internal HashedCacheKey Hash(CacheKey key)
{
using (var h = SHA256.Create())
{
var a = h.ComputeHash(key.Key1);
var b = h.ComputeHash(key.Key2).Take(16).ToArray();
var c = h.ComputeHash(key.Key3).Take(16).ToArray();
var masterHashData = new List <byte>(64);
masterHashData.AddRange(a);
masterHashData.AddRange(b);
masterHashData.AddRange(c);
var masterHash = h.ComputeHash(masterHashData.ToArray());
var readId = BitConverter.ToUInt32(masterHash, 0);
var shardSeed = BitConverter.ToUInt32(a, 8);
uint shard = (uint)(shardSeed % _shardCount);
var blobKey = new StringBuilder(75);
blobKey.Append("blobs/");
blobKey.AppendFormat("{0:x2}", masterHash[16]);
blobKey.Append('/');
blobKey.AppendFormat("{0:x2}", masterHash[17]);
blobKey.Append('/');
foreach (byte item in masterHash)
{
blobKey.AppendFormat("{0:x2}", item);
}
var result = new HashedCacheKey
{
Key1Hash = a,
Key2Hash = b,
Key3Hash = c,
ReadId = readId,
Shard = shard,
BlobKey = blobKey.ToString()
};
return(result);
}
}
internal void EnqueuePutBytes(HashedCacheKey hash, byte[] data, uint cost)
{
// TODO: have a temporary in-memory cache while the files are being written so that repeated requests for the same file aren't a miss
putByteTasks.Enqueue(Task.Run(async() =>
{
try
{
await evicter.EvictSpaceFor(data.Length, shutdownTokenSource.Token);
await evicter.WriteLogEventually(hash, data, cost);
await evicter.RecordBytesUsed(data.Length);
// Don't cancel while writing bytes
await store.WriteBytes(shardId, hash.BlobKey, data, CancellationToken.None);
}
catch (Exception e)
{
if (e is OperationCanceledException)
{
throw;
}
else
{
exceptionLog.Enqueue(e);
}
}
}, shutdownTokenSource.Token));
/// Try to cleanup tasks when possible. A long running task may block cleanup of others
if (putByteTasks.TryPeek(out Task t))
{
if (t.IsCompleted || t.IsFaulted || t.IsCanceled)
{
if (putByteTasks.TryDequeue(out Task task))
{
if (!(task.IsCompleted || task.IsFaulted || task.IsCanceled))
{
putByteTasks.Enqueue(task);
}
}
}
}
}
