public async Task <uint> GetLastKeyAsync(CancellationToken cancel = new CancellationToken())
{
// We need to look into the last blob, so we need to list all blobs first
await RefreshCache(cancel);
// Look into the last non-empty blob
if (_firstKey.Count == 0)
{
return(0);
}
var blob = _blobs[_firstKey.Count - 1];
// Download one event's worth of data to a local buffer.
// This will likely truncate an event somewhere at the beginning of the
// buffer, but we don't care, because looking for the *last* sequence only
// requires that the last event in the buffer isn't truncated.
var length = Math.Min(EventFormat.MaxEventFootprint, blob.Properties.Length);
var bytes = new byte[length];
await ReadSubRangeAsync(blob, bytes, blob.Properties.Length - length, 0, length, cancel);
// Look for the sequence number of the last event.
using (var stream = new MemoryStream(bytes))
return(await EventFormat.GetLastSequenceAsync(stream, cancel));
}
public async Task <uint> GetLastKeyAsync(CancellationToken cancel = new CancellationToken()) => await EventFormat.GetLastSequenceAsync(_file, cancel);
