fix(tvix/castore/blobservice): update bytes_read only on successful read r/7922

We previously updated this.pos also in case the underlying read returned
an error.

Also, use the ready! macro to remove the match block, and instrument
errors returned during start_seek.

Change-Id: Ic32e26579d964a76b45687134acc48d72d67c36f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11421
Reviewed-by: Brian Olsen <me@griff.name>
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>

1 files changed, 7 insertions, 11 deletions

diff --git a/tvix/castore/src/blobservice/naive_seeker.rs b/tvix/castore/src/blobservice/naive_seeker.rs
index e65a82c7f45a..1475de580814 100644
--- a/tvix/castore/src/blobservice/naive_seeker.rs
+++ b/tvix/castore/src/blobservice/naive_seeker.rs
@@ -1,4 +1,5 @@
 use super::BlobReader;
+use futures::ready;
 use pin_project_lite::pin_project;
 use std::io;
 use std::task::Poll;
@@ -83,18 +84,13 @@ impl<R: tokio::io::AsyncRead> tokio::io::AsyncRead for NaiveSeeker<R> {
         // The amount of data read can be determined by the increase
         // in the length of the slice returned by `ReadBuf::filled`.
         let filled_before = buf.filled().len();
-        let this = self.project();
-        let pos: &mut u64 = this.pos;
 
-        match this.r.poll_read(cx, buf) {
-            Poll::Ready(a) => {
-                let bytes_read = buf.filled().len() - filled_before;
-                *pos += bytes_read as u64;
+        let this = self.project();
+        ready!(this.r.poll_read(cx, buf))?;
+        let bytes_read = buf.filled().len() - filled_before;
+        *this.pos += bytes_read as u64;
 
-                Poll::Ready(a)
-            }
-            Poll::Pending => Poll::Pending,
-        }
+        Ok(()).into()
     }
 }
 
@@ -115,7 +111,7 @@ impl<R: tokio::io::AsyncRead> tokio::io::AsyncBufRead for NaiveSeeker<R> {
 }
 
 impl<R: tokio::io::AsyncRead> tokio::io::AsyncSeek for NaiveSeeker<R> {
-    #[instrument(skip(self))]
+    #[instrument(skip(self), err(Debug))]
     fn start_seek(
         self: std::pin::Pin<&mut Self>,
         position: std::io::SeekFrom,