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

   1 <?php
   2 // Own namespace
   3 namespace Org\Mxchange\CoreFramework\Stacker\Filesystem;
   4
   5 // Import framework stuff
   6 use Org\Mxchange\CoreFramework\Factory\Filesystem\Stack\FileStackIndexFactory;
   7 use Org\Mxchange\CoreFramework\Factory\ObjectFactory;
   8 use Org\Mxchange\CoreFramework\Filesystem\File\BaseBinaryFile;
   9 use Org\Mxchange\CoreFramework\Generic\UnsupportedOperationException;
  10 use Org\Mxchange\CoreFramework\Index\Indexable;
  11 use Org\Mxchange\CoreFramework\Iterator\Filesystem\SeekableWritableFileIterator;
  12 use Org\Mxchange\CoreFramework\Stacker\BaseStacker;
  13
  14 // Import SPL stuff
  15 use \SplFileInfo;
  16
  17 /**
  18  * A general file-based stack class
  19  *
  20  * @author              Roland Haeder <webmaster@ship-simu.org>
  21  * @version             0.0.0
  22  * @copyright   Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2020 Core Developer Team
  23  * @license             GNU GPL 3.0 or any newer version
  24  * @link                http://www.ship-simu.org
  25  *
  26  * This program is free software: you can redistribute it and/or modify
  27  * it under the terms of the GNU General Public License as published by
  28  * the Free Software Foundation, either version 3 of the License, or
  29  * (at your option) any later version.
  30  *
  31  * This program is distributed in the hope that it will be useful,
  32  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  33  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  34  * GNU General Public License for more details.
  35  *
  36  * You should have received a copy of the GNU General Public License
  37  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  38  */
  39 abstract class BaseFileStack extends BaseStacker {
  40         /**
  41          * Magic for this stack
  42          */
  43         const STACK_MAGIC = 'STACKv0.1';
  44
  45         /**
  46          * Name of array index for gap position
  47          */
  48         const ARRAY_INDEX_GAP_POSITION = 'gap';
  49
  50         /**
  51          * Name of array index for hash
  52          */
  53         const ARRAY_INDEX_HASH = 'hash';
  54
  55         /**
  56          * Name of array index for length of raw data
  57          */
  58         const ARRAY_INDEX_DATA_LENGTH = 'length';
  59
  60         /**
  61          * An instance of an Indexable class
  62          */
  63         private $indexInstance = NULL;
  64
  65         /**
  66          * Protected constructor
  67          *
  68          * @param       $className      Name of the class
  69          * @return      void
  70          */
  71         protected function __construct (string $className) {
  72                 // Call parent constructor
  73                 parent::__construct($className);
  74         }
  75
  76         /**
  77          * Setter for Indexable instance
  78          *
  79          * @param       $indexInstance  An instance of an Indexable class
  80          * @return      void
  81          */
  82         protected final function setIndexInstance (Indexable $indexInstance) {
  83                 $this->indexInstance = $indexInstance;
  84         }
  85
  86         /**
  87          * Getter for Indexable instance
  88          *
  89          * @return      $indexInstance  An instance of an Indexable class
  90          */
  91         public final function getIndexInstance () {
  92                 return $this->indexInstance;
  93         }
  94
  95         /**
  96          * Reads the file header
  97          *
  98          * @return      void
  99          * @todo        To hard assertions here, better rewrite them to exceptions
 100          */
 101         public function readFileHeader () {
 102                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: CALLED!', __METHOD__, __LINE__));
 103
 104                 // First rewind to beginning as the header sits at the beginning ...
 105                 $this->getIteratorInstance()->rewind();
 106
 107                 // Then read it (see constructor for calculation)
 108                 $data = $this->getIteratorInstance()->read($this->getIteratorInstance()->getHeaderSize());
 109                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Read %d bytes (%d wanted).', strlen($data), $this->getIteratorInstance()->getHeaderSize()));
 110
 111                 // Have all requested bytes been read?
