inc/classes/main/database/classes/class_LocalFileDatabase.php

   1 <?php
   2 /**
   3  * Database backend class for storing objects in locally created files.
   4  *
   5  * This class serializes objects and saves them to local files.
   6  *
   7  * @author              Roland Haeder <webmaster@ship-simu.org>
   8  * @version             0.0.0
   9  * @copyright   Copyright(c) 2007, 2008 Roland Haeder, this is free software
  10  * @license             GNU GPL 3.0 or any newer version
  11  * @link                http://www.ship-simu.org
  12  *
  13  * This program is free software: you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation, either version 3 of the License, or
  16  * (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  * GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  25  */
  26 class LocalFileDatabase extends BaseDatabaseFrontend implements DatabaseFrontendInterface {
  27         /**
  28          * Save path for "file database"
  29          */
  30         private $savePath = "";
  31
  32         /**
  33          * The file's extension
  34          */
  35         private $fileExtension = "serialized";
  36
  37         /**
  38          * The last read file's name
  39          */
  40         private $lastFile = "";
  41
  42         /**
  43          * The last read file's content including header information
  44          */
  45         private $lastContents = array();
  46
  47         /**
  48          * The private constructor. Do never instance from outside!
  49          * You need to set a local file path. The class will then validate it.
  50          *
  51          * @return      void
  52          */
  53         protected function __construct() {
  54                 // Call parent constructor
  55                 parent::__construct(__CLASS__);
  56
  57                 // Set description
  58                 $this->setObjectDescription("Class for local file databases");
  59
  60                 // Create unique ID
  61                 $this->createUniqueID();
  62
  63                 // Clean up a little
  64                 $this->removeSystemArray();
  65         }
  66
  67         /**
  68          * Create an object of LocalFileDatabase and set the save path for local files.
  69          * This method also validates the given file path.
  70          *
  71          * @param               $savePath                                       The local file path string
  72          * @param               $ioInstance                             The input/output handler. This
  73          *                                                                      should be FileIoHandler
  74          * @return      $dbInstance                             An instance of LocalFileDatabase
  75          * @throws      SavePathIsEmptyException                If the given save path is an
  76          *                                                                      empty string
  77          * @throws      SavePathIsNoDirectoryException  If the save path is no
  78          *                                                                              path (e.g. a file)
  79          * @throws      SavePathReadProtectedException  If the save path is read-
  80          *                                                                              protected
  81          * @throws      SavePathWriteProtectedException If the save path is write-
  82          *                                                                              protected
  83          */
  84         public final static function createLocalFileDatabase ($savePath, FileIoHandler $ioInstance) {
  85                 // Get an instance
  86                 $dbInstance = new LocalFileDatabase();
  87
  88                 if (empty($savePath)) {
  89                         // Empty string
  90                         throw new SavePathIsEmptyException($dbInstance, self::EXCEPTION_UNEXPECTED_EMPTY_STRING);
  91                 } elseif (!is_dir($savePath)) {
  92                         // Is not a dir
  93                         throw new SavePathIsNoDirectoryException($savePath, self::EXCEPTION_INVALID_PATH_NAME);
  94                 } elseif (!is_readable($savePath)) {
  95                         // Path not readable
  96                         throw new SavePathReadProtectedException($savePath, self::EXCEPTION_READ_PROTECED_PATH);
  97                 } elseif (!is_writeable($savePath)) {
  98                         // Path not writeable
  99                         throw new SavePathWriteProtectedException($savePath, self::EXCEPTION_WRITE_PROTECED_PATH);
 100                 }
 101
 102                 // Set save path and IO instance
 103                 $dbInstance->setSavePath($savePath);
 104                 $dbInstance->setFileIoInstance($ioInstance);
 105
 106                 // Return database instance
 107                 return $dbInstance;
 108         }
 109
 110         /**
 111          * Setter for save path
 112          *
 113          * @param               $savePath               The local save path where we shall put our serialized classes
 114          * @return      void
 115          */
 116         public final function setSavePath ($savePath) {
 117                 // Secure string
 118                 $savePath = (string) $savePath;
 119
 120                 // Set save path
 121                 $this->savePath = $savePath;
 122         }
 123
 124         /**
 125          * Getter for save path
 126          *
 127          * @return      $savePath               The local save path where we shall put our serialized classes
 128          */
 129         public final function getSavePath () {
 130                 return $this->savePath;
 131         }
 132
 133         /**
 134          * Saves a given object to the local file system by serializing and
 135          * transparently compressing it
 136          *
 137          * @param               $object                         The object we shall save to the local file system
 138          * @return      void
 139          * @throws      NullPointerException    If the object instance is null
 140          * @throws      NoObjectException               If the parameter $object is not
 141          *                                                              an object
 142          */
 143         public final function saveObject ($object) {
 144                 // Some tests on the parameter...
