chromium : How KeyedService was created

DependencyManager::CreateContextServices

void DependencyManager::CreateContextServices(base::SupportsUserData* context,
                                              bool is_testing_context) {
  MarkContextLive(context);

  std::vector<DependencyNode*> construction_order;
  if (!dependency_graph_.GetConstructionOrder(&construction_order)) {
    NOTREACHED();
  }

#ifndef NDEBUG
  DumpContextDependencies(context);
#endif

  for (auto* dependency_node : construction_order) {
    KeyedServiceBaseFactory* factory =
        static_cast<KeyedServiceBaseFactory*>(dependency_node);
    if (is_testing_context && factory->ServiceIsNULLWhileTesting() &&
        !factory->HasTestingFactory(context)) {
      factory->SetEmptyTestingFactory(context);
    } else if (factory->ServiceIsCreatedWithContext()) {
      factory->CreateServiceNow(context);
    }
  }
}

#14 0x7f08ec0395de DependencyManager::CreateContextServices()
#15 0x7f08eb2b2410 BrowserContextDependencyManager::DoCreateBrowserContextServices()
#16 0x7f08eb2b22df BrowserContextDependencyManager::CreateBrowserContextServices()
#17 0x55aa9c98a995 ProfileImpl::OnLocaleReady()
#18 0x55aa9c986389 ProfileImpl::OnPrefsLoaded()
#19 0x55aa9c98605d ProfileImpl::ProfileImpl()
#20 0x55aa9c982084 Profile::CreateProfile()
#21 0x55aa9c9f7887 ProfileManager::CreateProfileHelper()
#22 0x55aa9c9e96ba ProfileManager::CreateAndInitializeProfile()
#23 0x55aa9c9e9237 ProfileManager::GetProfile()
#24 0x55aaa015d608 GetStartupProfile()
#25 0x55aa9c56d68f (anonymous namespace)::CreatePrimaryProfile()
#26 0x55aa9c56b376 ChromeBrowserMainParts::PreMainMessageLoopRunImpl()
#27 0x55aa9c56a5dc ChromeBrowserMainParts::PreMainMessageLoopRun()
#28 0x7f08f12591e4 content::BrowserMainLoop::PreMainMessageLoopRun()
#29 0x7f08f0140cfd _ZN4base8internal13FunctorTraitsIMN7content14NetworkContext11DiskCheckerEFvvEvE6InvokeIPS4_JEEEvS6_OT_DpOT0_
#30 0x7f08f0140c74 _ZN4base8internal12InvokeHelperILb0EvE8MakeItSoIMN7content14NetworkContextEFvvEJPS5_EEEvOT_DpOT0_
#31 0x7f08f0140c25 _ZN4base8internal7InvokerINS0_9BindStateIMN7content14NetworkContext11DiskCheckerEFvvEJNS0_17UnretainedWrapperIS5_EEEEEFvvEE7RunImplIRKS7_RKNSt3__15tupleIJS9_EEEJLm0EEEEvOT_OT0_NSG_16integer_sequenceImJXspT1_EEEE
#32 0x7f08f01469dc _ZN4base8internal7InvokerINS0_9BindStateIMN7content14NetworkContext11DiskCheckerEFvvEJNS0_17UnretainedWrapperIS5_EEEEEFvvEE3RunEPNS0_13BindStateBaseE
#33 0x7f08f010150d _ZNKR4base17RepeatingCallbackIFvvEE3RunEv
#34 0x7f08f1ebeedd content::StartupTaskRunner::RunAllTasksNow()
#35 0x7f08f1254a67 content::BrowserMainLoop::CreateStartupTasks()
#36 0x7f08f126360d content::BrowserMainRunnerImpl::Initialize()
#37 0x7f08f124d644 content::BrowserMain()
#38 0x7f08f2e1b9b8 content::RunNamedProcessTypeMain()
#39 0x7f08f2e1e5aa content::ContentMainRunnerImpl::Run()
#40 0x7f08f2e14a6d content::ContentServiceManagerMainDelegate::RunEmbedderProcess()
#41 0x7f08f775689d service_manager::Main()
#42 0x7f08f2e1a7ff content::ContentMain()
#43 0x55aa9ad4d23e ChromeMain
#44 0x55aa9ad4d152 main
#45 0x7f08de135f45 __libc_start_main
#46 0x55aa9ad4d02a _start

BuildServiceInstanceFor AppShortcutManager

#9 0x55aa9b11a513 AppShortcutManager::AppShortcutManager()
#10 0x55aa9b11be82 AppShortcutManagerFactory::BuildServiceInstanceFor()
#11 0x7f08eb2b605a BrowserContextKeyedServiceFactory::BuildServiceInstanceFor()
#12 0x7f08ec03d727 KeyedServiceFactory::GetServiceForContext()
#13 0x7f08ec03ea52 KeyedServiceFactory::CreateServiceNow()

AppShortcutManagerFactory::GetInstance

#2 0x7f5a9625a2d6 DependencyGraph::AddNode()
#3 0x7f5a96269e3c DependencyManager::AddComponent()
#4 0x7f5a9626cdab KeyedServiceBaseFactory::KeyedServiceBaseFactory()
#5 0x7f5a9626d88a KeyedServiceFactory::KeyedServiceFactory()
#6 0x7f5a954e6d7a BrowserContextKeyedServiceFactory::BrowserContextKeyedServiceFactory()
#7 0x5635734e7de3 AppShortcutManagerFactory::AppShortcutManagerFactory()
#8 0x5635734e7fc0 base::DefaultSingletonTraits<>::New()
#9 0x5635734e7f36 base::Singleton<>::get()
#10 0x5635734e7da9 AppShortcutManagerFactory::GetInstance()
#11 0x5635734e3f92 chrome_apps::EnsureBrowserContextKeyedServiceFactoriesBuilt()
#12 0x563574ccc9f8 ChromeBrowserMainExtraPartsProfiles::EnsureBrowserContextKeyedServiceFactoriesBuilt()
#13 0x563574cccdf1 ChromeBrowserMainExtraPartsProfiles::PreProfileInit()
#14 0x5635749387b5 ChromeBrowserMainParts::PreProfileInit()
#15 0x56357492ef9c ChromeBrowserMainPartsLinux::PreProfileInit()
#16 0x5635749371e0 ChromeBrowserMainParts::PreMainMessageLoopRunImpl()
#17 0x5635749365dc ChromeBrowserMainParts::PreMainMessageLoopRun()
#18 0x7f5a9b48a1e4 content::BrowserMainLoop::PreMainMessageLoopRun()

Summary

each KeyedService, such as AppShortcutManager, has a KeyedServiceFactory which are derived from KeyedServiceBaseFactory.
each KeyedServiceFactory must implement BuildServiceInstanceFor interface.
When new instance for each KeyedServiceFactory, it will be added to DependencyManager as a component.
Chromium will call DependencyManager::CreateContextServices at the initial state.
Then traverse all node in DependencyGraph and call each BuildServiceInstanceFor to create the real KeyedService.

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