 112                 assert(strlen($data) == $this->getIteratorInstance()->getHeaderSize());
 113                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Passed assert().', __METHOD__, __LINE__));
 114
 115                 // Last character must be the separator
 116                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: data(-1)=%s', dechex(ord(substr($data, -1, 1)))));
 117                 assert(substr($data, -1, 1) == chr(BaseBinaryFile::SEPARATOR_HEADER_ENTRIES));
 118                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Passed assert().', __METHOD__, __LINE__));
 119
 120                 // Okay, then remove it
 121                 $data = substr($data, 0, -1);
 122
 123                 // And update seek position
 124                 $this->getIteratorInstance()->updateSeekPosition();
 125
 126                 /*
 127                  * Now split it:
 128                  *
 129                  * 0 => magic
 130                  * 1 => total entries
 131                  * 2 => current seek position
 132                  */
 133                 $header = explode(chr(BaseBinaryFile::SEPARATOR_HEADER_DATA), $data);
 134
 135                 // Set header here
 136                 $this->getIteratorInstance()->setHeader($header);
 137
 138                 // Check if the array has only 3 elements
 139                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: header(%d)=%s', count($header), print_r($header, true)));
 140                 assert(count($header) == 3);
 141                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Passed assert().', __METHOD__, __LINE__));
 142
 143                 // Check magic
 144                 assert($header[0] == self::STACK_MAGIC);
 145                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Passed assert().', __METHOD__, __LINE__));
 146
 147                 // Check length of count and seek position
 148                 assert(strlen($header[1]) == BaseBinaryFile::LENGTH_COUNT);
 149                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Passed assert().', __METHOD__, __LINE__));
 150                 assert(strlen($header[2]) == BaseBinaryFile::LENGTH_POSITION);
 151                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Passed assert().', __METHOD__, __LINE__));
 152
 153                 // Decode count and seek position
 154                 $header[1] = hex2bin($header[1]);
 155                 $header[2] = hex2bin($header[2]);
 156
 157                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: EXIT!', __METHOD__, __LINE__));
 158         }
 159
 160         /**
 161          * Flushes the file header
 162          *
 163          * @return      void
 164          */
 165         public function flushFileHeader () {
 166                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: CALLED!', __METHOD__, __LINE__));
 167
 168                 // Put all informations together
 169                 $header = sprintf('%s%s%s%s%s%s',
 170                         // Magic
 171                         self::STACK_MAGIC,
 172
 173                         // Separator magic<->count
 174                         chr(BaseBinaryFile::SEPARATOR_HEADER_DATA),
 175
 176                         // Total entries (will be zero) and pad it to 20 chars
 177                         str_pad($this->dec2hex($this->getIteratorInstance()->getCounter()), BaseBinaryFile::LENGTH_COUNT, '0', STR_PAD_LEFT),
 178
 179                         // Separator count<->seek position
 180                         chr(BaseBinaryFile::SEPARATOR_HEADER_DATA),
 181
 182                         // Position (will be zero)
 183                         str_pad($this->dec2hex($this->getIteratorInstance()->getSeekPosition(), 2), BaseBinaryFile::LENGTH_POSITION, '0', STR_PAD_LEFT),
 184
 185                         // Separator position<->entries
 186                         chr(BaseBinaryFile::SEPARATOR_HEADER_ENTRIES)
 187                 );
 188
 189                 // Write it to disk (header is always at seek position 0)
 190                 $this->getIteratorInstance()->writeData(0, $header, false);
 191
 192                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: EXIT!', __METHOD__, __LINE__));
 193         }
 194
 195         /**
 196          * Initializes this file-based stack.
 197          *
 198          * @param       $fileInfoInstance       An instance of a SplFileInfo class
 199          * @param       $type           Type of this stack (e.g. url_source for URL sources)
 200          * @return      void
 201          * @todo        Currently the stack file is not cached, please implement a memory-handling class and if enough RAM is found, cache the whole stack file.
