inc/classes/main/database/databases/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          * Wether the "connection is already up
  49          */
  50         private $alreadyConnected = false;
  51
  52         /**
  53          * The private constructor. Do never instance from outside!
  54          * You need to set a local file path. The class will then validate it.
  55          *
  56          * @return      void
  57          */
  58         protected function __construct() {
  59                 // Call parent constructor
  60                 parent::__construct(__CLASS__);
  61
  62                 // Set description
  63                 $this->setObjectDescription("Class for local file databases");
  64
  65                 // Create unique ID
  66                 $this->createUniqueID();
  67
  68                 // Clean up a little
  69                 $this->removeSystemArray();
  70         }
  71
  72         /**
  73          * Create an object of LocalFileDatabase and set the save path for local files.
  74          * This method also validates the given file path.
  75          *
  76          * @param               $savePath                                       The local file path string
  77          * @param               $ioInstance                             The input/output handler. This
  78          *                                                                      should be FileIoHandler
  79          * @return      $dbInstance                             An instance of LocalFileDatabase
  80          */
  81         public final static function createLocalFileDatabase ($savePath, FileIoHandler $ioInstance) {
  82                 // Get an instance
  83                 $dbInstance = new LocalFileDatabase();
  84
  85                 // Set save path and IO instance
  86                 $dbInstance->setSavePath($savePath);
  87                 $dbInstance->setFileIoInstance($ioInstance);
  88
  89                 // "Connect" to the database
  90                 $dbInstance->connectToDatabase();
  91
  92                 // Return database instance
  93                 return $dbInstance;
  94         }
  95
  96         /**
  97          * Setter for save path
  98          *
  99          * @param               $savePath               The local save path where we shall put our serialized classes
 100          * @return      void
 101          */
 102         public final function setSavePath ($savePath) {
 103                 // Secure string
 104                 $savePath = (string) $savePath;
 105
 106                 // Set save path
 107                 $this->savePath = $savePath;
 108         }
 109
 110         /**
 111          * Getter for save path
 112          *
 113          * @return      $savePath               The local save path where we shall put our serialized classes
 114          */
 115         public final function getSavePath () {
 116                 return $this->savePath;
 117         }
 118
 119         /**
 120          * Saves a given object to the local file system by serializing and
 121          * transparently compressing it
 122          *
 123          * @param               $object                         The object we shall save to the local file system
 124          * @return      void
 125          * @throws      NullPointerException    If the object instance is null
 126          * @throws      NoObjectException               If the parameter $object is not
 127          *                                                              an object
 128          */
 129         public final function saveObject ($object) {
 130                 // Some tests on the parameter...
 131                 if (is_null($object)) {
 132                         // Is null, throw exception
 133                         throw new NullPointerException($object, self::EXCEPTION_IS_NULL_POINTER);
 134                 } elseif (!is_object($object)) {
 135                         // Is not an object, throw exception
 136                         throw new NoObjectException($object, self::EXCEPTION_IS_NO_OBJECT);
 137                 } elseif (!method_exists($object, '__toString')) {
 138                         // A highly required method was not found... :-(
 139                         throw new MissingMethodException(array($object, '__toString'), self::EXCEPTION_MISSING_METHOD);
 140                 }
 141
 142                 // Get a string containing the serialized object. We cannot exchange
 143                 // $this and $object here because $object does not need to worry
 144                 // about it's limitations... ;-)
 145                 $serialized = $this->serializeObject($object);
 146
 147                 // Get a path name plus file name and append the extension
 148                 $fqfn = $this->getSavePath() . $object->getPathFileNameFromObject() . "." . $this->getFileExtension();
 149
 150                 // Save the file to disc we don't care here if the path is there,
 151                 // this must be done in later methods.
 152                 $this->getFileIoInstance()->saveFile($fqfn, array($this->getCompressorChannel()->getCompressorExtension(), $serialized));
 153         }
 154
 155         /**
 156          * Get a serialized string from the given object
 157          *
 158          * @param               $object         The object we want to serialize and transparently
 159          *                                              compress
 160          * @return      $serialized     A string containing the serialzed/compressed object
 161          * @see         ObjectLimits    An object holding limition information
 162          * @see         SerializationContainer  A special container class for e.g.
 163          *                                                              attributes from limited objects
 164          */
 165         private function serializeObject ($object) {
 166                 // If there is no limiter instance we serialize the whole object
 167                 // otherwise only in the limiter object (ObjectLimits) specified
 168                 // attributes summarized in a special container class
 169                 if ($this->getLimitInstance() === null) {
 170                         // Serialize the whole object. This tribble call is the reason
 171                         // why we need a fall-back implementation in CompressorChannel
 172                         // of the methods compressStream() and decompressStream().
