ProfileViewer: Add mode that shows percentages instead of sample counts

Sometimes it's much nicer to work with percentages than raw sample
counts when browsing through a profile. :^)

DevTools/ProfileViewer/Profile.cpp

@@ -69,6 +69,7 @@ GUI::Model& Profile::model()
 
 void Profile::rebuild_tree()
 {
+    u32 filtered_event_count = 0;
     Vector<NonnullRefPtr<ProfileNode>> roots;
 
     auto find_or_create_root = [&roots](const String& symbol, u32 address, u32 offset, u64 timestamp) -> ProfileNode& {
@@ -146,10 +147,13 @@ void Profile::rebuild_tree()
                 node->increment_self_count();
             return IterationDecision::Continue;
         });
+
+        ++filtered_event_count;
     }
 
     sort_profile_nodes(roots);
 
+    m_filtered_event_count = filtered_event_count;
     m_roots = move(roots);
     m_model->update();
 }
@@ -276,3 +280,10 @@ void Profile::set_inverted(bool inverted)
     m_inverted = inverted;
     rebuild_tree();
 }
+
+void Profile::set_show_percentages(bool show_percentages)
+{
+    if (m_show_percentages == show_percentages)
+        return;
+    m_show_percentages = show_percentages;
+}

DevTools/ProfileViewer/Profile.h

@@ -126,6 +126,8 @@ public:
         Vector<Frame> frames;
     };
 
+    u32 filtered_event_count() const { return m_filtered_event_count; }
+
     const Vector<Event>& events() const { return m_events; }
 
     u64 length_in_ms() const { return m_last_timestamp - m_first_timestamp; }
@@ -140,6 +142,9 @@ public:
     bool is_inverted() const { return m_inverted; }
     void set_inverted(bool);
 
+    bool show_percentages() const { return m_show_percentages; }
+    void set_show_percentages(bool);
+
 private:
     explicit Profile(Vector<Event>);
 
@@ -147,6 +152,7 @@ private:
 
     RefPtr<ProfileModel> m_model;
     Vector<NonnullRefPtr<ProfileNode>> m_roots;
+    u32 m_filtered_event_count { 0 };
     u64 m_first_timestamp { 0 };
     u64 m_last_timestamp { 0 };
 
@@ -158,4 +164,5 @@ private:
 
     u32 m_deepest_stack_depth { 0 };
     bool m_inverted { false };
+    bool m_show_percentages { false };
 };

DevTools/ProfileViewer/ProfileModel.cpp

@@ -97,9 +97,9 @@ String ProfileModel::column_name(int column) const
 {
     switch (column) {
     case Column::SampleCount:
-        return "# Samples";
+        return m_profile.show_percentages() ? "% Samples" : "# Samples";
     case Column::SelfCount:
-        return "# Self";
+        return m_profile.show_percentages() ? "% Self" : "# Self";
     case Column::StackFrame:
         return "Stack Frame";
     default:
@@ -127,10 +127,16 @@ GUI::Variant ProfileModel::data(const GUI::ModelIndex& index, Role role) const
         return {};
     }
     if (role == Role::Display) {
-        if (index.column() == Column::SampleCount)
+        if (index.column() == Column::SampleCount) {
+            if (m_profile.show_percentages())
+                return ((float)node->event_count() / (float)m_profile.filtered_event_count()) * 100.0f;
             return node->event_count();
-        if (index.column() == Column::SelfCount)
+        }
+        if (index.column() == Column::SelfCount) {
+            if (m_profile.show_percentages())
+                return ((float)node->self_count() / (float)m_profile.filtered_event_count()) * 100.0f;
             return node->self_count();
+        }
         if (index.column() == Column::StackFrame)
             return node->symbol();
         return {};

DevTools/ProfileViewer/main.cpp

@@ -84,6 +84,15 @@ int main(int argc, char** argv)
     invert_action->set_checked(false);
     view_menu->add_action(invert_action);
 
+    auto percent_action = GUI::Action::create("Show percentages", { Mod_Ctrl, Key_P }, [&](auto& action) {
+        action.set_checked(!action.is_checked());
+        profile->set_show_percentages(action.is_checked());
+        tree_view->update();
+    });
+    percent_action->set_checkable(true);
+    percent_action->set_checked(false);
+    view_menu->add_action(percent_action);
+
     menubar->add_menu(move(view_menu));
 
     app.set_menubar(move(menubar));