public virtual async Task BuildAsync(IBundleBuilderContext context)
{
// applying transforms to items
var itemTransformTasks = new ConcurrentQueue <Task <IBundleItemTransformContext> >();
CancellationToken cancellationToken = context.CancellationToken;
using (var errorCts = new CancellationTokenSource())
using (context.UseExternalCancellationToken(errorCts.Token))
{
var n = context.Bundle.Sources.Length;
for (var i = 0; i < n; i++)
{
cancellationToken.ThrowIfCancellationRequested();
IBundleSourceModel source = context.Bundle.Sources[i];
await source.ProvideBuildItemsAsync(context, it => itemTransformTasks.Enqueue(Task.Run(async() =>
{
try { return(await ApplyItemTransformsAsync(it.ItemTransformContext, it.ItemTransforms)); }
catch (Exception ex) when(!(ex is OperationCanceledException))
{
errorCts.Cancel(); // stop processing other enqueued items
throw;
}
}, cancellationToken)));
}
// "If any of the supplied tasks completes in a faulted state, the returned task will also complete in a Faulted state, where its exceptions will contain the aggregation of the set of unwrapped exceptions from each of the supplied tasks."
// "If none of the supplied tasks faulted but at least one of them was canceled, the returned task will end in the Canceled state."
// https://docs.microsoft.com/en-us/dotnet/api/system.threading.tasks.task.whenall?view=netcore-3.1
await Task.WhenAll(itemTransformTasks);
}
// aggregating items
var transformContext = new BundleTransformContext(context)
{
TransformedItemContexts = itemTransformTasks.Select(task => task.GetAwaiter().GetResult()).ToArray()
};
itemTransformTasks = null;
await AggregateAsync(transformContext, context.Bundle.Transforms);
// applying transforms to bundle
transformContext.TransformedItemContexts = null;
context.Result = await ApplyTransformsAsync(transformContext, context.Bundle.Transforms);
}
public virtual async Task BuildAsync(IBundleBuilderContext context)
{
// building items
CreateItemTransformPipeline(context, out ITargetBlock <IBundleSourceBuildItem> input, out ISourceBlock <IBundleItemTransformContext> output);
// consumer
async Task <List <IBundleItemTransformContext> > ConsumeAsync()
{
var itemContexts = new List <IBundleItemTransformContext>();
while (await output.OutputAvailableAsync(context.CancellationToken))
{
itemContexts.Add(output.Receive());
}
return(itemContexts);
};
Task <List <IBundleItemTransformContext> > consumeTask = ConsumeAsync();
// producer
var n = context.Bundle.Sources.Length;
for (var i = 0; i < n; i++)
{
context.CancellationToken.ThrowIfCancellationRequested();
IBundleSourceModel source = context.Bundle.Sources[i];
await source.ProvideBuildItemsAsync(context, it => input.Post(it));
}
input.Complete();
// building result
var transformContext = new BundleTransformContext(context)
{
TransformedItemContexts = await consumeTask
};
await AggregateAsync(transformContext, context.Bundle.Transforms);
transformContext.TransformedItemContexts = null;
context.Result = await ApplyTransformsAsync(transformContext, context.Bundle.Transforms);
}