 202          */
 203         protected function initFileStack (SplFileInfo $fileInfoInstance, string $type) {
 204                 // Get a stack file instance
 205                 $fileInstance = ObjectFactory::createObjectByConfiguredName('stack_file_class', array($fileInfoInstance, $this));
 206
 207                 // Get iterator instance
 208                 $iteratorInstance = ObjectFactory::createObjectByConfiguredName('file_iterator_class', array($fileInstance));
 209
 210                 // Is the instance implementing the right interface?
 211                 assert($iteratorInstance instanceof SeekableWritableFileIterator);
 212
 213                 // Set iterator here
 214                 $this->setIteratorInstance($iteratorInstance);
 215
 216                 // Calculate header size
 217                 $this->getIteratorInstance()->setHeaderSize(
 218                         strlen(self::STACK_MAGIC) +
 219                         strlen(chr(BaseBinaryFile::SEPARATOR_HEADER_DATA)) +
 220                         BaseBinaryFile::LENGTH_COUNT +
 221                         strlen(chr(BaseBinaryFile::SEPARATOR_HEADER_DATA)) +
 222                         BaseBinaryFile::LENGTH_POSITION +
 223                         strlen(chr(BaseBinaryFile::SEPARATOR_HEADER_ENTRIES))
 224                 );
 225
 226                 // Init counters and gaps array
 227                 $this->getIteratorInstance()->initCountersGapsArray();
 228
 229                 // Is the file's header initialized?
 230                 if (!$this->getIteratorInstance()->isFileHeaderInitialized()) {
 231                         // No, then create it (which may pre-allocate the stack)
 232                         $this->getIteratorInstance()->createFileHeader();
 233
 234                         // And pre-allocate a bit
 235                         $this->getIteratorInstance()->preAllocateFile('file_stack');
 236                 } // END - if
 237
 238                 // Load the file header
 239                 $this->readFileHeader();
 240
 241                 // Count all entries in file
 242                 $this->getIteratorInstance()->analyzeFile();
 243
 244                 /*
 245                  * Get stack index instance. This can be used for faster
 246                  * "defragmentation" and startup.
 247                  */
 248                 $indexInstance = FileStackIndexFactory::createFileStackIndexInstance($fileInfoInstance, $type);
 249
 250                 // And set it here
 251                 $this->setIndexInstance($indexInstance);
 252         }
 253
 254         /**
 255          * Adds a value to given stack
 256          *
 257          * @param       $stackerName    Name of the stack
 258          * @param       $value                  Value to add to this stacker
 259          * @return      void
 260          * @throws      FullStackerException    If the stack is full
 261          */
 262         protected function addValue (string $stackerName, $value) {
 263                 // Do some tests
 264                 if ($this->isStackFull($stackerName)) {
 265                         // Stacker is full
 266                         throw new FullStackerException(array($this, $stackerName, $value), self::EXCEPTION_STACKER_IS_FULL);
 267                 } // END - if
 268
 269                 // No objects/resources are allowed as their serialization takes to long
 270                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('[' . __METHOD__ . ':' . __LINE__ . '] stackerName=' . $stackerName . ',value[' . gettype($value) . ']=' . print_r($value, true));
 271                 assert(!is_object($value));
 272                 assert(!is_resource($value));
 273
 274                 /*
 275                  * Now add the value to the file stack which returns gap position, a
 276                  * hash and length of the raw data.
 277                  */
 278                 $data = $this->getIteratorInstance()->writeValueToFile($stackerName, $value);
 279
 280                 // Add the hash and gap position to the index
 281                 $this->getIndexInstance()->addHashToIndex($stackerName, $data);
 282         }
 283
 284         /**
 285          * Get last value from named stacker
 286          *
 287          * @param       $stackerName    Name of the stack
 288          * @return      $value                  Value of last added value
 289          * @throws      EmptyStackerException   If the stack is empty
 290          */
 291         protected function getLastValue (string $stackerName) {
 292                 // Is the stack not yet initialized or full?
