/// <summary>
/// A minimally blocking call that starts a background task to update the graph.
/// </summary>
/// <param name="compacted"></param>
/// <param name="pageUri"></param>
public void Add(JObject compacted, Uri pageUri)
{
Debug.Assert(pageUri.AbsoluteUri.IndexOf("#") == -1, "Add should be on the full Uri and not the child Uri!");
JsonLdPage page = new JsonLdPage(pageUri, compacted);
if (_pages.TryAdd(pageUri, page))
{
// start the graph load
page.BeginLoad(AddCallback);
}
else
{
// clean up
page.Dispose();
}
}
/// <summary>
/// Removes all pages not used within the given time span.
/// </summary>
private void CleanUp(TimeSpan keepPagesUsedWithin)
{
DateTime cutOff = DateTime.UtcNow.Subtract(keepPagesUsedWithin);
// lock to keep any new pages from being added during this
lock (this)
{
// just in case we show really late
if (_disposed)
{
return;
}
// create a working set of pages that can be considered locked
JsonLdPage[] pages = _pages.Values.ToArray();
// if pages are still loading we should skip the clean up
// TODO: post-preview this should force a clean up if the graph is huge
if (pages.All(p => p.IsLoaded))
{
// check if a clean up is needed
if (pages.Any(p => !p.UsedAfter(cutOff)))
{
List <JsonLdPage> keep = new List <JsonLdPage>(pages.Length);
List <JsonLdPage> remove = new List <JsonLdPage>(pages.Length);
// pages could potentially change last accessed times, so make the decisions in one shot
foreach (var page in pages)
{
if (page.UsedAfter(cutOff))
{
keep.Add(page);
}
else
{
remove.Add(page);
}
}
// second check to make sure we need to do this
if (remove.Count > 0)
{
DataTraceSources.Verbose("[EntityCache] EntityCache rebuild started.");
JsonLdGraph graph = new JsonLdGraph();
// graph merge
foreach (var page in keep)
{
graph.Merge(page.Graph);
}
_masterGraph = graph;
DataTraceSources.Verbose("[EntityCache] EntityCache rebuild complete.");
// remove and dispose of the old pages
foreach (var page in remove)
{
JsonLdPage removedPage = null;
if (_pages.TryRemove(page.Uri, out removedPage))
{
Debug.Assert(!removedPage.UsedAfter(cutOff), "Someone used a page that was scheduled to be removed. This should have been locked.");
removedPage.Dispose();
}
else
{
Debug.Fail(page.Uri.AbsoluteUri + " disappeared from the page cache.");
}
}
}
}
}
}
}