public async Task <IEnumerable <Item> > EnqueueItems(List <int> ids)
{
var stopwatch = Stopwatch.StartNew();
var(items, misses) = _cache.GetCachedItems(ids);
var newItems = new List <Item>();
var buffer = new BufferBlock <int>();
var downloader = new ActionBlock <int>(async id =>
{
var action = await _client.GetStringAsync($"item/{id}.json");
// handle data here
var storyItem = JsonConvert.DeserializeObject <Item>(action);
newItems.Add(storyItem);
var msg = new NewsItemMessage(this, storyItem);
_messenger.Publish(msg);
},
new ExecutionDataflowBlockOptions {
MaxDegreeOfParallelism = Environment.ProcessorCount
});
// notify TPL Dataflow to send messages from buffer to loader
buffer.LinkTo(downloader, new DataflowLinkOptions {
PropagateCompletion = true
});
foreach (var itemId in misses)
{
await buffer.SendAsync(itemId);
}
// queue is done
buffer.Complete();
// now it's safe to wait for completion of the downloader
await downloader.Completion;
var itemList = items.ToList();
foreach (var item in itemList)
{
var msg = new NewsItemMessage(this, item);
_messenger.Publish(msg);
}
_cache.AddItemsToCache(newItems);
stopwatch.Stop();
var ms = stopwatch.ElapsedMilliseconds;
Debug.WriteLine("Queue completed in {0} ms", ms);
return(itemList);
}
private void OnItemReceived(NewsItemMessage msg)
{
var id = msg.Data.Id;
if (!_storyLookup.TryGetValue(id, out var wrapper))
{
return;
}
wrapper.Fill(msg.Data);
_storyLookup.Remove(id);
}
public IEnumerable <Item> EnqueueItems(List <int> ids)
{
var stopwatch = Stopwatch.StartNew();
var(items, misses) = _cache.GetCachedItems(ids);
var newItems = new List <Item>();
var tasks = misses.Select(id => _client.GetStringAsync($"item/{id}.json")
.ContinueWith(task =>
{
if (task.Status != TaskStatus.RanToCompletion)
{
return;
}
var storyItem = JsonConvert.DeserializeObject <Item>(task.Result);
newItems.Add(storyItem);
var msg = new NewsItemMessage(this, storyItem);
_messenger.Publish(msg);
}));
var itemList = items.ToList();
foreach (var item in itemList)
{
var msg = new NewsItemMessage(this, item);
_messenger.Publish(msg);
}
Task.WhenAll(tasks).ContinueWith(x =>
{
_cache.AddItemsToCache(newItems);
stopwatch.Stop();
var ms = stopwatch.ElapsedMilliseconds;
Debug.WriteLine("Queue completed in {0} ms", ms);
});
return(itemList);
}
