Stop zeroing buffers in the local file storage. (#4712)

Author: fulmicoton

quickwit/quickwit-storage/src/file_descriptor_cache.rs

@@ -160,7 +160,11 @@ impl SplitFile {
         use std::os::unix::fs::FileExt;
         let file = self.clone();
         let buf = tokio::task::spawn_blocking(move || {
-            let mut buf = vec![0u8; range.len()];
+            let mut buf = Vec::with_capacity(range.len());
+            #[allow(clippy::uninit_vec)]
+            unsafe {
+                buf.set_len(range.len());
+            }
             file.0.file.read_exact_at(&mut buf, range.start as u64)?;
             io::Result::Ok(buf)
         })

quickwit/quickwit-storage/src/local_file_storage.rs

@@ -215,12 +215,15 @@ impl Storage for LocalFileStorage {
         let full_path = self.full_path(path)?;
         tokio::task::spawn_blocking(move || {
             use std::io::{Read, Seek};
-
             // we run these io in a spawn_blocking so there is no scheduling delay between each
             // step, as there would be if using tokio async File.
             let mut file = std::fs::File::open(full_path)?;
             file.seek(SeekFrom::Start(range.start as u64))?;
-            let mut content_bytes: Vec<u8> = vec![0u8; range.len()];
+            let mut content_bytes: Vec<u8> = Vec::with_capacity(range.len());
+            #[allow(clippy::uninit_vec)]
+            unsafe {
+                content_bytes.set_len(range.len());
+            }
             file.read_exact(&mut content_bytes)?;
             Ok(OwnedBytes::new(content_bytes))
         })