Boost C++ Libraries

Based on the scoped_thread class defined in C++ Concurrency in Action Boost.Thread defines a thread wrapper class that instead of calling terminate if the thread is joinable on destruction, call a specific action given as template parameter.

While the scoped_thread class defined in C++ Concurrency in Action is closer to strict_scoped_thread class that doesn't allows any change in the wrapped thread, Boost.Thread provides a class scoped_thread that provides the same non-deprecated interface as thread.

Scoped Threads are wrappers around a thread that allows the user to state what to do at destruction time. One of the common uses is to join the thread at destruction time so this is the default behavior. This is the single difference respect to a thread. While thread call std::terminate() on the destructor if the thread is joinable, strict_scoped_thread<> or scoped_thread<> join the thread if joinable.

The difference between strict_scoped_thread and scoped_thread is that the strict_scoped_thread hides completely the owned thread and so the user can do nothing with the owned thread other than the specific action given as parameter, while scoped_thread provide the same interface as thread and forwards all the operations.

boost::strict_scoped_thread<> t1((boost::thread(f)));
//t1.detach(); // compile fails
boost::scoped_thread<> t2((boost::thread(f)));
t2.detach();

//#include <boost/thread/scoped_thread.hpp>

struct detach;
struct join_if_joinable;
struct interrupt_and_join_if_joinable;

struct detach
{
  template <class Thread>
  void operator()(Thread& t)
  {
    t.detach();
  }
};

struct join_if_joinable
{
  template <class Thread>
  void operator()(Thread& t)
  {
    if (t.joinable())
    {
      t.join();
    }
  }
};

struct interrupt_and_join_if_joinable
{
  template <class Thread>
  void operator()(Thread& t)
  {
    t.interrupt();
    if (t.joinable())
    {
      t.join();
    }
  }
};

// #include <boost/thread/scoped_thread.hpp>

template <class CallableThread = join_if_joinable, class Thread = ::boost::thread>
class strict_scoped_thread
{
  thread t_; // for exposition purposes only
public:

  strict_scoped_thread(strict_scoped_thread const&) = delete;
  strict_scoped_thread& operator=(strict_scoped_thread const&) = delete;

  explicit strict_scoped_thread(Thread&& t) noexcept;
  template <typename F&&, typename ...Args>
  explicit strict_scoped_thread(F&&, Args&&...);

  ~strict_scoped_thread();

};

RAII thread wrapper adding a specific destroyer allowing to master what can be done at destruction time.

CallableThread: A callable void(thread&).

The default is a join_if_joinable.

Thread destructor terminates the program if the thread is joinable. This wrapper can be used to join the thread before destroying it.

Example

boost::strict_scoped_thread<> t((boost::thread(F)));

explicit strict_scoped_thread(Thread&& t) noexcept;

template <typename F&&, typename ...Args>
explicit strict_scoped_thread(F&&, Args&&...);

~strict_scoped_thread();

#include <boost/thread/scoped_thread.hpp>

template <class CallableThread, class Thread = thread>
class scoped_thread
{
  thread t_; // for exposition purposes only
public:
    scoped_thread() noexcept;
    scoped_thread(const scoped_thread&) = delete;
    scoped_thread& operator=(const scoped_thread&) = delete;

    explicit scoped_thread(thread&& th) noexcept;
    template <typename F&&, typename ...Args>
    explicit scoped_thread(F&&, Args&&...);

    ~scoped_thread();

    // move support
    scoped_thread(scoped_thread && x) noexcept;
    scoped_thread& operator=(scoped_thread && x) noexcept;

    void swap(scoped_thread& x) noexcept;

    typedef thread::id id;

    id get_id() const noexcept;

    bool joinable() const noexcept;
    void join();
#ifdef BOOST_THREAD_USES_CHRONO
    template <class Rep, class Period>
    bool try_join_for(const chrono::duration<Rep, Period>& rel_time);
    template <class Clock, class Duration>
    bool try_join_until(const chrono::time_point<Clock, Duration>& t);
#endif

    void detach();

    static unsigned hardware_concurrency() noexcept;
    static unsigned physical_concurrency() noexcept;

    typedef thread::native_handle_type native_handle_type;
    native_handle_type native_handle();

#if defined BOOST_THREAD_PROVIDES_INTERRUPTIONS
    void interrupt();
    bool interruption_requested() const noexcept;
#endif


};

template <class CallableThread, class Thread = thread>
void swap(scoped_thread<CallableThread,Thread>& lhs,scoped_thread<CallableThread,Thread>& rhs) noexcept;

RAII thread wrapper adding a specific destroyer allowing to master what can be done at destruction time.

CallableThread: A callable void(thread&). The default is join_if_joinable.

Thread destructor terminates the program if the thread is joinable. This wrapper can be used to join the thread before destroying it.

Remark: scoped_thread is not a thread as thread is not designed to be derived from as a polymorphic type.

Anyway scoped_thread can be used in most of the contexts a thread could be used as it has the same non-deprecated interface with the exception of the construction.

Example

boost::scoped_thread<> t((boost::thread(F)));
t.interrupt();

scoped_thread() noexcept;

scoped_thread(scoped_thread&& other) noexcept;

scoped_thread& operator=(scoped_thread&& other) noexcept;

scoped_thread(thread&& t);

template <typename F&&, typename ...Args>
explicit scoped_thread(F&&, Args&&...);

~scoped_thread();

bool joinable() const noexcept;

void join();

template <class Rep, class Period>
bool try_join_for(const chrono::duration<Rep, Period>& rel_time);

template <class Clock, class Duration>
bool try_join_until(const chrono::time_point<Clock, Duration>& abs_time);

void detach();

thread::id get_id() const noexcept;

void interrupt();

unsigned hardware_concurrency() noexecpt;

unsigned physical_concurrency() noexecpt;

typedef thread::native_handle_type native_handle_type;
native_handle_type native_handle();

void swap(scoped_thread& other) noexcept;

#include <boost/thread/scoped_thread.hpp>

template <class CallableThread, class Thread = thread>
void swap(scoped_thread<Callable, Thread>& lhs, scoped_threadCallable, Thread>& rhs) noexcept;