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 use Org\Mxchange\CoreFramework\Utils\String\StringUtils;
  14
  15 // Import SPL stuff
  16 use \SplFileInfo;
  17
  18 /**
  19  * A general file-based stack class
  20  *
  21  * @author              Roland Haeder <webmaster@ship-simu.org>
  22  * @version             0.0.0
  23  * @copyright   Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2020 Core Developer Team
  24  * @license             GNU GPL 3.0 or any newer version
  25  * @link                http://www.ship-simu.org
  26  *
  27  * This program is free software: you can redistribute it and/or modify
  28  * it under the terms of the GNU General Public License as published by
  29  * the Free Software Foundation, either version 3 of the License, or
  30  * (at your option) any later version.
  31  *
  32  * This program is distributed in the hope that it will be useful,
  33  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  34  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  35  * GNU General Public License for more details.
  36  *
  37  * You should have received a copy of the GNU General Public License
  38  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  39  */
  40 abstract class BaseFileStack extends BaseStacker {
  41         /**
  42          * Magic for this stack
  43          */
  44         const STACK_MAGIC = 'STACKv0.1';
  45
  46         /**
  47          * Name of array index for gap position
  48          */
  49         const ARRAY_INDEX_GAP_POSITION = 'gap';
  50
  51         /**
  52          * Name of array index for hash
  53          */
  54         const ARRAY_INDEX_HASH = 'hash';
  55
  56         /**
  57          * Name of array index for length of raw data
  58          */
  59         const ARRAY_INDEX_DATA_LENGTH = 'length';
  60
  61         /**
  62          * An instance of an Indexable class
  63          */
  64         private $indexInstance = NULL;
  65
  66         /**
  67          * Protected constructor
  68          *
  69          * @param       $className      Name of the class
  70          * @return      void
  71          */
  72         protected function __construct (string $className) {
  73                 // Call parent constructor
  74                 parent::__construct($className);
  75         }
  76
  77         /**
  78          * Setter for Indexable instance
  79          *
  80          * @param       $indexInstance  An instance of an Indexable class
  81          * @return      void
  82          */
  83         protected final function setIndexInstance (Indexable $indexInstance) {
  84                 $this->indexInstance = $indexInstance;
  85         }
  86
  87         /**
  88          * Getter for Indexable instance
  89          *
  90          * @return      $indexInstance  An instance of an Indexable class
  91          */
  92         public final function getIndexInstance () {
  93                 return $this->indexInstance;
  94         }
  95
  96         /**
  97          * Reads the file header
  98          *
  99          * @return      void
 100          * @todo        To hard assertions here, better rewrite them to exceptions
 101          */
 102         public function readFileHeader () {
 103                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: CALLED!', __METHOD__, __LINE__));
 104
 105                 // First rewind to beginning as the header sits at the beginning ...
 106                 $this->getIteratorInstance()->rewind();
 107
 108                 // Then read it (see constructor for calculation)
 109                 $data = $this->getIteratorInstance()->read($this->getIteratorInstance()->getHeaderSize());
 110                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Read %d bytes (%d wanted).', strlen($data), $this->getIteratorInstance()->getHeaderSize()));
 111
 112                 // Have all requested bytes been read?
 113                 assert(strlen($data) == $this->getIteratorInstance()->getHeaderSize());
 114                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Passed assert().', __METHOD__, __LINE__));
 115
 116                 // Last character must be the separator
 117                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: data(-1)=%s', dechex(ord(substr($data, -1, 1)))));
 118                 assert(substr($data, -1, 1) == chr(BaseBinaryFile::SEPARATOR_HEADER_ENTRIES));
 119                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Passed assert().', __METHOD__, __LINE__));
 120
 121                 // Okay, then remove it
 122                 $data = substr($data, 0, -1);
 123
 124                 // And update seek position
 125                 $this->getIteratorInstance()->updateSeekPosition();
 126
 127                 /*
 128                  * Now split it:
 129                  *
 130                  * 0 => magic
 131                  * 1 => total entries
 132                  * 2 => current seek position
 133                  */
 134                 $header = explode(chr(BaseBinaryFile::SEPARATOR_HEADER_DATA), $data);
 135
 136                 // Set header here
 137                 $this->getIteratorInstance()->setHeader($header);
 138
 139                 // Check if the array has only 3 elements
 140                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: header(%d)=%s', count($header), print_r($header, true)));
 141                 assert(count($header) == 3);
