Profiler: Parse and paint profile signpost events :^)

Signposts generated by perf_event(PERF_EVENT_SIGNPOST) now show up in
profile timelines, and if you hover them you get a tooltip with the two
arguments passed with the event.

Userland/DevTools/Profiler/Profile.cpp

@@ -31,9 +31,10 @@ static void sort_profile_nodes(Vector<NonnullRefPtr<ProfileNode>>& nodes)
         child->sort_children();
 }
 
-Profile::Profile(Vector<Process> processes, Vector<Event> events)
+Profile::Profile(Vector<Process> processes, Vector<Event> events, Vector<Event> signposts)
     : m_processes(move(processes))
     , m_events(move(events))
+    , m_signposts(move(signposts))
 {
     m_first_timestamp = m_events.first().timestamp;
     m_last_timestamp = m_events.last().timestamp;
@@ -216,6 +217,7 @@ Result<NonnullOwnPtr<Profile>, String> Profile::load_from_perfcore_file(const St
     NonnullOwnPtrVector<Process> all_processes;
     HashMap<pid_t, Process*> current_processes;
     Vector<Event> events;
+    Vector<Event> signposts;
     EventSerialNumber next_serial;
 
     for (auto& perf_event_value : perf_events.values()) {
@@ -231,11 +233,17 @@ Result<NonnullOwnPtr<Profile>, String> Profile::load_from_perfcore_file(const St
         event.pid = perf_event.get("pid").to_i32();
         event.tid = perf_event.get("tid").to_i32();
 
+        bool is_signpost = false;
+
         if (event.type == "malloc"sv) {
             event.ptr = perf_event.get("ptr").to_number<FlatPtr>();
             event.size = perf_event.get("size").to_number<size_t>();
         } else if (event.type == "free"sv) {
             event.ptr = perf_event.get("ptr").to_number<FlatPtr>();
+        } else if (event.type == "signpost"sv) {
+            is_signpost = true;
+            event.arg1 = perf_event.get("arg1").to_number<FlatPtr>();
+            event.arg2 = perf_event.get("arg2").to_number<FlatPtr>();
         } else if (event.type == "mmap"sv) {
             event.ptr = perf_event.get("ptr").to_number<FlatPtr>();
             event.size = perf_event.get("size").to_number<size_t>();
@@ -343,7 +351,10 @@ Result<NonnullOwnPtr<Profile>, String> Profile::load_from_perfcore_file(const St
         FlatPtr innermost_frame_address = event.frames.at(1).address;
         event.in_kernel = maybe_kernel_base.has_value() && innermost_frame_address >= maybe_kernel_base.value();
 
-        events.append(move(event));
+        if (is_signpost)
+            signposts.append(move(event));
+        else
+            events.append(move(event));
     }
 
     if (events.is_empty())
@@ -360,7 +371,7 @@ Result<NonnullOwnPtr<Profile>, String> Profile::load_from_perfcore_file(const St
     for (auto& it : all_processes)
         processes.append(move(it));
 
-    return adopt_own(*new Profile(move(processes), move(events)));
+    return adopt_own(*new Profile(move(processes), move(events), move(signposts)));
 }
 
 void ProfileNode::sort_children()

Userland/DevTools/Profiler/Profile.h

@@ -176,10 +176,16 @@ public:
         int tid { 0 };
         u32 lost_samples { 0 };
         bool in_kernel { false };
+
+        // FIXME: Put event type-specific arguments in a union to save memory.
+        FlatPtr arg1 {};
+        FlatPtr arg2 {};
+
         Vector<Frame> frames;
     };
 
     const Vector<Event>& events() const { return m_events; }
+    Vector<Event> const& signposts() const { return m_signposts; }
     const Vector<size_t>& filtered_event_indices() const { return m_filtered_event_indices; }
 
     u64 length_in_ms() const { return m_last_timestamp - m_first_timestamp; }
@@ -220,7 +226,7 @@ public:
     }
 
 private:
-    Profile(Vector<Process>, Vector<Event>);
+    Profile(Vector<Process>, Vector<Event> events, Vector<Event> signposts);
 
     void rebuild_tree();
 
@@ -237,6 +243,7 @@ private:
 