 145                 if (is_null($object)) {
 146                         // Is null, throw exception
 147                         throw new NullPointerException($object, self::EXCEPTION_IS_NULL_POINTER);
 148                 } elseif (!is_object($object)) {
 149                         // Is not an object, throw exception
 150                         throw new NoObjectException($object, self::EXCEPTION_IS_NO_OBJECT);
 151                 } elseif (!method_exists($object, '__toString')) {
 152                         // A highly required method was not found... :-(
 153                         throw new MissingMethodException(array($object, '__toString'), self::EXCEPTION_MISSING_METHOD);
 154                 }
 155
 156                 // Get a string containing the serialized object. We cannot exchange
 157                 // $this and $object here because $object does not need to worry
 158                 // about it's limitations... ;-)
 159                 $serialized = $this->serializeObject($object);
 160
 161                 // Get a path name plus file name and append the extension
 162                 $fqfn = $this->getSavePath() . $object->getPathFileNameFromObject() . "." . $this->getFileExtension();
 163
 164                 // Save the file to disc we don't care here if the path is there,
 165                 // this must be done in later methods.
 166                 $this->getFileIoInstance()->saveFile($fqfn, array($this->getCompressorChannel()->getCompressorExtension(), $serialized));
 167         }
 168
 169         /**
 170          * Get a serialized string from the given object
 171          *
 172          * @param               $object         The object we want to serialize and transparently
 173          *                                              compress
 174          * @return      $serialized     A string containing the serialzed/compressed object
 175          * @see         ObjectLimits    An object holding limition information
 176          * @see         SerializationContainer  A special container class for e.g.
 177          *                                                              attributes from limited objects
 178          */
 179         private function serializeObject ($object) {
 180                 // If there is no limiter instance we serialize the whole object
 181                 // otherwise only in the limiter object (ObjectLimits) specified
 182                 // attributes summarized in a special container class
 183                 if ($this->getLimitInstance() === null) {
 184                         // Serialize the whole object. This tribble call is the reason
 185                         // why we need a fall-back implementation in CompressorChannel
 186                         // of the methods compressStream() and decompressStream().
 187                         $serialized = $this->getCompressorChannel()->getCompressor()->compressStream(serialize($object));
 188                 } else {
 189                         // Serialize only given attributes in a special container
 190                         $container = SerializationContainer::createSerializationContainer($this->getLimitInstance(), $object);
 191
 192                         // Serialize the container
 193                         $serialized = $this->getCompressorChannel()->getCompressor()->compressStream(serialize($container));
 194                 }
 195
 196                 // Return the serialized object string
 197                 return $serialized;
 198         }
 199
 200         /**
 201          * Analyses if a unique ID has already been used or not by search in the
 202          * local database folder.
 203          *
 204          * @param               $uniqueID               A unique ID number which shall be checked
 205          *                                              before it will be used
 206          * @param               $inConstructor  If we got called in a de/con-structor or
 207          *                                              from somewhere else
 208          * @return      $isUnused               true    = The unique ID was not found in the database,
 209          *                                              false = It is already in use by an other object
 210          * @throws      NoArrayCreatedException If explode() fails to create an array
 211          * @throws      InvalidArrayCountException      If the array contains less or
 212          *                                                                      more than two elements
 213          */
 214         public function isUniqueIdUsed ($uniqueID, $inConstructor = false) {
 215                 // Currently not used... ;-)
 216                 $isUsed = false;
 217
 218                 // Split the unique ID up in path and file name
 219                 $pathFile = explode("@", $uniqueID);
 220
 221                 // Are there two elements? Index 0 is the path, 1 the file name + global extension
 222                 if (!is_array($pathFile)) {
 223                         // No array found
 224                         if ($inConstructor) {
 225                                 return false;
 226                         } else {
 227                                 throw new NoArrayCreatedException(array($this, "pathFile"), self::EXCEPTION_ARRAY_EXPECTED);
 228                         }
 229                 } elseif (count($pathFile) != 2) {
 230                         // Invalid ID returned!
