问题描述
这应该很简单,但我就是无法聚焦。
public static async Task<string> UnloadAsync(Assembly assy,bool silentFail = false)
{
if (AssyLoadContext.__alcd.ContainsKey(assy))
{
var assemblyName = __namd.Where(kvp => kvp.Value == assy).First().Key;
__alcd[assy].Unloading += alc => //signal the task to complete and return assemblyName
__namd.Remove(assemblyName);
__alcd[assy].Unload();
__alcd.Remove(assy);
Debug.WriteLine($"Unloaded assembly '{assy.GetName().Name}'");
}
if (silentFail)
{
return null;
}
else
{
throw new InvalidOperationException($"Assembly '{assy.GetName().Name}' cannot be unloaded. Did you load it using AssyLoadContext.LoadWithPrivateContext(string assyPath)?");
}
}
AssemblyLoadContext.Unload()
操作实际上是异步的,但不可等待。一旦不再有强 GC 引用等操作完成,程序集就会卸载并触发 Unloading 事件。
返回值在 assemblyName
中,我想提供给延续。
我可以找到所有关于需要 await
的废话,因为这是产生收益的地方,但我不能那样写。如果没有 await
,您如何做到这一点?
解决方法
您正在寻找TaskCompletionSource<string>
:
public static Task<string> UnloadAsync(Assembly assy,bool silentFail = false)
{
if (AssyLoadContext.__alcd.ContainsKey(assy))
{
var tcs = new TaskCompletionSource<string>();
var assemblyName = __namd.Where(kvp => kvp.Value == assy).First().Key;
__alcd[assy].Unloading += alc => tcs.SetResult(assemblyName);
__namd.Remove(assemblyName);
__alcd[assy].Unload();
__alcd.Remove(assy);
Debug.WriteLine($"Unloaded assembly '{assy.GetName().Name}'");
return tcs.Task;
}
if (silentFail)
{
return Task.FromResult<string>(null);
}
throw new InvalidOperationException($"Assembly '{assy.GetName().Name}' cannot be unloaded. Did you load it using AssyLoadContext.LoadWithPrivateContext(string assyPath)?");
}
}
注意,如果这抛出一个 InvalidOperationException
,它会在调用 UnloadAsync
时被抛出,而不是被包裹在返回的 Task
中(如果你的方法是 { {1}})。如果你想改变这个,你可以使用 TaskCompletionSource:
async
或者使用 public static Task<string> UnloadAsync(Assembly assy,bool silentFail = false)
{
var tcs = new TaskCompletionSource<string>();
if (AssyLoadContext.__alcd.ContainsKey(assy))
{
var assemblyName = __namd.Where(kvp => kvp.Value == assy).First().Key;
__alcd[assy].Unloading += alc => tcs.SetResult(assemblyName);
__namd.Remove(assemblyName);
__alcd[assy].Unload();
__alcd.Remove(assy);
Debug.WriteLine($"Unloaded assembly '{assy.GetName().Name}'");
}
else if (silentFail)
{
tcs.SetResult(null);
}
else
{
tcs.SetException(throw new InvalidOperationException($"Assembly '{assy.GetName().Name}' cannot be unloaded. Did you load it using AssyLoadContext.LoadWithPrivateContext(string assyPath)?"));
}
return tcs.Task;
}
方法:
async