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perf: Improve preview cold generation #65146

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CarlSchwan wants to merge 2 commits into from
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perf: Improve preview cold generation #65146

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63cee1e
perf(preview): reuse the generated max preview image
CarlSchwan Oct 5, 2026
b204f1e
perf(preview): resize from the smallest suitable cached preview
CarlSchwan Oct 5, 2026
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59 changes: 47 additions & 12 deletions lib/private/Preview/Generator.php
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Original file line number Diff line number Diff line change
Expand Up @@ -128,8 +128,11 @@ public function generatePreviews(File $file, array $specifications, ?string $mim
}

// Get the max preview and infer the max preview sizes from that
$maxPreview = $this->getMaxPreview($previews, $file, $mimeType, $previewVersion);
$maxPreviewImage = null; // only load the image when we need it
// The image is only set if the max preview was just generated
[$maxPreview, $maxPreviewImage] = $this->getMaxPreview($previews, $file, $mimeType, $previewVersion);
if ($maxPreviewImage instanceof IStreamImage) {
$maxPreviewImage = null;
}
if ($maxPreview->getSize() === 0) {
$this->storageFactory->deletePreview($maxPreview);
$this->previewMapper->delete($maxPreview);
Expand Down Expand Up @@ -180,12 +183,20 @@ public function generatePreviews(File $file, array $specifications, ?string $mim
throw new NotFoundException();
}

if ($maxPreviewImage === null) {
$maxPreviewImage = $this->helper->getImage(new PreviewFile($maxPreview, $this->storageFactory, $this->previewMapper));
}

$this->logger->debug('Cached preview not found for file {path}, generating a new preview.', ['path' => $file->getPath()]);
$previewFile = $this->generatePreview($file, $maxPreviewImage, $width, $height, $crop, $maxWidth, $maxHeight, $previewVersion, $cacheResult);
$source = $maxPreviewImage === null ? $this->findResizeSource($previews, $maxPreview, $width, $height, $previewVersion) : null;
if ($source !== null) {
$sourceImage = $this->helper->getImage(new PreviewFile($source, $this->storageFactory, $this->previewMapper));
$previewFile = $this->generatePreview($file, $sourceImage, $width, $height, $crop, $source->getWidth(), $source->getHeight(), $previewVersion, $cacheResult);
if ($sourceImage instanceof Image) {
$sourceImage->destroy();
}
} else {
if ($maxPreviewImage === null) {
$maxPreviewImage = $this->helper->getImage(new PreviewFile($maxPreview, $this->storageFactory, $this->previewMapper));
}
$previewFile = $this->generatePreview($file, $maxPreviewImage, $width, $height, $crop, $maxWidth, $maxHeight, $previewVersion, $cacheResult);
}
}
} catch (\InvalidArgumentException $e) {
throw new NotFoundException('', 0, $e);
Expand All @@ -207,6 +218,28 @@ public function generatePreviews(File $file, array $specifications, ?string $mim
return $previewFile;
}

/**
* Smallest cached, uncropped preview larger than the requested size
*
* @param Preview[] $previews
*/
private function findResizeSource(array $previews, Preview $maxPreview, int $width, int $height, ?string $version): ?Preview {
$source = null;
foreach ($previews as $preview) {
if ($preview->isMax() || $preview->isCropped()
|| $preview->getVersion() !== $version
|| $preview->getMimetype() !== $maxPreview->getMimetype()
|| $preview->getWidth() < $width || $preview->getHeight() < $height
|| ($preview->getWidth() === $width && $preview->getHeight() === $height)) {
continue;
}
if ($source === null || $preview->getWidth() * $preview->getHeight() < $source->getWidth() * $source->getHeight()) {
$source = $preview;
}
}
return $source;
}

/**
* @return Preview[]
*/
Expand Down Expand Up @@ -328,14 +361,15 @@ public function getNumConcurrentPreviews(string $type): int {

/**
* @param Preview[] $previews
* @return array{Preview, ?IImage} the max preview and its image, if it was generated
* @throws NotFoundException
*/
private function getMaxPreview(array $previews, File $file, string $mimeType, ?string $version): Preview {
private function getMaxPreview(array $previews, File $file, string $mimeType, ?string $version): array {
// We don't know the max preview size, so we can't use getCachedPreview.
// It might have been generated with a higher resolution than the current value.
foreach ($previews as $preview) {
if ($preview->isMax() && ($version === $preview->getVersion())) {
return $preview;
return [$preview, null];
}
}

Expand All @@ -350,7 +384,7 @@ private function getMaxPreview(array $previews, File $file, string $mimeType, ?s
[$file->getId() => $previews] = $this->previewMapper->getAvailablePreviews([$file->getId()]);
foreach ($previews as $preview) {
if ($preview->isMax() && ($version === $preview->getVersion())) {
return $preview;
return [$preview, null];
}
}
}
Expand All @@ -359,10 +393,11 @@ private function getMaxPreview(array $previews, File $file, string $mimeType, ?s
}

