Wait cloudtail termination in goma module

scripts/slave/recipe_modules/goma/resources/cloudtail_utils.py

Index: scripts/slave/recipe_modules/goma/resources/cloudtail_utils.py
diff --git a/scripts/slave/recipe_modules/goma/resources/cloudtail_utils.py b/scripts/slave/recipe_modules/goma/resources/cloudtail_utils.py
index 79f20dc1edd7c1ee81c9d20086e9b363e61c5bb5..6945bb9f93e7d2e2b614bc7370740e7e73155223 100644
--- a/scripts/slave/recipe_modules/goma/resources/cloudtail_utils.py
+++ b/scripts/slave/recipe_modules/goma/resources/cloudtail_utils.py
@@ -9,6 +9,7 @@ import os
 import signal
 import subprocess
 import sys
+import time
 
 from slave import goma_utils
 
@@ -24,6 +25,15 @@ def start_cloudtail(args):
   with open(args.pid_file, 'w') as f:
     f.write(str(proc.pid))
 
+def is_running_posix(pid):
+  try:
+    os.kill(pid, 0)
+  except OSError as e:
+    if e.errno == errno.ESRCH:

[ukai, 2016/10/03 02:52:52]

kill may get errno.EPERM and I think we should return false for it too?
0 may not cause EINVAL?

[Vadim Sh., 2016/10/03 19:07:06]

+1 for EPERM handling and returning false

[tikuta, 2016/10/04 03:45:26]

Done.

+      return False
+    raise e

[Yoshisato Yanagisawa, 2016/10/03 04:49:05]

So, in this case, we do not guarantee cloud tail died?

[tikuta, 2016/10/04 03:45:25]

I send SIGKILL

+  return True
+
 def main():
   parser = argparse.ArgumentParser(
       description='cloudtail utility for goma recipe module.')
@@ -52,7 +62,16 @@ def main():
     with open(args.killed_pid_file) as f:
       # cloudtail flushes log and terminates
       # within 5 seconds when it recieves SIGINT.
-      os.kill(int(f.read()), signal.SIGINT)
+      pid = int(f.read())
+      os.kill(pid, signal.SIGINT)
+      if os.name == 'nt':

[ukai, 2016/10/03 02:52:52]

factor out a func to wait for pid?

[Vadim Sh., 2016/10/03 19:07:06]

+1

[tikuta, 2016/10/04 03:45:26]

Done.

+        os.waitpid(pid, 0)
+      else:
+        while True:

[ukai, 2016/10/03 02:52:52]

might be better to abandon if it tried >5 sec or so, and kill with SIGKILL?

[Vadim Sh., 2016/10/03 19:07:06]

+1

also nit

while is_running_posix(pid):
  time.sleep(1)

[tikuta, 2016/10/04 03:45:26]

Done.

+          if is_running_posix(pid):
+            time.sleep(1)
+          else:
+            break
 
 if '__main__' == __name__:
   sys.exit(main())