Add a ProcessMonitor plugin for twistd

[rwall]

It would be useful to be able to launch t.r.procmon.ProcessMonitor from the command line as a simple way to monitor and automatically restart another (unreliable) process. eg

twistd procmon squid -N

A plugin would also provide a nice example of procmon use and replace the ugly main function currently at the bottom of the module.

[rwall]

A procmon plugin and tests.

[rwall]

Ready for review in attachment:procmon-plugin-4365.1.patch

• NB this patch is against source:branches/parameterize-procmon-3775-2

[rwall]

Looks like this isn't a new idea. Tv added a ProcMon plugin in 2003 which was later removed by moshez:

• r5715
• r8721

[glyph]

Applied patch to a branch so we can see  build results.

[glyph]

Gave the branch the wrong number, unfortunately. I'll fix it if I merge forward.

[cyli]

The tests pass, and running twistd procmon sleep 10 works - sleep 10 is restarted over and over.

Made two small changes:

1. Gave t.r.test.test_procmontap.ProcessMonitorTapTest a class (unittest.TestCase) level docstring.
2. Reflowed some of the text in t.r.procmontap.py's and t.r.test.test_procmontap.py's lines wrapped to 79 columns. Also put in extra newlines so that t.r.procmontap.py has the right number of newlines between methods/class and methods.

[cyli]

(In [29212]) Merge procmon-plugin-4365: Add a ProcessMonitor plugin for twistd

Author: rwall Reviewer: cyli Fixes: #4356

Added a twistd plugin to launch twisted.runner.procmon.ProcessMonitor from the command line.