FileLoadException:文件正在使用中

Question

我的任务是将每秒30次来自传感器的数据写入.csv文件。如果sersor发送了错误的数据，我不会写入它，只是等待。如果数据再次正常，我需要创建一个新文件并开始在其中写入数据。下面是我的代码：

class FileWriter
{
    string filename;

    public FileWriter()
    {

    }

    public void SetFilename(string filename)
    {
        this.filename = filename;
    }

    public async void WriteData(string data)
    {

        StorageFile file = await KnownFolders.PicturesLibrary.CreateFileAsync(filename, CreationCollisionOption.ReplaceExisting);

        var stream = await file.OpenAsync(FileAccessMode.ReadWrite);
        using (var outputStream = stream.GetOutputStreamAt(stream.Size))
        {
            using (var dataWriter = new Windows.Storage.Streams.DataWriter(outputStream))
            {
                dataWriter.WriteString(data);

                await dataWriter.StoreAsync();

            }
            await outputStream.FlushAsync();
        }
        stream.Dispose();
    }

}

但我总是得到：

Exception thrown: 'System.IO.FileLoadException' in 
System.Private.CoreLib.ni.dll
WinRT information: The file is in use. Please close the file before continuing.
FileLoadException: The process cannot access the file because it is being used by another process.

我想，这是因为文件是异步打开的，它没有时间每秒打开30次。但我不知道如何修复它。

编辑： more details。我把this example带走了。有一个类SpatialMappingObserver，它有一个Update()方法，它每秒被调用30次。在那里我调用我的WriteData()在文件中写入全息相机的状态。因为Update()不是异步的，所以我不能调用await WriteData()。

Answer 1

您应该使用锁来确保在给定时间只有一个线程在写入文件，如下所示：

class FileWriter
{
    static readonly object _filelock = new object();
    string filename;

    public FileWriter()
    {

    }

    public void SetFilename(string filename)
    {
        this.filename = filename;
    }

    public async void WriteData(string data)
    {
        lock (_filelock) 
        {

            StorageFile file = await KnownFolders.PicturesLibrary.CreateFileAsync(filename, CreationCollisionOption.OpenIfExists);

            using(var stream = await file.OpenAsync(FileAccessMode.ReadWrite))
            {
                using (var outputStream = stream.GetOutputStreamAt(stream.Size))
                {
                    using (var dataWriter = new Windows.Storage.Streams.DataWriter(outputStream))
                    {
                        dataWriter.WriteString(data);

                        await dataWriter.StoreAsync();

                    }
                    await outputStream.FlushAsync();
                }
            }
        }
    }
}

另外，我认为您的CreationCollisionOption必须设置为OpenIfExists。