Commits on Apr 10, 2022

1. aya: perf_buffer: call BytesMut::reserve() internally …

   This changes PerfBuffer::read_events() to call BytesMut::reserve()
   internally, and deprecates PerfBufferError::MoreSpaceNeeded.
   
   This makes for a more ergonomic API, and allows for a more idiomatic
   usage of BytesMut. For example consider:
   
       let mut buffers = vec![BytesMut::with_capacity(N), ...];
       loop {
           let events = oob_cpu_buf.read_events(&mut buffers).unwrap();
           for buf in &mut buffers[..events.read] {
               let sub: Bytes = buf.split_off(n).into();
               process_sub_buf(sub);
           }
           ...
       }
   
   This is a common way to process perf bufs, where a sub buffer is split
   off from the original buffer and then processed. In the next iteration
   of the loop when it's time to read again, two things can happen:
   
   - if processing of the sub buffer is complete and `sub` has been
   dropped, read_events() will call buf.reserve(sample_size) and hit a fast
   path in BytesMut that will just restore the original capacity of the
   buffer (assuming sample_size <= N).
   
   - if processing of the sub buffer hasn't ended (eg the buffer has been
   stored or is being processed in another thread),
   buf.reserve(sample_size) will actually allocate the new memory required
   to read the sample.
   
   In other words, calling buf.reserve(sample_size) inside read_events()
   simplifies doing zero-copy processing of buffers in many cases.

   

   alessandrod committed Apr 10, 2022
   Configuration menu

   • View commit details
   • Copy full SHA for ad1636d
   • Browse repository at this point

   Copy the full SHA

   ad1636d View commit details

   Browse the repository at this point in the history