public ContentStore(IPublishedSnapshotAccessor publishedSnapshotAccessor, IVariationContextAccessor variationContextAccessor, ILogger logger, BPlusTree <int, ContentNodeKit> localDb = null)
{
_publishedSnapshotAccessor = publishedSnapshotAccessor;
_variationContextAccessor = variationContextAccessor;
_logger = logger;
_localDb = localDb;
_contentNodes = new ConcurrentDictionary <int, LinkedNode <ContentNode> >();
_contentRootNodes = new ConcurrentDictionary <int, LinkedNode <object> >();
_contentTypesById = new ConcurrentDictionary <int, LinkedNode <PublishedContentType> >();
_contentTypesByAlias = new ConcurrentDictionary <string, LinkedNode <PublishedContentType> >(StringComparer.InvariantCultureIgnoreCase);
_xmap = new ConcurrentDictionary <Guid, int>();
_genRefRefs = new ConcurrentQueue <GenRefRef>();
_genRefRef = null; // no initial gen exists
_liveGen = _floorGen = 0;
_nextGen = false; // first time, must create a snapshot
_collectAuto = true; // collect automatically by default
}
public Snapshot CreateSnapshot()
{
var lockInfo = new ReadLockInfo();
try
{
Lock(lockInfo);
// if no next generation is required, and we already have one,
// use it and create a new snapshot
if (_nextGen == false && _genRefRef != null)
{
return(new Snapshot(this, _genRefRef.GetGenRef()
#if DEBUG
, _logger
#endif
));
}
// else we need to try to create a new gen ref
// whether we are wlocked or not, noone can rlock while we do,
// so _liveGen and _nextGen are safe
if (_wlocked > 0) // volatile, cannot ++ but could --
{
// write-locked, cannot use latest gen (at least 1) so use previous
var snapGen = _nextGen ? _liveGen - 1 : _liveGen;
// create a new gen ref unless we already have it
if (_genRefRef == null)
{
_genRefRefs.Enqueue(_genRefRef = new GenRefRef(snapGen));
}
else if (_genRefRef.Gen != snapGen)
{
throw new Exception("panic");
}
}
else
{
// not write-locked, can use latest gen, create a new gen ref
_genRefRefs.Enqueue(_genRefRef = new GenRefRef(_liveGen));
_nextGen = false; // this is the ONLY thing that triggers a _liveGen++
}
// so...
// the genRefRef has a weak ref to the genRef, and is queued
// the snapshot has a ref to the genRef, which has a ref to the genRefRef
// when the snapshot is disposed, it decreases genRefRef counter
// so after a while, one of these conditions is going to be true:
// - the genRefRef counter is zero because all snapshots have properly been disposed
// - the genRefRef weak ref is dead because all snapshots have been collected
// in both cases, we will dequeue and collect
var snapshot = new Snapshot(this, _genRefRef.GetGenRef()
#if DEBUG
, _logger
#endif
);
// reading _floorGen is safe if _collectTask is null
if (_collectTask == null && _collectAuto && _liveGen - _floorGen > CollectMinGenDelta)
{
CollectAsyncLocked();
}
return(snapshot);
}
finally
{
Release(lockInfo);
}
}
public GenRef(GenRefRef genRefRef, long gen)
{
GenRefRef = genRefRef;
Gen = gen;
}
