diff --git a/src/core/directory.rs b/src/core/directory.rs
index 53607e0aa..3caa90fa1 100644
--- a/src/core/directory.rs
+++ b/src/core/directory.rs
@@ -6,12 +6,15 @@ use std::collections::HashMap;
 use std::fs::File;
 use std::io;
 use std::rc::Rc;
+use std::ops::Deref;
+use std::cell::RefCell;
+use std::sync::Arc;
 
 #[derive(Clone, Debug)]
 pub struct SegmentId(String);
 
 pub trait Dir {
-    fn get_file<'a>(&'a self, segment_id: &SegmentId, component: SegmentComponent) -> Result<&'a MemoryPointer, io::Error>; // {
+    fn get_data(&self, segment_id: &SegmentId, component: SegmentComponent) -> Result<SharedMmapMemory, io::Error>; // {
 }
 
 #[derive(Clone)]
@@ -44,8 +47,8 @@ impl Directory {
 }
 
 impl Dir for Directory {
-    fn get_file<'a>(&'a self, segment_id: &SegmentId, component: SegmentComponent) -> Result<&'a MemoryPointer, io::Error> {
-        self.dir.get_file(segment_id, component)
+    fn get_data(&self, segment_id: &SegmentId, component: SegmentComponent) -> Result<SharedMmapMemory, io::Error> {
+        self.dir.get_data(segment_id, component)
     }
 }
 
@@ -67,34 +70,13 @@ impl Segment {
         }
     }
 
-    fn get_file<'a>(&'a self, component: SegmentComponent) -> Result<&'a MemoryPointer, io::Error> {
-        self.directory.get_file(&self.segment_id, component)
+    fn get_data(&self, component: SegmentComponent) -> Result<SharedMmapMemory, io::Error> {
+        self.directory.get_data(&self.segment_id, component)
     }
 }
 
 
 
-
-
-
-//////////////////////////////////////////////////////////
-//  FileDirectory
-
-pub struct FileDirectory {
-    index_path: PathBuf,
-}
-
-impl FileDirectory {
-    pub fn for_path(path: PathBuf)-> FileDirectory {
-        FileDirectory {
-            index_path: path,
-        }
-    }
-}
-
-
-
-
 /////////////////////////////////////////////////////////
 //  MemoryPointer
 
@@ -121,12 +103,13 @@ impl MemoryPointer for ResidentMemoryPointer {
 }
 
 
+
 /////////////////////////////////////////////////////////
 //
 //
 
 
-struct MmapMemory(Mmap);
+pub struct MmapMemory(Mmap);
 
 impl MemoryPointer for MmapMemory {
     fn len(&self) -> usize {
@@ -139,18 +122,51 @@ impl MemoryPointer for MmapMemory {
     }
 }
 
+#[derive(Clone)]
+pub struct SharedMmapMemory(Arc<MmapMemory>);
+
+impl SharedMmapMemory {
+    pub fn new(mmap_memory: MmapMemory) -> SharedMmapMemory {
+        SharedMmapMemory(Arc::new(mmap_memory))
+    }
+}
+
+//////////////////////////////////////////////////////////
+//  FileDirectory
+
+pub struct FileDirectory {
+    index_path: PathBuf,
+    mmap_cache: RefCell<HashMap<PathBuf, SharedMmapMemory >>,
+}
+
+impl FileDirectory {
+    pub fn for_path(path: PathBuf)-> FileDirectory {
+        FileDirectory {
+            index_path: path,
+            mmap_cache: RefCell::new(HashMap::new()),
+        }
+    }
+
+    fn get_or_open_mmap(&self, filepath: &PathBuf)->Result<SharedMmapMemory, io::Error> {
+        if !self.mmap_cache.borrow().contains_key(filepath) {
+            let file = try!(File::open(filepath));
+            let mmap = MmapMemory(try!(Mmap::open(&file, Protection::Read)));
+            self.mmap_cache.borrow_mut().insert(filepath.clone(), SharedMmapMemory::new(mmap));
+        }
+        let shared_map: SharedMmapMemory = self.mmap_cache.borrow().get(filepath).unwrap().clone();
+        Ok(shared_map)
+    }
+}
+
 impl Dir for FileDirectory {
-    fn get_file<'a>(&'a self, segment_id: &SegmentId, component: SegmentComponent) -> Result<&'a MemoryPointer, io::Error> {
-        let mut res = self.index_path.clone();
+    fn get_data(&self, segment_id: &SegmentId, component: SegmentComponent) -> Result<SharedMmapMemory, io::Error> {
+        let mut filepath = self.index_path.clone();
         let SegmentId(ref segment_id_str) = *segment_id;
         let filename = String::new() + segment_id_str + "." + Segment::path_suffix(component);
-        res.push(filename);
-        let file = try!(File::open(res));
-        let mmap = MmapMemory(try!(Mmap::open(&file, Protection::Read)));
-        // let boxed_mmap: Box<MemoryPointer> = Box::new(mmap);
-        // Ok(boxed_mmap)
-        Err(io::Error::new(io::ErrorKind::AddrInUse, "eee"))
+        filepath.push(filename);
+        self.get_or_open_mmap(&filepath)
     }
+
 }
 
 //////////////////////////////////////////////////////////
@@ -158,7 +174,7 @@ impl Dir for FileDirectory {
 //
 
 pub struct MemDirectory {
-    dir: HashMap<PathBuf, Box<MemoryPointer>>,
+    dir: HashMap<PathBuf, SharedMmapMemory>,
 }
 
 impl MemDirectory {
@@ -170,14 +186,12 @@ impl MemDirectory {
 }
 
 impl Dir for MemDirectory {
-    fn get_file<'a>(&'a self, segment_id: &SegmentId, component: SegmentComponent) -> Result<&'a MemoryPointer, io::Error> {
+    fn get_data(&self, segment_id: &SegmentId, component: SegmentComponent) -> Result<SharedMmapMemory, io::Error> {
         let SegmentId(ref segment_id_str) = *segment_id;
         let mut path = PathBuf::from(segment_id_str);
         path.push(Segment::path_suffix(component));
         match self.dir.get(&path) {
-            Some(buf) => {
-                Ok(buf.as_ref())
-            },
+            Some(buf) => Ok(buf.clone()),
             None => Err(io::Error::new(io::ErrorKind::NotFound, "File does not exists")),
         }
     }