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feat(tvix/castore/blob/chunked_reader): only reassemble on real seek

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If the resulting offset equals to our current position, there's no need
to recreate a reader.

Change-Id: I855f0c79c514c16ca48a78e12978af2835fbbd6a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11441
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
This commit is contained in:
Florian Klink 2024-04-16 13:50:34 +03:00 • committed by flokli
parent bccde31e77
commit 4d802fa0ae
1 changed files with 16 additions and 16 deletions
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32
tvix/castore/src/blobservice/chunked_reader.rs
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@ -76,12 +76,9 @@ where
#[instrument(skip(self), err(Debug))] #[instrument(skip(self), err(Debug))]
fn start_seek(self: Pin<&mut Self>, position: std::io::SeekFrom) -> std::io::Result<()> { fn start_seek(self: Pin<&mut Self>, position: std::io::SeekFrom) -> std::io::Result<()> {
let total_len = self.chunked_blob.blob_length(); let total_len = self.chunked_blob.blob_length();
let current_pos = self.pos; let mut this = self.project();
let this = self.project();
let pos: &mut u64 = this.pos;
let mut r: Pin<&mut Box<dyn AsyncRead + Send + Unpin>> = this.r;
let new_position: u64 = match position { let absolute_offset: u64 = match position {
std::io::SeekFrom::Start(from_start) => from_start, std::io::SeekFrom::Start(from_start) => from_start,
std::io::SeekFrom::End(from_end) => { std::io::SeekFrom::End(from_end) => {
// note from_end is i64, not u64, so this is usually negative. // note from_end is i64, not u64, so this is usually negative.
@ -94,7 +91,7 @@ where
} }
std::io::SeekFrom::Current(from_current) => { std::io::SeekFrom::Current(from_current) => {
// note from_end is i64, not u64, so this can be positive or negative. // note from_end is i64, not u64, so this can be positive or negative.
current_pos (*this.pos)
.checked_add_signed(from_current) .checked_add_signed(from_current)
.ok_or_else(|| { .ok_or_else(|| {
std::io::Error::new( std::io::Error::new(
@ -105,17 +102,20 @@ where
} }
}; };
// ensure the new position still is inside the file. // check if the position actually did change.
if new_position > total_len { if absolute_offset != *this.pos {
Err(std::io::Error::new( // ensure the new position still is inside the file.
std::io::ErrorKind::InvalidInput, if absolute_offset > total_len {
"seeked beyond EOF", Err(std::io::Error::new(
))? std::io::ErrorKind::InvalidInput,
} "seeked beyond EOF",
))?
}
// Update the position and the internal reader. // Update the position and the internal reader.
*pos = new_position; *this.pos = absolute_offset;
*r = this.chunked_blob.reader_skipped_offset(new_position); *this.r = this.chunked_blob.reader_skipped_offset(absolute_offset);
}
Ok(()) Ok(())
} }