implement recently visited memory index, add new global menu section

src/profile/history/memory/request.rs

@@ -0,0 +1,60 @@
+use gtk::glib::GString;
+use itertools::Itertools;
+use std::{cell::RefCell, collections::HashMap};
+
+pub struct Value {
+    pub unix_timestamp: i64,
+}
+
+/// Recent request history
+pub struct Request {
+    index: RefCell<HashMap<GString, Value>>,
+}
+
+impl Default for Request {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl Request {
+    // Constructors
+
+    /// Create new `Self`
+    pub fn new() -> Self {
+        Self {
+            index: RefCell::new(HashMap::new()),
+        }
+    }
+
+    // Actions
+
+    /// Add new record with `request` as key and `unix_timestamp` as value
+    /// * replace with new value if `request` already exists
+    pub fn set(&self, request: GString, unix_timestamp: i64) {
+        self.index
+            .borrow_mut()
+            .insert(request, Value { unix_timestamp });
+    }
+
+    /// Get recent requests vector
+    /// * sorted by `unix_timestamp` DESC
+    pub fn recent(&self, limit: usize) -> Vec<GString> {
+        let mut recent: Vec<GString> = Vec::new();
+        for (request, _) in self
+            .index
+            .borrow()
+            .iter()
+            .sorted_by(|a, b| Ord::cmp(&b.1.unix_timestamp, &a.1.unix_timestamp))
+            .take(limit)
+        {
+            recent.push(request.clone())
+        }
+        recent
+    }
+
+    /// Get records total
+    pub fn total(&self) -> usize {
+        self.index.borrow().len()
+    }
+}