/**
* Retrieves the {@link CachedLayer} for the layer with digest {@code layerDigest}.
*
* @param layerDigest the layer digest
* @return the {@link CachedLayer} referenced by the layer digest, if found
* @throws CacheCorruptedException if the cache was found to be corrupted
* @throws IOException if an I/O exception occurs
*/
public Maybe <CachedLayer> Retrieve(DescriptorDigest layerDigest)
{
layerDigest = layerDigest ?? throw new ArgumentNullException(nameof(layerDigest));
SystemPath layerDirectory = cacheStorageFiles.GetLayerDirectory(layerDigest);
if (!Files.Exists(layerDirectory))
{
return(Maybe.Empty <CachedLayer>());
}
CachedLayer.Builder cachedLayerBuilder = CachedLayer.CreateBuilder().SetLayerDigest(layerDigest);
foreach (SystemPath fileInLayerDirectory in Files.List(layerDirectory))
{
if (CacheStorageFiles.IsLayerFile(fileInLayerDirectory))
{
if (cachedLayerBuilder.HasLayerBlob())
{
throw new CacheCorruptedException(
cacheStorageFiles.GetCacheDirectory(),
"Multiple layer files found for layer with digest "
+ layerDigest.GetHash()
+ " in directory: "
+ layerDirectory);
}
cachedLayerBuilder
.SetLayerBlob(Blobs.From(fileInLayerDirectory))
.SetLayerDiffId(cacheStorageFiles.GetDiffId(fileInLayerDirectory))
.SetLayerSize(Files.Size(fileInLayerDirectory));
}
}
return(Maybe.Of(cachedLayerBuilder.Build()));
}
/**
* Writes an uncompressed {@code layerBlob} to the {@code layerDirectory}.
*
* @param uncompressedLayerBlob the uncompressed layer {@link Blob}
* @param layerDirectory the directory for the layer
* @return a {@link WrittenLayer} with the written layer information
* @throws IOException if an I/O exception occurs
*/
private async Task <WrittenLayer> WriteUncompressedLayerBlobToDirectoryAsync(
IBlob uncompressedLayerBlob, SystemPath layerDirectory)
{
using (TemporaryFile temporaryLayerFile = CacheStorageFiles.GetTemporaryLayerFile(layerDirectory))
{
DescriptorDigest layerDiffId;
BlobDescriptor blobDescriptor;
// Writes the layer with GZIP compression. The original bytes are captured as the layer's
// diff ID and the bytes outputted from the GZIP compression are captured as the layer's
// content descriptor.
using (CountingDigestOutputStream compressedDigestOutputStream =
new CountingDigestOutputStream(
Files.NewOutputStream(temporaryLayerFile.Path)))
{
using (GZipStream compressorStream = new GZipStream(compressedDigestOutputStream, CompressionMode.Compress, true))
{
BlobDescriptor descriptor = await uncompressedLayerBlob.WriteToAsync(compressorStream).ConfigureAwait(false);
layerDiffId = descriptor.GetDigest();
}
// The GZIPOutputStream must be closed in order to write out the remaining compressed data.
blobDescriptor = compressedDigestOutputStream.ComputeDigest();
}
DescriptorDigest layerDigest = blobDescriptor.GetDigest();
long layerSize = blobDescriptor.GetSize();
// Renames the temporary layer file to the correct filename.
SystemPath layerFile = layerDirectory.Resolve(cacheStorageFiles.GetLayerFilename(layerDiffId));
temporaryLayerFile.MoveIfDoesNotExist(layerFile);
return(new WrittenLayer(layerDigest, layerDiffId, layerSize));
}
}
/**
* Writes a compressed {@code layerBlob} to the {@code layerDirectory}.
*
* @param compressedLayerBlob the compressed layer {@link Blob}
* @param layerDirectory the directory for the layer
* @return a {@link WrittenLayer} with the written layer information
* @throws IOException if an I/O exception occurs
*/
private async Task <WrittenLayer> WriteCompressedLayerBlobToDirectoryAsync(
IBlob compressedLayerBlob, SystemPath layerDirectory)
{
// Writes the layer file to the temporary directory.
using (TemporaryFile temporaryLayerFile = CacheStorageFiles.GetTemporaryLayerFile(layerDirectory))
{
BlobDescriptor layerBlobDescriptor;
using (Stream fileOutputStream = Files.NewOutputStream(temporaryLayerFile.Path))
{
layerBlobDescriptor = await compressedLayerBlob.WriteToAsync(fileOutputStream).ConfigureAwait(false);
}
// Gets the diff ID.
DescriptorDigest layerDiffId = await GetDiffIdByDecompressingFileAsync(temporaryLayerFile.Path).ConfigureAwait(false);
// Renames the temporary layer file to the correct filename.
SystemPath layerFile = layerDirectory.Resolve(cacheStorageFiles.GetLayerFilename(layerDiffId));
temporaryLayerFile.MoveIfDoesNotExist(layerFile);
return(new WrittenLayer(
layerBlobDescriptor.GetDigest(), layerDiffId, layerBlobDescriptor.GetSize()));
}
}
public CacheStorageReader(CacheStorageFiles cacheStorageFiles)
{
this.cacheStorageFiles = cacheStorageFiles;
}
public CacheStorageWriter(CacheStorageFiles cacheStorageFiles)
{
this.cacheStorageFiles = cacheStorageFiles;
}
private LayersCache(CacheStorageFiles cacheStorageFiles)
{
cacheStorageWriter = new CacheStorageWriter(cacheStorageFiles);
cacheStorageReader = new CacheStorageReader(cacheStorageFiles);
}
