[core] Non-blocking input thread for i3bar events

Make input thread non-blocking by using select(). This increases the CPU
utilization a bit (depending on the timeout), but makes the thread exit
cleanly, even if an exception is thrown in the main thread.

see #23

bumblebee/input.py

@@ -4,6 +4,7 @@ import sys
 import json
 import uuid
 import time
+import select
 import threading
 import bumblebee.util
 
@@ -15,6 +16,13 @@ WHEEL_DOWN = 5
 def read_input(inp):
     """Read i3bar input and execute callbacks"""
     while inp.running:
+        for thread in threading.enumerate():
+            if thread.name == "MainThread" and not thread.is_alive():
+                return
+
+        rlist, _, _ = select.select([sys.stdin], [], [], 1)
+        if not rlist:
+            continue
         line = sys.stdin.readline().strip(",").strip()
         inp.has_event = True
         try:

tests/modules/test_cmus.py

@@ -29,9 +29,10 @@ class TestCmusModule(unittest.TestCase):
     def test_widgets(self):
         self.assertTrue(len(self.module.widgets()), 5)
 
+    @mock.patch("select.select")
     @mock.patch("subprocess.Popen")
     @mock.patch("sys.stdin")
-    def test_interaction(self, mock_input, mock_output):
+    def test_interaction(self, mock_input, mock_output, mock_select):
         events = [
             {"widget": "cmus.shuffle", "action": "cmus-remote -S"},
             {"widget": "cmus.repeat", "action": "cmus-remote -R"},
@@ -40,6 +41,8 @@ class TestCmusModule(unittest.TestCase):
             {"widget": "cmus.main", "action": "cmus-remote -u"},
         ]
 
+        mock_select.return_value = (1,2,3)
+
         for event in events:
             mock_input.readline.return_value = json.dumps({
                 "name": self.module.id,

tests/modules/test_cpu.py

@@ -24,14 +24,16 @@ class TestCPUModule(unittest.TestCase):
         for widget in self.module.widgets():
             self.assertEquals(len(widget.full_text()), len("100.00%"))
 
+    @mock.patch("select.select")
     @mock.patch("subprocess.Popen")
     @mock.patch("sys.stdin")
-    def test_leftclick(self, mock_input, mock_output):
+    def test_leftclick(self, mock_input, mock_output, mock_select):
         mock_input.readline.return_value = json.dumps({
             "name": self.module.id,
             "button": bumblebee.input.LEFT_MOUSE,
             "instance": None
         })
+        mock_select.return_value = (1,2,3)
         self.engine.input.start()
         self.engine.input.stop()
         mock_input.readline.assert_any_call()

tests/test_i3barinput.py

@@ -21,23 +21,29 @@ class TestI3BarInput(unittest.TestCase):
     def callback(self, event):
         self._called += 1
 
+    @mock.patch("select.select")
     @mock.patch("sys.stdin")
-    def test_basic_read_event(self, mock_input):
+    def test_basic_read_event(self, mock_input, mock_select):
+        mock_select.return_value = (1,2,3)
         mock_input.readline.return_value = ""
         self.input.start()
         self.input.stop()
         mock_input.readline.assert_any_call()
 
+    @mock.patch("select.select")
     @mock.patch("sys.stdin")
-    def test_ignore_invalid_data(self, mock_input):
+    def test_ignore_invalid_data(self, mock_input, mock_select):
+        mock_select.return_value = (1,2,3)
         mock_input.readline.return_value = "garbage"
         self.input.start()
         self.assertEquals(self.input.alive(), True)
         self.assertEquals(self.input.stop(), True)
         mock_input.readline.assert_any_call()
 
