scoped_chainablestack.hpp

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#ifndef STAN_MATH_REV_CORE_SCOPED_CHAINABLESTACK_HPP
#define STAN_MATH_REV_CORE_SCOPED_CHAINABLESTACK_HPP
 
#include <stan/math/rev/core/chainablestack.hpp>
 
#include <mutex>
#include <stdexcept>
#include <thread>
 
namespace stan {
namespace math {
 
class ScopedChainableStack {
  ChainableStack::AutodiffStackStorage local_stack_;
  std::mutex local_stack_mutex_;
 
  struct activate_scope {
    ChainableStack::AutodiffStackStorage* parent_stack_;
    ScopedChainableStack& scoped_stack_;
 
    explicit activate_scope(ScopedChainableStack& scoped_stack)
        : parent_stack_(ChainableStack::instance_),
          scoped_stack_(scoped_stack) {
      if (!scoped_stack_.local_stack_mutex_.try_lock()) {
        throw std::logic_error{"Cannot recurse same instance scoped stacks."};
      }
      ChainableStack::instance_ = &scoped_stack.local_stack_;
    }
 
    ~activate_scope() {
      ChainableStack::instance_ = parent_stack_;
      scoped_stack_.local_stack_mutex_.unlock();
    }
  };
 
 public:
  ScopedChainableStack() = default;
 
  template <typename F, typename... Args>
  decltype(auto) execute(F&& f, Args&&... args) {
    const activate_scope active_scope(*this);
    return std::forward<F>(f)(std::forward<Args>(args)...);
  }
 
  // Prevent undesirable operations
  ScopedChainableStack(const ScopedChainableStack&) = delete;
  ScopedChainableStack& operator=(const ScopedChainableStack&) = delete;
};
 
}  // namespace math
}  // namespace stan
#endif