 293                 if ($this->isStackEmpty($stackerName)) {
 294                         // Throw an exception
 295                         throw new EmptyStackerException(array($this, $stackerName), self::EXCEPTION_STACKER_IS_EMPTY);
 296                 } // END - if
 297
 298                 // Now get the last value
 299                 /* NOISY-DEBUG: */ $this->partialStub('[' . __METHOD__ . ':' . __LINE__ . '] stackerName=' . $stackerName);
 300                 $value = NULL;
 301
 302                 // Return it
 303                 return $value;
 304         }
 305
 306         /**
 307          * Get first value from named stacker
 308          *
 309          * @param       $stackerName    Name of the stack
 310          * @return      $value                  Value of last added value
 311          * @throws      EmptyStackerException   If the stack is empty
 312          */
 313         protected function getFirstValue (string $stackerName) {
 314                 // Is the stack not yet initialized or full?
 315                 if ($this->isStackEmpty($stackerName)) {
 316                         // Throw an exception
 317                         throw new EmptyStackerException(array($this, $stackerName), self::EXCEPTION_STACKER_IS_EMPTY);
 318                 } // END - if
 319
 320                 // Now get the first value
 321                 /* NOISY-DEBUG: */ $this->partialStub('[' . __METHOD__ . ':' . __LINE__ . '] stackerName=' . $stackerName);
 322                 $value = NULL;
 323
 324                 // Return it
 325                 return $value;
 326         }
 327
 328         /**
 329          * "Pops" last entry from stack
 330          *
 331          * @param       $stackerName    Name of the stack
 332          * @return      $value                  Value "poped" from array
 333          * @throws      EmptyStackerException   If the stack is empty
 334          */
 335         protected function popLast (string $stackerName) {
 336                 // Is the stack not yet initialized or full?
 337                 if ($this->isStackEmpty($stackerName)) {
 338                         // Throw an exception
 339                         throw new EmptyStackerException(array($this, $stackerName), self::EXCEPTION_STACKER_IS_EMPTY);
 340                 } // END - if
 341
 342                 // Now, remove the last entry, we don't care about the return value here, see elseif() block above
 343                 /* NOISY-DEBUG: */ $this->partialStub('[' . __METHOD__ . ':' . __LINE__ . '] stackerName=' . $stackerName);
 344                 return NULL;
 345         }
 346
 347         /**
 348          * "Pops" first entry from stack
 349          *
 350          * @param       $stackerName    Name of the stack
 351          * @return      $value                  Value "shifted" from array
 352          * @throws      EmptyStackerException   If the named stacker is empty
 353          */
 354         protected function popFirst (string $stackerName) {
 355                 // Is the stack not yet initialized or full?
 356                 if ($this->isStackEmpty($stackerName)) {
 357                         // Throw an exception
 358                         throw new EmptyStackerException(array($this, $stackerName), self::EXCEPTION_STACKER_IS_EMPTY);
 359                 } // END - if
 360
 361                 // Now, remove the last entry, we don't care about the return value here, see elseif() block above
 362                 /* NOISY-DEBUG: */ $this->partialStub('[' . __METHOD__ . ':' . __LINE__ . '] stackerName=' . $stackerName);
 363                 return NULL;
 364         }
 365
 366         /**
 367          * Checks whether the given stack is full
 368          *
 369          * @param       $stackerName    Name of the stack
 370          * @return      $isFull                 Whether the stack is full
 371          */
 372         protected function isStackFull (string $stackerName) {
 373                 // File-based stacks will only run full if the disk space is low.
 374                 // @TODO Please implement this, returning false
 375                 $isFull = false;
 376
 377                 // Return result
 378                 return $isFull;
 379         }
 380
 381         /**
 382          * Checks whether the given stack is empty
 383          *
 384          * @param       $stackerName            Name of the stack
 385          * @return      $isEmpty                        Whether the stack is empty
 386          * @throws      NoStackerException      If given stack is missing
 387          */
 388         public function isStackEmpty (string $stackerName) {
 389                 // So, is the stack empty?
