Re: [pbs-devel] [PATCH pxar] decoder: sync: remove needless wrapper around `decoder::Contents`

[Max Carrara <m.carrara@proxmox.com>]

On 8/22/23 13:35, Wolfgang Bumiller wrote:
> sorry for the late reply
> 
> NAK
> 
> On Fri, Aug 11, 2023 at 11:56:00AM +0200, Max Carrara wrote:
>> Similarly to the `impl` for `tokio::io::AsyncRead` in `decoder::aio`,
>> this implements the `std::io::Read` trait on `decoder::Contents`
>> directly while removing the wrapper.
>>
>> This allows `decoder::Contents` to be used in both synchronous
>> and asynchronous contexts.
>>
>> Signed-off-by: Max Carrara <m.carrara@proxmox.com>
>> ---
>>  src/decoder/sync.rs | 13 ++++---------
>>  1 file changed, 4 insertions(+), 9 deletions(-)
>>
>> diff --git a/src/decoder/sync.rs b/src/decoder/sync.rs
>> index 5597a03..be576f8 100644
>> --- a/src/decoder/sync.rs
>> +++ b/src/decoder/sync.rs
>> @@ -5,7 +5,7 @@ use std::path::Path;
>>  use std::pin::Pin;
>>  use std::task::{Context, Poll};
>>
>> -use crate::decoder::{self, SeqRead};
>> +use crate::decoder::{self, Contents, SeqRead};
>>  use crate::util::poll_result_once;
>>  use crate::Entry;
>>
>> @@ -69,7 +69,7 @@ impl<T: SeqRead> Decoder<T> {
>>
>>      /// Get a reader for the contents of the current entry, if the entry has contents.
>>      pub fn contents(&mut self) -> Option<Contents<T>> {
>> -        self.inner.content_reader().map(|inner| Contents { inner })
>> +        self.inner.content_reader()
>>      }
>>
>>      /// Get the size of the current contents, if the entry has contents.
>> @@ -118,13 +118,8 @@ impl<T: io::Read> SeqRead for StandardReader<T> {
>>      }
>>  }
>>
>> -/// Reader for file contents inside a pxar archive.
>> -pub struct Contents<'a, T: SeqRead> {
>> -    inner: decoder::Contents<'a, T>,
>> -}
>> -
>> -impl<'a, T: SeqRead> io::Read for Contents<'a, T> {
>> +impl<'a, T: SeqRead> io::Read for decoder::Contents<'a, T> {
> 
> `Read` is a sync interface and `poll_result_once()` *requires* it to
> actually return `Ready`, and panics otherwise. This is only allowed (and
> therefore "guaranteed" to work) when coming from the `sync` submodule,
> so only *its* readers should implement it.
> 
> If anything, I'd go the other way round, take `pxar::decoder::Contents`
> private and have one in `aio` (or just ... reexport it there :P)

Very fair; in that case I'll drop this patch, as it turned out not to be
necessary on my side either way. ;-)

> 
>>      fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
>> -        poll_result_once(super::seq_read(&mut self.inner, buf))
>> +        poll_result_once(super::seq_read(self.input, buf))
>>      }
>>  }
>> --
>> 2.39.2