RUST/TEST: test sync_manager

src/bindings/rust/tests/test_sync_manager.rs

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+// SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+use nixl_sys::{BackendSyncable, SyncManager};
+use std::cell::Cell;
+use std::rc::Rc;
+
+#[derive(Debug, PartialEq, Eq)]
+enum TestError {
+    SyncFailed,
+}
+
+#[derive(Debug, Clone)]
+struct DummyBackend {
+    sync_calls: Rc<Cell<u32>>,
+}
+
+#[derive(Debug, Clone)]
+struct DummyData {
+    value: Cell<i32>,
+    data_calls: Rc<Cell<u32>>,
+    should_fail: Cell<bool>,
+}
+
+impl BackendSyncable for DummyData {
+    type Backend = DummyBackend;
+    type Error = TestError;
+
+    fn sync_to_backend(&self, backend: &Self::Backend) -> Result<(), Self::Error> {
+        if self.should_fail.get() {
+            return Err(TestError::SyncFailed);
+        }
+        self.data_calls.set(self.data_calls.get() + 1);
+        backend
+            .sync_calls
+            .set(backend.sync_calls.get() + 1);
+        Ok(())
+    }
+}
+
+#[test]
+fn sync_manager_first_access_triggers_single_sync() {
+    let data_calls = Rc::new(Cell::new(0));
+    let backend_calls = Rc::new(Cell::new(0));
+
+    let data = DummyData {
+        value: Cell::new(0),
+        data_calls: data_calls.clone(),
+        should_fail: Cell::new(false),
+    };
+    let backend = DummyBackend {
+        sync_calls: backend_calls.clone(),
+    };
+    let mgr = SyncManager::new(data, backend);
+
+    // First access -> sync happens
+    let _ = mgr.backend().unwrap().sync_calls.get();
+    assert_eq!(data_calls.get(), 1);
+    assert_eq!(backend_calls.get(), 1);
+
+    // Second access without modification -> no sync
+    let _ = mgr.backend().unwrap().sync_calls.get();
+    assert_eq!(data_calls.get(), 1);
+    assert_eq!(backend_calls.get(), 1);
+}
+
+#[test]
+fn sync_manager_resyncs_after_modify() {
+    let data_calls = Rc::new(Cell::new(0));
+    let backend_calls = Rc::new(Cell::new(0));
+
+    let data = DummyData {
+        value: Cell::new(0),
+        data_calls: data_calls.clone(),
+        should_fail: Cell::new(false),
+    };
+    let backend = DummyBackend {
+        sync_calls: backend_calls.clone(),
+    };
+    let mut mgr = SyncManager::new(data, backend);
+
+    // Ensure initial sync
+    let _ = mgr.backend().unwrap();
+    assert_eq!(data_calls.get(), 1);
+
+    // Modify -> marks dirty
+    mgr.data_mut().value.set(42);
+
+    // Next access -> resync
+    let _ = mgr.backend().unwrap();
+    assert_eq!(data_calls.get(), 2);
+    assert_eq!(backend_calls.get(), 2);
+}
+
+#[test]
+fn sync_manager_backend_accessor_triggers_sync() {
+    let data_calls = Rc::new(Cell::new(0));
+    let backend_calls = Rc::new(Cell::new(0));
+
+    let data = DummyData {
+        value: Cell::new(0),
+        data_calls: data_calls.clone(),
+        should_fail: Cell::new(false),
+    };
+    let backend = DummyBackend {
+        sync_calls: backend_calls.clone(),
+    };
+    let mgr = SyncManager::new(data, backend);
+
+    // Read-only data access should not sync
+    let _ = mgr.data();
+    assert_eq!(data_calls.get(), 0);
+    assert_eq!(backend_calls.get(), 0);
+
+    // Backend accessor should sync
+    let _ = mgr.backend().unwrap();
+    assert_eq!(data_calls.get(), 1);
+    assert_eq!(backend_calls.get(), 1);
+}
+
+#[test]
+fn sync_manager_error_is_propagated_and_retry_succeeds() {
+    let data_calls = Rc::new(Cell::new(0));
+    let backend_calls = Rc::new(Cell::new(0));
+
+    let data = DummyData {
+        value: Cell::new(0),
+        data_calls: data_calls.clone(),
+        should_fail: Cell::new(false),
+    };
+    let backend = DummyBackend {
+        sync_calls: backend_calls.clone(),
+    };
+    let mut mgr = SyncManager::new(data, backend);
+
+    // Configure to fail on first sync
+    mgr.data_mut().should_fail.set(true);
+
+    // Attempting to access backend should error
+    let err = mgr.backend().unwrap_err();
+    assert_eq!(err, TestError::SyncFailed);
+    // No successful sync occurred
+    assert_eq!(data_calls.get(), 0);
+    assert_eq!(backend_calls.get(), 0);
+
+    // Clear failure and try again
+    mgr.data_mut().should_fail.set(false);
+    let _ = mgr.backend().unwrap();
+    assert_eq!(data_calls.get(), 1);
+    assert_eq!(backend_calls.get(), 1);
+}