async Task WriteLogsMerged(List <WriteEntry> entries, CancellationToken cancellationToken)
{
// Write logs unmerged unless we have too few entries.
var entryThreshold = (int)(.9 * (double)options.MaxWriteLogSize / (double)WriteEntry.RowBytes());
if (entries.Count > entryThreshold)
{
await FlushLogUnmerged();
return;
}
// List logs and sort for the smallest
var logList = (await store.List(shardId, WriteLogsDir(), cancellationToken)).ToList();
logList.Sort((a, b) => a.SizeInBytes.CompareTo(b.SizeInBytes));
var logs = new List <IBlobInfo>();
ulong totalBytes = (ulong)(entries.Count * WriteEntry.RowBytes());
// Add logs into `logs` until we have enough bytes
foreach (var log in logList)
{
if (totalBytes + log.SizeInBytes > options.MaxWriteLogSize)
{
break;
}
else
{
logs.Add(log);
totalBytes += log.SizeInBytes;
}
}
// Use a memory stream to buffer new and old entries in
var replacementBytes = new MemoryStream((int)totalBytes);
// Buffer new entries
var entryBuffer = new List <byte>(WriteEntry.RowBytes());
foreach (var entry in entries)
{
entryBuffer.Clear();
entry.SerializeTo(entryBuffer);
replacementBytes.Write(entryBuffer.ToArray(), 0, entryBuffer.Count);
}
// Append bytes from old logs
foreach (var mergeLog in logs)
{
using (var stream = await store.ReadStream(shardId, mergeLog.KeyName, cancellationToken))
{
if (stream != null)
{
await stream.CopyToAsync(replacementBytes, 81920, cancellationToken);
}
}
}
// Write new log
var fileBytes = replacementBytes.ToArray();
await store.WriteBytes(shardId, GetNewLogName(), fileBytes.ToArray(), cancellationToken);
// Delete old logs
foreach (var mergeLog in logs)
{
await store.Delete(shardId, mergeLog.KeyName, cancellationToken);
}
}