     Vector<Process> m_processes;
     Vector<Event> m_events;
+    Vector<Event> m_signposts;
 
     bool m_has_timestamp_filter_range { false };
     u64 m_timestamp_filter_range_start { 0 };

Userland/DevTools/Profiler/TimelineTrack.cpp

@@ -7,6 +7,7 @@
 #include "TimelineTrack.h"
 #include "Profile.h"
 #include "TimelineView.h"
+#include <LibGUI/Application.h>
 #include <LibGUI/Painter.h>
 #include <LibGfx/Palette.h>
 
@@ -61,7 +62,7 @@ void TimelineTrack::paint_event(GUI::PaintEvent& event)
         return min(end_of_trace, max(timestamp, start_of_trace));
     };
 
-    float column_width = (float)frame_inner_rect().width() / (float)m_profile.length_in_ms();
+    float column_width = this->column_width();
     size_t columns = frame_inner_rect().width() / column_width;
 
     recompute_histograms_if_needed({ start_of_trace, end_of_trace, columns });
@@ -97,6 +98,52 @@ void TimelineTrack::paint_event(GUI::PaintEvent& event)
     int select_hover_x = (int)((float)(normalized_hover_time - start_of_trace) * column_width);
     painter.fill_rect({ select_start_x, frame_thickness(), select_end_x - select_start_x, height() - frame_thickness() * 2 }, Color(0, 0, 0, 60));
     painter.fill_rect({ select_hover_x, frame_thickness(), 1, height() - frame_thickness() * 2 }, Color::NamedColor::Black);
+
+    for_each_signpost([&](auto& signpost) {
+        int x = (int)((float)(signpost.timestamp - start_of_trace) * column_width);
+        int y1 = frame_thickness();
+        int y2 = height() - frame_thickness() * 2;
+
+        painter.draw_line({ x, y1 }, { x, y2 }, Color::Magenta);
+
+        return IterationDecision::Continue;
+    });
+}
+
+template<typename Callback>
+void TimelineTrack::for_each_signpost(Callback callback)
+{
+    for (auto& signpost : m_profile.signposts()) {
+        if (signpost.pid != m_process.pid)
+            continue;
+
+        if (!m_process.valid_at(signpost.serial))
+            continue;
+
+        if (callback(signpost) == IterationDecision::Break)
+            break;
+    }
+}
+
+void TimelineTrack::mousemove_event(GUI::MouseEvent& event)
+{
+    auto column_width = this->column_width();
+    bool hovering_a_signpost = false;
+
+    for_each_signpost([&](auto& signpost) {
+        int x = (int)((float)(signpost.timestamp - m_profile.first_timestamp()) * column_width);
+        constexpr int hoverable_padding = 2;
+        Gfx::IntRect hoverable_rect { x - hoverable_padding, frame_thickness(), hoverable_padding * 2, height() - frame_thickness() * 2 };
+        if (hoverable_rect.contains_horizontally(event.x())) {
+            GUI::Application::the()->show_tooltip_immediately(String::formatted("Signpost {}, {}", signpost.arg1, signpost.arg2), this);
+            hovering_a_signpost = true;
+            return IterationDecision::Break;
+        }
+        return IterationDecision::Continue;
+    });
+
+    if (!hovering_a_signpost)
+        GUI::Application::the()->hide_tooltip();
 }
 
 void TimelineTrack::recompute_histograms_if_needed(HistogramInputs const& inputs)
@@ -129,4 +176,9 @@ void TimelineTrack::recompute_histograms_if_needed(HistogramInputs const& inputs
     }
 }
 
+float TimelineTrack::column_width() const
+{
+    return (float)frame_inner_rect().width() / (float)m_profile.length_in_ms();
+}
+
 }

Userland/DevTools/Profiler/TimelineTrack.h

@@ -24,8 +24,14 @@ public:
     void set_scale(float);
 
 private:
+    float column_width() const;
+
+    template<typename Callback>
+    void for_each_signpost(Callback);
+
     virtual void event(Core::Event&) override;
     virtual void paint_event(GUI::PaintEvent&) override;
+    virtual void mousemove_event(GUI::MouseEvent&) override;
 
     struct HistogramInputs {
         bool operator==(HistogramInputs const&) const = default;