[英]how to cast async Func or Action to Delegate and invoke it
我正在嘗試使這段代碼工作:
protected async Task RunIsolated<TServ1, TServ2>(Action<TServ1, TServ2> action)
{
await RunInScope(action, typeof(TServ1), typeof(TServ2));
}
protected async Task<TResult> RunIsolatedForResult<TService, TResult>(Func<TService, TResult> func)
{
return (TResult) await RunInScope(func, typeof(TService));
}
private Task<object> RunInScope(Delegate d, params object[] args)
{
using (var scope = _serviceProvider.CreateScope())
{
object[] parameters = args.Cast<Type>().Select(t => scope.ServiceProvider.GetService(t)).ToArray();
return Task.FromResult(d.DynamicInvoke(parameters));
}
}
這項工作用於同步版本的代碼,如下所示:
await RunIsolated<Service>(serv => serv.SaveAsync(item).Wait());
但是對於相同代碼的異步版本,不起作用(db操作拋出異常)
await RunIsolated<Service>(async serv => await serv.SaveAsync(item));
是否有可能將async Action
或Func
轉換為Delegate
並在不丟失異步狀態的情況下調用它?
您需要創建接受Func<Task>
新重載。 現在,你傳遞的匿名異步功能
await RunIsolated<Service>(async serv => await serv.SaveAsync(item));
被視為Action
,這意味着基本上是async void
方法,具有所有相應的缺點。 相反,你必須做這樣的事情(簡化為使用基本的Action和Func,根據你的需要調整):
protected Task RunIsolated(Action action) {
return RunInScope(action);
}
protected Task RunIsolated(Func<Task> action) {
return RunInScope(action);
}
protected Task<TResult> RunIsolatedForResult<TResult>(Func<Task<TResult>> action) {
return RunInScopeWithResult<TResult>(action);
}
protected Task<TResult> RunIsolatedForResult<TResult>(Func<TResult> action) {
return RunInScopeWithResult<TResult>(action);
}
private async Task RunInScope(Delegate d, params object[] args) {
// do some stuff
using (var scope = _serviceProvider.CreateScope()) {
object[] parameters = args.Cast<Type>().Select(t => scope.ServiceProvider.GetService(t)).ToArray();
var result = d.DynamicInvoke(parameters);
var resultTask = result as Task;
if (resultTask != null) {
await resultTask;
}
}
}
private async Task<TResult> RunInScopeWithResult<TResult>(Delegate d, params object[] args) {
// do some stuff
using (var scope = _serviceProvider.CreateScope()) {
object[] parameters = args.Cast<Type>().Select(t => scope.ServiceProvider.GetService(t)).ToArray();
var result = d.DynamicInvoke(parameters);
var resultTask = result as Task<TResult>;
if (resultTask != null) {
return await resultTask;
}
return (TResult) result;
}
}
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