diff options
Diffstat (limited to 'indra/llcommon')
| -rw-r--r-- | indra/llcommon/CMakeLists.txt | 2 | ||||
| -rw-r--r-- | indra/llcommon/ll_template_cast.h | 160 | ||||
| -rw-r--r-- | indra/llcommon/llevents.cpp | 25 | ||||
| -rw-r--r-- | indra/llcommon/llevents.h | 93 | ||||
| -rw-r--r-- | indra/llcommon/lllistenerwrapper.h | 181 |
5 files changed, 448 insertions, 13 deletions
diff --git a/indra/llcommon/CMakeLists.txt b/indra/llcommon/CMakeLists.txt index e41c75846b..a08f9b9ab4 100644 --- a/indra/llcommon/CMakeLists.txt +++ b/indra/llcommon/CMakeLists.txt @@ -163,6 +163,7 @@ set(llcommon_HEADER_FILES llinstancetracker.h llkeythrottle.h lllazy.h + lllistenerwrapper.h lllinkedqueue.h llliveappconfig.h lllivefile.h @@ -220,6 +221,7 @@ set(llcommon_HEADER_FILES llversionserver.h llversionviewer.h llworkerthread.h + ll_template_cast.h metaclass.h metaclasst.h metaproperty.h diff --git a/indra/llcommon/ll_template_cast.h b/indra/llcommon/ll_template_cast.h new file mode 100644 index 0000000000..cff58ce00d --- /dev/null +++ b/indra/llcommon/ll_template_cast.h @@ -0,0 +1,160 @@ +/** + * @file ll_template_cast.h + * @author Nat Goodspeed + * @date 2009-11-21 + * @brief Define ll_template_cast function + * + * $LicenseInfo:firstyear=2009&license=viewergpl$ + * Copyright (c) 2009, Linden Research, Inc. + * $/LicenseInfo$ + */ + +#if ! defined(LL_LL_TEMPLATE_CAST_H) +#define LL_LL_TEMPLATE_CAST_H + +/** + * Implementation for ll_template_cast() (q.v.). + * + * Default implementation: trying to cast two completely unrelated types + * returns 0. Typically you'd specify T and U as pointer types, but in fact T + * can be any type that can be initialized with 0. + */ +template <typename T, typename U> +struct ll_template_cast_impl +{ + T operator()(U) + { + return 0; + } +}; + +/** + * ll_template_cast<T>(some_value) is for use in a template function when + * some_value might be of arbitrary type, but you want to recognize type T + * specially. + * + * It's designed for use with pointer types. Example: + * @code + * struct SpecialClass + * { + * void someMethod(const std::string&) const; + * }; + * + * template <class REALCLASS> + * void somefunc(const REALCLASS& instance) + * { + * const SpecialClass* ptr = ll_template_cast<const SpecialClass*>(&instance); + * if (ptr) + * { + * ptr->someMethod("Call method only available on SpecialClass"); + * } + * } + * @endcode + * + * Why is this better than dynamic_cast<>? Because unless OtherClass is + * polymorphic, the following won't even compile (gcc 4.0.1): + * @code + * OtherClass other; + * SpecialClass* ptr = dynamic_cast<SpecialClass*>(&other); + * @endcode + * to say nothing of this: + * @code + * void function(int); + * SpecialClass* ptr = dynamic_cast<SpecialClass*>(&function); + * @endcode + * ll_template_cast handles these kinds of cases by returning 0. + */ +template <typename T, typename U> +T ll_template_cast(U value) +{ + return ll_template_cast_impl<T, U>()(value); +} + +/** + * Implementation for ll_template_cast() (q.v.). + * + * Implementation for identical types: return same value. + */ +template <typename T> +struct ll_template_cast_impl<T, T> +{ + T operator()(T value) + { + return value; + } +}; + +/** + * LL_TEMPLATE_CONVERTIBLE(dest, source) asserts that, for a value @c s of + * type @c source, <tt>ll_template_cast<dest>(s)</tt> will return @c s -- + * presuming that @c source can be converted to @c dest by the normal rules of + * C++. + * + * By default, <tt>ll_template_cast<dest>(s)</tt> will return 0 unless @c s's + * type is literally identical to @c dest. (This is because of the + * straightforward application of template specialization rules.) That can + * lead to surprising results, e.g.: + * + * @code + * Foo myFoo; + * const Foo* fooptr = ll_template_cast<const Foo*>(&myFoo); + * @endcode + * + * Here @c fooptr will be 0 because <tt>&myFoo</tt> is of type <tt>Foo*</tt> + * -- @em not <tt>const Foo*</tt>. (Declaring <tt>const Foo myFoo;</tt> would + * force the compiler to do the right thing.) + * + * More disappointingly: + * @code + * struct Base {}; + * struct Subclass: public Base {}; + * Subclass object; + * Base* ptr = ll_template_cast<Base*>(&object); + * @endcode + * + * Here @c ptr will be 0 because <tt>&object</tt> is of type + * <tt>Subclass*</tt> rather than <tt>Base*</tt>. We @em want this cast to + * succeed, but without our help ll_template_cast