HackStudio: Add a widget showing the state of console's running process

We now have a little widget that sits above the terminal view in the
build/application console. When a child process is running, we show its
PID, name, scheduling counter, and amount of resident memory in a live
little overview.

This is not working right just yet, since we don't know how to get to
the actually active PID on the TTY. Or, well, we find the active PID by
looking at the PGID of our fork()ed child.

This manages to find children spawned by Shell, but not children
spawned by make, for instance. I need to figure out how to find those.

DevTools/HackStudio/Makefile

@@ -5,6 +5,7 @@ OBJS = \
     TextDocument.o \
     TerminalWrapper.o \
     FindInFilesWidget.o \
+    ProcessStateWidget.o \
     main.o
 
 APP = HackStudio

DevTools/HackStudio/ProcessStateWidget.cpp

@@ -0,0 +1,71 @@
+#include "ProcessStateWidget.h"
+#include <LibCore/CProcessStatisticsReader.h>
+#include <LibCore/CTimer.h>
+#include <LibGUI/GBoxLayout.h>
+#include <LibGUI/GLabel.h>
+
+ProcessStateWidget::ProcessStateWidget(GWidget* parent)
+    : GWidget(parent)
+{
+    set_size_policy(SizePolicy::Fill, SizePolicy::Fixed);
+    set_preferred_size(0, 20);
+
+    set_layout(make<GBoxLayout>(Orientation::Horizontal));
+
+    auto pid_label_label = GLabel::construct("Process:", this);
+    pid_label_label->set_font(Font::default_bold_font());
+    m_pid_label = GLabel::construct("", this);
+
+    auto state_label_label = GLabel::construct("State:", this);
+    state_label_label->set_font(Font::default_bold_font());
+    m_state_label = GLabel::construct("", this);
+
+    // FIXME: This should show CPU% instead.
+    auto cpu_label_label = GLabel::construct("Times scheduled:", this);
+    cpu_label_label->set_font(Font::default_bold_font());
+    m_cpu_label = GLabel::construct("", this);
+
+    auto memory_label_label = GLabel::construct("Memory (resident):", this);
+    memory_label_label->set_font(Font::default_bold_font());
+    m_memory_label = GLabel::construct("", this);
+
+    m_timer = CTimer::construct(500, [this] {
+        refresh();
+    });
+}
+
+ProcessStateWidget::~ProcessStateWidget()
+{
+}
+
+void ProcessStateWidget::refresh()
+{
+    if (m_pid == -1) {
+        m_pid_label->set_text("(none)");
+        m_state_label->set_text("n/a");
+        m_cpu_label->set_text("n/a");
+        m_memory_label->set_text("n/a");
+        return;
+    }
+
+    auto processes = CProcessStatisticsReader::get_all();
+    auto child_process_data = processes.get(m_pid);
+
+    if (!child_process_data.has_value())
+        return;
+
+    auto active_process_data = processes.get(child_process_data.value().pgid);
+
+    auto& data = active_process_data.value();
+
+    m_pid_label->set_text(String::format("%s(%d)", data.name.characters(), m_pid));
+    m_state_label->set_text(data.state);
+    m_cpu_label->set_text(String::format("%d", data.times_scheduled));
+    m_memory_label->set_text(String::format("%d", data.amount_resident));
+}
+
+void ProcessStateWidget::set_pid(pid_t pid)
+{
+    m_pid = pid;
+    refresh();
+}

DevTools/HackStudio/ProcessStateWidget.h

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <LibGUI/GWidget.h>
+
+class CTimer;
+class GLabel;
+
+class ProcessStateWidget final : public GWidget {
+    C_OBJECT(ProcessStateWidget)
+public:
+    virtual ~ProcessStateWidget() override;
+
+    void set_pid(pid_t);
+
+private:
+    explicit ProcessStateWidget(GWidget* parent);
+
+    void refresh();
+
+    RefPtr<GLabel> m_pid_label;
+    RefPtr<GLabel> m_state_label;
+    RefPtr<GLabel> m_cpu_label;
+    RefPtr<GLabel> m_memory_label;
+
+    RefPtr<CTimer> m_timer;
+
+    pid_t m_pid { -1 };
+};

DevTools/HackStudio/TerminalWrapper.cpp

@@ -1,4 +1,5 @@
 #include "TerminalWrapper.h"
+#include "ProcessStateWidget.h"
 #include <AK/String.h>
 #include <LibCore/CConfigFile.h>
 #include <LibGUI/GBoxLayout.h>
@@ -44,6 +45,7 @@ void TerminalWrapper::run_command(const String& command)
         } else if (WIFSIGNALED(wstatus)) {
             m_terminal_widget->inject_string(String::format("\033[34;1m(Command signaled with %s!)\033[0m\n", strsignal(WTERMSIG(wstatus))));
         }
+        m_process_state_widget->set_pid(-1);
         m_pid = -1;
     };
 
@@ -106,6 +108,9 @@ void TerminalWrapper::run_command(const String& command)
         }
         ASSERT_NOT_REACHED();
     }
+
+    // Parent process, cont'd.
+    m_process_state_widget->set_pid(m_pid);
 }
 
 TerminalWrapper::TerminalWrapper(GWidget* parent)
@@ -113,6 +118,8 @@ TerminalWrapper::TerminalWrapper(GWidget* parent)
 {
     set_layout(make<GBoxLayout>(Orientation::Vertical));
 
+    m_process_state_widget = ProcessStateWidget::construct(this);
+
     RefPtr<CConfigFile> config = CConfigFile::get_for_app("Terminal");
     m_terminal_widget = TerminalWidget::construct(-1, false, config);
     add_child(*m_terminal_widget);

DevTools/HackStudio/TerminalWrapper.h

@@ -2,6 +2,7 @@
 
 #include <LibGUI/GWidget.h>
 
+class ProcessStateWidget;
 class TerminalWidget;
 
 class TerminalWrapper final : public GWidget {
@@ -14,6 +15,7 @@ public:
 private:
     explicit TerminalWrapper(GWidget* parent);
 
+    RefPtr<ProcessStateWidget> m_process_state_widget;
     RefPtr<TerminalWidget> m_terminal_widget;
     pid_t m_pid { -1 };
 };