Lock on KV + FST databases acquire()

This prevents two disk references to the same database to be open at the same time while 2 threads are concurring.

Signed-off-by: Valerian Saliou <valerian@valeriansaliou.name>

src/store/fst.rs

@@ -77,6 +77,7 @@ static LOOKUP_REGEX_RANGE_LATIN: &'static str = "[\\x{0000}-\\x{024F}]";
 
 lazy_static! {
     pub static ref GRAPH_ACCESS_LOCK: Arc<RwLock<bool>> = Arc::new(RwLock::new(false));
+    static ref GRAPH_ACQUIRE_LOCK: Arc<Mutex<bool>> = Arc::new(Mutex::new(false));
     static ref GRAPH_REBUILD_LOCK: Arc<Mutex<bool>> = Arc::new(Mutex::new(false));
     static ref GRAPH_POOL: Arc<RwLock<HashMap<StoreFSTKey, StoreFSTBox>>> =
         Arc::new(RwLock::new(HashMap::new()));
@@ -99,6 +100,10 @@ impl StoreFSTPool {
 
         let pool_key = StoreFSTKey::from_str(collection_str, bucket_str);
 
+        // Freeze acquire lock, and reference it in context
+        // Notice: this prevents two graphs on the same collection to be opened at the same time.
+        let _acquire = GRAPH_ACQUIRE_LOCK.lock().unwrap();
+
         // Acquire a thread-safe store pool reference in read mode
         let graph_pool_read = GRAPH_POOL.read().unwrap();
 

src/store/kv.rs

@@ -13,7 +13,7 @@ use std::fmt;
 use std::fs;
 use std::io::Cursor;
 use std::path::PathBuf;
-use std::sync::{Arc, RwLock};
+use std::sync::{Arc, Mutex, RwLock};
 use std::time::SystemTime;
 use std::vec::Drain;
 
@@ -57,6 +57,7 @@ type StoreKVBox = Arc<StoreKV>;
 
 lazy_static! {
     pub static ref STORE_ACCESS_LOCK: Arc<RwLock<bool>> = Arc::new(RwLock::new(false));
+    static ref STORE_ACQUIRE_LOCK: Arc<Mutex<bool>> = Arc::new(Mutex::new(false));
     static ref STORE_POOL: Arc<RwLock<HashMap<StoreKVKey, StoreKVBox>>> =
         Arc::new(RwLock::new(HashMap::new()));
 }
@@ -69,6 +70,10 @@ impl StoreKVPool {
         let collection_str = collection.into();
         let pool_key = StoreKVKey::from_str(collection_str);
 
+        // Freeze acquire lock, and reference it in context
+        // Notice: this prevents two databases on the same collection to be opened at the same time.
+        let _acquire = STORE_ACQUIRE_LOCK.lock().unwrap();
+
         // Acquire a thread-safe store pool reference in read mode
         let store_pool_read = STORE_POOL.read().unwrap();