SystemMonitor: Unbreak the memory stats graph

It was never updating because we'd just seek the start of /proc/memstat
over and over, which didn't generate new contents. Instead, open the
file on every iteration.

Applications/SystemMonitor/MemoryStatsWidget.cpp

@@ -1,6 +1,7 @@
 #include "MemoryStatsWidget.h"
 #include "GraphWidget.h"
 #include <AK/JsonObject.h>
+#include <LibCore/CFile.h>
 #include <LibDraw/StylePainter.h>
 #include <LibGUI/GBoxLayout.h>
 #include <LibGUI/GLabel.h>
@@ -18,13 +19,10 @@ MemoryStatsWidget* MemoryStatsWidget::the()
 MemoryStatsWidget::MemoryStatsWidget(GraphWidget& graph, GWidget* parent)
  : GWidget(parent)
  , m_graph(graph)
- , m_proc_memstat(CFile::construct("/proc/memstat"))
 {
  ASSERT(!s_the);
  s_the = this;
 
- if (!m_proc_memstat->open(CIODevice::OpenMode::ReadOnly))
- ASSERT_NOT_REACHED();
  set_size_policy(SizePolicy::Fill, SizePolicy::Fixed);
  set_preferred_size(0, 72);
 
@@ -69,9 +67,11 @@ static inline size_t bytes_to_kb(size_t bytes)
 
 void MemoryStatsWidget::refresh()
 {
- m_proc_memstat->seek(0);
+ auto proc_memstat = CFile::construct("/proc/memstat");
+ if (!proc_memstat->open(CIODevice::OpenMode::ReadOnly))
+ ASSERT_NOT_REACHED();
 
- auto file_contents = m_proc_memstat->read_all();
+ auto file_contents = proc_memstat->read_all();
  auto json = JsonValue::from_string(file_contents).as_object();
 
  unsigned kmalloc_eternal_allocated = json.get("kmalloc_eternal_allocated").to_u32();
@@ -97,8 +97,3 @@ void MemoryStatsWidget::refresh()
  m_graph.set_max(page_count_to_kb(user_pages_available));
  m_graph.add_value(page_count_to_kb(user_physical_allocated));
 }
-
-void MemoryStatsWidget::timer_event(CTimerEvent&)
-{
- refresh();
-}

Applications/SystemMonitor/MemoryStatsWidget.h

@@ -1,6 +1,5 @@
 #pragma once
 
-#include <LibCore/CFile.h>
 #include <LibGUI/GWidget.h>
 
 class GLabel;
@@ -18,12 +17,9 @@ class MemoryStatsWidget final : public GWidget {
 private:
  MemoryStatsWidget(GraphWidget& graph, GWidget* parent);
 
- virtual void timer_event(CTimerEvent&) override;
-
  GraphWidget& m_graph;
  RefPtr<GLabel> m_user_physical_pages_label;
  RefPtr<GLabel> m_supervisor_physical_pages_label;
  RefPtr<GLabel> m_kmalloc_label;
  RefPtr<GLabel> m_kmalloc_count_label;
- RefPtr<CFile> m_proc_memstat;
 };