/// <summary>
/// Compute a cache manifest from runtime data.
/// </summary>
/// <param name="version">The version of the cache</param>
/// <param name="graphicsApi">The graphics api used by the cache</param>
/// <param name="hashType">The hash type of the cache</param>
/// <param name="entries">The entries in the cache</param>
/// <returns>The cache manifest from runtime data</returns>
public static byte[] ComputeManifest(ulong version, CacheGraphicsApi graphicsApi, CacheHashType hashType, HashSet <Hash128> entries)
{
if (hashType != CacheHashType.XxHash128)
{
throw new NotImplementedException($"{hashType}");
}
CacheManifestHeader manifestHeader = new CacheManifestHeader(version, graphicsApi, hashType);
byte[] data = new byte[Unsafe.SizeOf <CacheManifestHeader>() + entries.Count * Unsafe.SizeOf <Hash128>()];
// CacheManifestHeader has the same size as a Hash128.
Span <Hash128> dataSpan = MemoryMarshal.Cast <byte, Hash128>(data.AsSpan()).Slice(1);
int i = 0;
foreach (Hash128 hash in entries)
{
dataSpan[i++] = hash;
}
manifestHeader.UpdateChecksum(data.AsSpan(Unsafe.SizeOf <CacheManifestHeader>()));
MemoryMarshal.Write(data, ref manifestHeader);
return(data);
}
/// <summary>
/// Save the manifest file.
/// </summary>
private void SaveManifest()
{
CacheManifestHeader manifestHeader = new CacheManifestHeader(_version, _graphicsApi, _hashType);
byte[] data;
lock (_hashTable)
{
data = new byte[Unsafe.SizeOf <CacheManifestHeader>() + _hashTable.Count * Unsafe.SizeOf <Hash128>()];
// CacheManifestHeader has the same size as a Hash128.
Span <Hash128> dataSpan = MemoryMarshal.Cast <byte, Hash128>(data.AsSpan()).Slice(1);
int i = 0;
foreach (Hash128 hash in _hashTable)
{
dataSpan[i++] = hash;
}
}
manifestHeader.UpdateChecksum(data.AsSpan().Slice(Unsafe.SizeOf <CacheManifestHeader>()));
MemoryMarshal.Write(data, ref manifestHeader);
File.WriteAllBytes(GetManifestPath(), data);
}
/// <summary>
/// Try to read the manifest header from a given file path.
/// </summary>
/// <param name="manifestPath">The path to the manifest file</param>
/// <param name="header">The manifest header read</param>
/// <returns>Return true if the manifest header was read</returns>
public static bool TryReadManifestHeader(string manifestPath, out CacheManifestHeader header)
{
header = default;
if (File.Exists(manifestPath))
{
Memory <byte> rawManifest = File.ReadAllBytes(manifestPath);
if (MemoryMarshal.TryRead(rawManifest.Span, out header))
{
return(true);
}
}
return(false);
}
/// <summary>
/// Try to read the manifest from a given file path.
/// </summary>
/// <param name="manifestPath">The path to the manifest file</param>
/// <param name="graphicsApi">The graphics api used by the cache</param>
/// <param name="hashType">The hash type of the cache</param>
/// <param name="header">The manifest header read</param>
/// <param name="entries">The entries read from the cache manifest</param>
/// <returns>Return true if the manifest was read</returns>
public static bool TryReadManifestFile(string manifestPath, CacheGraphicsApi graphicsApi, CacheHashType hashType, out CacheManifestHeader header, out HashSet <Hash128> entries)
{
header = default;
entries = new HashSet <Hash128>();
if (File.Exists(manifestPath))
{
Memory <byte> rawManifest = File.ReadAllBytes(manifestPath);
if (MemoryMarshal.TryRead(rawManifest.Span, out header))
{
Memory <byte> hashTableRaw = rawManifest.Slice(Unsafe.SizeOf <CacheManifestHeader>());
bool isValid = header.IsValid(graphicsApi, hashType, hashTableRaw.Span);
if (isValid)
{
ReadOnlySpan <Hash128> hashTable = MemoryMarshal.Cast <byte, Hash128>(hashTableRaw.Span);
foreach (Hash128 hash in hashTable)
{
entries.Add(hash);
}
}
return(isValid);
}
}
return(false);
}