 231                         if ($inConstructor) {
 232                                 return false;
 233                         } else {
 234                                 throw new InvalidArrayCountException(array($this, "pathFile", count($pathFile), 2), self::EXCEPTION_ARRAY_HAS_INVALID_COUNT);
 235                         }
 236                 }
 237
 238                 // Create full path name
 239                 $pathName = $this->getSavePath() . $pathFile[0];
 240
 241                 // Check if the file is there with a file handler
 242                 if ($inConstructor) {
 243                         // No exceptions in constructors and destructors!
 244                         $dirInstance = FrameworkDirectoryPointer::createFrameworkDirectoryPointer($pathName, true);
 245
 246                         // Has an object being created?
 247                         if (!is_object($dirInstance)) return false;
 248                 } else {
 249                         // Outside a constructor
 250                         try {
 251                                 $dirInstance = FrameworkDirectoryPointer::createFrameworkDirectoryPointer($pathName);
 252                         } catch (PathIsNoDirectoryException $e) {
 253                                 // Okay, path not found
 254                                 return false;
 255                         }
 256                 }
 257
 258                 // Initialize the search loop
 259                 $isValid = false;
 260                 while ($dataFile = $dirInstance->readDirectoryExcept(array(".", ".."))) {
 261                         // Generate FQFN for testing
 262                         $fqfn = sprintf("%s/%s", $pathName, $dataFile);
 263                         $this->setLastFile($fqfn);
 264
 265                         // Get instance for file handler
 266                         $inputHandler = $this->getFileIoInstance();
 267
 268                         // Try to read from it. This makes it sure that the file is
 269                         // readable and a valid database file
 270                         $this->setLastFileContents($inputHandler->loadFileContents($fqfn));
 271
 272                         // Extract filename (= unique ID) from it
 273                         $ID = substr(basename($fqfn), 0, -(strlen($this->getFileExtension()) + 1));
 274
 275                         // Is this the required unique ID?
 276                         if ($ID == $pathFile[1]) {
 277                                 // Okay, already in use!
 278                                 $isUsed = true;
 279                         }
 280                 }
 281
 282                 // Close the directory handler
 283                 $dirInstance->closeDirectory();
 284
 285                 // Now the same for the file...
 286                 return $isUsed;
 287         }
 288
 289         /**
 290          * Setter for the last read file
 291          *
 292          * @param               $fqfn   The FQFN of the last read file
 293          * @return      void
 294          */
 295         private final function setLastFile ($fqfn) {
 296                 // Cast string
 297                 $fqfn = (string) $fqfn;
 298                 $this->lastFile = $fqfn;
 299         }
 300
 301         /**
 302          * Getter for last read file
 303          *
 304          * @return      $lastFile               The last read file's name with full path
 305          */
 306         public final function getLastFile () {
 307                 return $this->lastFile;
 308         }
 309
 310         /**
 311          * Setter for contents of the last read file
 312          *
 313          * @param               $contents               An array with header and data elements
 314          * @return      void
 315          */
 316         private final function setLastFileContents ($contents) {
 317                 // Cast array
 318                 $contents = (array) $contents;
 319                 $this->lastContents = $contents;
 320         }
 321
 322         /**
 323          * Getter for last read file's content as an array
 324          *
 325          * @return      $lastContent    The array with elements 'header' and 'data'.
 326          */
 327         public final function getLastContents () {
 328                 return $this->lastContents;
 329         }
 330
 331         /**
 332          * Getter for file extension
 333          *
 334          * @return      $fileExtension  The array with elements 'header' and 'data'.
 335          */
 336         public final function getFileExtension () {
 337                 return $this->fileExtension;
 338         }
 339
 340         /**
 341          * Get cached (last fetched) data from the local file database
 342          *
 343          * @param               $uniqueID               The ID number for looking up the data
 344          * @return      $object         The restored object from the maybe compressed
 345          *                                              serialized data
 346          * @throws      MismatchingCompressorsException If the compressor from
 347          *                                                                              the loaded file
 348          *                                                                              mismatches with the
 349          *                                                                              current used one.
 350          * @throws      NullPointerException                    If the restored object
 351          *                                                                              is null
 352          * @throws      NoObjectException                               If the restored "object"
 353          *                                                                              is not an object instance
 354          * @throws      MissingMethodException                  If the required method
 355          *                                                                              toString() is missing
 356          */
 357         public final function getObjectFromCachedData ($uniqueID) {
 358                 // Get instance for file handler
 359                 $inputHandler = $this->getFileIoInstance();
 360
 361                 // Get last file's name and contents
 362                 $fqfn = $this->repairFQFN($this->getLastFile(), $uniqueID);
 363                 $contents = $this->repairContents($this->getLastContents(), $fqfn);
 364
 365                 // Let's decompress it. First we need the instance
 366                 $compressInstance = $this->getCompressorChannel();
 367
 368                 // Is the compressor's extension the same as the one from the data?
