make Manager consumable (#21, r=ncalexan)

Cargo.toml

@@ -14,6 +14,7 @@ backtrace = ["failure/backtrace", "failure/std"]
 [dependencies]
 arrayref = "0.3"
 bincode = "0.9"
+lazy_static = "1.0"
 lmdb = "0.7"
 ordered-float = "0.5"
 uuid = "0.5"

src/lib.rs

@@ -12,6 +12,7 @@
 
 #[macro_use] extern crate arrayref;
 #[macro_use] extern crate failure;
+#[macro_use] extern crate lazy_static;
 
 extern crate bincode;
 extern crate lmdb;
@@ -48,7 +49,7 @@ pub use integer::{
 };
 
 pub use manager::{
-    Manager,
+    Manager
 };
 
 pub use readwrite::{

src/manager.rs

@@ -27,7 +27,6 @@ use std::path::{
 
 use std::sync::{
     Arc,
-    Mutex,
     RwLock,
 };
 
@@ -39,22 +38,32 @@ use ::Rkv;
 
 /// A process is only permitted to have one open handle to each database. This manager
 /// exists to enforce that constraint: don't open databases directly.
+lazy_static! {
+    static ref MANAGER: RwLock<Manager> = {
+        RwLock::new(Manager::new())
+    };
+}
+
 pub struct Manager {
-    stores: Mutex<BTreeMap<PathBuf, Arc<RwLock<Rkv>>>>,
+    stores: BTreeMap<PathBuf, Arc<RwLock<Rkv>>>,
 }
 
 impl Manager {
     fn new() -> Manager {
         Manager {
-            stores: Mutex::new(Default::default()),
+            stores: Default::default(),
         }
     }
 
+    pub fn singleton() -> &'static RwLock<Manager> {
+        &*MANAGER
+    }
+
     /// Return the open store 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>
     where P: Into<&'p Path> {
         let canonical = path.into().canonicalize()?;
-        Ok(self.stores.lock().unwrap().get(&canonical).cloned())
+        Ok(self.stores.get(&canonical).cloned())
     }
 
     /// Return the open store at `path`, or create it by calling `f`.
@@ -62,8 +71,7 @@ impl Manager {
     where F: FnOnce(&Path) -> Result<Rkv, StoreError>,
           P: Into<&'p Path> {
         let canonical = path.into().canonicalize()?;
-        let mut map = self.stores.lock().unwrap();
-        Ok(match map.entry(canonical) {
+        Ok(match self.stores.entry(canonical) {
             Entry::Occupied(e) => e.get().clone(),
             Entry::Vacant(e) => {
                 let k = Arc::new(RwLock::new(f(e.key().as_path())?));
@@ -78,8 +86,7 @@ impl Manager {
     where F: FnOnce(&Path, c_uint) -> Result<Rkv, StoreError>,
           P: Into<&'p Path> {
         let canonical = path.into().canonicalize()?;
-        let mut map = self.stores.lock().unwrap();
-        Ok(match map.entry(canonical) {
+        Ok(match self.stores.entry(canonical) {
             Entry::Occupied(e) => e.get().clone(),
             Entry::Vacant(e) => {
                 let k = Arc::new(RwLock::new(f(e.key().as_path(), capacity)?));

tests/manager.rs

@@ -0,0 +1,40 @@
+// Copyright 2018 Mozilla
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
+// this file except in compliance with the License. You may obtain a copy of the
+// License at http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software distributed
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations under the License.
+
+extern crate rkv;
+extern crate tempdir;
+
+use rkv::{
+	Manager,
+	Rkv,
+};
+
+use self::tempdir::TempDir;
+
+use std::fs;
+
+use std::sync::{
+    Arc,
+};
+
+#[test]
+// Identical to the same-named unit test, but this one confirms that it works
+// via the public MANAGER singleton.
+fn test_same() {
+    let root = TempDir::new("test_same_singleton").expect("tempdir");
+    fs::create_dir_all(root.path()).expect("dir created");
+
+    let p = root.path();
+    assert!(Manager::singleton().read().unwrap().get(p).expect("success").is_none());
+
+    let created_arc = Manager::singleton().write().unwrap().get_or_create(p, Rkv::new).expect("created");
+    let fetched_arc = Manager::singleton().read().unwrap().get(p).expect("success").expect("existed");
+    assert!(Arc::ptr_eq(&created_arc, &fetched_arc));
+}