text: // Copyright (c) 2020-present Guy Blelloch and other contributors
  
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  
  // The above copyright notice and this permission notice shall be included in all
  // copies or substantial portions of the Software.
  
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  // SOFTWARE.
  
  #ifndef PARLAY_INTERNAL_WORK_STEALING_JOB_H_
  #define PARLAY_INTERNAL_WORK_STEALING_JOB_H_
  
  #include <cassert>
  
  #include <atomic>
  
  namespace parlay {
  
  // Jobs are thunks -- i.e., functions that take no arguments
  // and return nothing. Could be a lambda, e.g. [] () {}.
  
  struct WorkStealingJob {
    WorkStealingJob() {
      done.store(false, std::memory_order_relaxed);
    }
    ~WorkStealingJob() = default;
    void operator()() {
      assert(done.load(std::memory_order_relaxed) == false);
      execute();
      done.store(true, std::memory_order_relaxed);
    }
    bool finished() {
      return done.load(std::memory_order_relaxed);
    }
    virtual void execute() = 0;
    std::atomic<bool> done;
  };
  
  // Holds a type-specific reference to a callable object
  template<typename F>
  struct JobImpl : WorkStealingJob {
    explicit JobImpl(F& _f) : WorkStealingJob(), f(_f) { }
    void execute() override {
      f();
    }
    F& f;
  };
  
  template<typename F>
  JobImpl<F> make_job(F& f) { return JobImpl<F>(f); }
  
  }
  
  #endif  // PARLAY_INTERNAL_WORK_STEALING_JOB_H_
  