MimeDatabase: Add some startup phase tracking

... to warn about situations where Mime types are registered too
late (i.e. after Plugin::initialize() or used too early (i.e. before
Plugin::extensionsInitialized())

Change-Id: I22681e94bfdd508e954bb3457b834ec3ad1f0fee
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/extensionsystem/pluginmanager.cpp

@@ -49,6 +49,7 @@
 #include <utils/algorithm.h>
 #include <utils/executeondestruction.h>
 #include <utils/hostosinfo.h>
+#include <utils/mimetypes/mimedatabase.h>
 #include <utils/qtcassert.h>
 #include <utils/synchronousprocess.h>
 
@@ -271,9 +272,10 @@ enum { debugLeaks = 0 };
 */
 
 
-using namespace ExtensionSystem;
-using namespace ExtensionSystem::Internal;
 using namespace Utils;
+using namespace ExtensionSystem::Internal;
+
+namespace ExtensionSystem {
 
 static Internal::PluginManagerPrivate *d = 0;
 static PluginManager *m_instance = 0;
@@ -1232,12 +1234,15 @@ void PluginManagerPrivate::removeObject(QObject *obj)
 void PluginManagerPrivate::loadPlugins()
 {
     QList<PluginSpec *> queue = loadQueue();
+    MimeDatabase::setStartupPhase(MimeDatabase::PluginsLoading);
     foreach (PluginSpec *spec, queue) {
         loadPlugin(spec, PluginSpec::Loaded);
     }
+    MimeDatabase::setStartupPhase(MimeDatabase::PluginsInitializing);
     foreach (PluginSpec *spec, queue) {
         loadPlugin(spec, PluginSpec::Initialized);
     }
+    MimeDatabase::setStartupPhase(MimeDatabase::PluginsDelayedInitializing);
     Utils::reverseForeach(queue, [this](PluginSpec *spec) {
         loadPlugin(spec, PluginSpec::Running);
         if (spec->state() == PluginSpec::Running) {
@@ -1248,6 +1253,7 @@ void PluginManagerPrivate::loadPlugins()
         }
     });
     emit q->pluginsChanged();
+    MimeDatabase::setStartupPhase(MimeDatabase::UpAndRunning);
 
     delayedInitializeTimer = new QTimer;
     delayedInitializeTimer->setInterval(DELAYED_INITIALIZE_INTERVAL);
@@ -1699,3 +1705,5 @@ QObject *PluginManager::getObjectByClassName(const QString &className)
         return obj->inherits(ba.constData());
     });
 }
+
+} // ExtensionSystem

src/libs/utils/mimetypes/mimedatabase.cpp

@@ -335,6 +335,11 @@ void MimeDatabase::addMimeTypes(const QString &fileName)
 {
     auto d = MimeDatabasePrivate::instance();
     QMutexLocker locker(&d->mutex);
+
+    if (d->m_startupPhase >= MimeDatabase::PluginsDelayedInitializing)
+        qWarning("Adding items from %s to MimeDatabase after initialization time",
+                 qPrintable(fileName));
+
     auto xmlProvider = static_cast<MimeXMLProvider *>(d->provider());
     xmlProvider->addFile(fileName);
 }
@@ -364,11 +369,19 @@ QString MimeDatabase::allFiltersString(QString *allFilesFilter)
 
 QString MimeDatabase::allFilesFilterString()
 {
+    auto d = MimeDatabasePrivate::instance();
+    if (d->m_startupPhase <= MimeDatabase::PluginsInitializing)
+        qWarning("Accessing MimeDatabase files filter strings before plugins are initialized");
+
     return QCoreApplication::translate("Core", ALL_FILES_FILTER.source, ALL_FILES_FILTER.comment);
 }
 
 QStringList MimeDatabase::allGlobPatterns()
 {
+    auto d = MimeDatabasePrivate::instance();
+    if (d->m_startupPhase <= MimeDatabase::PluginsInitializing)
+        qWarning("Accessing MimeDatabase glob patterns before plugins are initialized");
+
     MimeDatabase mdb;
     QStringList patterns;
     foreach (const MimeType &mt, mdb.allMimeTypes())
@@ -384,6 +397,9 @@ MimeType MimeDatabase::mimeTypeForName(const QString &nameOrAlias) const
 {
     QMutexLocker locker(&d->mutex);
 
+    if (d->m_startupPhase <= MimeDatabase::PluginsInitializing)
+        qWarning("Accessing MimeDatabase for %s before plugins are initialized", qPrintable(nameOrAlias));
+
     return d->mimeTypeForName(nameOrAlias);
 }
 
@@ -686,3 +702,12 @@ void MimeDatabase::setMagicRulesForMimeType(const MimeType &mimeType, const QMap
     QMutexLocker locker(&d->mutex);
     return d->provider()->setMagicRulesForMimeType(mimeType, rules);
 }
+
+void MimeDatabase::setStartupPhase(MimeDatabase::StartupPhase phase)
+{
+    auto d = MimeDatabasePrivate::instance();
+    QMutexLocker locker(&d->mutex);
+    if (phase != d->m_startupPhase + 1)
+        qWarning("Unexpected jump in MimedDatabase lifetime from %d to %d", d->m_startupPhase, phase);
+    d->m_startupPhase = phase;
+}

src/libs/utils/mimetypes/mimedatabase.h

@@ -98,6 +98,16 @@ public:
     static void setMagicRulesForMimeType(const MimeType &mimeType,
                                          const QMap<int, QList<Internal::MimeMagicRule> > &rules); // priority -> rules
 
+    // For debugging purposes.
+    enum StartupPhase {
+        BeforeInitialize,
+        PluginsLoading,
+        PluginsInitializing, // Register up to here.
+        PluginsDelayedInitializing, // Use from here on.
+        UpAndRunning
+    };
+    static void setStartupPhase(StartupPhase);
+
 private:
     Internal::MimeDatabasePrivate *d;
 };

src/libs/utils/mimetypes/mimedatabase_p.h

@@ -96,6 +96,8 @@ public:
     mutable MimeProviderBase *m_provider;
     const QString m_defaultMimeType;
     QMutex mutex;
+
+    int m_startupPhase = 0;
 };
 
 } // Internal