can't recognize it. + * + * The following would suffice: + * @code + * LL_TEMPLATE_CONVERTIBLE(Base*, Subclass*); + * ... + * Base* ptr = ll_template_cast<Base*>(&object); + * @endcode + * + * However, as noted earlier, this is easily fooled: + * @code + * const Base* ptr = ll_template_cast<const Base*>(&object); + * @endcode + * would still produce 0 because we haven't yet seen: + * @code + * LL_TEMPLATE_CONVERTIBLE(const Base*, Subclass*); + * @endcode + * + * @TODO + * This macro should use Boost type_traits facilities for stripping and + * re-adding @c const and @c volatile qualifiers so that invoking + * LL_TEMPLATE_CONVERTIBLE(dest, source) will automatically generate all + * permitted permutations. It's really not fair to the coder to require + * separate: + * @code + * LL_TEMPLATE_CONVERTIBLE(Base*, Subclass*); + * LL_TEMPLATE_CONVERTIBLE(const Base*, Subclass*); + * LL_TEMPLATE_CONVERTIBLE(const Base*, const Subclass*); + * @endcode + * + * (Naturally we omit <tt>LL_TEMPLATE_CONVERTIBLE(Base*, const Subclass*)</tt> + * because that's not permitted by normal C++ assignment anyway.) + */ +#define LL_TEMPLATE_CONVERTIBLE(DEST, SOURCE) \ +template <> \ +struct ll_template_cast_impl<DEST, SOURCE> \ +{ \ + DEST operator()(SOURCE wrapper) \ + { \ + return wrapper; \ + } \ +} + +#endif /* ! defined(LL_LL_TEMPLATE_CAST_H) */ diff --git a/indra/llcommon/llevents.cpp b/indra/llcommon/llevents.cpp index 4bdfe5a867..31fdd9e60a 100644 --- a/indra/llcommon/llevents.cpp +++ b/indra/llcommon/llevents.cpp @@ -459,11 +459,25 @@ void LLEventPump::stopListening(const std::string& name) bool LLEventStream::post(const LLSD& event) { if (! mEnabled) + { return false; + } + // NOTE NOTE NOTE: Any new access to member data beyond this point should + // cause us to move our LLStandardSignal object to a pimpl class along + // with said member data. Then the local shared_ptr will preserve both. + + // DEV-43463: capture a local copy of mSignal. We've turned up a + // cross-coroutine scenario (described in the Jira) in which this post() + // call could end up destroying 'this', the LLEventPump subclass instance + // containing mSignal, during the call through *mSignal. So -- capture a + // *stack* instance of the shared_ptr, ensuring that our heap + // LLStandardSignal object will live at least until post() returns, even + // if 'this' gets destroyed during the call. + boost::shared_ptr<LLStandardSignal> signal(mSignal); // Let caller know if any one listener handled the event. This is mostly // useful when using LLEventStream as a listener for an upstream // LLEventPump. - return (*mSignal)(event); + return (*signal)(event); } /***************************************************************************** @@ -492,9 +506,16 @@ void LLEventQueue::flush() // be processed in the *next* flush() call. EventQueue queue(mEventQueue); mEventQueue.clear(); + // NOTE NOTE NOTE: Any new access to member data beyond this point should + // cause us to move our LLStandardSignal object to a pimpl class along + // with said member data. Then the local shared_ptr will preserve both. + + // DEV-43463: capture a local copy of mSignal. See LLEventStream::post() + // for detailed comments. + boost::shared_ptr<LLStandardSignal> signal(mSignal); for ( ; ! queue.empty(); queue.pop_front()) { - (*mSignal)(queue.front()); + (*signal)(queue.front()); } } diff --git a/indra/llcommon/llevents.h b/indra/llcommon/llevents.h index f52cf33fd8..5646407f6a 100644 --- a/indra/llcommon/llevents.h +++ b/indra/llcommon/llevents.h @@ -44,6 +44,7 @@ #include "llsd.h" #include "llsingleton.h" #include "lldependencies.h" +#include "ll_template_cast.h" /*==========================================================================*| // override this to allow binding free functions with more parameters @@ -266,6 +267,14 @@ namespace LLEventDetail */ template <typename LISTENER> LLBoundListener visit_and_connect(const LISTENER& listener, + const ConnectFunc& connect_func) + { + return visit_and_connect("", listener, connect_func); + } + /// 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); } // namespace LLEventDetail @@ -468,7 +477,8 @@ public: // 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(listener, + return LLEventDetail::visit_and_connect(name, + listener, boost::bind(&LLEventPump::listen_impl, this, name, @@ -522,7 +532,7 @@ private: protected: /// implement