/**
* 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()));
}
}
