[doxygen] add description for "exception" group

Author: KFilipek

doc/groups_definitions.dox

@@ -163,4 +163,30 @@
 /** @defgroup data_view Data View*/
 /** @defgroup synchronization Synchronization Primitives*/
 /** @defgroup primitives Primitives*/
-/** @defgroup exceptions Exceptions*/
+/** @defgroup exceptions Exceptions
+  * Possible exceptions that could be thrown by the libpmemobj++.
+  *
+  * In runtime, some operations may fail, then all you need is to catch the exception.
+  * Every pmem exception has **std::runtime_error** in its inheritance tree
+  * and contains proper message with an error description.
+  * All exceptions can be caught using just **std::runtime_error**.
+  * Look at the list on this page to explore all exceptions with their descriptions.
+  *
+  * Transaction handles uncaught exceptions thrown inside its scope, then aborts
+  * and rethrow the previous exception. That way you never loose the original
+  * exception and at the same time, the transaction state is handled
+  * properly by the library.
+  *
+  * Let's consider following example:
+  * @snippet examples/mpsc_queue/mpsc_queue.cpp mpsc_main
+  *
+  * There are plenty of try-catch blocks placed to handle possible errors that can happen in some conditions.
+  * E.g. @ref pmem::obj::pool<T>::open can lead to @ref pmem::pool_error.
+  * Next exception, **std::exception**, is placed to handle possible errors during allocation,
+  * coming from @ref pmem::obj::make_persistent. Worth being careful using every new function
+  * because some of exceptions are not obvious, e.g., pmem::obj::pool<T>::close
+  * at the end of the code which may throw **std::logic_error**.
+  *
+  * You should check every function you will use in context of possible
+  * exceptions and then handle them to avoid crash.
+  **/

examples/mpsc_queue/mpsc_queue.cpp

@@ -80,6 +80,7 @@ single_threaded(pmem::obj::pool<root> pop)
 
 //! [mpsc_queue_single_threaded_example]
 
+//! [mpsc_main]
 int
 main(int argc, char *argv[])
 {
@@ -120,3 +121,4 @@ main(int argc, char *argv[])
 	}
 	return 0;
 }
+//! [mpsc_main]