 390                 $isEmpty = (($this->getStackCount($stackerName)) == 0);
 391
 392                 // Return result
 393                 return $isEmpty;
 394         }
 395
 396         /**
 397          * Initializes given stacker
 398          *
 399          * @param       $stackerName    Name of the stack
 400          * @param       $forceReInit    Force re-initialization
 401          * @return      void
 402          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 403          */
 404         public function initStack (string $stackerName, bool $forceReInit = false) {
 405                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 406         }
 407
 408         /**
 409          * Initializes all stacks
 410          *
 411          * @return      void
 412          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 413          */
 414         public function initStacks (array $stacks, bool $forceReInit = false) {
 415                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 416         }
 417
 418         /**
 419          * Checks whether the given stack is initialized (set in array $stackers)
 420          *
 421          * @param       $stackerName    Name of the stack
 422          * @return      $isInitialized  Whether the stack is initialized
 423          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 424          */
 425         public function isStackInitialized (string $stackerName) {
 426                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 427         }
 428
 429         /**
 430          * Determines whether the EOF has been reached
 431          *
 432          * @return      $isEndOfFileReached             Whether the EOF has been reached
 433          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 434          */
 435         public function isEndOfFileReached () {
 436                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 437         }
 438
 439         /**
 440          * Getter for size of given stack (array count)
 441          *
 442          * @param       $stackerName    Name of the stack
 443          * @return      $count                  Size of stack (array count)
 444          */
 445         public function getStackCount (string $stackerName) {
 446                 // Now, simply return the found count value, this must be up-to-date then!
 447                 return $this->getIteratorInstance()->getCounter();
 448         }
 449
 450         /**
 451          * Calculates minimum length for one entry/block
 452          *
 453          * @return      $length         Minimum length for one entry/block
 454          */
 455         public function calculateMinimumBlockLength () {
 456                 // Calulcate it
 457                 $length =
 458                         // Length of entry group
 459                         BaseBinaryFile::LENGTH_GROUP + strlen(chr(BaseBinaryFile::SEPARATOR_GROUP_HASH)) +
 460                         // Hash + value
 461                         self::getHashLength() + strlen(chr(BaseBinaryFile::SEPARATOR_HASH_VALUE)) + 1 +
 462                         // Final separator
 463                         strlen(chr(BaseBinaryFile::SEPARATOR_ENTRIES));
 464
 465                 // Return it
 466                 return $length;
 467         }
 468
 469         /**
 470          * Initializes counter for valid entries, arrays for damaged entries and
 471          * an array for gap seek positions. If you call this method on your own,
 472          * please re-analyze the file structure. So you are better to call
 473          * analyzeFile() instead of this method.
 474          *
 475          * @return      void
 476          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 477          */
 478         public function initCountersGapsArray () {
 479                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 480         }
 481
 482         /**
 483          * Getter for header size
 484          *
 485          * @return      $totalEntries   Size of file header
 486          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 487          */
 488         public final function getHeaderSize () {
 489                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 490         }
 491
 492         /**
 493          * Setter for header size
 494          *
 495          * @param       $headerSize             Size of file header
 496          * @return      void
 497          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 498          */
 499         public final function setHeaderSize (int $headerSize) {
 500                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 501         }
 502
 503         /**
 504          * Getter for header array
 505          *
 506          * @return      $totalEntries   Size of file header
 507          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 508          */
 509         public final function getHeader () {
 510                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 511         }
 512
 513         /**
 514          * Setter for header
 515          *
 516          * @param       $header         Array for a file header
 517          * @return      void
 518          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 519          */
 520         public final function setHeader (array $header) {
 521                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 522         }
 523
 524         /**
 525          * Updates seekPosition attribute from file to avoid to much access on file.
