AsyncObserver (#4444)

* feat(AsyncObserver): Improve NotificationCenter speed and usability #4414

* fix(Notification): add missing header

* feat(Any): add checkers for holding nullptr #4447

* feat(NotificationCenter): g++ build and refactoring #4414

* fix(Observer): compile errors on some compilers #4414

* fix(NotificationCenter): compile errors #4414

* chore(ParallelSocketAcceptor): remove unnecessary include and using from header

* feat(AsyncNotificationCenter): add #4414

* test(AsyncNotificationCenter): add mixed observer types to the test #4414

* fix(AsyncNotificationCenter): hangs on program exit #4414

* fix(dev): friend not honored, temporarily make private members public

* fix(AsyncNotificationCenter); remove default #4414

Foundation/Foundation_vs160.vcxproj

@@ -577,6 +577,7 @@
     <ClCompile Include="src\Ascii.cpp" />
     <ClCompile Include="src\ASCIIEncoding.cpp" />
     <ClCompile Include="src\AsyncChannel.cpp" />
+    <ClCompile Include="src\AsyncNotificationCenter.cpp" />
     <ClCompile Include="src\AtomicCounter.cpp" />
     <ClCompile Include="src\Base32Decoder.cpp" />
     <ClCompile Include="src\Base32Encoder.cpp" />
@@ -1493,6 +1494,7 @@
     <ClInclude Include="include\Poco\AccessExpireStrategy.h" />
     <ClInclude Include="include\Poco\ActiveDispatcher.h" />
     <ClInclude Include="include\Poco\ActiveMethod.h" />
+    <ClInclude Include="include\Poco\AsyncObserver.h" />
     <ClInclude Include="include\Poco\ActiveResult.h" />
     <ClInclude Include="include\Poco\ActiveRunnable.h" />
     <ClInclude Include="include\Poco\ActiveStarter.h" />
@@ -1502,6 +1504,8 @@
     <ClInclude Include="include\Poco\Ascii.h" />
     <ClInclude Include="include\Poco\ASCIIEncoding.h" />
     <ClInclude Include="include\Poco\AsyncChannel.h" />
+    <ClInclude Include="include\Poco\AsyncObserver.h" />
+    <ClInclude Include="include\Poco\AsyncNotificationCenter.h" />
     <ClInclude Include="include\Poco\AtomicCounter.h" />
     <ClInclude Include="include\Poco\AutoPtr.h" />
     <ClInclude Include="include\Poco\AutoReleasePool.h" />

Foundation/Foundation_vs160.vcxproj.filters

@@ -573,6 +573,9 @@
     <ClCompile Include="src\AbstractObserver.cpp">
       <Filter>Notifications\Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="src\AsyncNotificationCenter.cpp">
+      <Filter>Notifications\Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="src\Notification.cpp">
       <Filter>Notifications\Source Files</Filter>
     </ClCompile>
@@ -1448,6 +1451,12 @@
     <ClInclude Include="include\Poco\NObserver.h">
       <Filter>Notifications\Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="include\Poco\AsyncObserver.h">
+      <Filter>Notifications\Header Files</Filter>
+    </ClInclude>
+    <ClInclude Include="include\Poco\AsyncNotificationCenter.h">
+      <Filter>Notifications\Header Files</Filter>
+    </ClInclude>
     <ClInclude Include="include\Poco\Notification.h">
       <Filter>Notifications\Header Files</Filter>
     </ClInclude>

Foundation/Foundation_vs170.vcxproj

@@ -878,6 +878,7 @@
     <ClCompile Include="src\Ascii.cpp" />
     <ClCompile Include="src\ASCIIEncoding.cpp" />
     <ClCompile Include="src\AsyncChannel.cpp" />
+    <ClCompile Include="src\AsyncNotificationCenter.cpp" />
     <ClCompile Include="src\AtomicCounter.cpp" />
     <ClCompile Include="src\Base32Decoder.cpp" />
     <ClCompile Include="src\Base32Encoder.cpp" />
@@ -2109,6 +2110,8 @@
     <ClInclude Include="include\Poco\Ascii.h" />
     <ClInclude Include="include\Poco\ASCIIEncoding.h" />
     <ClInclude Include="include\Poco\AsyncChannel.h" />
+    <ClInclude Include="include\Poco\AsyncObserver.h" />
+    <ClInclude Include="include\Poco\AsyncNotificationCenter.h" />
     <ClInclude Include="include\Poco\AtomicCounter.h" />
     <ClInclude Include="include\Poco\AutoPtr.h" />
     <ClInclude Include="include\Poco\AutoReleasePool.h" />

Foundation/Foundation_vs170.vcxproj.filters

@@ -579,6 +579,9 @@
     <ClCompile Include="src\NotificationCenter.cpp">
       <Filter>Notifications\Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="src\AsyncNotificationCenter.cpp">
+      <Filter>Notifications\Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="src\NotificationQueue.cpp">
       <Filter>Notifications\Source Files</Filter>
     </ClCompile>
@@ -1447,6 +1450,12 @@
     <ClInclude Include="include\Poco\AbstractObserver.h">
       <Filter>Notifications\Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="include\Poco\AsyncObserver.h">
+      <Filter>Notifications\Header Files</Filter>
+    </ClInclude>
+    <ClInclude Include="include\Poco\AsyncNotificationCenter.h">
+      <Filter>Notifications\Header Files</Filter>
+    </ClInclude>
     <ClInclude Include="include\Poco\NObserver.h">
       <Filter>Notifications\Header Files</Filter>
     </ClInclude>

