我对如何为 dotnetcore 控制台应用程序实施单一实例策略感兴趣。令我惊讶的是，似乎没有太多关于这个话题的内容。我找到了这个stacko，@ 987654321@，但它似乎不适用于我在带有ubuntu 的dotnetcore 上。这里有人做过吗？
【问题讨论】：
deandob 解决方案的缺点是可以从另一条路径启动应用程序。因此，您可能更喜欢所有用户的静态路径或 tmp 路径。
这是我的尝试：
//second instance launch guard
var tempPath = Environment.GetEnvironmentVariable("TEMP", EnvironmentVariableTarget.Machine)
??
Path.GetTempPath();
var lockPath = Path.Combine(tempPath, "SingleInstance.lock");
await using var lockFile = File.OpenWrite(lockPath);
在这里，我试图在机器范围内获取TEMP 系统变量（不是用户TEMP），如果它为空 - 回退到 Windows 上的用户临时文件夹或在某些 linux 上共享 /tmp。
【讨论】：
这是我使用 命名管道 的实现。它支持从第二个实例传递参数。
注意：我没有在 Linux 或 Mac 上进行测试，但理论上应该可以工作。
用法
public static int Main(string[] args)
{
instanceManager = new SingleInstanceManager("8A3B7DE2-6AB4-4983-BBC0-DF985AB56703");
if (!instanceManager.Start())
{
return 0; // exit, if same app is running
}
instanceManager.SecondInstanceLaunched += InstanceManager_SecondInstanceLaunched;
// Initialize app. Below is an example in WPF.
app = new App();
app.InitializeComponent();
return app.Run();
}
private static void InstanceManager_SecondInstanceLaunched(object sender, SecondInstanceLaunchedEventArgs e)
{
app.Dispatcher.Invoke(() => new MainWindow().Show());
}
您的复制粘贴代码
public class SingleInstanceManager
{
private readonly string applicationId;
public SingleInstanceManager(string applicationId)
{
this.applicationId = applicationId;
}
/// <summary>
/// Detect if this is the first instance. If it is, start a named pipe server to listen for subsequent instances. Otherwise, send <see cref="Environment.GetCommandLineArgs()"/> to the first instance.
/// </summary>
/// <returns>True if this is tthe first instance. Otherwise, false.</returns>
public bool Start()
{
using var client = new NamedPipeClientStream(applicationId);
try
{
client.Connect(0);
}
catch (TimeoutException)
{
Task.Run(() => StartListeningServer());
return true;
}
var args = Environment.GetCommandLineArgs();
using (var writer = new BinaryWriter(client, Encoding.UTF8))
{
writer.Write(args.Length);
for (int i = 0; i < args.Length; i++)
{
writer.Write(args[i]);
}
}
return false;
}
private void StartListeningServer()
{
var server = new NamedPipeServerStream(applicationId);
server.WaitForConnection();
using (var reader = new BinaryReader(server, Encoding.UTF8))
{
var argc = reader.ReadInt32();
var args = new string[argc];
for (int i = 0; i < argc; i++)
{
args[i] = reader.ReadString();
}
SecondInstanceLaunched?.Invoke(this, new SecondInstanceLaunchedEventArgs { Arguments = args });
}
StartListeningServer();
}
public event EventHandler<SecondInstanceLaunchedEventArgs> SecondInstanceLaunched;
}
public class SecondInstanceLaunchedEventArgs
{
public string[] Arguments { get; set; }
}
单元测试
[TestClass]
public class SingleInstanceManagerTests
{
[TestMethod]
public void SingleInstanceManagerTest()
{
var id = Guid.NewGuid().ToString();
var manager = new SingleInstanceManager(id);
string[] receivedArguments = null;
var correctArgCount = Environment.GetCommandLineArgs().Length;
manager.SecondInstanceLaunched += (sender, e) => receivedArguments = e.Arguments;
var instance1 = manager.Start();
Thread.Sleep(200);
var manager2 = new SingleInstanceManager(id);
Assert.IsFalse(manager2.Start());
Thread.Sleep(200);
Assert.IsTrue(instance1);
Assert.IsNotNull(receivedArguments);
Assert.AreEqual(correctArgCount, receivedArguments.Length);
var receivedArguments2 = receivedArguments;
var manager3 = new SingleInstanceManager(id);
Thread.Sleep(200);
Assert.IsFalse(manager3.Start());
Assert.AreNotSame(receivedArguments, receivedArguments2);
Assert.AreEqual(correctArgCount, receivedArguments.Length);
}
}
【讨论】：
StartListeningServer完成，检查管道服务器是否创建成功。如果您确实走这条路，请随时修改答案:)
由于 Linux/MacOS 上的互斥检查问题（如上所述），这在 .NET 核心上比应有的要困难一些。此外，Theyouthis 的解决方案也无济于事，因为所有 .NET 核心应用程序都通过 CLI 运行，该 CLI 的进程名称为“dotnet”，如果您在同一台机器上运行多个 .NET 核心应用程序，重复实例检查将错误地触发。
执行此操作的一种简单且多平台稳健的方法是在应用程序启动时打开一个文件进行写入，并在最后关闭它。如果文件无法打开，那是由于另一个实例同时运行，您可以在 try/catch 中处理它。如果文件首先不存在，使用 FileStream 打开文件也会创建它。
try
{
lockFile = File.OpenWrite("SingleInstance.lck");
}
catch (Exception)
{
Console.WriteLine("ERROR - Server is already running. End that instance before re-running. Exiting in 5 seconds...");
System.Threading.Thread.Sleep(5000);
return;
}
【讨论】：
@MusuNaji 解决方案的变体：How to restrict a program to a single instance
private static bool AlreadyRunning()
{
Process[] processes = Process.GetProcesses();
Process currentProc = Process.GetCurrentProcess();
logger.LogDebug("Current proccess: {0}", currentProc.ProcessName);
foreach (Process process in processes)
{
if (currentProc.ProcessName == process.ProcessName && currentProc.Id != process.Id)
{
logger.LogInformation("Another instance of this process is already running: {pid}", process.Id);
return true;
}
}
return false;
}
【讨论】：