 173                         $serialized = $this->getCompressorChannel()->getCompressor()->compressStream(serialize($object));
 174                 } else {
 175                         // Serialize only given attributes in a special container
 176                         $container = SerializationContainer::createSerializationContainer($this->getLimitInstance(), $object);
 177
 178                         // Serialize the container
 179                         $serialized = $this->getCompressorChannel()->getCompressor()->compressStream(serialize($container));
 180                 }
 181
 182                 // Return the serialized object string
 183                 return $serialized;
 184         }
 185
 186         /**
 187          * Analyses if a unique ID has already been used or not by search in the
 188          * local database folder.
 189          *
 190          * @param               $uniqueID               A unique ID number which shall be checked
 191          *                                              before it will be used
 192          * @param               $inConstructor  If we got called in a de/con-structor or
 193          *                                              from somewhere else
 194          * @return      $isUnused               true    = The unique ID was not found in the database,
 195          *                                              false = It is already in use by an other object
 196          * @throws      NoArrayCreatedException If explode() fails to create an array
 197          * @throws      InvalidArrayCountException      If the array contains less or
 198          *                                                                      more than two elements
 199          */
 200         public function isUniqueIdUsed ($uniqueID, $inConstructor = false) {
 201                 // Currently not used... ;-)
 202                 $isUsed = false;
 203
 204                 // Split the unique ID up in path and file name
 205                 $pathFile = explode("@", $uniqueID);
 206
 207                 // Are there two elements? Index 0 is the path, 1 the file name + global extension
 208                 if (!is_array($pathFile)) {
 209                         // No array found
 210                         if ($inConstructor) {
 211                                 return false;
 212                         } else {
 213                                 throw new NoArrayCreatedException(array($this, "pathFile"), self::EXCEPTION_ARRAY_EXPECTED);
 214                         }
 215                 } elseif (count($pathFile) != 2) {
 216                         // Invalid ID returned!
 217                         if ($inConstructor) {
 218                                 return false;
 219                         } else {
 220                                 throw new InvalidArrayCountException(array($this, "pathFile", count($pathFile), 2), self::EXCEPTION_ARRAY_HAS_INVALID_COUNT);
 221                         }
 222                 }
 223
 224                 // Create full path name
 225                 $pathName = $this->getSavePath() . $pathFile[0];
 226
 227                 // Check if the file is there with a file handler
 228                 if ($inConstructor) {
 229                         // No exceptions in constructors and destructors!
 230                         $dirInstance = FrameworkDirectoryPointer::createFrameworkDirectoryPointer($pathName, true);
 231
 232                         // Has an object being created?
 233                         if (!is_object($dirInstance)) return false;
 234                 } else {
 235                         // Outside a constructor
 236                         try {
 237                                 $dirInstance = FrameworkDirectoryPointer::createFrameworkDirectoryPointer($pathName);
 238                         } catch (PathIsNoDirectoryException $e) {
 239                                 // Okay, path not found
 240                                 return false;
 241                         }
 242                 }
 243
 244                 // Initialize the search loop
 245                 $isValid = false;
 246                 while ($dataFile = $dirInstance->readDirectoryExcept(array(".", ".."))) {
 247                         // Generate FQFN for testing
 248                         $fqfn = sprintf("%s/%s", $pathName, $dataFile);
 249                         $this->setLastFile($fqfn);
 250
 251                         // Get instance for file handler
 252                         $inputHandler = $this->getFileIoInstance();
 253
 254                         // Try to read from it. This makes it sure that the file is
 255                         // readable and a valid database file
 256                         $this->setLastFileContents($inputHandler->loadFileContents($fqfn));
 257
 258                         // Extract filename (= unique ID) from it
 259                         $ID = substr(basename($fqfn), 0, -(strlen($this->getFileExtension()) + 1));
 260
 261                         // Is this the required unique ID?
 262                         if ($ID == $pathFile[1]) {
 263                                 // Okay, already in use!
 264                                 $isUsed = true;
 265                         }
 266                 }
 267
 268                 // Close the directory handler
 269                 $dirInstance->closeDirectory();
 270
 271                 // Now the same for the file...
 272                 return $isUsed;
 273         }
 274
 275         /**
 276          * Setter for the last read file
 277          *
 278          * @param               $fqfn   The FQFN of the last read file
 279          * @return      void
 280          */
 281         private final function setLastFile ($fqfn) {
 282                 // Cast string
 283                 $fqfn = (string) $fqfn;
 284                 $this->lastFile = $fqfn;
 285         }
 286
 287         /**
 288          * Getter for last read file
 289          *
 290          * @return      $lastFile               The last read file's name with full path
 291          */
 292         public final function getLastFile () {
 293                 return $this->lastFile;
 294         }
 295
 296         /**
 297          * Setter for contents of the last read file
 298          *
 299          * @param               $contents               An array with header and data elements
 300          * @return      void
 301          */
 302         private final function setLastFileContents ($contents) {
 303                 // Cast array
 304                 $contents = (array) $contents;
 305                 $this->lastContents = $contents;
 306         }
 307
 308         /**
 309          * Getter for last read file's content as an array
 310          *
 311          * @return      $lastContent    The array with elements 'header' and 'data'.
