Introduce ResettableMutexGuardScopedReleaser

And use it to guarantee reretting a guard, without having to do that
explicitly in exception handlers.

Change-Id: I4727cb5b7f37b25e203396957797d24a093e0797
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/165775
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

2 files changed, 22 insertions, 8 deletions

diff --git a/desktop/source/deployment/registry/package/dp_package.cxx b/desktop/source/deployment/registry/package/dp_package.cxx
index d5c1feeb4992..494ce437e1e9 100644
--- a/desktop/source/deployment/registry/package/dp_package.cxx
+++ b/desktop/source/deployment/registry/package/dp_package.cxx
@@ -808,14 +808,11 @@ void BackendImpl::PackageImpl::processPackage_(
                 // can occur if the main thread calls isRegistered() on this
                 // package or any of its parents. So, temporarily release
                 // this package's mutex while registering the child package.
-                guard.clear();
+                osl::ResettableMutexGuardScopedReleaser releaser(guard);
                 xPackage->registerPackage( startup, xSubAbortChannel, xCmdEnv );
-                guard.reset();
             }
             catch (const Exception &)
             {
-                guard.reset();
-
                //We even try a rollback if the user cancelled the action (CommandAbortedException)
                 //in order to prevent invalid database entries.
                 Any exc( ::cppu::getCaughtException() );
@@ -866,10 +863,6 @@ void BackendImpl::PackageImpl::processPackage_(
                     ::cppu::throwException(exc);
                 }
             }
-            catch (...) {
-                guard.reset();
-                throw;
-            }
 
             data.items.emplace_back(xPackage->getURL(),
                                  xPackage->getPackageType()->getMediaType());
diff --git a/include/osl/mutex.hxx b/include/osl/mutex.hxx
index 481a2bb55002..ca75cc9fb2dc 100644
--- a/include/osl/mutex.hxx
+++ b/include/osl/mutex.hxx
@@ -252,9 +252,30 @@ namespace osl
         }
     };
 
+#ifdef LIBO_INTERNAL_ONLY
+    // A RAII helper to allow exception-safe scoped release of an acquired object
+    template<class ResettableGuard_t>
+    class ResettableGuardScopedReleaser
+    {
+    public:
+        ResettableGuardScopedReleaser(ResettableGuard_t& r)
+            : m_rResettableGuard(r)
+        {
+            m_rResettableGuard.clear();
+        }
+        ~ResettableGuardScopedReleaser() { m_rResettableGuard.reset(); }
+
+    private:
+        ResettableGuard_t& m_rResettableGuard;
+    };
+#endif
+
     typedef Guard<Mutex> MutexGuard;
     typedef ClearableGuard<Mutex> ClearableMutexGuard;
     typedef ResettableGuard< Mutex > ResettableMutexGuard;
+#ifdef LIBO_INTERNAL_ONLY
+    typedef ResettableGuardScopedReleaser<ResettableMutexGuard> ResettableMutexGuardScopedReleaser;
+#endif
 }
 
 #endif // INCLUDED_OSL_MUTEX_HXX