public async Task QueryAsync(IClientProxy caller, string rawQuery)
{
CancelOngoingQuery(out var currentCt);
var query = new Query(rawQuery);
using (_logger.BeginScope(LogProperties.QueryId, query.Id))
{
currentCt.ThrowIfCancellationRequested();
_logger.Verbose("Notifying frontend that query is received.");
await caller.InvokeAsync(new QueryReceived(query), currentCt);
var providers = GetProviders(query);
_logger.Verbose("Notifying frontend that query will be handled by {providerCount} providers.", providers.Count);
await caller.InvokeAsync(QueryExecuting.By(providers), currentCt);
// Execute query
var allTasks = providers.Select(p => Task.Run(async() =>
{
var providerName = p.GetType().Name;
using (var operation = _logger.Timed("Query from {queryProvider}", providerName))
{
try
{
var results = (await p.QueryAsync(query, currentCt)).ToList();
currentCt.ThrowIfCancellationRequested();
_logger.Debug("Provider {queryProvider} executed query successfully. {resultCount} results available.", providerName, results.Count);
await caller.InvokeAsync(new ResultsAvailable(query.Id, results), currentCt);
return(results);
}
catch (Exception)
{
operation.Cancel();
throw;
}
}
}, currentCt))
.ToList();
// Wait for provider tasks
await Task.WhenAll(allTasks).ContinueWith(async _ =>
{
Task.WaitAll(allTasks.ToArray <Task>());
var allResults = allTasks.Where(t => t.IsCompleted).SelectMany(t => t.Result).ToList();
if (allTasks.Any(t => !t.IsCompletedSuccessfully))
{
_logger.Debug("One or more sub queries have failed.");
await caller.InvokeAsync(new QueryCancelled(query.Id), currentCt);
}
else
{
_logger.Verbose("Query completed. Total result count is {resultCount}", allResults.Count);
await caller.InvokeAsync(new QueryCompleted(query.Id, allResults), currentCt);
}
});
}
}
public async Task QueryAsync(string rawQuery, IObserver <BackendEvent> observer)
{
if (string.IsNullOrWhiteSpace(rawQuery))
{
return;
}
IQuery query = new Query(rawQuery);
using (_logger.BeginScope(LogProperties.QueryId, query.Id))
using (_logger.Timed("Query {rawQuery}", rawQuery))
{
CancelOngoingQuery(out var currentCt);
_logger.Verbose("Notifying observers that query is received.");
observer.OnNext(new QueryReceived(query));
var providers = GetProviders(query);
if (!providers.Any())
{
providers = _queryProviders.ToList();
query = new DefaultQuery(query);
}
_logger.Verbose("Notifying observers that query will be handled by {providerCount} providers.", providers.Count);
observer.OnNext(QueryExecuting.By(providers));
var providerTasks = providers
.Select(provider =>
Task.Run(async() =>
{
var operation = _logger.Timed("{queryProvider} provider", provider.GetType().Name);
var providerObserver = Observer.Create <BackendEvent>(observer.OnNext, operation.Cancel, operation.Complete);
try
{
await provider.QueryAsync(query, providerObserver, currentCt);
}
catch (OperationCanceledException)
{
_logger.Information("Query {rawQuery} has been cancelled for {queryProvider}", rawQuery, providerObserver.GetType().Name);
/* Cancellation is OK */
}
catch (Exception e)
{
_logger.Information(e, "An unhandle exception was thrown.");
}
finally
{
providerObserver.OnCompleted();
}
}, currentCt))
.ToArray();
await Task.WhenAll(providerTasks);
observer.OnNext(new QueryCompleted(query.Id, null));
}
}