FileShare.None是否使线程等待文件流关闭? [英] Does FileShare.None make threads wait until the filestream is closed?

问题描述

使用文件流时，将FileShare设置为None，并说两个同时访问同一功能的用户想要对该文件进行读/写. FileShare.None是让第二个用户请求等待还是第二个用户的请求抛出异常?

When using a file stream, and setting FileShare to None, and say two users accessing the same function at the same time want to read/write to that file. Will FileShare.None make the second users request waiting or will the second user's request throw an exception?

//two users get to this this code at the same time

using (FileStream filestream = new FileStream(chosenFile, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None))
using (StreamReader sr = new StreamReader(filestream))
using (StreamWriter sw = new StreamWriter(filestream))
{
    //reading and writing to file
}

Msdn说:无拒绝共享当前文件.在打开文件之前，任何通过该过程或其他过程打开文件的请求都将失败.

但是请求会一直尝试直到关闭文件流吗?

But will requests keep trying until the filestream is closed?

推荐答案

当某个进程选择使用FileShare.None对文件进行读/写操作时，任何随后对该文件进行的任何访问都将导致Acess Denied Exception.要回答您的问题，第二个用户将获得例外.

When a process opean a file for Read/Write with FileShare.None any subsequent access by any process on this same file will result in Acess Denied Exception. To answer your question, Second user will get exception.

MSDN :FileShare.None-拒绝共享当前文件.任何要求打开 文件(通过此过程或其他过程)将失败，直到该文件被 关闭.

MSDN: FileShare.None - Declines sharing of the current file. Any request to open the file (by this process or another process) will fail until the file is closed.

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您可以通过多种方式处理此类并发文件访问问题，以下代码演示了一种解决这种情况的简单方法.

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There are many ways you can handle these kind of concurrent file access issues, Following code demonstrates a simple approach to tackle this situation.

//Retry 5 times when file access fails
int retryCounter = 5;

while (!isFileAccessSuccess && retryCounter > 0)
{
    try
    {
       //Put file access logic here

        //If the file has been accessed successfully set the flag to true
        isFileAccessSuccess = true;
    }
    catch (Exception exception)
    {
        //Log exception
    }
    finally
    {
        //Decrease the retry count
        --retryCounter;
    }

    if (!isFileAccessSuccess)
    {
        //Wait sometime until initiating next try
        Thread.Sleep(10000);
    }
}

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