[pbs-devel] [PATCH proxmox-backup v2 09/12] chunk store: refactor method for chunk insertion

[Christian Ebner]

Extend the current implementation of the chunk insertion by a method
to provide a callback to be executed before writing the chunk file,
but after checking if the file is pre-existing.

This is in preparation for different methods for chunk insertion,
with differentiated handling of the non pre-existing chunk file case.

Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
 pbs-datastore/src/chunk_store.rs | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/pbs-datastore/src/chunk_store.rs b/pbs-datastore/src/chunk_store.rs
index 6e50327cb..65d74d68e 100644
--- a/pbs-datastore/src/chunk_store.rs
+++ b/pbs-datastore/src/chunk_store.rs
@@ -558,6 +558,15 @@ impl ChunkStore {
     }
 
     pub fn insert_chunk(&self, chunk: &DataBlob, digest: &[u8; 32]) -> Result<(bool, u64), Error> {
+        self.insert_chunk_impl(chunk, digest, |_, _| Ok(()))
+    }
+
+    fn insert_chunk_impl(
+        &self,
+        chunk: &DataBlob,
+        digest: &[u8; 32],
+        before_create: impl FnOnce(&[u8; 32], bool) -> Result<(), Error>,
+    ) -> Result<(bool, u64), Error> {
         // unwrap: only `None` in unit tests
         assert!(self.locker.is_some());
 
@@ -572,7 +581,7 @@ impl ChunkStore {
 
         let name = &self.name;
 
-        if let Ok(metadata) = std::fs::metadata(&chunk_path) {
+        let pre_existing = if let Ok(metadata) = std::fs::metadata(&chunk_path) {
             if !metadata.is_file() {
                 bail!("got unexpected file type on store '{name}' for chunk {digest_str}");
             }
@@ -612,7 +621,12 @@ impl ChunkStore {
             } else {
                 log::debug!("Got another copy of chunk with digest '{digest_str}', existing chunk is bigger, replacing with uploaded one.");
             }
-        }
+            true
+        } else {
+            false
+        };
+
+        before_create(digest, pre_existing)?;
 
         let chunk_dir_path = chunk_path
             .parent()
-- 
2.47.3