Foundation/Makefile

@@ -6,7 +6,7 @@
 
 include $(POCO_BASE)/build/rules/global
 
-objects = ArchiveStrategy Ascii ASCIIEncoding AsyncChannel ActiveThreadPool\
+objects = ArchiveStrategy Ascii ASCIIEncoding AsyncChannel AsyncNotificationCenter ActiveThreadPool\
 	Base32Decoder Base32Encoder Base64Decoder Base64Encoder \
 	BinaryReader BinaryWriter Bugcheck ByteOrder Channel Checksum Clock Configurable ConsoleChannel \
 	Condition CountingStream DateTime LocalDateTime DateTimeFormat DateTimeFormatter DateTimeParser \

Foundation/include/Poco/AbstractObserver.h

@@ -37,12 +37,42 @@ class Foundation_API AbstractObserver
 	AbstractObserver& operator = (const AbstractObserver& observer);
 
 	virtual void notify(Notification* pNf) const = 0;
+
 	virtual bool equals(const AbstractObserver& observer) const = 0;
-	virtual bool accepts(Notification* pNf, const char* pName = 0) const = 0;
+
+	[[deprecated("use `Poco::Any accepts(Notification*)` instead")]]
+	virtual bool accepts(Notification* pNf, const char* pName) const = 0;
+
+	virtual bool accepts(const Notification::Ptr& pNf) const = 0;
+
 	virtual AbstractObserver* clone() const = 0;
+
+	virtual void start();
+		/// No-op.
+		/// This method can be implemented by inheriting classes which require
+		/// explicit start in order to begin processing notifications.
+
 	virtual void disable() = 0;
+
+	virtual int backlog() const;
+		/// Returns number of queued messages that this Observer has.
+		/// For non-active (synchronous) observers, always returns zero.
 };
 
+//
+// inlines
+//
+
+inline void AbstractObserver::start()
+{
+}
+
+
+inline int AbstractObserver::backlog() const
+{
+	return 0;
+}
+
 
 } // namespace Poco
 

Foundation/include/Poco/Any.h

@@ -24,13 +24,12 @@
 #include <cstddef>
 
 
-#define poco_any_assert(cond) do { if (!(cond)) std::abort(); } while (0)
-
-
 namespace Poco {
 
 class Any;
 
+using namespace std::string_literals;
+
 namespace Dynamic {
 
 class Var;
@@ -409,12 +408,12 @@ ValueType* AnyCast(Any* operand)
 	/// to the stored value.
 	///
 	/// Example Usage:
-	///	 MyType* pTmp = AnyCast<MyType*>(pAny).
-	/// Will return NULL if the cast fails, i.e. types don't match.
+	///	 MyType* pTmp = AnyCast<MyType>(pAny).
+	/// Returns nullptr if the types don't match.
 {
 	return operand && operand->type() == typeid(ValueType)
 				? &static_cast<Any::Holder<ValueType>*>(operand->content())->_held
-				: 0;
+				: nullptr;
 }
 
 
@@ -424,8 +423,8 @@ const ValueType* AnyCast(const Any* operand)
 	/// to the stored value.
 	///
 	/// Example Usage:
-	///	 const MyType* pTmp = AnyCast<MyType*>(pAny).
-	/// Will return NULL if the cast fails, i.e. types don't match.
+	///	 const MyType* pTmp = AnyCast<MyType>(pAny).
+	/// Returns nullptr if the types don't match.
 {
 	return AnyCast<ValueType>(const_cast<Any*>(operand));
 }
@@ -442,18 +441,19 @@ ValueType AnyCast(Any& operand)
 	/// Some compilers will accept this code although a copy is returned. Use the RefAnyCast in
 	/// these cases.
 {
-	typedef typename TypeWrapper<ValueType>::TYPE NonRef;
+	using NonRef = typename TypeWrapper<ValueType>::TYPE;
 
