How to Interrupt Non-Blocking File Copy and Rename Operations in Qt?

Interrupting Non-blocking File Copy Operations

In Qt, there is currently no built-in mechanism to interrupt file copy or rename operations once they have been initiated using the QFile::copy() and QFile::rename() functions. This can be problematic when dealing with large files, as the user may realize they have made a mistake and wish to cancel the operation before it completes.

To address this limitation, you have two options:

1. Implement a Custom Copy/Rename Worker

You can create your own non-blocking worker class that handles file copy or rename operations in a separate thread. This worker can continuously poll for any cancellation requests from the user and interrupt the operation accordingly.

Implementing this approach requires you to create a dedicated thread and implement a "fragmented" copying mechanism, where you read and write data chunks from the source to the destination file in intervals. This allows you to respond to cancellation requests between intervals.

2. Use the CopyHelper Class

Another solution is to utilize the CopyHelper class provided in the response. This class is a QObject-derived worker that tracks various parameters related to the file copy process, such as progress, cancellation status, and buffer size.

To use the CopyHelper class, you can follow these steps:

1. Create a CopyHelper object with the source and destination paths and desired buffer size.
2. Invoke the begin() method to initiate the copy process.
3. Connect to the progressChanged() signal to track the progress.
4. If the user requests cancellation, call the cancel() method on the CopyHelper.
5. Connect to the done() signal to be notified when the copy is complete or canceled.

The CopyHelper class handles the fragmentation and event processing internally, providing a more convenient solution for interrupting file copy operations.

Note that interrupting file rename operations poses additional challenges and may require further customization to implement the desired behavior.

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