 369                 if ($compressInstance->getCompressorExtension() != $contents['header'][0]) {
 370                         /**
 371                          * @todo        For now we abort here but later we need to make this a little more dynamic.
 372                          */
 373                         throw new MismatchingCompressorsException(array($this, $contents['header'][0], $fqfn, $compressInstance->getCompressorExtension()), self::EXCEPTION_MISMATCHING_COMPRESSORS);
 374                 }
 375
 376                 // Decompress the data now
 377                 $serialized = $compressInstance->getCompressor()->decompressStream($contents['data']);
 378
 379                 // And unserialize it...
 380                 $object = unserialize($serialized);
 381
 382                 // This must become a valid object, so let's check it...
 383                 if (is_null($object)) {
 384                         // Is null, throw exception
 385                         throw new NullPointerException($object, self::EXCEPTION_IS_NULL_POINTER);
 386                 } elseif (!is_object($object)) {
 387                         // Is not an object, throw exception
 388                         throw new NoObjectException($object, self::EXCEPTION_IS_NO_OBJECT);
 389                 } elseif (!method_exists($object, '__toString')) {
 390                         // A highly required method was not found... :-(
 391                         throw new MissingMethodException(array($object, '__toString'), self::EXCEPTION_MISSING_METHOD);
 392                 }
 393
 394                 // And return the object
 395                 return $object;
 396         }
 397
 398         /**
 399          * Private method for re-gathering (repairing) the FQFN
 400          *
 401          * @param               $fqfn           The current FQFN we shall validate
 402          * @param               $uniqueID               The unique ID number
 403          * @return      $fqfn           The repaired FQFN when it is empty
 404          * @throws      NoArrayCreatedException         If explode() has not
 405          *                                                                      created an array
 406          * @throws      InvalidArrayCountException      If the array count is not
 407          *                                                                      as the expected
 408          */
 409         private function repairFQFN ($fqfn, $uniqueID) {
 410                 // Cast both strings
 411                 $fqfn     = (string) $fqfn;
 412                 $uniqueID = (string) $uniqueID;
 413
 414                 // Is there pre-cached data available?
 415                 if (empty($fqfn)) {
 416                         // Split the unique ID up in path and file name
 417                         $pathFile = explode("@", $uniqueID);
 418
 419                         // Are there two elements? Index 0 is the path, 1 the file name + global extension
 420                         if (!is_array($pathFile)) {
 421                                 // No array found
 422                                 throw new NoArrayCreatedException(array($this, "pathFile"), self::EXCEPTION_ARRAY_EXPECTED);
 423                         } elseif (count($pathFile) != 2) {
 424                                 // Invalid ID returned!
 425                                 throw new InvalidArrayCountException(array($this, "pathFile", count($pathFile), 2), self::EXCEPTION_ARRAY_HAS_INVALID_COUNT);
 426                         }
 427
 428                         // Create full path name
 429                         $pathName = $this->getSavePath() . $pathFile[0];
 430
 431                         // Nothing cached, so let's create a FQFN first
 432                         $fqfn = sprintf("%s/%s.%s", $pathName, $pathFile[1], $this->getFileExtension());
 433                         $this->setLastFile($fqfn);
 434                 }
 435
 436                 // Return repaired FQFN
 437                 return $fqfn;
 438         }
 439
 440         /**
 441          * Private method for re-gathering the contents of a given file
 442          *
 443          * @param               $contents               The (maybe) already cached contents as an array
 444          * @param               $fqfn           The current FQFN we shall validate
 445          * @return      $contents               The repaired contents from the given file
 446          */
 447         private function repairContents ($contents, $fqfn) {
 448                 // Is there some content and header (2 indexes) in?
 449                 if ((!is_array($contents)) || (count($contents) != 2) || (!isset($contents['header'])) || (!isset($contents['data']))) {
 450                         // No content found so load the file again
 451                         $contents = $inputHandler->loadFileContents($fqfn);
 452
 453                         // And remember all data for later usage
 454                         $this->setLastContents($contents);
 455                 }
 456
 457                 // Return the repaired contents
 458                 return $contents;
 459         }
 460
 461         /* DUMMY */ public final function loadObject () {}
 462 }
 463
 464 // [EOF]
 465 ?>