/// <summary>
/// Get the most recent 20 meetings from our local database
/// </summary>
/// <param name="m"></param>
/// <returns></returns>
private static async Task <IWalker.MRU[]> FetchMeetingsFromDB(MRUDatabaseAccess m)
{
// Run this in the SQL engine
var mruMeetings =
(await m.QueryMRUDB())
.OrderByDescending(mru => mru.LastLookedAt)
.Take(NumberOfMRUMeetings)
.ToListAsync();
var r = (await mruMeetings)
.Distinct(new MURCompare())
.ToArray();
return(r);
}
/// <summary>
/// Generate a MRU[] stream from the local database. Each time it updates, we update here too.
/// </summary>
/// <returns></returns>
private static IObservable <IWalker.MRU[]> FetchMRUSFromLocalDB()
{
// Generate an observable that will grab everything from our local MRU database.
var m = new MRUDatabaseAccess();
// Return the MRU updated guy
return(MRUDatabaseAccess.MRUDBUpdated
.StartWith(default(Unit))
.SelectMany(async _ =>
{
IWalker.MRU[] r = await FetchMeetingsFromDB(m);
return r;
}));
}
/// <summary>
/// Returns an observable stream.
/// </summary>
/// <returns>The observable of the MRU listing</returns>
/// <remarks>
/// As soon as you subscribe you'll get the most recent version of the MRU list.
///
/// Combines MRU's from the following sources:
/// 1. The internal database we maintain of our own stuff (that we've visited on this machine).
/// </remarks>
public static IObservable <IWalker.MRU[]> GetMRUListStream()
{
if (_MRUStream != null)
{
return(_MRUStream);
}
// Get streams from all the sources we are going to have to deal with
var locals = FetchMRUSFromLocalDB();
var remotes = FetchMRUSFromRoamingData();
// Combine the streams (without crossing them!!)
var result = locals
.CombineLatest(remotes, (l, r) => MergeStreams(l, r))
.Select(mlst => mlst
.OrderByDescending(k => k.StartTime)
.Take(NumberOfMRUMeetings)
.ToArray())
.Distinct(lst => MRUListHash(lst));
// Make sure that it replays so when new folks join us (or a page gets re-initialized) they get the same
// thing.
_MRUStream = result
.Replay(1)
.RefCount();
// When there is a MRU update, cache MRU to our remote file so others can see it.
var db = new MRUDatabaseAccess();
_MRUDBSubscription = MRUDatabaseAccess.MRUDBUpdated
.SelectMany(_ => FetchMeetingsFromDB(db))
.Subscribe(mrus =>
{
MRUSettingsCache.UpdateForMachine(MachineName, mrus);
});
return(_MRUStream);
}
