[pbs-devel] [PATCH v2 pxar 01/20] decoder/aio: add contents() and content_size() calls
Stefan Reiter
s.reiter at proxmox.com
Thu Mar 25 10:23:59 CET 2021
On 3/25/21 10:08 AM, Wolfgang Bumiller wrote:
> On Wed, Mar 24, 2021 at 04:18:08PM +0100, Stefan Reiter wrote:
>> Returns a decoder::Contents without a wrapper type, since in this case
>> we don't want to hide the SeqRead implementation (as done in
>> decoder::sync). For conviencience also implement AsyncRead if "tokio-io"
>> is enabled.
>>
>> Signed-off-by: Stefan Reiter <s.reiter at proxmox.com>
>> ---
>>
>> proxmox-backup requires a dependency bump on this!
>>
>> v2:
>> * make contents() call available without tokio-io feature
>> * drop peek() implementation
>>
>> src/decoder/aio.rs | 36 +++++++++++++++++++++++++++++++++++-
>> 1 file changed, 35 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/decoder/aio.rs b/src/decoder/aio.rs
>> index 82030b0..ee4d51f 100644
>> --- a/src/decoder/aio.rs
>> +++ b/src/decoder/aio.rs
>> @@ -5,7 +5,7 @@ use std::io;
>> #[cfg(feature = "tokio-fs")]
>> use std::path::Path;
>>
>> -use crate::decoder::{self, SeqRead};
>> +use crate::decoder::{self, Contents, SeqRead};
>> use crate::Entry;
>>
>> /// Asynchronous `pxar` decoder.
>> @@ -56,6 +56,16 @@ impl<T: SeqRead> Decoder<T> {
>> self.inner.next_do().await.transpose()
>> }
>>
>> + /// 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()
>> + }
>> +
>> + /// Get the size of the current contents, if the entry has contents.
>> + pub fn content_size(&self) -> Option<u64> {
>> + self.inner.content_size()
>> + }
>> +
>> /// Include goodbye tables in iteration.
>> pub fn enable_goodbye_entries(&mut self, on: bool) {
>> self.inner.with_goodbye_tables = on;
>> @@ -67,6 +77,7 @@ mod tok {
>> use std::io;
>> use std::pin::Pin;
>> use std::task::{Context, Poll};
>> + use crate::decoder::{Contents, SeqRead};
>>
>> /// Read adapter for `futures::io::AsyncRead`
>> pub struct TokioReader<T> {
>> @@ -93,6 +104,29 @@ mod tok {
>> }
>> }
>> }
>> +
>> + impl<'a, T: crate::decoder::SeqRead> tokio::io::AsyncRead for Contents<'a, T> {
>> + fn poll_read(
>> + self: Pin<&mut Self>,
>> + cx: &mut Context<'_>,
>> + buf: &mut tokio::io::ReadBuf<'_>,
>> + ) -> Poll<io::Result<()>> {
>> + unsafe {
>> + // Safety: poll_seq_read will *probably* only write to the buffer, so we don't
>> + // initialize it first, instead we treat is a &[u8] immediately and uphold the
>> + // ReadBuf invariants in the conditional below.
>> + let write_buf =
>> + &mut *(buf.unfilled_mut() as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]);
>> + let result = self.poll_seq_read(cx, write_buf);
>> + if let Poll::Ready(Ok(n)) = result {
>> + // if we've written data, advance both initialized and filled bytes cursor
>> + buf.assume_init(buf.filled().len() + n);
>> + buf.advance(n);
>
> The differences here look fishy. The docs about `assume_init()` say it
> marks the "first `n` *unfilled* bytes`, so IMO both calls should use
> just `n` as they both start from the beginning of the unfilled range?
>
Hm, you're right:
https://docs.rs/tokio/1.4.0/src/tokio/io/read_buf.rs.html#240
That doc is a bit confusing IMO...
>> + }
>> + result.map(|_| Ok(()))
>> + }
>> + }
>> + }
>> }
>>
>> #[cfg(feature = "tokio-io")]
>> --
>> 2.20.1
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