diff options
Diffstat (limited to 'indra/llcommon/llevents.h')
| -rw-r--r-- | indra/llcommon/llevents.h | 343 |
1 files changed, 3 insertions, 340 deletions
diff --git a/indra/llcommon/llevents.h b/indra/llcommon/llevents.h index 253592256d..3c388bf176 100644 --- a/indra/llcommon/llevents.h +++ b/indra/llcommon/llevents.h @@ -310,37 +310,6 @@ testable: }; /***************************************************************************** -* details -*****************************************************************************/ -namespace LLEventDetail -{ - /// Any callable capable of connecting an LLEventListener to an - /// LLStandardSignal to produce an LLBoundListener can be mapped to this - /// signature. - typedef boost::function<LLBoundListener(const LLEventListener&)> ConnectFunc; - - /// overload of visit_and_connect() when we have a string identifier available - template <typename LISTENER> - LLBoundListener visit_and_connect(const std::string& name, - const LISTENER& listener, - const ConnectFunc& connect_func); - /** - * Utility template function to use Visitor appropriately - * - * @param listener Callable to connect, typically a boost::bind() - * expression. This will be visited by Visitor using boost::visit_each(). - * @param connect_func Callable that will connect() @a listener to an - * LLStandardSignal, returning LLBoundListener. - */ - template <typename LISTENER> - LLBoundListener visit_and_connect(const LISTENER& listener, - const ConnectFunc& connect_func) - { - return visit_and_connect("", listener, connect_func); - } -} // namespace LLEventDetail - -/***************************************************************************** * LLEventTrackable *****************************************************************************/ /** @@ -374,11 +343,6 @@ namespace LLEventDetail * instance, it attempts to dereference the <tt>Foo*</tt> pointer that was * <tt>delete</tt>d but not zeroed.) * - Undefined behavior results. - * If you suspect you may encounter any such scenario, you're better off - * managing the lifespan of your object with <tt>boost::shared_ptr</tt>. - * Passing <tt>LLEventPump::listen()</tt> a <tt>boost::bind()</tt> expression - * involving a <tt>boost::weak_ptr<Foo></tt> is recognized specially, engaging - * thread-safe Boost.Signals2 machinery. */ typedef boost::signals2::trackable LLEventTrackable; @@ -517,44 +481,13 @@ public: * the result be assigned to a LLTempBoundListener or the listener is * manually disconnected when no longer needed since there will be no * way to later find and disconnect this listener manually. - * - * If (as is typical) you pass a <tt>boost::bind()</tt> expression as @a - * listener, listen() will inspect the components of that expression. If a - * bound object matches any of several cases, the connection will - * automatically be disconnected when that object is destroyed. - * - * * You bind a <tt>boost::weak_ptr</tt>. - * * Binding a <tt>boost::shared_ptr</tt> that way would ensure that the - * referenced object would @em never be destroyed, since the @c - * shared_ptr stored in the LLEventPump would remain an outstanding - * reference. Use the weaken() function to convert your @c shared_ptr to - * @c weak_ptr. Because this is easy to forget, binding a @c shared_ptr - * will produce a compile error (@c BOOST_STATIC_ASSERT failure). - * * You bind a simple pointer or reference to an object derived from - * <tt>boost::enable_shared_from_this</tt>. (UNDER CONSTRUCTION) - * * You bind a simple pointer or reference to an object derived from - * LLEventTrackable. Unlike the cases described above, though, this is - * vulnerable to a couple of cross-thread race conditions, as described - * in the LLEventTrackable documentation. */ - template <typename LISTENER> - LLBoundListener listen(const std::string& name, const LISTENER& listener, + LLBoundListener listen(const std::string& name, + const LLEventListener& listener, const NameList& after=NameList(), const NameList& before=NameList()) { - // Examine listener, using our listen_impl() method to make the - // actual connection. - // This is why listen() is a template. Conversion from boost::bind() - // to LLEventListener performs type erasure, so it's important to look - // at the boost::bind object itself before that happens. - return LLEventDetail::visit_and_connect(name, - listener, - boost::bind(&LLEventPump::listen_invoke, - this, - name, - _1, - after, - before)); + return listen_impl(name, listener, after, before); } /// Get the LLBoundListener associated with the passed name (dummy @@ -598,13 +531,6 @@ private: private: - LLBoundListener listen_invoke(const std::string& name, const LLEventListener& listener, - const NameList& after, - const NameList& before) - { - return this->listen_impl(name, listener, after, before); - } - // must precede mName; see LLEventPump::LLEventPump() LLHandle<LLEventPumps> mRegistry; @@ -814,261 +740,6 @@ private: LL_COMMON_API bool sendReply(const LLSD& reply, const LLSD& request, const std::string& replyKey="reply"); -/***************************************************************************** -* Underpinnings -*****************************************************************************/ -/** - * We originally provided a suite of overloaded - * LLEventTrackable::listenTo(LLEventPump&, ...) methods that would call - * LLEventPump::listen(...) and then pass the returned LLBoundListener to - * LLEventTrackable::track(). This was workable but error-prone: the coder - * must remember to call listenTo() rather than the more straightforward - * listen() method. - * - * Now we publish only the single canonical listen() method, so there's a - * uniform mechanism. Having a single way to do this is good, in that there's - * no question in the coder's mind which of several alternatives to choose. - * - * To support automatic connection management, we use boost::visit_each - * (http://www.boost.org/doc/libs/1_37_0/doc/html/boost/visit_each.html) to - * inspect each argument of a boost::bind expression. (Although the visit_each - * mechanism was first introduced with the original Boost.Signals library, it - * was only later documented.) - * - * Cases: - * * At least one of the function's arguments is a boost::weak_ptr<T>. Pass - * the corresponding shared_ptr to slot_type::track(). Ideally that would be - * the object whose method we want to call, but in fact we do the same for - * any weak_ptr we might find among the bound arguments. If we're passing - * our bound method a weak_ptr to some object, wouldn't the destruction of - * that object invalidate the call? So we disconnect automatically when any - * such object is destroyed. This is the mechanism preferred by boost:: - * signals2. - * * One of the functions's arguments is a boost::shared_ptr<T>. This produces - * a compile error: the bound copy of the shared_ptr stored in the - * boost_bind object stored in the signal object would make the referenced - * T object immortal. We provide a weaken() function. Pass - * weaken(your_shared_ptr) instead. (We can inspect, but not modify, the - * boost::bind object. Otherwise we'd replace the shared_ptr with weak_ptr - * implicitly and just proceed.) - * * One of the function's arguments is a plain pointer/reference to an object - * derived from boost::enable_shared_from_this. We assume that this object - * is managed using boost::shared_ptr, so we implicitly extract a shared_ptr - * and track that. (UNDER CONSTRUCTION) - * * One of the function's arguments is derived from LLEventTrackable. Pass - * the LLBoundListener to its LLEventTrackable::track(). This is vulnerable - * to a couple different race conditions, as described in LLEventTrackable - * documentation. (NOTE: Now that LLEventTrackable is a typedef for - * boost::signals2::trackable, the Signals2 library handles this itself, so - * our visitor needs no special logic for this case.) - * * Any other argument type is irrelevant to automatic connection management. - */ - -namespace LLEventDetail -{ - template <typename F> - const F& unwrap(const F& f) { return f; } - - template <typename F> - const F& unwrap(const boost::reference_wrapper<F>& f) { return f.get(); } - - // Most of the following is lifted from the Boost.Signals use of - // visit_each. - template<bool Cond> struct truth {}; - - /** - * boost::visit_each() Visitor, used on a template argument <tt>const F& - * f</tt> as follows (see visit_and_connect()): - * @code - * LLEventListener listener(f); - * Visitor visitor(listener); // bind listener so it can track() shared_ptrs - * using boost::visit_each; // allow unqualified visit_each() call for ADL - * visit_each(visitor, unwrap(f)); - * @endcode - */ - class Visitor - { - public: - /** - * Visitor binds a reference to LLEventListener so we can track() any - * shared_ptrs we find in the argument list. - */ - Visitor(LLEventListener& listener): - mListener(listener) - { - } - - /** - * boost::visit_each() calls this method for each component of a - * boost::bind() expression. - */ - template <typename T> - void operator()(const T& t) const - { - decode(t, 0); - } - - private: - // decode() decides between a reference wrapper and anything else - // boost::ref() variant - template<typename T> - void decode(const boost::reference_wrapper<T>& t, int) const - { -// add_if_trackable(t.get_pointer()); - } - - // decode() anything else - template<typename T> - void decode(const T& t, long) const - { - typedef truth<(boost::is_pointer<T>::value)> is_a_pointer; - maybe_get_pointer(t, is_a_pointer()); - } - - // maybe_get_pointer() decides between a pointer and a non-pointer - // plain pointer variant - template<typename T> - void maybe_get_pointer(const T& t, truth<true>) const - { -// add_if_trackable(t); - } - - // shared_ptr variant - template<typename T> - void maybe_get_pointer(const boost::shared_ptr<T>& t, truth<false>) const - { - // If we have a shared_ptr to this object, it doesn't matter - // whether the object is derived from LLEventTrackable, so no - // further analysis of T is needed. -// mListener.track(t); - - // Make this case illegal. Passing a bound shared_ptr to - // slot_type::track() is useless, since the bound shared_ptr will - // keep the object alive anyway! Force the coder to cast to weak_ptr. - - // Trivial as it is, make the BOOST_STATIC_ASSERT() condition - // dependent on