Io uring

[alexliyu7352]

Initial implementation of event loop supporting io_uring, asynchronous reading and writing not yet implemented

[alexliyu7352]

AI Review for src/Poller/EventPoller.cpp:

Code Review: Patch for EventPoller.cpp

Summary

This patch introduces initial support for io_uring in the EventPoller class. It adds the necessary structures and functions for io_uring setup, event handling, and task management. However, asynchronous reading and writing are not yet implemented.

Detailed Feedback

Code Overview

The patch introduces io_uring support to the EventPoller class, providing an alternative to epoll and kqueue for event handling. It includes:

• io_uring setup: Initializes the io_uring ring and sets up parameters for fast polling.
• Event addition and removal: Implements addEvent, delEvent, and modifyEvent functions for io_uring.
• Event handling: Processes io_uring completion queue entries and dispatches events to registered callbacks.
• Task management: Extends the existing task management system to work with io_uring.

Strengths

• Clear and well-structured code: The io_uring implementation is well-organized and follows the existing code style.
• Comprehensive support: The patch covers essential aspects of io_uring, including setup, event handling, and task management.
• Good documentation: The code includes comments explaining the purpose of each section and function.

Areas for Improvement

1. Asynchronous Reading and Writing

• Issue: The patch currently only implements event handling for io_uring, but it lacks support for asynchronous reading and writing.
• Suggestion: Implement asynchronous read and write operations using io_uring. This will allow for more efficient and scalable I/O handling.
• Example:

  // Example for asynchronous read operation
  struct io_uring_sqe *sqe = io_uring_get_sqe(&_ring);
  io_uring_prep_read(sqe, fd, buffer, buffer_size, 0);
  io_uring_sqe_set_data(sqe, this); // Associate the sqe with the current object
  io_uring_submit(&_ring);

2. Error Handling

• Issue: The patch includes some basic error handling, but it could be more robust.
• Suggestion: Implement more comprehensive error handling for io_uring operations, including:
  • Checking return values: Ensure that all io_uring functions are checked for errors.
  • Handling specific errors: Handle specific io_uring errors gracefully, such as EAGAIN and EINTR.
  • Logging errors: Log errors to provide debugging information.
• Example:

  int ret = io_uring_submit(&_ring);
  if (ret < 0) {
      ErrorL << "Failed to submit io_uring request: " << strerror(-ret);
      // Handle the error appropriately
  }

3. Performance Optimization

• Issue: The current implementation might not be fully optimized for performance.
• Suggestion: Explore potential performance optimizations, such as:
  • Batching io_uring requests: Submit multiple io_uring requests in a single batch to reduce overhead.
  • Using io_uring_enter with flags: Use the IORING_ENTER_GETEVENTS flag to avoid unnecessary polling.
  • Tuning io_uring parameters: Experiment with different io_uring parameters to find the optimal configuration.

4. Testing

• Issue: The patch lacks comprehensive testing for the io_uring implementation.
• Suggestion: Add unit tests to verify the functionality and performance of the io_uring code. This will help ensure that the implementation is correct and robust.

Conclusion

This patch is a good starting point for io_uring support in EventPoller. However, it needs further development to implement asynchronous reading and writing, improve error handling, and optimize performance. Adding comprehensive testing is also crucial to ensure the correctness and robustness of the implementation.

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[alexliyu7352]

AI Review for src/Poller/EventPoller.h:

Code Review: Patch to src/Poller/EventPoller.h

Summary

This patch introduces initial support for io_uring in the EventPoller class. It adds the necessary headers, defines a IOBuffer struct, and implements basic functions for converting between poll events and io_uring events. However, it lacks the actual implementation for asynchronous reading and writing using io_uring.

Detailed Feedback

Code Overview

The patch introduces the HAS_IO_URING macro and conditionally includes the liburing.h header. It also defines a IOBuffer struct to hold data, file descriptor, and callback for io_uring operations. The convert_to_poll_mask and convert_from_poll_mask functions are added to convert between poll events and io_uring events.

Strengths

• Clear conditional compilation: The use of HAS_IO_URING macro ensures that io_uring-related code is only compiled when the feature is available.
• IOBuffer struct: The IOBuffer struct provides a convenient way to store data, file descriptor, and callback for io_uring operations.
• Conversion functions: The convert_to_poll_mask and convert_from_poll_mask functions provide a clear way to convert between poll events and io_uring events.

Areas for Improvement

1. Incomplete Implementation

• Issue: The patch only provides the basic infrastructure for io_uring support. It lacks the actual implementation for asynchronous reading and writing using io_uring.
• Suggestion: Implement the necessary functions to handle asynchronous reading and writing using io_uring. This would involve using the io_uring_prep_read and io_uring_prep_write functions to submit read and write requests to the io_uring ring.
• Example:

  void EventPoller::rearm_io_uring(int fd, uint32_t events) {
      // ...
      if (events & Event_Read) {
          io_uring_prep_read(&sqe, fd, buffer->data, sizeof(buffer->data), 0);
          // ...
      }
      if (events & Event_Write) {
          io_uring_prep_write(&sqe, fd, buffer->data, sizeof(buffer->data), 0);
          // ...
      }
      // ...
  }

2. Missing Error Handling

• Issue: The patch lacks proper error handling for io_uring operations.
• Suggestion: Implement error handling for all io_uring functions, including io_uring_queue_init, io_uring_submit, io_uring_wait_cq, etc.
• Example:

  if (io_uring_queue_init(1024, &_ring, 0)) {
      // Handle error
  }

3. Lack of Documentation

• Issue: The patch lacks documentation for the new io_uring-related functions and structures.
• Suggestion: Add clear and concise documentation for the new functions and structures, explaining their purpose and usage.

4. Potential Performance Bottleneck

• Issue: The current implementation uses a separate IOBuffer for each file descriptor. This could lead to a performance bottleneck if there are many file descriptors.
• Suggestion: Consider using a pool of IOBuffer objects to reduce memory allocation overhead.

5. Missing Unit Tests

• Issue: The patch lacks unit tests for the new io_uring-related code.
• Suggestion: Add unit tests to ensure the correctness and robustness of the io_uring implementation.

Conclusion

This patch is a good starting point for adding io_uring support to the EventPoller class. However, it needs to be completed by implementing asynchronous reading and writing, adding error handling, and providing proper documentation. Unit tests are also essential to ensure the correctness and robustness of the implementation.

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[jy4340132]

Why hasn't it been merged yet?

怎么还不合并呀？

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[xia-chu]

This submission is still immature after our private discussion and has not yet achieved managed read and write, so its performance is not much better than epoll.

这个提交我们私下交流后了 还不成熟 而且目前还未实现读写的托管 所以性能相对epoll并没有什么优势

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