 312          */
 313         public final function getLastContents () {
 314                 return $this->lastContents;
 315         }
 316
 317         /**
 318          * Getter for file extension
 319          *
 320          * @return      $fileExtension  The array with elements 'header' and 'data'.
 321          */
 322         public final function getFileExtension () {
 323                 return $this->fileExtension;
 324         }
 325
 326         /**
 327          * Get cached (last fetched) data from the local file database
 328          *
 329          * @param       $uniqueID       The ID number for looking up the data
 330          * @return      $object         The restored object from the maybe compressed
 331          *                                              serialized data
 332          * @throws      MismatchingCompressorsException         If the compressor from
 333          *                                                                      the loaded file
 334          *                                                                      mismatches with the
 335          *                                                                      current used one.
 336          * @throws      NullPointerException    If the restored object
 337          *                                                                      is null
 338          * @throws      NoObjectException               If the restored "object"
 339          *                                                                      is not an object instance
 340          * @throws      MissingMethodException  If the required method
 341          *                                                                      toString() is missing
 342          */
 343         public final function getObjectFromCachedData ($uniqueID) {
 344                 // Get instance for file handler
 345                 $inputHandler = $this->getFileIoInstance();
 346
 347                 // Get last file's name and contents
 348                 $fqfn = $this->repairFQFN($this->getLastFile(), $uniqueID);
 349                 $contents = $this->repairContents($this->getLastContents(), $fqfn);
 350
 351                 // Let's decompress it. First we need the instance
 352                 $compressInstance = $this->getCompressorChannel();
 353
 354                 // Is the compressor's extension the same as the one from the data?
 355                 if ($compressInstance->getCompressorExtension() != $contents['header'][0]) {
 356                         /**
 357                          * @todo        For now we abort here but later we need to make this a little more dynamic.
 358                          */
 359                         throw new MismatchingCompressorsException(array($this, $contents['header'][0], $fqfn, $compressInstance->getCompressorExtension()), self::EXCEPTION_MISMATCHING_COMPRESSORS);
 360                 }
 361
 362                 // Decompress the data now
 363                 $serialized = $compressInstance->getCompressor()->decompressStream($contents['data']);
 364
 365                 // And unserialize it...
 366                 $object = unserialize($serialized);
 367
 368                 // This must become a valid object, so let's check it...
 369                 if (is_null($object)) {
 370                         // Is null, throw exception
 371                         throw new NullPointerException($object, self::EXCEPTION_IS_NULL_POINTER);
 372                 } elseif (!is_object($object)) {
 373                         // Is not an object, throw exception
 374                         throw new NoObjectException($object, self::EXCEPTION_IS_NO_OBJECT);
 375                 } elseif (!$object instanceof FrameworkInterface) {
 376                         // A highly required method was not found... :-(
 377                         throw new MissingMethodException(array($object, '__toString'), self::EXCEPTION_MISSING_METHOD);
 378                 }
 379
 380                 // And return the object
 381                 return $object;
 382         }
 383
 384         /**
 385          * Private method for re-gathering (repairing) the FQFN
 386          *
 387          * @param               $fqfn           The current FQFN we shall validate
 388          * @param               $uniqueID               The unique ID number
 389          * @return      $fqfn           The repaired FQFN when it is empty
 390          * @throws      NoArrayCreatedException         If explode() has not
 391          *                                                                      created an array
 392          * @throws      InvalidArrayCountException      If the array count is not
 393          *                                                                      as the expected
 394          */
 395         private function repairFQFN ($fqfn, $uniqueID) {
 396                 // Cast both strings
 397                 $fqfn     = (string) $fqfn;
 398                 $uniqueID = (string) $uniqueID;
 399
 400                 // Is there pre-cached data available?
 401                 if (empty($fqfn)) {
 402                         // Split the unique ID up in path and file name
 403                         $pathFile = explode("@", $uniqueID);
 404
 405                         // Are there two elements? Index 0 is the path, 1 the file name + global extension
 406                         if (!is_array($pathFile)) {
 407                                 // No array found
 408                                 throw new NoArrayCreatedException(array($this, "pathFile"), self::EXCEPTION_ARRAY_EXPECTED);
 409                         } elseif (count($pathFile) != 2) {
 410                                 // Invalid ID returned!
