BIND 10 #3123: Select wrapper & mutex around ModuleCCSession

[BIND 10 Development]

#3123: Select wrapper & mutex around ModuleCCSession
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                   Reporter:         |                 Owner:
  vorner                             |                Status:  new
                       Type:  task   |             Milestone:  New Tasks
                   Priority:         |              Keywords:
  medium                             |             Sensitive:  0
                  Component:  shmem  |           Sub-Project:  DNS
  manager                            |  Estimated Difficulty:  0
               CVSS Scoring:         |           Total Hours:  0
            Defect Severity:  N/A    |
Feature Depending on Ticket:         |
  Simplified memmgr                  |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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 Implement the usual work-around wrapper with select around check_command
 for module CC session in the memory manager. Also, include a mutex around
 the command (there's one inside, but the other thread will need to hold
 the module CC session for longer than just one command when synchronizing
 and it will not want the main thread to interfere).

 Something like:

 {{{#!python
 while True:
         if fd in select([fd], [], [])[0]:
                 with mutex:
                         module_cc_session.check_command(blocking=False)
 }}}

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Ticket URL: <http://bind10.isc.org/ticket/3123>
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BIND 10 Development