 	NonRef* result = AnyCast<NonRef>(&operand);
 	if (!result)
 	{
-		std::string s = "RefAnyCast: Failed to convert between Any types ";
+		std::string s(__func__);
+		s.append(": Failed to convert between Any types "s);
 		if (operand.content())
 		{
 			s.append(1, '(');
-			s.append(operand.content()->type().name());
+			s.append(Poco::demangle(operand.content()->type().name()));
 			s.append(" => ");
-			s.append(typeid(ValueType).name());
+			s.append(Poco::demangle<ValueType>());
 			s.append(1, ')');
 		}
 		throw BadCastException(s);
@@ -473,7 +473,7 @@ ValueType AnyCast(const Any& operand)
 	/// Some compilers will accept this code although a copy is returned. Use the RefAnyCast in
 	/// these cases.
 {
-	typedef typename TypeWrapper<ValueType>::TYPE NonRef;
+	using NonRef = typename TypeWrapper<ValueType>::TYPE;
 
 	return AnyCast<NonRef&>(const_cast<Any&>(operand));
 }
@@ -489,13 +489,14 @@ const ValueType& RefAnyCast(const Any & operand)
 	ValueType* result = AnyCast<ValueType>(const_cast<Any*>(&operand));
 	if (!result)
 	{
-		std::string s = "RefAnyCast: Failed to convert between Any types ";
+		std::string s(__func__);
+		s.append(": Failed to convert between Any types "s);
 		if (operand.content())
 		{
 			s.append(1, '(');
-			s.append(operand.content()->type().name());
+			s.append(Poco::demangle(operand.content()->type().name()));
 			s.append(" => ");
-			s.append(typeid(ValueType).name());
+			s.append(Poco::demangle<ValueType>());
 			s.append(1, ')');
 		}
 		throw BadCastException(s);
@@ -514,13 +515,14 @@ ValueType& RefAnyCast(Any& operand)
 	ValueType* result = AnyCast<ValueType>(&operand);
 	if (!result)
 	{
-		std::string s = "RefAnyCast: Failed to convert between Any types ";
+		std::string s(__func__);
+		s.append(": Failed to convert between Any types "s);
 		if (operand.content())
 		{
 			s.append(1, '(');
-			s.append(operand.content()->type().name());
+			s.append(Poco::demangle(operand.content()->type().name()));
 			s.append(" => ");
-			s.append(typeid(ValueType).name());
+			s.append(Poco::demangle<ValueType>());
 			s.append(1, ')');
 		}
 		throw BadCastException(s);
@@ -553,6 +555,26 @@ const ValueType* UnsafeAnyCast(const Any* operand)
 }
 
 
+template <typename ValueType>
+bool AnyHoldsNullPtr(const Any& any)
+	/// Returns true if any holds a null pointer.
+	/// Fails to compile if `ValueType` is not a pointer.
+{
+	poco_static_assert_ptr(ValueType);
+	return (AnyCast<ValueType>(any) == nullptr);
+}
+
+
+template <typename ValueType>
+bool AnyHoldsNullPtr(const Any* pAny)
+	/// Returns true if the Any pointed to holds a null pointer.
+	/// Returns false if `pAny` is a null pointer.
+{
+	if (!pAny) return false;
+	return (AnyHoldsNullPtr<ValueType>(*pAny));
+}
+
+
 } // namespace Poco
 
 

Foundation/include/Poco/AsyncNotificationCenter.h

@@ -0,0 +1,77 @@
+//
+// AsyncNotificationCenter.h
+//
+// Library: Foundation
+// Package: Notifications
+// Module:  AsyncNotificationCenter
+//
+// Definition of the AsyncNotificationCenter class.
+//
+// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
+// Aleph ONE Software Engineering d.o.o.,
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef Foundation_AsyncNotificationCenter_INCLUDED
+#define Foundation_AsyncNotificationCenter_INCLUDED
+
+
+#include "Poco/Foundation.h"
+#include "Poco/NotificationCenter.h"
+#include "Poco/Thread.h"
+#include "Poco/Stopwatch.h"
+#include "Poco/Debugger.h"
+#include "Poco/ErrorHandler.h"
+#include "Poco/Format.h"
+#include "Poco/RunnableAdapter.h"
+#include "Poco/NotificationQueue.h"
+
+
+namespace Poco {
+
+
+class Foundation_API AsyncNotificationCenter: public NotificationCenter
+	/// AsyncNotificationCenter decouples posting of notifications
+	/// from notifying subscribers by calling observers' notification
+	/// handler in a dedicated thread.
+{
+public:
+	AsyncNotificationCenter();
+		/// Creates the AsyncNotificationCenter and starts the notifying thread.
+
+	~AsyncNotificationCenter();
+		/// Stops the notifying thread and destroys the AsyncNotificationCenter.
+
+	AsyncNotificationCenter& operator = (const AsyncNotificationCenter&) = delete;
+	AsyncNotificationCenter(const AsyncNotificationCenter&) = delete;
+	AsyncNotificationCenter& operator = (AsyncNotificationCenter&&) = delete;
+	AsyncNotificationCenter(AsyncNotificationCenter&&) = delete;
+
+	virtual void postNotification(Notification::Ptr pNotification);
+		/// Enqueues notification into the notification queue.
+
+	virtual int backlog() const;
+		/// Returns the numbner of notifications in the notification queue.
+
+private:
+	void start();
+	void stop();
+	void dequeue();
+
+	using Adapter = RunnableAdapter<AsyncNotificationCenter>;
+
+	Thread _thread;
+	NotificationQueue _nq;
+	Adapter _ra;
+	std::atomic<bool> _started;
+	std::atomic<bool> _done;
+};
+
+
+} // namespace Poco
+
+
+#endif // Foundation_AsyncNotificationCenter_INCLUDED