 142                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Passed assert().', __METHOD__, __LINE__));
 143
 144                 // Check magic
 145                 assert($header[0] == self::STACK_MAGIC);
 146                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Passed assert().', __METHOD__, __LINE__));
 147
 148                 // Check length of count and seek position
 149                 assert(strlen($header[1]) == BaseBinaryFile::LENGTH_COUNT);
 150                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Passed assert().', __METHOD__, __LINE__));
 151                 assert(strlen($header[2]) == BaseBinaryFile::LENGTH_POSITION);
 152                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: Passed assert().', __METHOD__, __LINE__));
 153
 154                 // Decode count and seek position
 155                 $header[1] = hex2bin($header[1]);
 156                 $header[2] = hex2bin($header[2]);
 157
 158                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: EXIT!', __METHOD__, __LINE__));
 159         }
 160
 161         /**
 162          * Flushes the file header
 163          *
 164          * @return      void
 165          */
 166         public function flushFileHeader () {
 167                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: CALLED!', __METHOD__, __LINE__));
 168
 169                 // Put all informations together
 170                 $header = sprintf('%s%s%s%s%s%s',
 171                         // Magic
 172                         self::STACK_MAGIC,
 173
 174                         // Separator magic<->count
 175                         chr(BaseBinaryFile::SEPARATOR_HEADER_DATA),
 176
 177                         // Total entries (will be zero) and pad it to 20 chars
 178                         str_pad(StringUtils::dec2hex($this->getIteratorInstance()->getCounter()), BaseBinaryFile::LENGTH_COUNT, '0', STR_PAD_LEFT),
 179
 180                         // Separator count<->seek position
 181                         chr(BaseBinaryFile::SEPARATOR_HEADER_DATA),
 182
 183                         // Position (will be zero)
 184                         str_pad(StringUtils::dec2hex($this->getIteratorInstance()->getSeekPosition(), 2), BaseBinaryFile::LENGTH_POSITION, '0', STR_PAD_LEFT),
 185
 186                         // Separator position<->entries
 187                         chr(BaseBinaryFile::SEPARATOR_HEADER_ENTRIES)
 188                 );
 189
 190                 // Write it to disk (header is always at seek position 0)
 191                 $this->getIteratorInstance()->writeData(0, $header, false);
 192
 193                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: EXIT!', __METHOD__, __LINE__));
 194         }
 195
 196         /**
 197          * Initializes this file-based stack.
 198          *
 199          * @param       $fileInfoInstance       An instance of a SplFileInfo class
 200          * @param       $type           Type of this stack (e.g. url_source for URL sources)
 201          * @return      void
 202          * @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.
 203          */
 204         protected function initFileStack (SplFileInfo $fileInfoInstance, string $type) {
 205                 // Get a stack file instance
 206                 $fileInstance = ObjectFactory::createObjectByConfiguredName('stack_file_class', array($fileInfoInstance, $this));
 207
 208                 // Get iterator instance
 209                 $iteratorInstance = ObjectFactory::createObjectByConfiguredName('file_iterator_class', array($fileInstance));
 210
 211                 // Is the instance implementing the right interface?
 212                 assert($iteratorInstance instanceof SeekableWritableFileIterator);
 213
 214                 // Set iterator here
 215                 $this->setIteratorInstance($iteratorInstance);
 216
 217                 // Calculate header size
 218                 $this->getIteratorInstance()->setHeaderSize(
 219                         strlen(self::STACK_MAGIC) +
 220                         strlen(chr(BaseBinaryFile::SEPARATOR_HEADER_DATA)) +
 221                         BaseBinaryFile::LENGTH_COUNT +
 222                         strlen(chr(BaseBinaryFile::SEPARATOR_HEADER_DATA)) +
 223                         BaseBinaryFile::LENGTH_POSITION +
 224                         strlen(chr(BaseBinaryFile::SEPARATOR_HEADER_ENTRIES))
 225                 );
 226
 227                 // Init counters and gaps array
 228                 $this->getIteratorInstance()->initCountersGapsArray();
 229
 230                 // Is the file's header initialized?
 231                 if (!$this->getIteratorInstance()->isFileHeaderInitialized()) {
 232                         // No, then create it (which may pre-allocate the stack)
 233                         $this->getIteratorInstance()->createFileHeader();
 234
 235                         // And pre-allocate a bit
 236                         $this->getIteratorInstance()->preAllocateFile('file_stack');
 237                 } // END - if
 238
 239                 // Load the file header
 240                 $this->readFileHeader();
 241
 242                 // Count all entries in file
 243                 $this->getIteratorInstance()->analyzeFile();
 244
 245                 /*
 246                  * Get stack index instance. This can be used for faster
 247                  * "defragmentation" and startup.