 411                                 throw new InvalidArrayCountException(array($this, "pathFile", count($pathFile), 2), self::EXCEPTION_ARRAY_HAS_INVALID_COUNT);
 412                         }
 413
 414                         // Create full path name
 415                         $pathName = $this->getSavePath() . $pathFile[0];
 416
 417                         // Nothing cached, so let's create a FQFN first
 418                         $fqfn = sprintf("%s/%s.%s", $pathName, $pathFile[1], $this->getFileExtension());
 419                         $this->setLastFile($fqfn);
 420                 }
 421
 422                 // Return repaired FQFN
 423                 return $fqfn;
 424         }
 425
 426         /**
 427          * Private method for re-gathering the contents of a given file
 428          *
 429          * @param               $contents               The (maybe) already cached contents as an array
 430          * @param               $fqfn           The current FQFN we shall validate
 431          * @return      $contents               The repaired contents from the given file
 432          */
 433         private function repairContents ($contents, $fqfn) {
 434                 // Is there some content and header (2 indexes) in?
 435                 if ((!is_array($contents)) || (count($contents) != 2) || (!isset($contents['header'])) || (!isset($contents['data']))) {
 436                         // No content found so load the file again
 437                         $contents = $inputHandler->loadFileContents($fqfn);
 438
 439                         // And remember all data for later usage
 440                         $this->setLastContents($contents);
 441                 }
 442
 443                 // Return the repaired contents
 444                 return $contents;
 445         }
 446
 447         /**
 448          * Makes sure that the database connection is alive
 449          *
 450          * @return      void
 451          */
 452         public function connectToDatabase () {
 453                 // @TODO Do some checks on the database directory and files here
 454         }
 455
 456         /**
 457          * Loads data saved with saveObject from the database and re-creates a
 458          * full object from it.
 459          * If limitObject() was called before a new object ObjectContainer with
 460          * all requested attributes will be returned instead.
 461          *
 462          * @return      Object  The fully re-created object or instance to
 463          *                                      ObjectContainer
 464          * @throws      SavePathIsEmptyException                If the given save path is an
 465          *                                                                                      empty string
 466          * @throws      SavePathIsNoDirectoryException  If the save path is no
 467          *                                                                                      path (e.g. a file)
 468          * @throws      SavePathReadProtectedException  If the save path is read-
 469          *                                                                                      protected
 470          * @throws      SavePathWriteProtectedException If the save path is write-
 471          *                                                                                      protected
 472          */
 473         public function loadObject () {
 474                 // Already connected? Then abort here
 475                 if ($this->alreadyConnected === true) return true;
 476
 477                 // Get the save path
 478                 $savePath = $this->getSavePath();
 479
 480                 if (empty($savePath)) {
 481                         // Empty string
 482                         throw new SavePathIsEmptyException($dbInstance, self::EXCEPTION_UNEXPECTED_EMPTY_STRING);
 483                 } elseif (!is_dir($savePath)) {
 484                         // Is not a dir
 485                         throw new SavePathIsNoDirectoryException($savePath, self::EXCEPTION_INVALID_PATH_NAME);
 486                 } elseif (!is_readable($savePath)) {
 487                         // Path not readable
 488                         throw new SavePathReadProtectedException($savePath, self::EXCEPTION_READ_PROTECED_PATH);
 489                 } elseif (!is_writeable($savePath)) {
 490                         // Path not writeable
 491                         throw new SavePathWriteProtectedException($savePath, self::EXCEPTION_WRITE_PROTECED_PATH);
 492                 }
 493
 494                 // "Connection" established... ;-)
 495                 $this->alreadyConnected = true;
 496         }
 497
 498         /**
 499          * Starts a SELECT query on the database by given return type, table name
 500          * and search criteria
 501          *
 502          * @param       $resultType             Result type ("array", "object" and "indexed" are valid)
 503          * @param       $tableName              Name of the database table
 504          * @param       $criteria               Local search criteria class
 505          * @return      $resultData             Result data of the query
 506          * @throws      UnsupportedCriteriaException    If the criteria is unsupported
 507          */
 508         public function querySelect ($resultType, $tableName, Criteria $criteriaInstance) {
 509                 // Is this criteria supported?
 510                 if (!$criteriaInstance instanceof LocalCriteria) {
 511                         // Not supported by this database layer
 512                         throw new UnsupportedCriteriaException(array($this, $criteriaInstance), self::EXCEPTION_REQUIRED_INTERFACE_MISSING);
 513                 }
 514
 515                 // A "select" query on local files is not that easy, so begin slowly with it...
 516                 $this->partialStub(sprintf("type=%s,table=%s,criteria=%s", $resultType, $tableName, $criteriaInstance));
 517         }
 518 }
 519
 520 // [EOF]
 521 ?>