From 4d802fa0aefbc22b5f78bf7281c0028ad3bf2fff Mon Sep 17 00:00:00 2001 From: Florian Klink Date: Tue, 16 Apr 2024 13:50:34 +0300 Subject: feat(tvix/castore/blob/chunked_reader): only reassemble on real seek 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 --- tvix/castore/src/blobservice/chunked_reader.rs | 32 +++++++++++++------------- 1 file changed, 16 insertions(+), 16 deletions(-) (limited to 'tvix') diff --git a/tvix/castore/src/blobservice/chunked_reader.rs b/tvix/castore/src/blobservice/chunked_reader.rs index 3f2949f1a7..e193ff0295 100644 --- a/tvix/castore/src/blobservice/chunked_reader.rs +++ b/tvix/castore/src/blobservice/chunked_reader.rs @@ -76,12 +76,9 @@ where #[instrument(skip(self), err(Debug))] fn start_seek(self: Pin<&mut Self>, position: std::io::SeekFrom) -> std::io::Result<()> { let total_len = self.chunked_blob.blob_length(); - let current_pos = self.pos; - let this = self.project(); - let pos: &mut u64 = this.pos; - let mut r: Pin<&mut Box> = this.r; + let mut this = self.project(); - let new_position: u64 = match position { + let absolute_offset: u64 = match position { std::io::SeekFrom::Start(from_start) => from_start, std::io::SeekFrom::End(from_end) => { // note from_end is i64, not u64, so this is usually negative. @@ -94,7 +91,7 @@ where } std::io::SeekFrom::Current(from_current) => { // note from_end is i64, not u64, so this can be positive or negative. - current_pos + (*this.pos) .checked_add_signed(from_current) .ok_or_else(|| { std::io::Error::new( @@ -105,17 +102,20 @@ where } }; - // ensure the new position still is inside the file. - if new_position > total_len { - Err(std::io::Error::new( - std::io::ErrorKind::InvalidInput, - "seeked beyond EOF", - ))? - } + // check if the position actually did change. + if absolute_offset != *this.pos { + // ensure the new position still is inside the file. + if absolute_offset > total_len { + Err(std::io::Error::new( + std::io::ErrorKind::InvalidInput, + "seeked beyond EOF", + ))? + } - // Update the position and the internal reader. - *pos = new_position; - *r = this.chunked_blob.reader_skipped_offset(new_position); + // Update the position and the internal reader. + *this.pos = absolute_offset; + *this.r = this.chunked_blob.reader_skipped_offset(absolute_offset); + } Ok(()) } -- cgit 1.4.1