QDBusMetaTypeId: don't cache the result of qMetaTypeId<>() in static ints

There's not much point in caching the result of qMetaTypeId<>,
because it's already internally memoised.

In addition, the code that initialised the static int caches wasn't
protected against concurrent access under the assumption that the
operations performed were thread-safe.

That is true for most of them, but not for the stores to the static ints,
which race against each other:

   // Thread A               // Thread B
   r1 = initialized /*=false*/
                             r1 = initialized /*=false*/
   r2 = qMetaTypeId<...>();
                             r2 = qMetaTypeId<...>();
   message = r2;             message = r2; // race, ditto for all other ints

To fix, turn the ints into inline functions that just call the respective
qMetaTypeId<>() function.

Change-Id: I5aa80c624872c3867232abc26ffdcde70cd54022
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/dbus/qdbuspendingcall.cpp b/src/dbus/qdbuspendingcall.cpp
index 9ae68c7abc..6d318d9345 100644
--- a/src/dbus/qdbuspendingcall.cpp
+++ b/src/dbus/qdbuspendingcall.cpp
@@ -172,12 +172,12 @@ bool QDBusPendingCallPrivate::setReplyCallback(QObject *target, const char *memb
     // success
     // construct the expected signature
     int count = metaTypes.count() - 1;
-    if (count == 1 && metaTypes.at(1) == QDBusMetaTypeId::message) {
+    if (count == 1 && metaTypes.at(1) == QDBusMetaTypeId::message()) {
         // wildcard slot, can receive anything, so don't set the signature
         return true;
     }
 
-    if (metaTypes.at(count) == QDBusMetaTypeId::message)
+    if (metaTypes.at(count) == QDBusMetaTypeId::message())
         --count;
 
     setMetaTypes(count, count ? metaTypes.constData() + 1 : 0);