C# TrackingCollection.Listen方法代码示例

        void Run2()
        {
            var count = 10;
            var col = new TrackingCollection<Thing>();
            col.ProcessingDelay = TimeSpan.FromMilliseconds(20);

            col.NewerComparer = OrderedComparer<Thing>.OrderByDescending(x => x.UpdatedAt).Compare;
            list.ItemsSource = col;

            var source = Observable.Merge(
                Observable.Generate(0, i => i < count, i => i + 1, i => i, i => TimeSpan.FromMilliseconds(5))
                    .Select(i => GetThing(i, i, i, "Run 1")),
                Observable.Generate(0, i => i < count, i => i + 1, i => i, i => TimeSpan.FromMilliseconds(7))
                    .Select(i => GetThing(i, i, i + 1, "Run 2"))
            );

            col.Listen(source);
            col.Subscribe();
        }

    public void ListeningTwiceWorks()
    {
        var count = 10;
        ITrackingCollection<Thing> col = new TrackingCollection<Thing>();
        col.NewerComparer = OrderedComparer<Thing>.OrderByDescending(x => x.UpdatedAt).Compare;
        col.ProcessingDelay = TimeSpan.Zero;

        var list1 = new List<Thing>(Enumerable.Range(1, count).Select(i => GetThing(i, i, count - i, "Run 1")).ToList());
        var list2 = new List<Thing>(Enumerable.Range(1, count).Select(i => GetThing(i, i, i + count, "Run 2")).ToList());

        var subj = new ReplaySubject<Unit>();
        subj.OnNext(Unit.Default);
        var disp = col.OriginalCompleted.Subscribe(x => subj.OnCompleted());
        col.Listen(list1.ToObservable());
        col.Subscribe();
        subj.Wait();

        disp.Dispose();
        col.Listen(list2.ToObservable());
        subj = new ReplaySubject<Unit>();
        subj.OnNext(Unit.Default);
        disp = col.OriginalCompleted.Subscribe(x => subj.OnCompleted());
        col.Subscribe();
        subj.Wait();
        disp.Dispose();

        CollectionAssert.AreEqual(list2, col);
    }

        public ITrackingCollection<IPullRequestModel> GetPullRequests(ISimpleRepositoryModel repo)
        {
            // Since the api to list pull requests returns all the data for each pr, cache each pr in its own entry
            // and also cache an index that contains all the keys for each pr. This way we can fetch prs in bulk
            // but also individually without duplicating information. We store things in a custom observable collection
            // that checks whether an item is being updated (coming from the live stream after being retrieved from cache)
            // and replaces it instead of appending, so items get refreshed in-place as they come in.

            var keyobs = GetUserFromCache()
                .Select(user => string.Format(CultureInfo.InvariantCulture, "{0}|{1}|pr", user.Login, repo.Name));

            var col = new TrackingCollection<IPullRequestModel>();

            var source = Observable.Defer(() => keyobs
                .SelectMany(key =>
                    hostCache.GetAndFetchLatestFromIndex(key, () =>
                        apiClient.GetPullRequestsForRepository(repo.CloneUrl.Owner, repo.CloneUrl.RepositoryName)
                                 .Select(PullRequestCacheItem.Create),
                        item => col.RemoveItem(Create(item)),
                        TimeSpan.FromMinutes(5),
                        TimeSpan.FromDays(1))
                )
                .Select(Create)
            );

            col.Listen(source);
            return col;
        }