From 5a260e0cc3beec45da1d29578855524977206022 Mon Sep 17 00:00:00 2001 From: Nat Goodspeed Date: Thu, 30 May 2019 10:39:37 -0400 Subject: SL-11216: Convert LLVersionInfo to an LLSingleton. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This changeset is meant to exemplify how to convert a "namespace" class whose methods are static -- and whose data are module-static -- to an LLSingleton. LLVersionInfo has no initClass() or cleanupClass() methods, but the general idea is the same. * Derive the class from LLSingleton: class LLSomeSingleton: public LLSingleton { ... }; * Add LLSINGLETON(LLSomeSingleton); in the private section of the class. This usage implies a separate LLSomeSingleton::LLSomeSingleton() definition, as described in indra/llcommon/llsingleton.h. * Move module-scope data in the .cpp file to non-static class members. Change any sVariableName to mVariableName to avoid being outright misleading. * Make static class methods non-static. Remove '//static' comments from method definitions as needed. * For LLVersionInfo specifically, the 'const std::string&' return type was replaced with 'std::string'. Returning a reference to a static or a member, const or otherwise, is an anti-pattern: the interface constrains the implementation, prohibiting possibly later returning a temporary (an expression). * For LLVersionInfo specifically, 'const S32' return type was replaced with simple 'S32'. 'const' is just noise in that usage. * Simple member initialization (e.g. the original initializer expressions for static variables) can be done with member{ value } initializers (no examples here though). * Delete initClass() method. * LLSingleton's forté is of course lazy initialization. It might work to simply delete any calls to initClass(). But if there are side effects that must happen at that moment, replace LLSomeSingleton::initClass() with (void)LLSomeSingleton::instance(); * Most initClass() initialization can be done in the constructor, as would normally be the case. * Initialization that might cause a circular LLSingleton reference should be moved to initSingleton(). Override 'void initSingleton();' should be private. * For LLVersionInfo specifically, certain initialization that used to be lazily performed was made unconditional, due to its low cost. * For LLVersionInfo specifically, certain initialization involved calling methods that have become non-static. This was moved to initSingleton() because, in a constructor body, 'this' does not yet point to the enclosing class. * Delete cleanupClass() method. * There is already a generic LLSingletonBase::deleteAll() call in LLAppViewer::cleanup(). It might work to let this new LLSingleton be cleaned up with all the rest. But if there are side effects that must happen at that moment, replace LLSomeSingleton::cleanupClass() with LLSomeSingleton::deleteSingleton(). That said, much of the benefit of converting to LLSingleton is deleteAll()'s guarantee that cross-LLSingleton dependencies will be properly honored: we're trying to migrate the code base away from the present fragile manual cleanup sequence. * Most cleanupClass() cleanup can be done in the destructor, as would normally be the case. * Cleanup that might throw an exception should be moved to cleanupSingleton(). Override 'void cleanupSingleton();' should be private. * Within LLSomeSingleton methods, remove any existing LLSomeSingleton::methodName() qualification: simple methodName() is better. * In the rest of the code base, convert most LLSomeSingleton::methodName() references to LLSomeSingleton::instance().methodName(). (Prefer instance() to getInstance() because a reference does not admit the possibility of NULL.) * Of course, LLSomeSingleton::ENUM_VALUE can remain unchanged. In general, for many successive references to an LLSingleton instance, it can be useful to capture the instance() as in: auto& versionInfo{LLVersionInfo::instance()}; // ... versionInfo.getVersion() ... We did not do that here only to simplify the code review. The STRINGIZE(expression) macro encapsulates: std::ostringstream out; out << expression; return out.str(); We used that in a couple places. For LLVersionInfo specifically, lllogininstance_test.cpp used to dummy out a couple specific static methods. It's harder to dummy out LLSingleton::instance() references, so we add the real class to that test. --- indra/newview/CMakeLists.txt | 1 + 1 file changed, 1 insertion(+) (limited to 'indra/newview/CMakeLists.txt') diff --git a/indra/newview/CMakeLists.txt b/indra/newview/CMakeLists.txt index 800696825f..dc0d737540 100644 --- a/indra/newview/CMakeLists.txt +++ b/indra/newview/CMakeLists.txt @@ -2434,6 +2434,7 @@ if (LL_TESTS) set_source_files_properties( lllogininstance.cpp PROPERTIES + LL_TEST_ADDITIONAL_SOURCE_FILES llversioninfo.cpp LL_TEST_ADDITIONAL_LIBRARIES "${BOOST_SYSTEM_LIBRARY}" ) -- cgit v1.2.3