manage immutable Arc<Rkv> rather than interiorly mutable Arc<RwLock<Rkv>>

examples/iterator.rs

@@ -25,8 +25,7 @@ fn main() {
     fs::create_dir_all(root.path()).unwrap();
     let p = root.path();
 
-    let created_arc = Manager::singleton().write().unwrap().get_or_create(p, Rkv::new).unwrap();
-    let k = created_arc.read().unwrap();
+    let k = Manager::singleton().write().unwrap().get_or_create(p, Rkv::new).unwrap();
     let store = k.open_single("store", StoreOptions::create()).unwrap();
 
     populate_store(&k, store).unwrap();

examples/simple-store.rs

@@ -53,8 +53,7 @@ fn main() {
     let p = root.path();
 
     // The manager enforces that each process opens the same lmdb environment at most once
-    let created_arc = Manager::singleton().write().unwrap().get_or_create(p, Rkv::new).unwrap();
-    let k = created_arc.read().unwrap();
+    let k = Manager::singleton().write().unwrap().get_or_create(p, Rkv::new).unwrap();
 
     // Creates a store called "store"
     let store = k.open_single("store", StoreOptions::create()).unwrap();

src/lib.rs

@@ -60,8 +60,7 @@
 //! // at most once by caching a handle to each environment that it opens.
 //! // Use it to retrieve the handle to an opened environment—or create one
 //! // if it hasn't already been opened:
-//! let created_arc = Manager::singleton().write().unwrap().get_or_create(path, Rkv::new).unwrap();
-//! let env = created_arc.read().unwrap();
+//! let env = Manager::singleton().write().unwrap().get_or_create(path, Rkv::new).unwrap();
 //!
 //! // Then you can use the environment handle to get a handle to a datastore:
 //! let store: SingleStore = env.open_single("mydb", StoreOptions::create()).unwrap();

src/manager.rs

@@ -58,7 +58,7 @@ where
 }
 
 pub struct Manager {
-    environments: BTreeMap<PathBuf, Arc<RwLock<Rkv>>>,
+    environments: BTreeMap<PathBuf, Arc<Rkv>>,
 }
 
 impl Manager {
@@ -73,7 +73,7 @@ impl Manager {
     }
 
     /// Return the open env at `path`, returning `None` if it has not already been opened.
-    pub fn get<'p, P>(&self, path: P) -> Result<Option<Arc<RwLock<Rkv>>>, ::std::io::Error>
+    pub fn get<'p, P>(&self, path: P) -> Result<Option<Arc<Rkv>>, ::std::io::Error>
     where
         P: Into<&'p Path>,
     {
@@ -82,7 +82,7 @@ impl Manager {
     }
 
     /// Return the open env at `path`, or create it by calling `f`.
-    pub fn get_or_create<'p, F, P>(&mut self, path: P, f: F) -> Result<Arc<RwLock<Rkv>>, StoreError>
+    pub fn get_or_create<'p, F, P>(&mut self, path: P, f: F) -> Result<Arc<Rkv>, StoreError>
     where
         F: FnOnce(&Path) -> Result<Rkv, StoreError>,
         P: Into<&'p Path>,
@@ -91,7 +91,7 @@ impl Manager {
         Ok(match self.environments.entry(canonical) {
             Entry::Occupied(e) => e.get().clone(),
             Entry::Vacant(e) => {
-                let k = Arc::new(RwLock::new(f(e.key().as_path())?));
+                let k = Arc::new(f(e.key().as_path())?);
                 e.insert(k).clone()
             },
         })
@@ -104,7 +104,7 @@ impl Manager {
         path: P,
         capacity: c_uint,
         f: F,
-    ) -> Result<Arc<RwLock<Rkv>>, StoreError>
+    ) -> Result<Arc<Rkv>, StoreError>
     where
         F: FnOnce(&Path, c_uint) -> Result<Rkv, StoreError>,
         P: Into<&'p Path>,
@@ -113,7 +113,7 @@ impl Manager {
         Ok(match self.environments.entry(canonical) {
             Entry::Occupied(e) => e.get().clone(),
             Entry::Vacant(e) => {
-                let k = Arc::new(RwLock::new(f(e.key().as_path(), capacity)?));
+                let k = Arc::new(f(e.key().as_path(), capacity)?);
                 e.insert(k).clone()
             },
         })