implement memory pool for bookmark index

src/profile/bookmark/memory.rs

@@ -0,0 +1,38 @@
+use gtk::glib::DateTime;
+use std::{cell::RefCell, collections::HashMap};
+
+/// Reduce disk usage by cache results in memory
+pub struct Memory {
+    index: RefCell<HashMap<String, DateTime>>,
+}
+
+impl Memory {
+    // Constructors
+
+    pub fn new() -> Self {
+        Self {
+            index: RefCell::new(HashMap::new()),
+        }
+    }
+
+    // Actions
+
+    /// Set new record
+    /// * replace existing record with new value
+    pub fn set(&self, request: String, time: DateTime) {
+        // Borrow index to update
+        let mut index = self.index.borrow_mut();
+
+        // Cleanup previous record
+        if index.get(&request).is_some() {
+            index.remove(&request);
+        }
+
+        // Insert new record with actual data
+        index.insert(request, time);
+    }
+
+    pub fn is_exist(&self, request: &str) -> bool {
+        self.index.borrow().get(request).is_some()
+    }
+}