ensure only one subprocess is running at a time

bin/simple-apt-update

@@ -60,9 +60,8 @@ class UpdateWindow(Gtk.ApplicationWindow):
         self.buffer.set_text("")
 
     def scroll_to_bottom(self):
-        adj = self.scrolledwindow.get_vadjustment()
+        self.buffer.get_end_iter()
-        adj.set_value(adj.get_upper())
+        self.text_view.scroll_to_mark(self.text_mark_end, 0, False, 0, 0)
-        self.scrolledwindow.set_vadjustment(adj)
 
     def level_to_color(self, level):
         if level == "INFO":
@@ -113,6 +112,25 @@ class UpdateWindow(Gtk.ApplicationWindow):
     def insert(self, text, iter):
         self.buffer.insert(iter, text + "\n")
 
+    def run_thread(self, args, env):
+        if self.thread is None:
+            do_run = True
+        elif not self.thread.is_alive():
+            do_run = True
+        else:
+            do_run = False
+
+        if do_run:
+            self.thread = threading.Thread(
+                target=self.run,
+                args=(args, env,))
+
+            self.thread.start()
+
+            return False
+        else:
+            return True
+
     def execute(
         self,
         args,
@@ -136,11 +154,7 @@ class UpdateWindow(Gtk.ApplicationWindow):
             "INFO",
             "Running command \"%s\" ..." % " ".join(args))
 
-        thread = threading.Thread(
+        GLib.timeout_add(250, self.run_thread, args, env)
-            target=self.run,
-            args=(args, env,))
-
-        thread.start()
 
     def run(self, args, env={}):
         p = subprocess.Popen(
@@ -192,16 +206,15 @@ class UpdateWindow(Gtk.ApplicationWindow):
             env=env,
             empty_msg="No package upgrades were performed.")
 
-    def on_upgrade(self, *args):
-        self.upgrade()
-
     def update(self, clear=True):
         args = ['/usr/bin/apt-get', '-y', 'update']
         env = {'DEBIAN_FRONTEND': 'noninteractive'}
-        self.execute(args, env=env, clear=clear)
+        self.execute(
-
+            args,
-    def on_update(self, *args):
+            env=env,
-        self.update()
+            clear=clear,
+            output_msg="The package cache was refreshed."
+        )
 
     def list(self, clear=True):
         args = ['/usr/bin/apt', '-qq', 'list', '--upgradable']
@@ -210,7 +223,14 @@ class UpdateWindow(Gtk.ApplicationWindow):
             ignore_stderr=True,
             clear=clear,
             output_msg="Found the following package upgrades:",
-            empty_msg="No package upgrades found.")
+            empty_msg="No package upgrades found."
+        )
+
+    def on_update(self, *args):
+        self.update()
+
+    def on_upgrade(self, *args):
+        self.upgrade()
 
     def on_list(self, *args):
         self.list()
@@ -228,15 +248,17 @@ class UpdateWindow(Gtk.ApplicationWindow):
                 self.append_mesg("STDOUT", text)
             else:
                 exit_code = int(match.group(1))
+                self.thread.join()
 
                 if exit_code != 0:
                     self.append_mesg(
                         "ERROR",
-                        "Command exited with code %d" % exit_code)
+                        "Command exited with code %d" % exit_code
+                    )
                 elif self.stdout == '' and self.empty_msg is not None:
                     self.append_mesg("INFO", self.empty_msg)
                 elif self.stdout != '' and self.output_msg is not None:
-                    self.append_mesg("INFO", self.empty_msg)
+                    self.append_mesg("INFO", self.output_msg)
 
                 self.unlock()
 
@@ -265,6 +287,7 @@ class UpdateWindow(Gtk.ApplicationWindow):
         )
 
         self.application = application
+        self.thread = None
         self.stdout_queue = queue.Queue()
         self.stderr_queue = queue.Queue()
 
@@ -327,12 +350,16 @@ class UpdateWindow(Gtk.ApplicationWindow):
         self.scrolledwindow.set_max_content_height(300)
         self.buffer = Gtk.TextBuffer()
 
-        text_view = Gtk.TextView(buffer=self.buffer)
+        self.text_view = Gtk.TextView(buffer=self.buffer)
-        text_view.set_editable(False)
+        self.text_view.set_editable(False)
-        text_view.set_monospace(True)
+        self.text_view.set_monospace(True)
-        text_view.set_cursor_visible(False)
+        self.text_view.set_cursor_visible(False)
 
-        self.scrolledwindow.add(text_view)
+        text_buffer = self.text_view.get_buffer()
+        iter = text_buffer.get_end_iter()
+        self.text_mark_end = text_buffer.create_mark("", iter, False)
+
+        self.scrolledwindow.add(self.text_view)
         hbox.pack_start(self.scrolledwindow, True, True, 0)
 
 
@@ -350,9 +377,6 @@ class SimpleAptUpdate(Gtk.Application):
 
         signal.signal(signal.SIGINT, signal.SIG_DFL)
 
-    def do_command_line(self, cmdline):
-        pass
-
     def on_activate(self, application):
         self.window = UpdateWindow(application)
 
@@ -381,7 +405,6 @@ class SimpleAptUpdate(Gtk.Application):
 
         self.window.present()
         self.window.show_all()
-        self.window.update()
         self.window.list(clear=False)
 
