From: David Wells Date: Thu, 13 Apr 2017 01:27:06 +0000 (-0400) Subject: Clarify Subscriptor's documentation. X-Git-Tag: v9.0.0-rc1~1693^2 X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2d198e8bb40d1f5bf4089d7389b2d64a8c0cc301;p=dealii.git Clarify Subscriptor's documentation. We no longer use volatile variables, so just state that some features of Subscriptor are disabled when we enable threads. --- diff --git a/include/deal.II/base/subscriptor.h b/include/deal.II/base/subscriptor.h index 37f3b1acad..e46874e91b 100644 --- a/include/deal.II/base/subscriptor.h +++ b/include/deal.II/base/subscriptor.h @@ -42,14 +42,17 @@ DEAL_II_NAMESPACE_OPEN * The utility of this class is even enhanced by providing identifying strings * to the functions subscribe() and unsubscribe(). In case of a hanging * subscription during destruction, this string will be listed in the - * exception's message. For reasons of efficiency, these strings are handled - * as const char*. Therefore, the pointers provided to subscribe() - * and to unsubscribe() must be the same. Strings with equal contents will not - * be recognized to be the same. The handling in SmartPointer will take care - * of this. + * exception's message. These strings are represented as const char + * * pointers since the underlying buffer comes from (and is managed + * by) the run-time type information system: more exactly, these pointers are + * the result the function call typeid(x).name() where + * x is some object. Therefore, the pointers provided to + * subscribe() and to unsubscribe() must be the same. Strings with equal + * contents will not be recognized to be the same. The handling in + * SmartPointer will take care of this. * - * @note Due to a problem with volatile declarations, this additional - * feature is switched off if multithreading is used. + * @note This feature is switched off if multithreading is used (i.e., if + * DEAL_II_WITH_THREADS is on). * * @ingroup memory * @author Guido Kanschat, 1998 - 2005 diff --git a/source/base/subscriptor.cc b/source/base/subscriptor.cc index ce05a88509..5b460a6629 100644 --- a/source/base/subscriptor.cc +++ b/source/base/subscriptor.cc @@ -152,6 +152,8 @@ Subscriptor::subscribe(const char *id) const object_info = &typeid(*this); ++counter; + // This feature is disabled when we compile with threads: see the + // documentation of this class. # ifndef DEAL_II_WITH_THREADS const char *const name = (id != 0) ? id : unknown_subscriber; @@ -183,6 +185,8 @@ Subscriptor::unsubscribe(const char *id) const --counter; + // This feature is disabled when we compile with threads: see the + // documentation of this class. # ifndef DEAL_II_WITH_THREADS map_iterator it = counter_map.find(name); AssertNothrow (it != counter_map.end(), ExcNoSubscriber(object_info->name(), name));