chromium/third_party/webrtc/rtc_base/third_party/sigslot/sigslot.h

// sigslot.h: Signal/Slot classes
//
// Written by Sarah Thompson ([email protected]) 2002.
//
// License: Public domain. You are free to use this code however you like, with
// the proviso that the author takes on no responsibility or liability for any
// use.
//
// QUICK DOCUMENTATION
//
//        (see also the full documentation at http://sigslot.sourceforge.net/)
//
//    #define switches
//      SIGSLOT_PURE_ISO:
//        Define this to force ISO C++ compliance. This also disables all of
//        the thread safety support on platforms where it is available.
//
//      SIGSLOT_USE_POSIX_THREADS:
//        Force use of Posix threads when using a C++ compiler other than gcc
//        on a platform that supports Posix threads. (When using gcc, this is
//        the default - use SIGSLOT_PURE_ISO to disable this if necessary)
//
//      SIGSLOT_DEFAULT_MT_POLICY:
//        Where thread support is enabled, this defaults to
//        multi_threaded_global. Otherwise, the default is single_threaded.
//        #define this yourself to override the default. In pure ISO mode,
//        anything other than single_threaded will cause a compiler error.
//
//    PLATFORM NOTES
//
//      Win32:
//        On Win32, the WEBRTC_WIN symbol must be #defined. Most mainstream
//        compilers do this by default, but you may need to define it yourself
//        if your build environment is less standard. This causes the Win32
//        thread support to be compiled in and used automatically.
//
//      Unix/Linux/BSD, etc.:
//        If you're using gcc, it is assumed that you have Posix threads
//        available, so they are used automatically. You can override this (as
//        under Windows) with the SIGSLOT_PURE_ISO switch. If you're using
//        something other than gcc but still want to use Posix threads, you
//        need to #define SIGSLOT_USE_POSIX_THREADS.
//
//      ISO C++:
//        If none of the supported platforms are detected, or if
//        SIGSLOT_PURE_ISO is defined, all multithreading support is turned
//        off, along with any code that might cause a pure ISO C++ environment
//        to complain. Before you ask, gcc -ansi -pedantic won't compile this
//        library, but gcc -ansi is fine. Pedantic mode seems to throw a lot of
//        errors that aren't really there. If you feel like investigating this,
//        please contact the author.
//
//
//    THREADING MODES
//
//      single_threaded:
//        Your program is assumed to be single threaded from the point of view
//        of signal/slot usage (i.e. all objects using signals and slots are
//        created and destroyed from a single thread). Behaviour if objects are
//        destroyed concurrently is undefined (i.e. you'll get the occasional
//        segmentation fault/memory exception).
//
//      multi_threaded_global:
//        Your program is assumed to be multi threaded. Objects using signals
//        and slots can be safely created and destroyed from any thread, even
//        when connections exist. In multi_threaded_global mode, this is
//        achieved by a single global mutex (actually a critical section on
//        Windows because they are faster). This option uses less OS resources,
//        but results in more opportunities for contention, possibly resulting
//        in more context switches than are strictly necessary.
//
//      multi_threaded_local:
//        Behaviour in this mode is essentially the same as
//        multi_threaded_global, except that each signal, and each object that
//        inherits has_slots, all have their own mutex/critical section. In
//        practice, this means that mutex collisions (and hence context
//        switches) only happen if they are absolutely essential. However, on
//        some platforms, creating a lot of mutexes can slow down the whole OS,
//        so use this option with care.
//
//    USING THE LIBRARY
//
//      See the full documentation at http://sigslot.sourceforge.net/
//
// Libjingle specific:
//
// This file has been modified such that has_slots and signalx do not have to be
// using the same threading requirements. E.g. it is possible to connect a
// has_slots<single_threaded> and signal0<multi_threaded_local> or
// has_slots<multi_threaded_local> and signal0<single_threaded>.
// If has_slots is single threaded the user must ensure that it is not trying
// to connect or disconnect to signalx concurrently or data race may occur.
// If signalx is single threaded the user must ensure that disconnect, connect
// or signal is not happening concurrently or data race may occur.