the dispatching - boost::scoped_ptr<LLStandardSignal> mSignal; + boost::shared_ptr<LLStandardSignal> mSignal; /// valve open? bool mEnabled; @@ -664,6 +674,60 @@ private: LLSD mReqid; }; +/** + * Base class for LLListenerWrapper. See visit_and_connect() and llwrap(). We + * provide virtual @c accept_xxx() methods, customization points allowing a + * subclass access to certain data visible at LLEventPump::listen() time. + * Example subclass usage: + * + * @code + * myEventPump.listen("somename", + * llwrap<MyListenerWrapper>(boost::bind(&MyClass::method, instance, _1))); + * @endcode + * + * Because of the anticipated usage (note the anonymous temporary + * MyListenerWrapper instance in the example above), the @c accept_xxx() + * methods must be @c const. + */ +class LL_COMMON_API LLListenerWrapperBase +{ +public: + /// New instance. The accept_xxx() machinery makes it important to use + /// shared_ptrs for our data. Many copies of this object are made before + /// the instance that actually ends up in the signal, yet accept_xxx() + /// will later be called on the @em original instance. All copies of the + /// same original instance must share the same data. + LLListenerWrapperBase(): + mName(new std::string), + mConnection(new LLBoundListener) + { + } + /// Copy constructor. Copy shared_ptrs to original instance data. + LLListenerWrapperBase(const LLListenerWrapperBase& that): + mName(that.mName), + mConnection(that.mConnection) + { + } + + /// Ask LLEventPump::listen() for the listener name + virtual void accept_name(const std::string& name) const + { + *mName = name; + } + + /// Ask LLEventPump::listen() for the new connection + virtual void accept_connection(const LLBoundListener& connection) const + { + *mConnection = connection; + } + +protected: + /// Listener name. + boost::shared_ptr<std::string> mName; + /// Connection. + boost::shared_ptr<LLBoundListener> mConnection; +}; + /***************************************************************************** * Underpinnings *****************************************************************************/ @@ -898,7 +962,8 @@ namespace LLEventDetail * LLStandardSignal, returning LLBoundListener. */ template <typename LISTENER> - LLBoundListener visit_and_connect(const LISTENER& raw_listener, + LLBoundListener visit_and_connect(const std::string& name, + const LISTENER& raw_listener, const ConnectFunc& connect_func) { // Capture the listener @@ -913,14 +978,20 @@ namespace LLEventDetail // 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. At present, wrapping - // this functionality into this function is a bit silly: we don't - // really need a visit_and_connect() function any more, just a visit() - // function. The definition of this function dates from when, after - // visit_each(), after establishing the connection, we had to - // postprocess the new connection with the visitor object. That's no - // longer necessary. - return connect_func(listener); + // Make the connection using passed function. + LLBoundListener connection(connect_func(listener)); + // If the LISTENER is an LLListenerWrapperBase subclass, pass it the + // desired information. It's important that we pass the raw_listener + // so the compiler can make decisions based on its original type. + const LLListenerWrapperBase* lwb = + ll_template_cast<const LLListenerWrapperBase*>(&raw_listener); + if (lwb) + { + lwb->accept_name(name); + lwb->accept_connection(connection); + } + // In any case, show new connection to caller. + return connection; } } // namespace LLEventDetail diff --git a/indra/llcommon/lllistenerwrapper.h b/indra/llcommon/lllistenerwrapper.h new file mode 100644 index 0000000000..e7bad1423a --- /dev/null +++ b/indra/llcommon/lllistenerwrapper.h @@ -0,0 +1,181 @@ +/** + * @file lllistenerwrapper.h + * @author Nat Goodspeed + * @date 2009-11-30 + * @brief Introduce LLListenerWrapper template + * + * $LicenseInfo:firstyear=2009&license=viewergpl$ + * Copyright (c) 2009, Linden Research, Inc. + * $/LicenseInfo$ + */ + +#if ! defined(LL_LLLISTENERWRAPPER_H) +#define LL_LLLISTENERWRAPPER_H + +#include "llevents.h" // LLListenerWrapperBase +#include <boost/visit_each.hpp> + +/** + * Template base class for coding wrappers for LLEventPump listeners. + * + * Derive your listener wrapper from LLListenerWrapper. You must use + * LLLISTENER_WRAPPER_SUBCLASS() so your subclass will play nicely