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Long Term Support Release

  • Bug fixes for general core bugs in 4.1.x will end 13 November 2023 (12 months).
  • Bug fixes for security issues in 4.1.x will end 10 November 2025 (36 months).
  • PHP version: minimum PHP 7.4.0 Note: minimum PHP version has increased since Moodle 4.0. PHP 8.0.x is supported too.
<?php

namespace Box\Spout\Reader\XLSX\Manager\SharedStringsCaching;

use Box\Spout\Reader\Exception\SharedStringNotFoundException;
use Box\Spout\Reader\XLSX\Creator\HelperFactory;

/**
 * Class FileBasedStrategy
 *
 * This class implements the file-based caching strategy for shared strings.
 * Shared strings are stored in small files (with a max number of strings per file).
 * This strategy is slower than an in-memory strategy but is used to avoid out of memory crashes.
 */
class FileBasedStrategy implements CachingStrategyInterface
{
    /** Value to use to escape the line feed character ("\n") */
    const ESCAPED_LINE_FEED_CHARACTER = '_x000A_';

    /** @var \Box\Spout\Common\Helper\GlobalFunctionsHelper Helper to work with global functions */
    protected $globalFunctionsHelper;

    /** @var \Box\Spout\Common\Helper\FileSystemHelper Helper to perform file system operations */
    protected $fileSystemHelper;

    /** @var string Temporary folder where the temporary files will be created */
    protected $tempFolder;

    /**
     * @var int Maximum number of strings that can be stored in one temp file
     * @see CachingStrategyFactory::MAX_NUM_STRINGS_PER_TEMP_FILE
     */
    protected $maxNumStringsPerTempFile;

    /** @var resource Pointer to the last temp file a shared string was written to */
    protected $tempFilePointer;

    /**
     * @var string Path of the temporary file whose contents is currently stored in memory
     * @see CachingStrategyFactory::MAX_NUM_STRINGS_PER_TEMP_FILE
     */
    protected $inMemoryTempFilePath;

    /**
     * @var array Contents of the temporary file that was last read
     * @see CachingStrategyFactory::MAX_NUM_STRINGS_PER_TEMP_FILE
     */
    protected $inMemoryTempFileContents;

    /**
     * @param string $tempFolder Temporary folder where the temporary files to store shared strings will be stored
     * @param int $maxNumStringsPerTempFile Maximum number of strings that can be stored in one temp file
     * @param HelperFactory $helperFactory Factory to create helpers
     */
    public function __construct($tempFolder, $maxNumStringsPerTempFile, $helperFactory)
    {
        $this->fileSystemHelper = $helperFactory->createFileSystemHelper($tempFolder);
< $this->tempFolder = $this->fileSystemHelper->createFolder($tempFolder, uniqid('sharedstrings'));
> $this->tempFolder = $this->fileSystemHelper->createFolder($tempFolder, \uniqid('sharedstrings'));
$this->maxNumStringsPerTempFile = $maxNumStringsPerTempFile; $this->globalFunctionsHelper = $helperFactory->createGlobalFunctionsHelper(); $this->tempFilePointer = null; } /** * Adds the given string to the cache. * * @param string $sharedString The string to be added to the cache * @param int $sharedStringIndex Index of the shared string in the sharedStrings.xml file * @return void */ public function addStringForIndex($sharedString, $sharedStringIndex) { $tempFilePath = $this->getSharedStringTempFilePath($sharedStringIndex); if (!$this->globalFunctionsHelper->file_exists($tempFilePath)) { if ($this->tempFilePointer) { $this->globalFunctionsHelper->fclose($this->tempFilePointer); } $this->tempFilePointer = $this->globalFunctionsHelper->fopen($tempFilePath, 'w'); } // The shared string retrieval logic expects each cell data to be on one line only // Encoding the line feed character allows to preserve this assumption $lineFeedEncodedSharedString = $this->escapeLineFeed($sharedString); $this->globalFunctionsHelper->fwrite($this->tempFilePointer, $lineFeedEncodedSharedString . PHP_EOL); } /** * Returns the path for the temp file that should contain the string for the given index * * @param int $sharedStringIndex Index of the shared string in the sharedStrings.xml file * @return string The temp file path for the given index */ protected function getSharedStringTempFilePath($sharedStringIndex) { $numTempFile = (int) ($sharedStringIndex / $this->maxNumStringsPerTempFile); return $this->tempFolder . '/sharedstrings' . $numTempFile; } /** * Closes the cache after the last shared string was added. * This prevents any additional string from being added to the cache. * * @return void */ public function closeCache() { // close pointer to the last temp file that was written if ($this->tempFilePointer) { $this->globalFunctionsHelper->fclose($this->tempFilePointer); } } /** * Returns the string located at the given index from the cache. * * @param int $sharedStringIndex Index of the shared string in the sharedStrings.xml file * @throws \Box\Spout\Reader\Exception\SharedStringNotFoundException If no shared string found for the given index * @return string The shared string at the given index */ public function getStringAtIndex($sharedStringIndex) { $tempFilePath = $this->getSharedStringTempFilePath($sharedStringIndex); $indexInFile = $sharedStringIndex % $this->maxNumStringsPerTempFile; if (!$this->globalFunctionsHelper->file_exists($tempFilePath)) { throw new SharedStringNotFoundException("Shared string temp file not found: $tempFilePath ; for index: $sharedStringIndex"); } if ($this->inMemoryTempFilePath !== $tempFilePath) { // free memory unset($this->inMemoryTempFileContents);
< $this->inMemoryTempFileContents = explode(PHP_EOL, $this->globalFunctionsHelper->file_get_contents($tempFilePath));
> $this->inMemoryTempFileContents = \explode(PHP_EOL, $this->globalFunctionsHelper->file_get_contents($tempFilePath));
$this->inMemoryTempFilePath = $tempFilePath; } $sharedString = null; // Using isset here because it is way faster than array_key_exists... if (isset($this->inMemoryTempFileContents[$indexInFile])) { $escapedSharedString = $this->inMemoryTempFileContents[$indexInFile]; $sharedString = $this->unescapeLineFeed($escapedSharedString); } if ($sharedString === null) { throw new SharedStringNotFoundException("Shared string not found for index: $sharedStringIndex"); }
< return rtrim($sharedString, PHP_EOL);
> return \rtrim($sharedString, PHP_EOL);
} /** * Escapes the line feed characters (\n) * * @param string $unescapedString * @return string */ private function escapeLineFeed($unescapedString) {
< return str_replace("\n", self::ESCAPED_LINE_FEED_CHARACTER, $unescapedString);
> return \str_replace("\n", self::ESCAPED_LINE_FEED_CHARACTER, $unescapedString);
} /** * Unescapes the line feed characters (\n) * * @param string $escapedString * @return string */ private function unescapeLineFeed($escapedString) {
< return str_replace(self::ESCAPED_LINE_FEED_CHARACTER, "\n", $escapedString);
> return \str_replace(self::ESCAPED_LINE_FEED_CHARACTER, "\n", $escapedString);
} /** * Destroys the cache, freeing memory and removing any created artifacts * * @return void */ public function clearCache() { if ($this->tempFolder) { $this->fileSystemHelper->deleteFolderRecursively($this->tempFolder); } } }