Merge branch 'retry_commands'

diff --combined autorandr.py
index 0b16695befb639a8b25a4d298f6f689db974bed0,812329ddf72e78d8dd01bc158fa37cc74ed1cdc1..c8b8f8fcebbd15f2de349876c82bf605cf98181a
--- 1/autorandr.py
--- 2/autorandr.py
+++ b/autorandr.py
@@@ -23,6 -23,7 +23,6 @@@
  #
  
  from __future__ import print_function
 -import time
  
  import binascii
  import copy
@@@ -34,6 -35,6 +34,7 @@@ import r
  import subprocess
  import sys
  import shutil
++import time
  
  from collections import OrderedDict
  from distutils.version import LooseVersion as Version
@@@ -112,8 -113,7 +113,8 @@@ class AutorandrException(Exception)
              retval.append(":\n  ")
              retval.append(str(self.original_exception).replace("\n", "\n  "))
          if self.report_bug:
 -            retval.append("\nThis appears to be a bug. Please help improving autorandr by reporting it upstream."
 +            retval.append("\nThis appears to be a bug. Please help improving autorandr by reporting it upstream:"
 +                          "\nhttps://github.com/phillipberndt/autorandr/issues"
                           "\nPlease attach the output of `xrandr --verbose` to your bug report if appropriate.")
          return "".join(retval)
  
@@@ -529,6 -529,25 +530,25 @@@ def update_mtime(filename)
      except:
          return False
  
+ def call_and_retry(*args, **kwargs):
+     """Wrapper around subprocess.call that retries failed calls.
+ 
+     This function calls subprocess.call and on non-zero exit states,
+     waits a second and then retries once. This mitigates #47,
+     a timing issue with some drivers.
+     """
+     kwargs_redirected = dict(kwargs)
+     if hasattr(subprocess, "DEVNULL"):
+         kwargs_redirected["stdout"] = getattr(subprocess, "DEVNULL")
+     else:
+         kwargs_redirected["stdout"] = open(os.devnull, "w")
+     kwargs_redirected["stderr"] = kwargs_redirected["stdout"]
+     retval = subprocess.call(*args, **kwargs_redirected)
+     if retval != 0:
+         time.sleep(1)
+         retval = subprocess.call(*args, **kwargs)
+     return retval
+ 
  def apply_configuration(new_configuration, current_configuration, dry_run=False):
      "Apply a configuration"
      outputs = sorted(new_configuration.keys(), key=lambda x: new_configuration[x].sort_key)
@@@ -582,13 -601,13 +602,13 @@@
      # Perform pe-change auxiliary changes
      if auxiliary_changes_pre:
          argv = base_argv + list(chain.from_iterable(auxiliary_changes_pre))
-         if subprocess.call(argv) != 0:
+         if call_and_retry(argv) != 0:
              raise AutorandrException("Command failed: %s" % " ".join(argv))
  
      # Disable unused outputs, but make sure that there always is at least one active screen
      disable_keep = 0 if remain_active_count else 1
      if len(disable_outputs) > disable_keep:
-         if subprocess.call(base_argv + list(chain.from_iterable(disable_outputs[:-1] if disable_keep else disable_outputs))) != 0:
+         if call_and_retry(base_argv + list(chain.from_iterable(disable_outputs[:-1] if disable_keep else disable_outputs))) != 0:
              # Disabling the outputs failed. Retry with the next command:
              # Sometimes disabling of outputs fails due to an invalid RRSetScreenSize.
              # This does not occur if simultaneously the primary screen is reset.
@@@ -607,7 -626,7 +627,7 @@@
      operations = disable_outputs + enable_outputs
      for index in range(0, len(operations), 2):
          argv = base_argv + list(chain.from_iterable(operations[index:index+2]))
-         if subprocess.call(argv) != 0:
+         if call_and_retry(argv) != 0:
              raise AutorandrException("Command failed: %s" % " ".join(argv))
  
  def is_equal_configuration(source_configuration, target_configuration):
@@@ -926,5 -945,5 +946,5 @@@ if __name__ == '__main__'
              print("Exception: {0}".format(e.__class__.__name__))
              sys.exit(2)
  
 -        print("Unhandled exception ({0}). Please report this as a bug.".format(e), file=sys.stderr)
 +        print("Unhandled exception ({0}). Please report this as a bug at https://github.com/phillipberndt/autorandr/issues.".format(e), file=sys.stderr)
          raise