template param so the macro is only evaluated if - // this method is in fact instantiated, as described here: - // http://www.boost.org/doc/libs/1_34_1/doc/html/boost_staticassert.html - - // ATTENTION: Don't bind a shared_ptr<anything> using - // LLEventPump::listen(boost::bind()). Doing so captures a copy of - // the shared_ptr, making the referenced object effectively - // immortal. Use the weaken() function, e.g.: - // somepump.listen(boost::bind(...weaken(my_shared_ptr)...)); - // This lets us automatically disconnect when the referenced - // object is destroyed. - BOOST_STATIC_ASSERT(sizeof(T) == 0); - } - - // weak_ptr variant - template<typename T> - void maybe_get_pointer(const boost::weak_ptr<T>& t, truth<false>) const - { - // If we have a weak_ptr to this object, it doesn't matter - // whether the object is derived from LLEventTrackable, so no - // further analysis of T is needed. - mListener.track(t); -// std::cout << "Found weak_ptr<" << typeid(T).name() << ">!\n"; - } - -#if 0 - // reference to anything derived from boost::enable_shared_from_this - template <typename T> - inline void maybe_get_pointer(const boost::enable_shared_from_this<T>& ct, - truth<false>) const - { - // Use the slot_type::track(shared_ptr) mechanism. Cast away - // const-ness because (in our code base anyway) it's unusual - // to find shared_ptr<const T>. - boost::enable_shared_from_this<T>& - t(const_cast<boost::enable_shared_from_this<T>&>(ct)); - std::cout << "Capturing shared_from_this()" << std::endl; - boost::shared_ptr<T> sp(t.shared_from_this()); -/*==========================================================================*| - std::cout << "Capturing weak_ptr" << std::endl; - boost::weak_ptr<T> wp(sp); -|*==========================================================================*/ - std::cout << "Tracking shared__ptr" << std::endl; - mListener.track(sp); - } -#endif - - // non-pointer variant - template<typename T> - void maybe_get_pointer(const T& t, truth<false>) const - { - // Take the address of this object, because the object itself may be - // trackable -// add_if_trackable(boost::addressof(t)); - } - -/*==========================================================================*| - // add_if_trackable() adds LLEventTrackable objects to mTrackables - inline void add_if_trackable(const LLEventTrackable* t) const - { - if (t) - { - } - } - - // pointer to anything not an LLEventTrackable subclass - inline void add_if_trackable(const void*) const - { - } - - // pointer to free function - // The following construct uses the preprocessor to generate - // add_if_trackable() overloads accepting pointer-to-function taking - // 0, 1, ..., LLEVENTS_LISTENER_ARITY parameters of arbitrary type. -#define BOOST_PP_LOCAL_MACRO(n) \ - template <typename R \ - BOOST_PP_COMMA_IF(n) \ - BOOST_PP_ENUM_PARAMS(n, typename T)> \ - inline void \ - add_if_trackable(R (*)(BOOST_PP_ENUM_PARAMS(n, T))) const \ - { \ - } -#define BOOST_PP_LOCAL_LIMITS (0, LLEVENTS_LISTENER_ARITY) -#include BOOST_PP_LOCAL_ITERATE() -#undef BOOST_PP_LOCAL_MACRO -#undef BOOST_PP_LOCAL_LIMITS -|*==========================================================================*/ - - /// Bind a reference to the LLEventListener to call its track() method. - LLEventListener& mListener; - }; - - /** - * Utility template function to use Visitor appropriately - * - * @param raw_listener Callable to connect, typically a boost::bind() - * expression. This will be visited by Visitor using boost::visit_each(). - * @param connect_funct Callable that will connect() @a raw_listener to an - * LLStandardSignal, returning LLBoundListener. - */ - template <typename LISTENER> - LLBoundListener visit_and_connect(const std::string& name, - const LISTENER& raw_listener, - const ConnectFunc& connect_func) - { - // Capture the listener - LLEventListener listener(raw_listener); - // Define our Visitor, binding the listener so we can call - // listener.track() if we discover any shared_ptr<Foo>. - LLEventDetail::Visitor visitor(listener); - // Allow unqualified visit_each() call for ADL - using boost::visit_each; - // Visit each component of a boost::bind() expression. Pass - // 'raw_listener', our template argument, rather than 'listener' from - // which type details have been erased. unwrap() comes from - // Boost.Signals, in case we were passed a boost::ref(). - visit_each(visitor, LLEventDetail::unwrap(raw_listener)); - // Make the connection using passed function. - return connect_func(listener); - } -} // namespace LLEventDetail - // Somewhat to my surprise, passing boost::bind(...boost::weak_ptr<T>...) to // listen() fails in Boost code trying to instantiate LLEventListener (i.e. // LLStandardSignal::slot_type) because the boost::get_pointer() utility function isn't @@ -1079,12 +750,4 @@ namespace boost T* get_pointer(const weak_ptr<T>& ptr) { return shared_ptr<T>(ptr).get(); } } -/// Since we forbid use of listen(boost::bind(...shared_ptr<T>...)), provide an -/// easy way to cast to the corresponding weak_ptr. -template <typename T> -boost::weak_ptr<T> weaken(const boost::shared_ptr<T>& ptr) -{ - return boost::weak_ptr<T>(ptr); -} - #endif /* ! defined(LL_LLEVENTS_H) */ |