Method recover

src/slave/slave.cpp:7736–7985

Future<Nothing> Slave::recover(const Try<state::State>& state)
{
  if (state.isError()) {
    return Failure(state.error());
  }

  LOG(INFO) << "Finished recovering checkpointed state from '" << metaDir
            << "', beginning agent recovery";

  Option<ResourcesState> resourcesState = state->resources;
  Option<SlaveState> slaveState = state->slave;

  // With the addition of frameworks with multiple roles, we
  // need to inject the allocated role into each allocated
  // `Resource` object that we've persisted. Note that we
  // also must do this for MULTI_ROLE frameworks since they
  // may have tasks that were present before the framework
  // upgraded into MULTI_ROLE.
  auto injectAllocationInfo = [](
      RepeatedPtrField<Resource>* resources,
      const FrameworkInfo& frameworkInfo) {
    set<string> roles = protobuf::framework::getRoles(frameworkInfo);

    bool injectedAllocationInfo = false;
    foreach (Resource& resource, *resources) {
      if (!resource.has_allocation_info()) {
        if (roles.size() != 1) {
          LOG(FATAL) << "Missing 'Resource.AllocationInfo' for resources"
                     << " allocated to MULTI_ROLE framework"
                     << " '" << frameworkInfo.name() << "'";
        }

        resource.mutable_allocation_info()->set_role(*roles.begin());
        injectedAllocationInfo = true;
      }
    }

    return injectedAllocationInfo;
  };

  // In order to allow frameworks to change their role(s), we need to keep
  // track of the fact that the resources used to be implicitly allocated to
  // `FrameworkInfo.role` before the agent upgrade. To this end, we inject
  // the `AllocationInfo` to the resources in `ExecutorState` and `TaskState`,
  // and re-checkpoint them if necessary.

  hashset<ExecutorID> injectedExecutors;
  hashmap<ExecutorID, hashset<TaskID>> injectedTasks;

  if (slaveState.isSome()) {
    foreachvalue (FrameworkState& frameworkState, slaveState->frameworks) {
      if (!frameworkState.info.isSome()) {
        continue;
      }

      foreachvalue (ExecutorState& executorState, frameworkState.executors) {
        if (!executorState.info.isSome()) {
          continue;