#ifndef RTC_BASE_THIRD_PARTY_SIGSLOT_SIGSLOT_H_
#define RTC_BASE_THIRD_PARTY_SIGSLOT_SIGSLOT_H_

#include <cstring>
#include <list>
#include <set>

// On our copy of sigslot.h, we set single threading as default.
#define SIGSLOT_DEFAULT_MT_POLICY …

#if defined(SIGSLOT_PURE_ISO) ||                   \
    (!defined(WEBRTC_WIN) && !defined(__GNUG__) && \
     !defined(SIGSLOT_USE_POSIX_THREADS))
#define _SIGSLOT_SINGLE_THREADED
#elif defined(WEBRTC_WIN)
#define _SIGSLOT_HAS_WIN32_THREADS
#include "windows.h"
#elif defined(__GNUG__) || defined(SIGSLOT_USE_POSIX_THREADS)
#define _SIGSLOT_HAS_POSIX_THREADS
#include <pthread.h>
#else
#define _SIGSLOT_SINGLE_THREADED
#endif

#ifndef SIGSLOT_DEFAULT_MT_POLICY
#ifdef _SIGSLOT_SINGLE_THREADED
#define SIGSLOT_DEFAULT_MT_POLICY …
#else
#define SIGSLOT_DEFAULT_MT_POLICY …
#endif
#endif

// TODO: change this namespace to rtc?
namespace sigslot {

class single_threaded { … };

#ifdef _SIGSLOT_HAS_WIN32_THREADS
// The multi threading policies only get compiled in if they are enabled.
class multi_threaded_global {
 public:
  multi_threaded_global() {
    static bool isinitialised = false;

    if (!isinitialised) {
      InitializeCriticalSection(get_critsec());
      isinitialised = true;
    }
  }

  void lock() { EnterCriticalSection(get_critsec()); }

  void unlock() { LeaveCriticalSection(get_critsec()); }

 private:
  CRITICAL_SECTION* get_critsec() {
    static CRITICAL_SECTION g_critsec;
    return &g_critsec;
  }
};

class multi_threaded_local {
 public:
  multi_threaded_local() { InitializeCriticalSection(&m_critsec); }

  multi_threaded_local(const multi_threaded_local&) {
    InitializeCriticalSection(&m_critsec);
  }

  ~multi_threaded_local() { DeleteCriticalSection(&m_critsec); }

  void lock() { EnterCriticalSection(&m_critsec); }

  void unlock() { LeaveCriticalSection(&m_critsec); }

 private:
  CRITICAL_SECTION m_critsec;
};
#endif  // _SIGSLOT_HAS_WIN32_THREADS

#ifdef _SIGSLOT_HAS_POSIX_THREADS
// The multi threading policies only get compiled in if they are enabled.
class multi_threaded_global { … };

class multi_threaded_local { … };
#endif  // _SIGSLOT_HAS_POSIX_THREADS

template <class mt_policy>
class lock_block { … };

class _signal_base_interface;

class has_slots_interface { … };

class _signal_base_interface { … };

class _opaque_connection { … };

template <class mt_policy>
class _signal_base : public _signal_base_interface, public mt_policy { … };

template <class mt_policy = SIGSLOT_DEFAULT_MT_POLICY>
class has_slots : public has_slots_interface, public mt_policy { … };

template <class mt_policy, typename... Args>
class signal_with_thread_policy : public _signal_base<mt_policy> { … };

// Alias with default thread policy. Needed because both default arguments
// and variadic template arguments must go at the end of the list, so we
// can't have both at once.
signal;

// The previous verion of sigslot didn't use variadic templates, so you would
// need to write "sigslot::signal2<Arg1, Arg2>", for example.
// Now you can just write "sigslot::signal<Arg1, Arg2>", but these aliases
// exist for backwards compatibility.
signal0;

signal1;

signal2;

signal3;

signal4;

signal5;

signal6;

signal7;

signal8;

}  // namespace sigslot

#endif /* RTC_BASE_THIRD_PARTY_SIGSLOT_SIGSLOT_H_ */