Add read cache for zip archive entries in XLSX reader

composer.json

@@ -13,7 +13,7 @@
     ],
     "config": {
         "platform": {
-            "php" : "8.1.99"
+            "php": "8.1.99"
         },
         "process-timeout": 600,
         "sort-packages": true,
@@ -120,7 +120,8 @@
     "autoload-dev": {
         "psr-4": {
             "PhpOffice\\PhpSpreadsheetTests\\": "tests/PhpSpreadsheetTests",
-            "PhpOffice\\PhpSpreadsheetInfra\\": "infra"
+            "PhpOffice\\PhpSpreadsheetInfra\\": "infra",
+            "PhpOffice\\PhpSpreadsheetBenchmarks\\": "tests/Benchmark"
         }
     }
 }

src/PhpSpreadsheet/Reader/Xlsx.php

@@ -64,6 +64,9 @@ class Xlsx extends BaseReader
 
     private bool $parseHuge = false;
 
+    /** @var array<string, string> Cache for zip archive entry contents, keyed by normalized file name */
+    private array $zipCache = [];
+
     /**
      * Allow use of LIBXML_PARSEHUGE.
      * This option can lead to memory leaks and failures,
@@ -94,6 +97,7 @@ public function canRead(string $filename): bool
             return false;
         }
 
+        $this->clearZipCache();
         $result = false;
         $this->zip = $zip = new ZipArchive();
 
@@ -102,6 +106,7 @@ public function canRead(string $filename): bool
             $result = !empty($workbookBasename);
 
             $zip->close();
+            $this->clearZipCache();
         }
 
         return $result;
@@ -182,6 +187,7 @@ private function loadZipNonamespace(string $filename, string $ns): SimpleXMLElem
     public function listWorksheetNames(string $filename): array
     {
         File::assertFile($filename, self::INITIAL_FILE);
+        $this->clearZipCache();
 
         $worksheetNames = [];
 
@@ -207,6 +213,7 @@ public function listWorksheetNames(string $filename): array
         }
 
         $zip->close();
+        $this->clearZipCache();
 
         return $worksheetNames;
     }
@@ -219,6 +226,7 @@ public function listWorksheetNames(string $filename): array
     public function listWorksheetInfo(string $filename): array
     {
         File::assertFile($filename, self::INITIAL_FILE);
+        $this->clearZipCache();
 
         $worksheetInfo = [];
 
@@ -315,6 +323,7 @@ public function listWorksheetInfo(string $filename): array
         }
 
         $zip->close();
+        $this->clearZipCache();
 
         return $worksheetInfo;
     }
@@ -400,6 +409,8 @@ private function fileExistsInArchive(ZipArchive $archive, string $fileName = '')
 
     private function getFromZipArchive(ZipArchive $archive, string $fileName = ''): string
     {
+        assert($archive === $this->zip, 'Cache assumes all reads use the same archive');
+
         // Root-relative paths
         if (str_contains($fileName, '//')) {
             $fileName = substr($fileName, strpos($fileName, '//') + 1);
@@ -409,6 +420,11 @@ private function getFromZipArchive(ZipArchive $archive, string $fileName = ''):
         $fileName = Preg::replace('/^\.\//', '', $fileName);
         $fileName = File::realpath($fileName);
 
+        // Return from cache if available
+        if (isset($this->zipCache[$fileName])) {
+            return $this->zipCache[$fileName];
+        }
+
         // Sadly, some 3rd party xlsx generators don't use consistent case for filenaming
         //    so we need to load case-insensitively from the zip file
 
@@ -424,7 +440,22 @@ private function getFromZipArchive(ZipArchive $archive, string $fileName = ''):
             $contents = $archive->getFromName(str_replace('/', '\\', $fileName), 0, ZipArchive::FL_NOCASE);
         }
 
-        return ($contents === false) ? '' : $contents;
+        $result = ($contents === false) ? '' : $contents;
+
+        // Cache the result for subsequent reads of the same entry
+        $this->zipCache[$fileName] = $result;
+
+        return $result;
+    }
+
+    /**
+     * Clear the zip archive read cache.
+     * Called at the start of each load operation to ensure
+     * stale data from a previous load does not persist.
+     */
+    private function clearZipCache(): void
+    {
+        $this->zipCache = [];
     }
 
     /**
@@ -433,6 +464,7 @@ private function getFromZipArchive(ZipArchive $archive, string $fileName = ''):
     protected function loadSpreadsheetFromFile(string $filename): Spreadsheet
     {
         File::assertFile($filename, self::INITIAL_FILE);
+        $this->clearZipCache();
 
         // Initialisations
         $excel = $this->newSpreadsheet();
@@ -2051,6 +2083,7 @@ protected function loadSpreadsheetFromFile(string $filename): Spreadsheet
         $excel->setUnparsedLoadedData($unparsedLoadedData);
 
         $zip->close();
+        $this->clearZipCache();
 
         return $excel;
     }