/**
* @return array{Preview, IImage}
* @throws DBException
* @throws NotFoundException
*/
private function generateProviderPreview(File $file, int $width, int $height, bool $crop, bool $max, string $mimeType, ?string $version): Preview {
private function generateProviderPreview(File $file, int $width, int $height, bool $crop, bool $max, string $mimeType, ?string $version): array {
$previewProviders = $this->previewManager->getProviders();
foreach ($previewProviders as $supportedMimeType => $providers) {
// Filter out providers that does not support this mime
Expand Down Expand Up @@ -413,7 +448,7 @@ private function generateProviderPreview(File $file, int $width, int $height, bo
$previewEntry->setMimetype($preview->dataMimeType());
$previewEntry->setEtag($file->getEtag());
$previewEntry->setMtime((new \DateTime())->getTimestamp());
return $this->savePreview($previewEntry, $preview);
return [$this->savePreview($previewEntry, $preview), $preview];
} catch (NotPermittedException) {
throw new NotFoundException();
}
Expand Down
61 changes: 55 additions & 6 deletions tests/lib/Preview/GeneratorTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
use OCP\Files\File;
use OCP\Files\Mount\IMountPoint;
use OCP\Files\NotFoundException;
use OCP\Files\SimpleFS\ISimpleFile;
use OCP\IAppConfig;
use OCP\IConfig;
use OCP\IImage;
Expand Down Expand Up @@ -169,6 +170,9 @@ public function testGetNewPreview(bool $hasVersion): void {
$image->method('height')->willReturn(2048);
$image->method('valid')->willReturn(true);
$image->method('dataMimeType')->willReturn('image/png');
$image->method('data')->willReturn('my data');
$image->method('resizeCopy')
->willReturnCallback(fn (int $size): IImage => $this->getMockImage($size, $size, 'my resized data'));

$this->getAutoMock(GeneratorHelper::class)->method('getThumbnail')
->willReturnCallback(function ($provider, $file, $x, $y) use ($invalidProvider, $validProvider, $image): false|IImage {
Expand All @@ -179,9 +183,6 @@ public function testGetNewPreview(bool $hasVersion): void {
}
});

$image->method('data')
->willReturn('my data');

$this->getAutoMock(PreviewMapper::class)->method('insert')
->willReturnCallback(fn (Preview $preview): Preview => $preview);

Expand Down Expand Up @@ -213,9 +214,9 @@ public function testGetNewPreview(bool $hasVersion): void {
$this->fail('file name is wrong:' . $preview->getName());
});

$image = $this->getMockImage(2048, 2048, 'my resized data');
$this->getAutoMock(GeneratorHelper::class)->method('getImage')
->willReturn($image);
// The generated max preview is reused, not decoded again
$this->getAutoMock(GeneratorHelper::class)->expects($this->never())
->method('getImage');

$this->getAutoMock(IEventDispatcher::class)->expects($this->once())
->method('dispatchTyped')
Expand Down Expand Up @@ -505,6 +506,54 @@ public function testHardwareConcurrencyIsCached(): void {
$this->generator->getNumConcurrentPreviews('preview_concurrency_new');
}

#[TestWith([false, '256-256.png'])]
#[TestWith([true, '2048-2048-max.png'])]
public function testResizeFromSmallestCachedPreview(bool $cropped, string $expectedSource): void {
$file = $this->getFile(42, 'myMimeType');

$this->getAutoMock(IPreview::class)->method('isMimeSupported')
->willReturn(true);

$maxPreview = new Preview();
$maxPreview->setWidth(2048);
$maxPreview->setHeight(2048);
$maxPreview->setMax(true);
$maxPreview->setSize(1000);
$maxPreview->setVersion(null);
$maxPreview->setMimeType('image/png');

$previews = [$maxPreview];
foreach ([1024, 256] as $size) {
$preview = new Preview();
$preview->setWidth($size);
$preview->setHeight($size);
$preview->setMax(false);
$preview->setSize(1000);
$preview->setCropped($cropped);
$preview->setVersion(null);
$preview->setMimeType('image/png');
$previews[] = $preview;
}

$this->getAutoMock(PreviewMapper::class)->method('getAvailablePreviews')
->willReturn([42 => $previews]);

$this->getAutoMock(GeneratorHelper::class)->expects($this->once())
->method('getImage')
->willReturnCallback(function (ISimpleFile $source) use ($expectedSource): IImage {
$this->assertSame($expectedSource, $source->getName());
return $this->getMockImage(256, 256);
});

$this->getAutoMock(PreviewMapper::class)->method('insert')
->willReturnCallback(fn (Preview $preview): Preview => $preview);
$this->getAutoMock(StorageFactory::class)->method('writePreview')
->willReturn(1000);

$result = $this->generator->getPreview($file, 32, 32);
$this->assertSame('64-64.png', $result->getName());
}

public function testUnreadbleFile(): void {
$file = $this->createMock(File::class);
$file->method('isReadable')
Expand Down
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