[pbs-devel] [PATCH v2 proxmox-backup-qemu 9/9] access: use CachedChunkReader
Stefan Reiter
s.reiter at proxmox.com
Mon Jun 7 17:35:32 CEST 2021
Use the new CachedChunkReader with the shared_cache implementation to
provide a concurrency-safe async way of accessing data. This provides
two benefits:
* uses a shared LRU cache, which is very helpful for random-access like
during a live-restore
* does away with the global Mutex in read_image_at, providing real
concurrency without lock contention
Signed-off-by: Stefan Reiter <s.reiter at proxmox.com>
---
src/restore.rs | 30 ++++++++----------------------
1 file changed, 8 insertions(+), 22 deletions(-)
diff --git a/src/restore.rs b/src/restore.rs
index 0790d7f..33959d9 100644
--- a/src/restore.rs
+++ b/src/restore.rs
@@ -1,10 +1,8 @@
use std::sync::{Arc, Mutex};
-use std::io::SeekFrom;
use std::convert::TryInto;
use anyhow::{format_err, bail, Error};
use once_cell::sync::OnceCell;
-use tokio::io::{AsyncReadExt, AsyncSeekExt};
use tokio::runtime::Runtime;
use proxmox_backup::tools::runtime::get_runtime_with_builder;
@@ -14,9 +12,10 @@ use proxmox_backup::client::{HttpClient, HttpClientOptions, BackupReader, Remote
use super::BackupSetup;
use crate::registry::Registry;
use crate::capi_types::DataPointer;
+use crate::shared_cache::get_shared_chunk_cache;
struct ImageAccessInfo {
- reader: Arc<tokio::sync::Mutex<AsyncIndexReader<RemoteChunkReader, FixedIndexReader>>>,
+ reader: Arc<CachedChunkReader<FixedIndexReader, RemoteChunkReader>>,
_archive_name: String,
archive_size: u64,
}
@@ -229,12 +228,13 @@ impl RestoreTask {
most_used,
);
- let reader = AsyncIndexReader::new(index, chunk_reader);
+ let cache = get_shared_chunk_cache();
+ let reader = Arc::new(CachedChunkReader::new_with_cache(chunk_reader, index, cache));
let info = ImageAccessInfo {
archive_size,
_archive_name: archive_name, /// useful to debug
- reader: Arc::new(tokio::sync::Mutex::new(reader)),
+ reader,
};
(*self.image_registry.lock().unwrap()).register(info)
@@ -258,23 +258,9 @@ impl RestoreTask {
bail!("read index {} out of bounds {}", offset, image_size);
}
- let mut reader = reader.lock().await;
-
- let buf: &mut [u8] = unsafe { std::slice::from_raw_parts_mut(data.0 as *mut u8, size as usize)};
- let mut read = 0;
-
- while read < size {
- reader.seek(SeekFrom::Start(offset + read)).await?;
- let bytes = reader.read(&mut buf[read as usize..]).await?;
-
- if bytes == 0 {
- // EOF
- break;
- }
-
- read += bytes as u64;
- }
-
+ let buf: &mut [u8] =
+ unsafe { std::slice::from_raw_parts_mut(data.0 as *mut u8, size as usize) };
+ let read = reader.read_at(buf, offset).await?;
Ok(read.try_into()?)
}
}
--
2.30.2
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