{"id":1913,"date":"2014-01-31T07:00:00","date_gmt":"2014-01-31T07:00:00","guid":{"rendered":"https:\/\/blogs.msdn.microsoft.com\/oldnewthing\/2014\/01\/31\/non-psychic-debugging-if-somebodys-complaining-that-a-collection-should-be-empty-but-isnt-you-might-want-to-see-whats-in-there\/"},"modified":"2014-01-31T07:00:00","modified_gmt":"2014-01-31T07:00:00","slug":"non-psychic-debugging-if-somebodys-complaining-that-a-collection-should-be-empty-but-isnt-you-might-want-to-see-whats-in-there","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20140131-00\/?p=1913","title":{"rendered":"Non-psychic debugging: If somebody's complaining that a collection should be empty but isn't, you might want to see what's in there"},"content":{"rendered":"

\nA programmer on the GHI team\n(yes,\n\nthe same GHI team<\/a>)\nreported that they were hitting an assertion failure\nusing an internal library and asked for help debugging it.\n<\/p>\n

\n\/\/ All factories should be unregistered by now\nassert(m_pFactoryList->IsEmpty());\n<\/pre>\n
\n“Can somebody help me figure out which factory it is that\ndid not get unregistered?”\n<\/p>\n
\nI didn’t work on this internal library, but on the other hand\nI’m not afraid to look inside.\n<\/p>\n
\nLet’s see what a m_pFactory­List<\/code> looks like.\n<\/p>\n
\n0:000> ?? this->m_pFactoryList\nclass LookupTable<CFactory*>\n   +0x000 m_uListSize      : 1<\/span> \/\/ this probably means that the list has one element<\/font>\n   +0x004 m_pList          : 0x00212e60<\/span> LookupTable<CFactory*>::ENTRY \/\/ this is probably the list<\/font>\n   +0x008 m_uCapacity      : 0x7f\n0:000> ?? this->m_pFactoryList->m_pList\nstruct LookupTable<CFactory*>::ENTRY * 0x00212e60\n   +0x000 pszName          : 0x02cf4048<\/span>  \"GHI_factory\"\n   +0x004 data             : 0x02cf4ce0<\/span> CFactory* \/\/ I bet this is the item that got leaked<\/font>\n0:000> dps 0x02cf4ce0 l1\n02cf4ce0  6b626d58 GHI!CGhiFactory::`vftable`\n<\/pre>\n
\nNo psychic powers needed here.\nI just followed my nose.\n<\/p>\n
\nThe assertion says that a list is not empty.\nTherefore, we should look to see what is on the list.\n<\/p>\n
\nAs a general rule, code is not intentionally written to be\nimpossible to understand.\nThe person who wrote it meant well,\nso if you see a member called\nm_uList­Size<\/code>, it’s a pretty safe bet that it\nrepresents the list size.\nAnd if you see a member called\nm_pList<\/code>,\nit probably points to the start of the list.<\/p>\n","protected":false},"excerpt":{"rendered":"
A programmer on the GHI team (yes, the same GHI team) reported that they were hitting an assertion failure using an internal library and asked for help debugging it. \/\/ All factories should be unregistered by now assert(m_pFactoryList->IsEmpty()); “Can somebody help me figure out which factory it is that did not get unregistered?” I didn’t […]<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[25],"class_list":["post-1913","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":"
A programmer on the GHI team (yes, the same GHI team) reported that they were hitting an assertion failure using an internal library and asked for help debugging it. \/\/ All factories should be unregistered by now assert(m_pFactoryList->IsEmpty()); “Can somebody help me figure out which factory it is that did not get unregistered?” I didn’t […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/1913","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=1913"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/1913\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=1913"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=1913"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=1913"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}