From 4fc06ee233d1c0990ff92694df350339b472190c Mon Sep 17 00:00:00 2001
From: kronecker <2026692687@qq.com>
Date: Thu, 29 Oct 2026 17:13:17 +0800
Subject: [PATCH] perf(delivery): release copied large source pages

---
 .../crates/sandbox/src/restore_copy/files.rs  | 12 ++++
 judge/crates/sandbox/src/restore_copy/main.rs | 64 +++++++++++++++++++
 scripts/release/README.md                     |  2 +
 3 files changed, 78 insertions(+)

diff --git a/judge/crates/sandbox/src/restore_copy/files.rs b/judge/crates/sandbox/src/restore_copy/files.rs
index fbf0411..21bc87b 100644
--- a/judge/crates/sandbox/src/restore_copy/files.rs
+++ b/judge/crates/sandbox/src/restore_copy/files.rs
@@ -414,6 +414,18 @@ fn transfer(input: &mut File, output: &mut File, bytes: u64, deadline: u64) -> R
             return Err(Error::Bytes);
         }
         total += count as u64;
+        if bytes > kf_contracts::restore_io::MAX_BATCH_BYTES {
+            // A large singleton cannot share source pages with another batch.
+            // Only release the already copied range of this read-only object;
+            // destination sync, complete readback and every witness still follow.
+            rustix::fs::fadvise(
+                &*input,
+                total - count as u64,
+                std::num::NonZeroU64::new(count as u64),
+                rustix::fs::Advice::DontNeed,
+            )
+            .map_err(|_| Error::Filesystem)?;
+        }
     }
     remaining(deadline)?;
     if input.read(&mut [0; 1]).map_err(|_| Error::Filesystem)? != 0 {
diff --git a/judge/crates/sandbox/src/restore_copy/main.rs b/judge/crates/sandbox/src/restore_copy/main.rs
index 1e8611c..cbc3c15 100644
--- a/judge/crates/sandbox/src/restore_copy/main.rs
+++ b/judge/crates/sandbox/src/restore_copy/main.rs
@@ -630,4 +630,68 @@ mod tests {
         assert!(request(&mut &b""[..]).is_err());
         assert!(request(&mut &vec![b' '; restore_io::MAX_REQUEST_BYTES + 1][..]).is_err());
     }
+
+    #[test]
+    fn large_singleton_keeps_complete_source_and_destination_after_cache_advice() {
+        let fixture = files::Fixture::new();
+        let roots = Arc::new(fixture.roots());
+        let data = vec![b's'; restore_io::MAX_BATCH_BYTES as usize + 17];
+        let hash = format!("{:x}", Sha256::digest(&data));
+        let source = fixture.source().join(&hash);
+        fs::write(&source, &data).unwrap();
+        fs::set_permissions(&source, fs::Permissions::from_mode(0o600)).unwrap();
+        use std::os::unix::fs::MetadataExt;
+        let stamp = |m: fs::Metadata| {
+            (
+                m.dev(),
+                m.ino(),
+                m.mode(),
+                m.nlink(),
+                m.uid(),
+                m.gid(),
+                m.size(),
+                (m.mtime(), m.mtime_nsec()),
+                (m.ctime(), m.ctime_nsec()),
+            )
+        };
+        let owner = fs::metadata(&source).unwrap();
+        let before = stamp(fs::metadata(&source).unwrap());
+        let rows = vec![restore_io::RestoreFile {
+            path: "artifacts/large-singleton".into(),
+            uid: owner.uid(),
+            gid: owner.gid(),
+            mode: 0o644,
+            bytes: data.len() as u64,
+            sha256: hash,
+        }];
+        // Validate the real wire owner policy separately from the unprivileged
+        // ordinary fixture's owner. Production never accepts the host test UID.
+        let mut wire_rows = rows.clone();
+        wire_rows[0].uid = 1200;
+        wire_rows[0].gid = 1200;
+        Request::Batch {
+            schema_version: SchemaVersion,
+            batch_id: 1,
+            files: wire_rows,
+        }
+        .validate()
+        .unwrap();
+        assert_eq!(rows.len(), 1);
+        let pool = Pool::new(Arc::clone(&roots)).unwrap_or_else(|_| panic!("pool"));
+        let verified = pool
+            .materialize(rows, &roots, now().unwrap() + 30_000_000_000)
+            .unwrap_or_else(|_| panic!("large singleton verified"));
+        assert_eq!(verified.len(), 1);
+        roots
+            .final_file(&verified[0])
+            .unwrap_or_else(|_| panic!("final witness"));
+        assert_eq!(
+            fs::read(fixture.target().join("large-singleton")).unwrap(),
+            data
+        );
+        assert_eq!(fs::read(&source).unwrap(), data);
+        assert_eq!(stamp(fs::metadata(&source).unwrap()), before);
+        drop(pool);
+        roots.unchanged().unwrap_or_else(|_| panic!("root anchors"));
+    }
 }
diff --git a/scripts/release/README.md b/scripts/release/README.md
index 04f0346..9453050 100644
--- a/scripts/release/README.md
+++ b/scripts/release/README.md
@@ -637,3 +637,5 @@ outside public API, Git and CI artifacts.
   [namespace interface](https://github.com/systemd/systemd/blob/v262/man/systemd.exec.xml),
   [journal configuration](https://github.com/systemd/systemd/blob/v262/man/journald.conf.xml).
 - Linux: [proc mountinfo](https://github.com/torvalds/linux/blob/v6.18/fs/proc_namespace.c).
+
+恢复大于 64 MiB 的单对象文件时，复制器仅对已复制的只读源区间发出有界缓存回收建议，避免源和目标页面同时占满原恢复单元。目标仍在原同步屏障后完整读回、逐字节/SHA 校验，并在结束前复核全部文件身份；原内存、CPU、线程、期限和失败保留规则保持不变。