Create utils.py

patches/background_task/utils.py

@@ -0,0 +1,36 @@
+# -*- coding: utf-8 -*-
+import signal
+import platform
+
+TTW_SLOW = [0.5, 1.5]
+TTW_FAST = [0.0, 0.1]
+
+
+class SignalManager():
+    """Manages POSIX signals."""
+
+    kill_now = False
+    time_to_wait = TTW_SLOW
+
+    def __init__(self):
+        signal.signal(signal.SIGINT, self.exit_gracefully)
+        # On Windows, signal() can only be called with:
+        # SIGABRT, SIGFPE, SIGILL, SIGINT, SIGSEGV, SIGTERM, or SIGBREAK.
+        if platform.system() == 'Windows':
+            signal.signal(signal.SIGBREAK, self.exit_gracefully)
+        else:
+            signal.signal(signal.SIGHUP, self.exit_gracefully)
+            signal.signal(signal.SIGUSR1, self.speed_up)
+            signal.signal(signal.SIGUSR2, self.slow_down)
+
+    def exit_gracefully(self, signum, frame):
+        self.kill_now = True
+        # Using interrupt again should raise
+        # a KeyboardInterrupt exception.
+        signal.signal(signal.SIGINT, signal.SIG_DFL)
+
+    def speed_up(self, signum, frame):
+        self.time_to_wait = TTW_FAST
+
+    def slow_down(self, signum, frame):
+        self.time_to_wait = TTW_SLOW