[PATCH datacenter-manager 11/15] task cache: use ArchiveFileWriter when creating new archive files

[Lukas Wagner <l.wagner@proxmox.com>]

As a nice side-effect this ensures that any zstd-compressed files are
initialized atomically, making it impossible to have a missing zstd
header if the process is terminated during the `new_file` call.

Signed-off-by: Lukas Wagner <l.wagner@proxmox.com>
---
 server/src/remote_tasks/task_cache.rs | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/server/src/remote_tasks/task_cache.rs b/server/src/remote_tasks/task_cache.rs
index 969a8124..3677de2c 100644
--- a/server/src/remote_tasks/task_cache.rs
+++ b/server/src/remote_tasks/task_cache.rs
@@ -256,19 +256,16 @@ impl<'a> WritableTaskCache<'a> {
     fn new_file(&self, now: i64, compress: bool) -> Result<ArchiveFile, Error> {
         let path = self.cache.archive_path(now, compress);
 
-        let mut file = File::create(&path)?;
-        self.cache.create_options.apply_to(&mut file, &path)?;
-
-        if compress {
-            let encoder = zstd::stream::write::Encoder::new(file, zstd::DEFAULT_COMPRESSION_LEVEL)?;
-            encoder.finish()?;
-        }
-
-        Ok(ArchiveFile {
+        let file = ArchiveFile {
             path,
             compressed: compress,
             starttime: now,
-        })
+        };
+
+        let writer = file.writer(self.cache.create_options)?;
+        writer.finalize_and_replace()?;
+
+        Ok(file)
     }
 
     /// Rotate task archive if the the newest archive file is older than `rotate_after`.
-- 
2.47.3