impl: use interior mut for flush_on_exit

This restores previous behavior where flush on exit behavior can be set
without marking KVS object as `mut`.

Author: arkjedrz

src/rust/rust_kvs/examples/flush.rs

@@ -34,7 +34,7 @@ fn main() -> Result<(), ErrorCode> {
         {
             // Build KVS instance for given instance ID and temporary directory.
             let builder = KvsBuilder::<Kvs>::new(instance_id.clone()).dir(dir_string.clone());
-            let mut kvs = builder.build()?;
+            let kvs = builder.build()?;
 
             // Disable flush on exit.
             kvs.set_flush_on_exit(FlushOnExit::No);
@@ -55,7 +55,7 @@ fn main() -> Result<(), ErrorCode> {
         {
             // Build KVS instance for given instance ID and temporary directory.
             let builder = KvsBuilder::<Kvs>::new(instance_id.clone()).dir(dir_string.clone());
-            let mut kvs = builder.build()?;
+            let kvs = builder.build()?;
 
             // Explicitly enable flush on exit - this is the default.
             kvs.set_flush_on_exit(FlushOnExit::Yes);
@@ -76,7 +76,7 @@ fn main() -> Result<(), ErrorCode> {
         {
             // Build KVS instance for given instance ID and temporary directory.
             let builder = KvsBuilder::<Kvs>::new(instance_id.clone()).dir(dir_string.clone());
-            let mut kvs = builder.build()?;
+            let kvs = builder.build()?;
 
             // Disable flush on exit.
             kvs.set_flush_on_exit(FlushOnExit::No);
@@ -94,7 +94,7 @@ fn main() -> Result<(), ErrorCode> {
             let builder = KvsBuilder::<Kvs>::new(instance_id.clone())
                 .dir(dir_string)
                 .need_kvs(true);
-            let mut kvs = builder.build()?;
+            let kvs = builder.build()?;
             kvs.set_flush_on_exit(FlushOnExit::No);
 
             let k1_key = "k1";

src/rust/rust_kvs/examples/snapshots.rs

@@ -18,7 +18,7 @@ fn main() -> Result<(), ErrorCode> {
 
         // Build KVS instance for given instance ID and temporary directory.
         let builder = KvsBuilder::<Kvs>::new(instance_id.clone()).dir(dir_string.clone());
-        let mut kvs = builder.build()?;
+        let kvs = builder.build()?;
         kvs.set_flush_on_exit(FlushOnExit::No);
 
         let max_count = Kvs::snapshot_max_count() as u32;
@@ -40,7 +40,7 @@ fn main() -> Result<(), ErrorCode> {
 
         // Build KVS instance for given instance ID and temporary directory.
         let builder = KvsBuilder::<Kvs>::new(instance_id.clone()).dir(dir_string.clone());
-        let mut kvs = builder.build()?;
+        let kvs = builder.build()?;
         kvs.set_flush_on_exit(FlushOnExit::No);
 
         let max_count = Kvs::snapshot_max_count() as u32;

src/rust/rust_kvs/src/kvs.rs

@@ -9,7 +9,7 @@
 //
 // SPDX-License-Identifier: Apache-2.0
 
-//std dependencies
+use std::cell::RefCell;
 use std::collections::HashMap;
 use std::fs;
 use std::path::PathBuf;
@@ -42,7 +42,7 @@ pub struct GenericKvs<J: KvsBackend> {
     filename_prefix: PathBuf,
 
     /// Flush on exit flag
-    flush_on_exit: FlushOnExit,
+    flush_on_exit: RefCell<FlushOnExit>,
 
     _backend: std::marker::PhantomData<J>,
 }
@@ -236,7 +236,7 @@ impl<J: KvsBackend> KvsApi for GenericKvs<J> {
             kvs: Mutex::new(kvs),
             default,
             filename_prefix,
-            flush_on_exit: FlushOnExit::Yes,
+            flush_on_exit: RefCell::new(FlushOnExit::Yes),
             _backend: std::marker::PhantomData,
         })
     }
@@ -246,15 +246,15 @@ impl<J: KvsBackend> KvsApi for GenericKvs<J> {
     /// # Return Values
     ///    * `FlushOnExit`: Current flush on exit behavior.
     fn flush_on_exit(&self) -> FlushOnExit {
-        self.flush_on_exit.clone()
+        self.flush_on_exit.borrow().clone()
     }
 
