public bool TrySetNext(StreamBlockProxy next)
{
lock (this)
{
if (!NextTable.TryGetValue(this, out _))
{
NextTable.Add(this, next);
return(true);
}
return(false);
}
}
public StreamBlockProxy TryRentIndexedStreamBlockProxy(StreamLog streamLog, StreamBlockRecord record)
{
StreamBlockProxy p = null;
while (p == null)
{
var blockKey = new BlockKey(streamLog.Slid, record.Version);
// ReSharper disable once InconsistentlySynchronizedField
if (_blocks.TryGetValue(blockKey, out var handle))
{
p = handle.Target as StreamBlockProxy;
}
else
{
// CD.GetOrAdd factory is not atomic, lock manually.
// Lock on SL, not a global object. This also helps
// to avoid a capturing lambda and the risk of collecting
// an object held only by a weak reference during that lambda return.
lock (streamLog)
{
if (_blocks.TryGetValue(blockKey, out handle))
{
p = handle.Target as StreamBlockProxy;
}
else
{
p = StreamBlockProxy.Create(blockKey, this);
var sb = streamLog.GetBlockFromRecord(record);
// Could set directly without SetStreamBlock
p.Block = sb;
handle = GCHandle.Alloc(p, GCHandleType.Weak);
if (!_blocks.TryAdd(blockKey, handle))
{
// this should never happen unless there are different streamLog instances for the same slid,
// which in turn should never happen because SLs are stored in SLM dictionary.
ThrowHelper.FailFast("Cannot add newly created StreamBlockProxy to cache from inside a lock.");
}
}
}
}
// will be null if cannot retain, then will start over
p = p?.TryRetain();
}
return(p);
}