Method checkout

async_simple/executors/SimpleExecutor.h:67–70

    size_t currentContextId() const override { return _pool.getCurrentId(); }

    Context checkout() override {
        // avoid CurrentId equal to NULLCTX
        return reinterpret_cast<Context>(_pool.getCurrentId() | kContextMask);
    }

    bool checkin(Func func, Context ctx, ScheduleOptions opts) override {
        int64_t id = reinterpret_cast<int64_t>(ctx);