Merge pull request #266 from tobes/SIGUSR2

Keep alive when i3bar hidden by @tobes and @cornerman

py3status/core.py

@@ -7,7 +7,7 @@
 
 from json import dumps
 from signal import signal
-from signal import SIGTERM, SIGUSR1
+from signal import SIGTERM, SIGUSR1, SIGUSR2, SIGCONT
 from subprocess import Popen
 from subprocess import call
 from threading import Event
@@ -37,6 +37,7 @@ def __init__(self):
         Useful variables we'll need.
         """
         self.config = {}
+        self.i3bar_running = True
         self.last_refresh_ts = time()
         self.lock = Event()
         self.modules = {}
@@ -235,6 +236,14 @@ def setup(self):
         # set the Event lock
         self.lock.set()
 
+        # SIGUSR2 will be recieced from i3bar indicating that all output should
+        # stop and we should consider py3status suspended.  It is however
+        # important that any processes using i3 ipc should continue to recieve
+        # those events otherwise it can lead to a stall in i3.
+        signal(SIGUSR2, self.i3bar_stop)
+        # SIGCONT indicates output should be resumed.
+        signal(SIGCONT, self.i3bar_start)
+
         # setup configuration
         self.config = self.get_config()
 
@@ -473,6 +482,14 @@ def create_output_modules(self):
 
         self.output_modules = output_modules
 
+    def i3bar_stop(self, signum, frame):
+        self.i3bar_running = False
+        # i3status should be stopped
+        self.i3status_thread.suspend_i3status()
+
+    def i3bar_start(self, signum, frame):
+        self.i3bar_running = True
+
     @profile
     def run(self):
         """
@@ -501,6 +518,9 @@ def run(self):
 
         # main loop
         while True:
+            while not self.i3bar_running:
+                sleep(0.1)
+
             sec = int(time())
 
             # only check everything is good each second

py3status/i3status.py

@@ -7,6 +7,7 @@
 from subprocess import Popen
 from subprocess import PIPE
 from syslog import syslog, LOG_INFO
+from signal import SIGUSR2, SIGSTOP, SIG_IGN, signal
 from tempfile import NamedTemporaryFile
 from threading import Thread
 from time import time
@@ -49,6 +50,7 @@ class I3statusModule:
     """
 
     def __init__(self, module_name, py3_wrapper):
+        self.i3status_pipe = None
         self.module_name = module_name
         self.i3status = py3_wrapper.i3status_thread
         self.is_time_module = module_name.split()[0] in TIME_MODULES
@@ -504,6 +506,11 @@ def write_tmp_i3status_config(self, tmpfile):
                 self.write_in_tmpfile('}\n\n', tmpfile)
         tmpfile.flush()
 
+    def suspend_i3status(self):
+        # Put i3status to sleep
+        if self.i3status_pipe:
+            self.i3status_pipe.send_signal(SIGSTOP)
+
     @profile
     def run(self):
         """
@@ -519,11 +526,17 @@ def run(self):
                 i3status_pipe = Popen(
                     ['i3status', '-c', tmpfile.name],
                     stdout=PIPE,
-                    stderr=PIPE, )
+                    stderr=PIPE,
+                    # Ignore the SIGUSR2 signal for this subprocess
+                    preexec_fn=lambda:  signal(SIGUSR2, SIG_IGN)
+                )
                 self.poller_inp = IOPoller(i3status_pipe.stdout)
                 self.poller_err = IOPoller(i3status_pipe.stderr)
                 self.tmpfile_path = tmpfile.name
 
+                # Store the pipe so we can signal it
+                self.i3status_pipe = i3status_pipe
+
                 try:
                     # loop on i3status output
                     while self.lock.is_set():
@@ -540,6 +553,8 @@ def run(self):
                                 if 'version' in line:
                                     header = loads(line)
                                     header.update({'click_events': True})
+                                    # set custom stop signal
+                                    header['stop_signal'] = SIGUSR2
                                     line = dumps(header)
                                 print_line(line)
                             else:
@@ -564,6 +579,7 @@ def run(self):
             # we cleanup the tmpfile ourselves so when the delete will occur
             # it will usually raise an OSError: No such file or directory
             pass
+        self.i3status_pipe = None
 
     def cleanup_tmpfile(self):
         """