 526          *
 527          * @return      void
 528          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 529          */
 530         public function updateSeekPosition () {
 531                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 532         }
 533
 534         /**
 535          * Getter for total entries
 536          *
 537          * @return      $totalEntries   Total entries in this file
 538          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 539          */
 540         public final function getCounter () {
 541                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 542         }
 543
 544         /**
 545          * Writes data at given position
 546          *
 547          * @param       $seekPosition   Seek position
 548          * @param       $data                   Data to be written
 549          * @param       $flushHeader    Whether to flush the header (default: flush)
 550          * @return      void
 551          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 552          */
 553         public function writeData ($seekPosition, $data, bool $flushHeader = true) {
 554                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: seekPosition=%s,data[]=%s,flushHeader=%d', $seekPosition, gettype($data), intval($flushHeader)));
 555                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 556         }
 557
 558         /**
 559          * Writes given value to the file and returns a hash and gap position for it
 560          *
 561          * @param       $groupId        Group identifier
 562          * @param       $value          Value to be added to the stack
 563          * @return      $data           Hash and gap position
 564          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 565          */
 566         public function writeValueToFile ($groupId, $value) {
 567                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: groupId=%s,value[%s]=%s', $groupId, gettype($value), print_r($value, true)));
 568                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 569         }
 570
 571         /**
 572          * Searches for next suitable gap the given length of data can fit in
 573          * including padding bytes.
 574          *
 575          * @param       $length                 Length of raw data
 576          * @return      $seekPosition   Found next gap's seek position
 577          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 578          */
 579         public function searchNextGap (int $length) {
 580                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: length=%s', $length));
 581                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 582         }
 583
 584         /**
 585          * "Getter" for file size
 586          *
 587          * @return      $fileSize       Size of currently loaded file
 588          */
 589         public function getFileSize () {
 590                 // Call iterator's method
 591                 return $this->getIteratorInstance()->getFileSize();
 592         }
 593
 594         /**
 595          * Writes given raw data to the file and returns a gap position and length
 596          *
 597          * @param       $groupId        Group identifier
 598          * @param       $hash           Hash from encoded value
 599          * @param       $encoded        Encoded value to be written to the file
 600          * @return      $data           Gap position and length of the raw data
 601          */
 602         public function writeDataToFreeGap ($groupId, string $hash, $encoded) {
 603                 // Raw data been written to the file
 604                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: groupId=%s,hash=%s,encoded()=%d - CALLED!', $groupId, $hash, strlen($encoded)));
 605                 $rawData = sprintf('%s%s%s%s%s',
 606                         $groupId,
 607                         BaseBinaryFile::SEPARATOR_GROUP_HASH,
 608                         hex2bin($hash),
 609                         BaseBinaryFile::SEPARATOR_HASH_VALUE,
 610                         $encoded
 611                 );
 612
 613                 // Search for next free gap
 614                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: groupId=%s,hash=%s,rawData()=%d', $groupId, $hash, strlen($rawData)));
 615                 $gapPosition = $this->getIteratorInstance()->searchNextGap(strlen($rawData));
 616
 617                 // Gap position cannot be smaller than header length + 1
 618                 assert($gapPosition > $this->getIteratorInstance()->getHeaderSize());
 619
 620                 // Then write the data at that gap
 621                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: groupId=%s,hash=%s,gapPosition=%s', $groupId, $hash, $gapPosition));
 622                 $this->getIteratorInstance()->writeData($gapPosition, $rawData);
 623
 624                 // Return gap position, hash and length of raw data
 625                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: groupId=%s,hash=%s,rawData()=%d - EXIT!', $groupId, $hash, strlen($rawData)));
 626                 return [
 627                         self::ARRAY_INDEX_GAP_POSITION => $gapPosition,
 628                         self::ARRAY_INDEX_HASH         => $hash,
 629                         self::ARRAY_INDEX_DATA_LENGTH  => strlen($rawData),
 630                 ];
 631         }
 632
 633 }