 

res/icons/simple-apt-update.svg

@@ -7,19 +7,14 @@
    xmlns:svg="http://www.w3.org/2000/svg"
    xmlns="http://www.w3.org/2000/svg"
    xmlns:xlink="http://www.w3.org/1999/xlink"
-   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
-   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
    width="31.72216mm"
    height="36.307823mm"
    viewBox="0 0 31.72216 36.307823"
    version="1.1"
-   id="svg8"
+   id="svg8">
-   inkscape:version="1.0.2 (e86c870879, 2021-01-15)"
-   sodipodi:docname="simple-apt-update.svg">
   <defs
      id="defs2">
     <linearGradient
-       inkscape:collect="always"
        id="linearGradient4117">
       <stop
          style="stop-color:#000000;stop-opacity:1;"
@@ -55,7 +50,6 @@
          id="stop4093" />
     </linearGradient>
     <linearGradient
-       inkscape:collect="always"
        id="linearGradient1878"
        osb:paint="gradient">
       <stop
@@ -72,24 +66,14 @@
        id="Arrow2Lend"
        refX="0"
        refY="0"
-       orient="auto"
+       orient="auto">
-       inkscape:stockid="Arrow2Lend"
-       inkscape:isstock="true">
       <path
          transform="matrix(-1.1,0,0,-1.1,-1.1,0)"
          d="M 8.7185878,4.0337352 -2.2072895,0.01601326 8.7185884,-4.0017078 c -1.7454984,2.3720609 -1.7354408,5.6174519 -6e-7,8.035443 z"
          style="fill:#000000;fill-opacity:1;fill-rule:evenodd;stroke:#000000;stroke-width:0.625;stroke-linejoin:round;stroke-opacity:1"
          id="path892" />
     </marker>
-    <inkscape:perspective
-       sodipodi:type="inkscape:persp3d"
-       inkscape:vp_x="177.41502 : 38.534923 : 1"
-       inkscape:vp_y="57.01026 : -606.09557 : 0"
-       inkscape:vp_z="-849.50931 : -58.059119 : 1"
-       inkscape:persp3d-origin="-338.86915 : 20.239614 : 1"
-       id="perspective833" />
     <linearGradient
-       inkscape:collect="always"
        xlink:href="#linearGradient4095"
        id="linearGradient4087"
        x1="41.938935"
@@ -98,7 +82,6 @@
        y2="60.562257"
        gradientUnits="userSpaceOnUse" />
     <linearGradient
-       inkscape:collect="always"
        xlink:href="#linearGradient4095"
        id="linearGradient4089"
        x1="22.932867"
@@ -107,7 +90,6 @@
        y2="48.843493"
        gradientUnits="userSpaceOnUse" />
     <linearGradient
-       inkscape:collect="always"
        xlink:href="#linearGradient4095"
        id="linearGradient4097"
        gradientUnits="userSpaceOnUse"
@@ -116,7 +98,6 @@
        x2="51.607597"
        y2="48.390368" />
     <linearGradient
-       inkscape:collect="always"
        xlink:href="#linearGradient4117"
        id="linearGradient4121"
        x1="22.932867"
@@ -125,7 +106,6 @@
        y2="48.843493"
        gradientUnits="userSpaceOnUse" />
     <linearGradient
-       inkscape:collect="always"
        xlink:href="#linearGradient4117"
        id="linearGradient4123"
        x1="19.885436"
@@ -134,29 +114,6 @@
        y2="48.390368"
        gradientUnits="userSpaceOnUse" />
   </defs>
-  <sodipodi:namedview
-     id="base"
-     pagecolor="#ffffff"
-     bordercolor="#666666"
-     borderopacity="1.0"
-     inkscape:pageopacity="0.0"
-     inkscape:pageshadow="2"
-     inkscape:zoom="3.959798"
-     inkscape:cx="81.30198"
-     inkscape:cy="102.74857"
-     inkscape:document-units="mm"
-     inkscape:current-layer="layer1"
-     inkscape:document-rotation="0"
-     showgrid="false"
-     inkscape:window-width="1885"
-     inkscape:window-height="1236"
-     inkscape:window-x="2101"
-     inkscape:window-y="111"
-     inkscape:window-maximized="0"
-     fit-margin-top="0"
-     fit-margin-left="0"
-     fit-margin-right="0"
-     fit-margin-bottom="0" />
   <metadata
      id="metadata5">
     <rdf:RDF>
@@ -170,8 +127,6 @@
     </rdf:RDF>
   </metadata>
   <g
-     inkscape:label="Layer 1"
-     inkscape:groupmode="layer"
      id="layer1"
      transform="translate(-19.885436,-34.013894)">
     <rect
@@ -181,18 +136,14 @@
        height="27.752951"
        x="20.385435"
        y="34.513893"
-       ry="2.9184699"
+       ry="2.9184699" />
-       inkscape:transform-center-x="13.051673"
-       inkscape:transform-center-y="11.996269" />
     <path
        style="fill:url(#linearGradient4121);stroke:url(#linearGradient4089);stroke-width:3.765;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1;fill-opacity:1"
        d="m 24.815338,34.950563 c 0.145105,26.252732 17.704313,25.913942 17.704313,25.913942"
-       id="path1321"
+       id="path1321" />
-       sodipodi:nodetypes="cc" />
     <path
        style="fill:#bebebe;fill-opacity:1;stroke:url(#linearGradient4087);stroke-width:0.264583px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1"
        d="m 42.10017,59.891406 -0.02493,-8.714785 8.491092,10.446869 -8.494225,8.380984 z"
-       id="path1869"
+       id="path1869" />
-       sodipodi:nodetypes="ccccc" />
   </g>
 </svg>