List preview directory only once

getCachedPreview used to call `getFile`, and this calls `getDirectoryListing` (or underlying function that list directory) to find the file. This was done for every preview spec.
Now, this is done only once at the beginning of the loop, and the array is just iterated when needed to find the correct entry.

Signed-off-by: Glandos <bugs-github@antipoul.fr>

1 files changed, 13 insertions, 5 deletions

diff --git a/lib/private/Preview/Generator.php b/lib/private/Preview/Generator.php
index 47f2952c6e6..a005d46adb4 100644
--- a/lib/private/Preview/Generator.php
+++ b/lib/private/Preview/Generator.php
@@ -171,6 +171,8 @@ class Generator {
 		[$maxWidth, $maxHeight] = $this->getPreviewSize($maxPreview, $previewVersion);
 
 		$preview = null;
+		// List every existing preview first instead of trying to find them one by one
+		$previewFiles = $previewFolder->getDirectoryListing();
 
 		foreach ($specifications as $specification) {
 			$width = $specification['width'] ?? -1;
@@ -197,7 +199,7 @@ class Generator {
 			// Try to get a cached preview. Else generate (and store) one
 			try {
 				try {
-					$preview = $this->getCachedPreview($previewFolder, $width, $height, $crop, $maxPreview->getMimeType(), $previewVersion);
+					$preview = $this->getCachedPreview($previewFiles, $width, $height, $crop, $maxPreview->getMimeType(), $previewVersion);
 				} catch (NotFoundException $e) {
 					if (!$this->previewManager->isMimeSupported($mimeType)) {
 						throw new NotFoundException();
@@ -208,6 +210,8 @@ class Generator {
 					}
 
 					$preview = $this->generatePreview($previewFolder, $maxPreviewImage, $width, $height, $crop, $maxWidth, $maxHeight, $previewVersion);
+					// New file, augment our array
+					$previewFiles[] = $preview;
 				}
 			} catch (\InvalidArgumentException $e) {
 				throw new NotFoundException("", 0, $e);
@@ -649,7 +653,7 @@ class Generator {
 	}
 
 	/**
-	 * @param ISimpleFolder $previewFolder
+	 * @param array $files Array of FileInfo, as the result of getDirectoryListing()
 	 * @param int $width
 	 * @param int $height
 	 * @param bool $crop
@@ -659,10 +663,14 @@ class Generator {
 	 *
 	 * @throws NotFoundException
 	 */
-	private function getCachedPreview(ISimpleFolder $previewFolder, $width, $height, $crop, $mimeType, $prefix) {
+	private function getCachedPreview($files, $width, $height, $crop, $mimeType, $prefix) {
 		$path = $this->generatePath($width, $height, $crop, $mimeType, $prefix);
-
-		return $previewFolder->getFile($path);
+		foreach($files as $file) {
+			if ($file->getName() === $path) {
+				return $file;
+			}
+		}
+		throw new NotFoundException();
 	}
 
 	/**