+    @mock.patch("select.select")
     @mock.patch("sys.stdin")
-    def test_ignore_invalid_event(self, mock_input):
+    def test_ignore_invalid_event(self, mock_input, mock_select):
+        mock_select.return_value = (1,2,3)
         mock_input.readline.return_value = json.dumps({
             "name": None,
             "instance": None,
@@ -48,8 +54,10 @@ class TestI3BarInput(unittest.TestCase):
         self.assertEquals(self.input.stop(), True)
         mock_input.readline.assert_any_call()
 
+    @mock.patch("select.select")
     @mock.patch("sys.stdin")
-    def test_global_callback(self, mock_input):
+    def test_global_callback(self, mock_input, mock_select):
+        mock_select.return_value = (1,2,3)
         mock_input.readline.return_value = json.dumps({
             "name": "somename",
             "instance": "someinstance",
@@ -61,8 +69,10 @@ class TestI3BarInput(unittest.TestCase):
         mock_input.readline.assert_any_call()
         self.assertTrue(self._called > 0)
 
+    @mock.patch("select.select")
     @mock.patch("sys.stdin")
-    def test_remove_global_callback(self, mock_input):
+    def test_remove_global_callback(self, mock_input, mock_select):
+        mock_select.return_value = (1,2,3)
         mock_input.readline.return_value = json.dumps({
             "name": "somename",
             "instance": "someinstance",
@@ -75,8 +85,10 @@ class TestI3BarInput(unittest.TestCase):
         mock_input.readline.assert_any_call()
         self.assertTrue(self._called == 0)
 
+    @mock.patch("select.select")
     @mock.patch("sys.stdin")
-    def test_global_callback_button_missmatch(self, mock_input):
+    def test_global_callback_button_missmatch(self, mock_input, mock_select):
+        mock_select.return_value = (1,2,3)
         mock_input.readline.return_value = json.dumps({
             "name": "somename",
             "instance": "someinstance",
@@ -88,8 +100,10 @@ class TestI3BarInput(unittest.TestCase):
         mock_input.readline.assert_any_call()
         self.assertTrue(self._called == 0)
 
+    @mock.patch("select.select")
     @mock.patch("sys.stdin")
-    def test_module_callback(self, mock_input):
+    def test_module_callback(self, mock_input, mock_select):
+        mock_select.return_value = (1,2,3)
         mock_input.readline.return_value = json.dumps({
             "name": self.anyModule.id,
             "instance": None,
@@ -101,8 +115,10 @@ class TestI3BarInput(unittest.TestCase):
         mock_input.readline.assert_any_call()
         self.assertTrue(self._called > 0)
 
+    @mock.patch("select.select")
     @mock.patch("sys.stdin")
-    def test_remove_module_callback(self, mock_input):
+    def test_remove_module_callback(self, mock_input, mock_select):
+        mock_select.return_value = (1,2,3)
         mock_input.readline.return_value = json.dumps({
             "name": self.anyModule.id,
             "instance": None,
@@ -115,8 +131,10 @@ class TestI3BarInput(unittest.TestCase):
         mock_input.readline.assert_any_call()
         self.assertTrue(self._called == 0)
 
+    @mock.patch("select.select")
     @mock.patch("sys.stdin")
-    def test_widget_callback(self, mock_input):
+    def test_widget_callback(self, mock_input, mock_select):
+        mock_select.return_value = (1,2,3)
         mock_input.readline.return_value = json.dumps({
             "name": "test",
             "instance": self.anyWidget.id,
@@ -128,9 +146,11 @@ class TestI3BarInput(unittest.TestCase):
         mock_input.readline.assert_any_call()
         self.assertTrue(self._called > 0)
 
+    @mock.patch("select.select")
     @mock.patch("subprocess.Popen")
     @mock.patch("sys.stdin")
-    def test_widget_cmd_callback(self, mock_input, mock_output):
+    def test_widget_cmd_callback(self, mock_input, mock_output, mock_select):
+        mock_select.return_value = (1,2,3)
         mock_input.readline.return_value = json.dumps({
             "name": "test",
             "instance": self.anyWidget.id,