Document that QLoggingCategory is thread-safe

Task-number: QTBUG-60475
Change-Id: Idced5e1a8ad1d2d28839fd23126a7bf084141eca
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>

src/corelib/io/qloggingcategory.cpp

@@ -63,6 +63,7 @@ static void setBoolLane(QBasicAtomicInt *atomic, bool enable, int shift)
     \class QLoggingCategory
     \inmodule QtCore
     \since 5.2
+    \threadsafe
 
     \brief The QLoggingCategory class represents a category, or 'area' in the
     logging infrastructure.
@@ -95,6 +96,9 @@ static void setBoolLane(QBasicAtomicInt *atomic, bool enable, int shift)
        \li Category names starting with \c{qt} are reserved for Qt modules.
     \endlist
 
+    QLoggingCategory objects implicitly defined by Q_LOGGING_CATEGORY()
+    are created on first use in a thread-safe manner.
+
     \section1 Checking Category Configuration
 
     QLoggingCategory provides \l isDebugEnabled(), \l isInfoEnabled(),
@@ -458,6 +462,8 @@ void QLoggingCategory::setFilterRules(const QString &rules)
     \note Arguments are not processed if debug output for the category is not
     enabled, so do not rely on any side effects.
 
+    \note Using the macro is thread-safe.
+
     \sa qDebug()
 */
 
@@ -477,6 +483,8 @@ void QLoggingCategory::setFilterRules(const QString &rules)
     \note Arguments might not be processed if debug output for the category is
     not enabled, so do not rely on any side effects.
 
+    \note Using the macro is thread-safe.
+
     \sa qDebug()
 */
 
@@ -499,6 +507,8 @@ void QLoggingCategory::setFilterRules(const QString &rules)
     \note Arguments are not processed if debug output for the category is not
     enabled, so do not rely on any side effects.
 
+    \note Using the macro is thread-safe.
+
     \sa qInfo()
 */
 
@@ -518,6 +528,8 @@ void QLoggingCategory::setFilterRules(const QString &rules)
     \note Arguments might not be processed if debug output for the category is
     not enabled, so do not rely on any side effects.
 
+    \note Using the macro is thread-safe.
+
     \sa qInfo()
 */
 
@@ -540,6 +552,8 @@ void QLoggingCategory::setFilterRules(const QString &rules)
     \note Arguments are not processed if warning output for the category is not
     enabled, so do not rely on any side effects.
 
+    \note Using the macro is thread-safe.
+
     \sa qWarning()
 */
 
@@ -559,6 +573,8 @@ void QLoggingCategory::setFilterRules(const QString &rules)
     \note Arguments might not be processed if warning output for the category is
     not enabled, so do not rely on any side effects.
 
+    \note Using the macro is thread-safe.
+
     \sa qWarning()
 */
 
@@ -581,6 +597,8 @@ void QLoggingCategory::setFilterRules(const QString &rules)
     \note Arguments are not processed if critical output for the category is not
     enabled, so do not rely on any side effects.
 
+    \note Using the macro is thread-safe.
+
     \sa qCritical()
 */
 
@@ -600,6 +618,8 @@ void QLoggingCategory::setFilterRules(const QString &rules)
     \note Arguments might not be processed if critical output for the category
     is not enabled, so do not rely on any side effects.
 
+    \note Using the macro is thread-safe.
+
     \sa qCritical()
 */
 /*!
@@ -624,7 +644,8 @@ void QLoggingCategory::setFilterRules(const QString &rules)
     \a string identifier. By default, all message types are enabled.
 
     Only one translation unit in a library or executable can define a category
-    with a specific name.
+    with a specific name. The implicitly defined QLoggingCategory object is
+    created on first use, in a thread-safe manner.
 
     This macro must be used outside of a class or method.
 */
@@ -640,7 +661,8 @@ void QLoggingCategory::setFilterRules(const QString &rules)
     and more severe are enabled, types with a lower severity are disabled.
 
     Only one translation unit in a library or executable can define a category
-    with a specific name.
+    with a specific name. The implicitly defined QLoggingCategory object is
+    created on first use, in a thread-safe manner.
 
     This macro must be used outside of a class or method. It is only defined
     if variadic macros are supported.