 248                  */
 249                 $indexInstance = FileStackIndexFactory::createFileStackIndexInstance($fileInfoInstance, $type);
 250
 251                 // And set it here
 252                 $this->setIndexInstance($indexInstance);
 253         }
 254
 255         /**
 256          * Adds a value to given stack
 257          *
 258          * @param       $stackerName    Name of the stack
 259          * @param       $value                  Value to add to this stacker
 260          * @return      void
 261          * @throws      FullStackerException    If the stack is full
 262          */
 263         protected function addValue (string $stackerName, $value) {
 264                 // Do some tests
 265                 if ($this->isStackFull($stackerName)) {
 266                         // Stacker is full
 267                         throw new FullStackerException(array($this, $stackerName, $value), self::EXCEPTION_STACKER_IS_FULL);
 268                 } // END - if
 269
 270                 // No objects/resources are allowed as their serialization takes to long
 271                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('[' . __METHOD__ . ':' . __LINE__ . '] stackerName=' . $stackerName . ',value[' . gettype($value) . ']=' . print_r($value, true));
 272                 assert(!is_object($value));
 273                 assert(!is_resource($value));
 274
 275                 /*
 276                  * Now add the value to the file stack which returns gap position, a
 277                  * hash and length of the raw data.
 278                  */
 279                 $data = $this->getIteratorInstance()->writeValueToFile($stackerName, $value);
 280
 281                 // Add the hash and gap position to the index
 282                 $this->getIndexInstance()->addHashToIndex($stackerName, $data);
 283         }
 284
 285         /**
 286          * Get last value from named stacker
 287          *
 288          * @param       $stackerName    Name of the stack
 289          * @return      $value                  Value of last added value
 290          * @throws      EmptyStackerException   If the stack is empty
 291          */
 292         protected function getLastValue (string $stackerName) {
 293                 // Is the stack not yet initialized or full?
 294                 if ($this->isStackEmpty($stackerName)) {
 295                         // Throw an exception
 296                         throw new EmptyStackerException(array($this, $stackerName), self::EXCEPTION_STACKER_IS_EMPTY);
 297                 } // END - if
 298
 299                 // Now get the last value
 300                 /* NOISY-DEBUG: */ $this->partialStub('[' . __METHOD__ . ':' . __LINE__ . '] stackerName=' . $stackerName);
 301                 $value = NULL;
 302
 303                 // Return it
 304                 return $value;
 305         }
 306
 307         /**
 308          * Get first value from named stacker
 309          *
 310          * @param       $stackerName    Name of the stack
 311          * @return      $value                  Value of last added value
 312          * @throws      EmptyStackerException   If the stack is empty
 313          */
 314         protected function getFirstValue (string $stackerName) {
 315                 // Is the stack not yet initialized or full?
 316                 if ($this->isStackEmpty($stackerName)) {
 317                         // Throw an exception
 318                         throw new EmptyStackerException(array($this, $stackerName), self::EXCEPTION_STACKER_IS_EMPTY);
 319                 } // END - if
 320
 321                 // Now get the first value
 322                 /* NOISY-DEBUG: */ $this->partialStub('[' . __METHOD__ . ':' . __LINE__ . '] stackerName=' . $stackerName);
 323                 $value = NULL;
 324
 325                 // Return it
 326                 return $value;
 327         }
 328
 329         /**
 330          * "Pops" last entry from stack
 331          *
 332          * @param       $stackerName    Name of the stack
 333          * @return      $value                  Value "poped" from array
 334          * @throws      EmptyStackerException   If the stack is empty
 335          */
 336         protected function popLast (string $stackerName) {
 337                 // Is the stack not yet initialized or full?
 338                 if ($this->isStackEmpty($stackerName)) {
 339                         // Throw an exception
 340                         throw new EmptyStackerException(array($this, $stackerName), self::EXCEPTION_STACKER_IS_EMPTY);
 341                 } // END - if
 342
 343                 // Now, remove the last entry, we don't care about the return value here, see elseif() block above
 344                 /* NOISY-DEBUG: */ $this->partialStub('[' . __METHOD__ . ':' . __LINE__ . '] stackerName=' . $stackerName);
 345                 return NULL;
 346         }
 347
 348         /**
 349          * "Pops" first entry from stack
 350          *
 351          * @param       $stackerName    Name of the stack
 352          * @return      $value                  Value "shifted" from array
 353          * @throws      EmptyStackerException   If the named stacker is empty
 354          */
 355         protected function popFirst (string $stackerName) {
 356                 // Is the stack not yet initialized or full?