with + * boost::visit_each (q.v.). That way boost::signals2 can still detect + * derivation from LLEventTrackable, and so forth. + */ +template <typename LISTENER> +class LL_COMMON_API LLListenerWrapper: public LLListenerWrapperBase +{ +public: + /// Wrap an arbitrary listener object + LLListenerWrapper(const LISTENER& listener): + mListener(listener) + {} + + /// call + virtual bool operator()(const LLSD& event) + { + return mListener(event); + } + + /// Allow boost::visit_each() to peek at our mListener. + template <class V> + void accept_visitor(V& visitor) const + { + using boost::visit_each; + visit_each(visitor, mListener, 0); + } + +private: + LISTENER mListener; +}; + +/** + * Specialize boost::visit_each() (leveraging ADL) to peek inside an + * LLListenerWrapper<T> to traverse its LISTENER. We borrow the + * accept_visitor() pattern from boost::bind(), avoiding the need to make + * mListener public. + */ +template <class V, typename T> +void visit_each(V& visitor, const LLListenerWrapper<T>& wrapper, int) +{ + wrapper.accept_visitor(visitor); +} + +/// use this (sigh!) for each subclass of LLListenerWrapper<T> you write +#define LLLISTENER_WRAPPER_SUBCLASS(CLASS) \ +template <class V, typename T> \ +void visit_each(V& visitor, const CLASS<T>& wrapper, int) \ +{ \ + visit_each(visitor, static_cast<const LLListenerWrapper<T>&>(wrapper), 0); \ +} \ + \ +/* Have to state this explicitly, rather than using LL_TEMPLATE_CONVERTIBLE, */ \ +/* because the source type is itself a template. */ \ +template <typename T> \ +struct ll_template_cast_impl<const LLListenerWrapperBase*, const CLASS<T>*> \ +{ \ + const LLListenerWrapperBase* operator()(const CLASS<T>* wrapper) \ + { \ + return wrapper; \ + } \ +} + +/** + * Make an instance of a listener wrapper. Every wrapper class must be a + * template accepting a listener object of arbitrary type. In particular, the + * type of a boost::bind() expression is deliberately undocumented. So we + * can't just write Wrapper<CorrectType>(boost::bind(...)). Instead we must + * write llwrap<Wrapper>(boost::bind(...)). + */ +template <template<typename> class WRAPPER, typename T> +WRAPPER<T> LL_COMMON_API llwrap(const T& listener) +{ + return WRAPPER<T>(listener); +} + +/** + * This LLListenerWrapper template subclass is used to report entry/exit to an + * event listener, by changing this: + * @code + * someEventPump.listen("MyClass", + * boost::bind(&MyClass::method, ptr, _1)); + * @endcode + * to this: + * @code + * someEventPump.listen("MyClass", + * llwrap<LLCoutListener>( + * boost::bind(&MyClass::method, ptr, _1))); + * @endcode + */ +template <class LISTENER> +class LL_COMMON_API LLCoutListener: public LLListenerWrapper<LISTENER> +{ + typedef LLListenerWrapper<LISTENER> super; + +public: + /// Wrap an arbitrary listener object + LLCoutListener(const LISTENER& listener): + super(listener) + {} + + /// call + virtual bool operator()(const LLSD& event) + { + std::cout << "Entering listener " << *super::mName << " with " << event << std::endl; + bool handled = super::operator()(event); + std::cout << "Leaving listener " << *super::mName; + if (handled) + { + std::cout << " (handled)"; + } + std::cout << std::endl; + return handled; + } +}; + +LLLISTENER_WRAPPER_SUBCLASS(LLCoutListener); + +/** + * This LLListenerWrapper template subclass is used to log entry/exit to an + * event listener, by changing this: + * @code + * someEventPump.listen("MyClass", + * boost::bind(&MyClass::method, ptr, _1)); + * @endcode + * to this: + * @code + * someEventPump.listen("MyClass", + * llwrap<LLLogListener>( + * boost::bind(&MyClass::method, ptr, _1))); + * @endcode + */ +template <class LISTENER> +class LL_COMMON_API LLLogListener: public LLListenerWrapper<LISTENER> +{ + typedef LLListenerWrapper<LISTENER> super; + +public: + /// Wrap an arbitrary listener object + LLLogListener(const LISTENER& listener): + super(listener) + {} + + /// call + virtual bool operator()(const LLSD& event) + { + LL_DEBUGS("LLLogListener") << "Entering listener " << *super::mName << " with " << event << LL_ENDL; + bool handled = super::operator()(event); + LL_DEBUGS("LLLogListener") << "Leaving listener " << *super::mName; + if (handled) + { + LL_CONT << " (handled)"; + } + LL_CONT << LL_ENDL; + return handled; + } +}; + +LLLISTENER_WRAPPER_SUBCLASS(LLLogListener); + +#endif /* ! defined(LL_LLLISTENERWRAPPER_H) */ |