664          * @param       $stackerName    Name of the stack
 665          * @return      $count                  Size of stack (array count)
 666          */
 667         public function getStackCount ($stackerName) {
 668                 // Now, simply return the found count value, this must be up-to-date then!
 669                 return $this->getCounter();
 670         }
 671 }
 672
 673 // [EOF]
 674 ?>