[GitHub] mesos pull request #279: WIP: Remove unknown unreachable tasks when agent re...

[xujyan <gi...@git.apache.org>]

Github user xujyan commented on a diff in the pull request:

    https://github.com/apache/mesos/pull/279#discussion_r179539166
  
    --- Diff: src/master/master.hpp ---
    @@ -1913,6 +1913,10 @@ class Master : public ProtobufProcess<Master>
         // `registry_max_agent_age`, and `registry_max_agent_count` flags.
         LinkedHashMap<SlaveID, TimeInfo> unreachable;
     
    +
    +    // Holds the `FrameworkID` and set of `TaskID` for the agents marked unreachable.
    +    hashmap<SlaveID, hashmap<FrameworkID, hashset<TaskID>>> unreachableAgentsToTasks;
    --- End diff --
    
    I would suggest s/unreachableAgentsToTasks/unreachableTasks/. It's under the `slaves` struct already so the longer name would be a bit redundant. However we probably need a long comment explaining why we need to do this, in particular:
    
    - This helps us look up all unreachable tasks on an agent so we can remove them from their primary storage`framework.unreacahbleTasks` when an agent reregisters.
    - This map is bounded by the same GC behavior as `unreachable`. i.e., the agent is GC'd from `unreachable` it's also erased from `unreachableTasks`.
    
    Can we use an multihashmap (in stout)?


---