 357                 if ($this->isStackEmpty($stackerName)) {
 358                         // Throw an exception
 359                         throw new EmptyStackerException(array($this, $stackerName), self::EXCEPTION_STACKER_IS_EMPTY);
 360                 } // END - if
 361
 362                 // Now, remove the last entry, we don't care about the return value here, see elseif() block above
 363                 /* NOISY-DEBUG: */ $this->partialStub('[' . __METHOD__ . ':' . __LINE__ . '] stackerName=' . $stackerName);
 364                 return NULL;
 365         }
 366
 367         /**
 368          * Checks whether the given stack is full
 369          *
 370          * @param       $stackerName    Name of the stack
 371          * @return      $isFull                 Whether the stack is full
 372          */
 373         protected function isStackFull (string $stackerName) {
 374                 // File-based stacks will only run full if the disk space is low.
 375                 // @TODO Please implement this, returning false
 376                 $isFull = false;
 377
 378                 // Return result
 379                 return $isFull;
 380         }
 381
 382         /**
 383          * Checks whether the given stack is empty
 384          *
 385          * @param       $stackerName            Name of the stack
 386          * @return      $isEmpty                        Whether the stack is empty
 387          * @throws      NoStackerException      If given stack is missing
 388          */
 389         public function isStackEmpty (string $stackerName) {
 390                 // So, is the stack empty?
 391                 $isEmpty = (($this->getStackCount($stackerName)) == 0);
 392
 393                 // Return result
 394                 return $isEmpty;
 395         }
 396
 397         /**
 398          * Initializes given stacker
 399          *
 400          * @param       $stackerName    Name of the stack
 401          * @param       $forceReInit    Force re-initialization
 402          * @return      void
 403          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 404          */
 405         public function initStack (string $stackerName, bool $forceReInit = false) {
 406                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 407         }
 408
 409         /**
 410          * Initializes all stacks
 411          *
 412          * @return      void
 413          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 414          */
 415         public function initStacks (array $stacks, bool $forceReInit = false) {
 416                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 417         }
 418
 419         /**
 420          * Checks whether the given stack is initialized (set in array $stackers)
 421          *
 422          * @param       $stackerName    Name of the stack
 423          * @return      $isInitialized  Whether the stack is initialized
 424          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 425          */
 426         public function isStackInitialized (string $stackerName) {
 427                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 428         }
 429
 430         /**
 431          * Determines whether the EOF has been reached
 432          *
 433          * @return      $isEndOfFileReached             Whether the EOF has been reached
 434          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 435          */
 436         public function isEndOfFileReached () {
 437                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 438         }
 439
 440         /**
 441          * Getter for size of given stack (array count)
 442          *
 443          * @param       $stackerName    Name of the stack
 444          * @return      $count                  Size of stack (array count)
 445          */
 446         public function getStackCount (string $stackerName) {
 447                 // Now, simply return the found count value, this must be up-to-date then!
 448                 return $this->getIteratorInstance()->getCounter();
 449         }
 450
 451         /**
 452          * Calculates minimum length for one entry/block
 453          *
 454          * @return      $length         Minimum length for one entry/block
 455          */
 456         public function calculateMinimumBlockLength () {
 457                 // Calulcate it
 458                 $length =
 459                         // Length of entry group
 460                         BaseBinaryFile::LENGTH_GROUP + strlen(chr(BaseBinaryFile::SEPARATOR_GROUP_HASH)) +
 461                         // Hash + value
 462                         self::getHashLength() + strlen(chr(BaseBinaryFile::SEPARATOR_HASH_VALUE)) + 1 +
 463                         // Final separator
 464                         strlen(chr(BaseBinaryFile::SEPARATOR_ENTRIES));
 465
 466                 // Return it
 467                 return $length;
 468         }
 469
 470         /**
 471          * Initializes counter for valid entries, arrays for damaged entries and
 472          * an array for gap seek positions. If you call this method on your own,
 473          * please re-analyze the file structure. So you are better to call
 474          * analyzeFile() instead of this method.
 475          *
 476          * @return      void
 477          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 478          */
 479         public function initCountersGapsArray () {
 480                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 481         }
 482
 483         /**
 484          * Getter for header size
 485          *
 486          * @return      $totalEntries   Size of file header
 487          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 488          */
 489         public final function getHeaderSize () {
 490                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 491         }
 492
 493         /**
 494          * Setter for header size
 495          *
 496          * @param       $headerSize             Size of file header
 497          * @return      void
 498          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 499          */
 500         public final function setHeaderSize (int $headerSize) {
 501                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 502         }
 503
 504         /**
 505          * Getter for header array
 506          *
 507          * @return      $totalEntries   Size of file header
 508          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 509          */
 510         public final function getHeader () {
 511                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 512         }
 513
 514         /**
 515          * Setter for header
 516          *
 517          * @param       $header         Array for a file header
 518          * @return      void
 519          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 520          */
 521         public final function setHeader (array $header) {
 522                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 523         }
 524
 525         /**
 526          * Updates seekPosition attribute from file to avoid to much access on file.
