public async Task<StorageValue> ReadAsync(StorageKey key)
{
for (int i = 0; i < _retries; ++i)
{
if (_cancellation.IsCancellationRequested) throw new ObjectDisposedException(nameof(SaveFile));
lock (_mutex)
{
/* If we find the value in the write queue, return the queued value. (It's more recent than what's on disk.) */
StorageValue value;
if (_queuedValues.TryGetValue(key, out value)) return value;
}
var filename = GetFilename(key);
if (!File.Exists(filename)) return null;
try
{
using (var stream = File.Open(GetFilename(key), FileMode.Open, FileAccess.Read, FileShare.Read))
{
using (var memoryStream = new MemoryStream((int)stream.Length))
{
await stream.CopyToAsync(memoryStream);
return new StorageValue(memoryStream.ToArray());
}
}
}
catch (IOException)
{
}
}
/* Ignore read errors (for now). */
return null;
}
public void Write(StorageKey key, StorageValue value)
{
if (key == null) throw new ArgumentNullException(nameof(key));
if (value == null) throw new ArgumentNullException(nameof(value));
lock (_mutex)
{
_queuedValues[key] = value;
}
_queuedKeys.Add(key);
}
private string GetFilename(StorageKey key)
{
using (var sha1 = new SHA1Managed())
{
var hashBytes = sha1.ComputeHash(key.Bytes);
return Path.Combine(
_path,
HexConverter.ToHex(hashBytes, 0, 1),
HexConverter.ToHex(hashBytes, 1, hashBytes.Length - 2)) + ".cubedata";
}
}
private void SaveValue(StorageKey key)
{
StorageValue value;
lock (_mutex)
{
if (!_queuedValues.TryGetValue(key, out value)) return;
}
string filename = GetFilename(key);
string directoryName = Path.GetDirectoryName(filename);
for (int i = 0; i < _retries; ++i)
{
try
{
Directory.CreateDirectory(directoryName);
using (var stream = File.Open(filename, FileMode.Create, FileAccess.Write, FileShare.None))
{
stream.Write(value.Bytes, 0, value.Bytes.Length);
}
break;
}
catch (IOException)
{
}
}
lock (_mutex)
{
StorageValue newValue;
if (_queuedValues.TryGetValue(key, out newValue) && object.ReferenceEquals(value, newValue))
{
/* Value is still current; remove it from the queue. */
_queuedValues.Remove(key);
}
}
}
public void Write(StorageKey key, StorageValue value)
{
}
public Task<StorageValue> ReadAsync(StorageKey key)
{
return null;
}
public void Write(StorageKey key, StorageValue value)
{
}
public Task <StorageValue> ReadAsync(StorageKey key)
{
return(null);
}
