[pbs-devel] [PATCH proxmox-backup v6 14/37] datastore: local chunk reader: read chunks based on backend

[Christian Ebner]

Get and store the datastore's backend on local chunk reader
instantiantion and fetch chunks based on the variant from either the
filesystem or the s3 object store.

By storing the backend variant, the s3 client is instantiated only
once and reused until the local chunk reader instance is dropped.

Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
 pbs-datastore/Cargo.toml                |  1 +
 pbs-datastore/src/local_chunk_reader.rs | 38 +++++++++++++++++++++----
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/pbs-datastore/Cargo.toml b/pbs-datastore/Cargo.toml
index 7e56dbd31..8ce930a94 100644
--- a/pbs-datastore/Cargo.toml
+++ b/pbs-datastore/Cargo.toml
@@ -13,6 +13,7 @@ crc32fast.workspace = true
 endian_trait.workspace = true
 futures.workspace = true
 hex = { workspace = true, features = [ "serde" ] }
+http-body-util.workspace = true
 hyper.workspace = true
 libc.workspace = true
 log.workspace = true
diff --git a/pbs-datastore/src/local_chunk_reader.rs b/pbs-datastore/src/local_chunk_reader.rs
index 05a70c068..f5aa217ae 100644
--- a/pbs-datastore/src/local_chunk_reader.rs
+++ b/pbs-datastore/src/local_chunk_reader.rs
@@ -3,17 +3,21 @@ use std::pin::Pin;
 use std::sync::Arc;
 
 use anyhow::{bail, Error};
+use http_body_util::BodyExt;
 
 use pbs_api_types::CryptMode;
 use pbs_tools::crypt_config::CryptConfig;
+use proxmox_s3_client::S3Client;
 
 use crate::data_blob::DataBlob;
+use crate::datastore::DatastoreBackend;
 use crate::read_chunk::{AsyncReadChunk, ReadChunk};
 use crate::DataStore;
 
 #[derive(Clone)]
 pub struct LocalChunkReader {
     store: Arc<DataStore>,
+    backend: DatastoreBackend,
     crypt_config: Option<Arc<CryptConfig>>,
     crypt_mode: CryptMode,
 }
@@ -24,8 +28,11 @@ impl LocalChunkReader {
         crypt_config: Option<Arc<CryptConfig>>,
         crypt_mode: CryptMode,
     ) -> Self {
+        // TODO: Error handling!
+        let backend = store.backend().unwrap();
         Self {
             store,
+            backend,
             crypt_config,
             crypt_mode,
         }
@@ -47,10 +54,26 @@ impl LocalChunkReader {
     }
 }
 
+async fn fetch(s3_client: Arc<S3Client>, digest: &[u8; 32]) -> Result<DataBlob, Error> {
+    let object_key = crate::s3::object_key_from_digest(digest)?;
+    if let Some(response) = s3_client.get_object(object_key).await? {
+        let bytes = response.content.collect().await?.to_bytes();
+        DataBlob::from_raw(bytes.to_vec())
+    } else {
+        bail!("no object with digest {}", hex::encode(digest));
+    }
+}
+
 impl ReadChunk for LocalChunkReader {
     fn read_raw_chunk(&self, digest: &[u8; 32]) -> Result<DataBlob, Error> {
-        let chunk = self.store.load_chunk(digest)?;
+        let chunk = match &self.backend {
+            DatastoreBackend::Filesystem => self.store.load_chunk(digest)?,
+            DatastoreBackend::S3(s3_client) => {
+                proxmox_async::runtime::block_on(fetch(s3_client.clone(), digest))?
+            }
+        };
         self.ensure_crypt_mode(chunk.crypt_mode()?)?;
+
         Ok(chunk)
     }
 
@@ -69,11 +92,14 @@ impl AsyncReadChunk for LocalChunkReader {
         digest: &'a [u8; 32],
     ) -> Pin<Box<dyn Future<Output = Result<DataBlob, Error>> + Send + 'a>> {
         Box::pin(async move {
-            let (path, _) = self.store.chunk_path(digest);
-
-            let raw_data = tokio::fs::read(&path).await?;
-
-            let chunk = DataBlob::load_from_reader(&mut &raw_data[..])?;
+            let chunk = match &self.backend {
+                DatastoreBackend::Filesystem => {
+                    let (path, _) = self.store.chunk_path(digest);
+                    let raw_data = tokio::fs::read(&path).await?;
+                    DataBlob::load_from_reader(&mut &raw_data[..])?
+                }
+                DatastoreBackend::S3(s3_client) => fetch(s3_client.clone(), digest).await?,
+            };
             self.ensure_crypt_mode(chunk.crypt_mode()?)?;
 
             Ok(chunk)
-- 
2.47.2