     /// Control the flush on exit behavior
     ///
     /// # Parameters
     ///   * `flush_on_exit`: Flag to control flush-on-exit behavior
-    fn set_flush_on_exit(&mut self, flush_on_exit: FlushOnExit) {
-        self.flush_on_exit = flush_on_exit;
+    fn set_flush_on_exit(&self, flush_on_exit: FlushOnExit) {
+        *self.flush_on_exit.borrow_mut() = flush_on_exit
     }
 
     /// Resets a key-value-storage to its initial state
@@ -1025,7 +1025,7 @@ mod kvs_tests {
 
     #[test]
     fn test_set_flush_on_exit() {
-        let mut kvs = get_kvs::<MockBackend>(PathBuf::new(), KvsMap::new(), KvsMap::new());
+        let kvs = get_kvs::<MockBackend>(PathBuf::new(), KvsMap::new(), KvsMap::new());
 
         kvs.set_flush_on_exit(FlushOnExit::Yes);
         assert_eq!(kvs.flush_on_exit(), FlushOnExit::Yes);
@@ -1201,7 +1201,7 @@ mod kvs_tests {
         let dir = tempdir().unwrap();
         let dir_path = dir.path().to_path_buf();
         {
-            let mut kvs = get_kvs::<JsonBackend>(dir_path.clone(), KvsMap::new(), KvsMap::new());
+            let kvs = get_kvs::<JsonBackend>(dir_path.clone(), KvsMap::new(), KvsMap::new());
             kvs.set_flush_on_exit(FlushOnExit::Yes);
             kvs.set_value("key", "value").unwrap();
         }

src/rust/rust_kvs/src/kvs_api.rs

@@ -127,7 +127,7 @@ pub trait KvsApi {
     ) -> Result<(), ErrorCode>;
     fn remove_key(&self, key: &str) -> Result<(), ErrorCode>;
     fn flush_on_exit(&self) -> FlushOnExit;
-    fn set_flush_on_exit(&mut self, flush_on_exit: FlushOnExit);
+    fn set_flush_on_exit(&self, flush_on_exit: FlushOnExit);
     fn flush(&self) -> Result<(), ErrorCode>;
     fn snapshot_count(&self) -> usize;
     fn snapshot_max_count() -> usize

src/rust/rust_kvs/src/kvs_builder.rs

@@ -215,7 +215,7 @@ mod tests {
             unimplemented!()
         }
 
-        fn set_flush_on_exit(&mut self, _flush_on_exit: FlushOnExit) {
+        fn set_flush_on_exit(&self, _flush_on_exit: FlushOnExit) {
             unimplemented!()
         }
 

src/rust/rust_kvs/src/kvs_mock.rs

@@ -46,7 +46,7 @@ impl KvsApi for MockKvs {
     fn flush_on_exit(&self) -> FlushOnExit {
         FlushOnExit::No
     }
-    fn set_flush_on_exit(&mut self, _flush_on_exit: FlushOnExit) {}
+    fn set_flush_on_exit(&self, _flush_on_exit: FlushOnExit) {}
     fn reset(&self) -> Result<(), ErrorCode> {
         if self.fail {
             return Err(ErrorCode::UnmappedError);

src/rust/rust_kvs/tests/cit_persistency.rs

@@ -100,7 +100,7 @@ fn cit_persistency_flush_on_exit_disabled_drop_data() -> Result<(), ErrorCode> {
 
     {
         // First KVS run.
-        let mut kvs = Kvs::open(
+        let kvs = Kvs::open(
             InstanceId(0),
             OpenNeedDefaults::Optional,
             OpenNeedKvs::Optional,
@@ -158,7 +158,7 @@ fn cit_persistency_flush_on_exit_disabled_manual_flush() -> Result<(), ErrorCode
 
     {
         // First KVS run.
-        let mut kvs = Kvs::open(
+        let kvs = Kvs::open(
             InstanceId(0),
             OpenNeedDefaults::Optional,
             OpenNeedKvs::Optional,

tests/rust_test_scenarios/src/test_basic.rs

@@ -46,7 +46,7 @@ impl Scenario for BasicScenario {
         }
 
         // Create KVS.
-        let mut kvs: Kvs = builder.build().unwrap();
+        let kvs: Kvs = builder.build().unwrap();
         if let Some(flag) = params.flush_on_exit {
             let mode = if flag {
                 FlushOnExit::Yes