Wait Until File Is Completely Written

Wait Until File Is Completely Written

There is only workaround for the issue you are facing.

Check whether file id in process before starting the process of copy. You can call the following function until you get the False value.

1st Method, copied directly from this answer:

private bool IsFileLocked(FileInfo file)
{
    FileStream stream = null;

    try
    {
        stream = file.Open(FileMode.Open, FileAccess.ReadWrite, FileShare.None);
    }
    catch (IOException)
    {
        //the file is unavailable because it is:
        //still being written to
        //or being processed by another thread
        //or does not exist (has already been processed)
        return true;
    }
    finally
    {
        if (stream != null)
            stream.Close();
    }

    //file is not locked
    return false;
}

2nd Method:

const int ERROR_SHARING_VIOLATION = 32;
const int ERROR_LOCK_VIOLATION = 33;
private bool IsFileLocked(string file)
{
    //check that problem is not in destination file
    if (File.Exists(file) == true)
    {
        FileStream stream = null;
        try
        {
            stream = File.Open(file, FileMode.Open, FileAccess.ReadWrite, FileShare.None);
        }
        catch (Exception ex2)
        {
            //_log.WriteLog(ex2, "Error in checking whether file is locked " + file);
            int errorCode = Marshal.GetHRForException(ex2) & ((1 << 16) - 1);
            if ((ex2 is IOException) && (errorCode == ERROR_SHARING_VIOLATION || errorCode == ERROR_LOCK_VIOLATION))
            {
                return true;
            }
        }
        finally
        {
            if (stream != null)
                stream.Close();
        }
    }
    return false;
}

Wait for file to be freed by process

A function like this will do it:

public static bool IsFileReady(string filename)
{
    // If the file can be opened for exclusive access it means that the file
    // is no longer locked by another process.
    try
    {
        using (FileStream inputStream = File.Open(filename, FileMode.Open, FileAccess.Read, FileShare.None))
            return inputStream.Length > 0;
    }
    catch (Exception)
    {
        return false;
    }
}

Stick it in a while loop and you have something which will block until the file is accessible:

public static void WaitForFile(string filename)
{
    //This will lock the execution until the file is ready
    //TODO: Add some logic to make it async and cancelable
    while (!IsFileReady(filename)) { }
}

Checking if file is completely written

Does the producer process close the file when its finished writing? If so, trying to open the file in the consumer process with an exclusive lock will fail if the producer process is still producing.

How to test if a file is complete (completely written) with Java

You could use an external marker file. The writing process could create a file XYZ.lock before it starts creating file XYZ, and delete XYZ.lock after XYZ is completed. The reader would then easily know that it can consider a file complete only if the corresponding .lock file is not present.

bash script inotifywait wait for file completely written before proceding

As pointed out by pacholik close_write as event option alone is sufficient:

inotifywait -m -e close_write $1 | while read line

Python wait and check if file is created completely by external program

This method apparently only works on Windows (ref. comment below), and relies on the fact that your external program only open and closes the file once during the creation of it.

import time

filename = 'my_file.txt'
while True:
    try:
        with open(filename, 'rb') as _:
            break
    except IOError:
        time.sleep(3)

If you want to set a maximum limit to the number of access attempts, you can do something like this:

import time

filename = 'my_file.txt'
max_i = 10

for i in xrange(max_i):
    try:
        with open(filename, 'rb') as _:
            break
    except IOError:
        time.sleep(3)
else:
    raise IOError('Could not access {} after {} attempts'.format(filename, str(max_i)))

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