 527          *
 528          * @return      void
 529          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 530          */
 531         public function updateSeekPosition () {
 532                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 533         }
 534
 535         /**
 536          * Getter for total entries
 537          *
 538          * @return      $totalEntries   Total entries in this file
 539          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 540          */
 541         public final function getCounter () {
 542                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 543         }
 544
 545         /**
 546          * Writes data at given position
 547          *
 548          * @param       $seekPosition   Seek position
 549          * @param       $data                   Data to be written
 550          * @param       $flushHeader    Whether to flush the header (default: flush)
 551          * @return      void
 552          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 553          */
 554         public function writeData ($seekPosition, $data, bool $flushHeader = true) {
 555                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: seekPosition=%s,data[]=%s,flushHeader=%d', $seekPosition, gettype($data), intval($flushHeader)));
 556                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 557         }
 558
 559         /**
 560          * Writes given value to the file and returns a hash and gap position for it
 561          *
 562          * @param       $groupId        Group identifier
 563          * @param       $value          Value to be added to the stack
 564          * @return      $data           Hash and gap position
 565          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 566          */
 567         public function writeValueToFile ($groupId, $value) {
 568                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: groupId=%s,value[%s]=%s', $groupId, gettype($value), print_r($value, true)));
 569                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 570         }
 571
 572         /**
 573          * Searches for next suitable gap the given length of data can fit in
 574          * including padding bytes.
 575          *
 576          * @param       $length                 Length of raw data
 577          * @return      $seekPosition   Found next gap's seek position
 578          * @throws      UnsupportedOperationException   This method is not (and maybe never will be) supported
 579          */
 580         public function searchNextGap (int $length) {
 581                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: length=%s', $length));
 582                 throw new UnsupportedOperationException(array($this, __FUNCTION__, $this->getIteratorInstance()->getPointerInstance()), self::EXCEPTION_UNSPPORTED_OPERATION);
 583         }
 584
 585         /**
 586          * "Getter" for file size
 587          *
 588          * @return      $fileSize       Size of currently loaded file
 589          */
 590         public function getFileSize () {
 591                 // Call iterator's method
 592                 return $this->getIteratorInstance()->getFileSize();
 593         }
 594
 595         /**
 596          * Writes given raw data to the file and returns a gap position and length
 597          *
 598          * @param       $groupId        Group identifier
 599          * @param       $hash           Hash from encoded value
 600          * @param       $encoded        Encoded value to be written to the file
 601          * @return      $data           Gap position and length of the raw data
 602          */
 603         public function writeDataToFreeGap ($groupId, string $hash, $encoded) {
 604                 // Raw data been written to the file
 605                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: groupId=%s,hash=%s,encoded()=%d - CALLED!', $groupId, $hash, strlen($encoded)));
 606                 $rawData = sprintf('%s%s%s%s%s',
 607                         $groupId,
 608                         BaseBinaryFile::SEPARATOR_GROUP_HASH,
 609                         hex2bin($hash),
 610                         BaseBinaryFile::SEPARATOR_HASH_VALUE,
 611                         $encoded
 612                 );
 613
 614                 // Search for next free gap
 615                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: groupId=%s,hash=%s,rawData()=%d', $groupId, $hash, strlen($rawData)));
 616                 $gapPosition = $this->getIteratorInstance()->searchNextGap(strlen($rawData));
 617
 618                 // Gap position cannot be smaller than header length + 1
 619                 assert($gapPosition > $this->getIteratorInstance()->getHeaderSize());
 620
 621                 // Then write the data at that gap
 622                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: groupId=%s,hash=%s,gapPosition=%s', $groupId, $hash, $gapPosition));
 623                 $this->getIteratorInstance()->writeData($gapPosition, $rawData);
 624
 625                 // Return gap position, hash and length of raw data
 626                 /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-STACK: groupId=%s,hash=%s,rawData()=%d - EXIT!', $groupId, $hash, strlen($rawData)));
 627                 return [
 628                         self::ARRAY_INDEX_GAP_POSITION => $gapPosition,
 629                         self::ARRAY_INDEX_HASH         => $hash,
 630                         self::ARRAY_INDEX_DATA_LENGTH  => strlen($rawData),
 631                 ];
 632         }
 633
 634 }