Don't use std::function in scope guard for performance reasons

Change-Id: I1d2f0307c0bf9ff5abde74d3326899a1aaa69c40
Reviewed-on: https://gerrit.libreoffice.org/71346
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

2 files changed, 47 insertions, 33 deletions

diff --git a/include/comphelper/flagguard.hxx b/include/comphelper/flagguard.hxx
index 17c78ec5ddc6..44d2f4f73ab4 100644
--- a/include/comphelper/flagguard.hxx
+++ b/include/comphelper/flagguard.hxx
@@ -28,46 +28,44 @@ namespace comphelper
 
     //= FlagRestorationGuard
 
-    class COMPHELPER_DLLPUBLIC FlagRestorationGuard : public ScopeGuard
+    // note: can't store the originalValue in a FlagRestorationGuard member,
+    // because it will be used from base class dtor
+    struct FlagRestorationGuard_Impl
+    {
+        bool & rFlag;
+        bool const originalValue;
+        FlagRestorationGuard_Impl(bool & i_flagRef)
+            : rFlag(i_flagRef), originalValue(i_flagRef) {}
+        void operator()()
+        {
+            rFlag = originalValue;
+        }
+    };
+
+    class FlagRestorationGuard : public ScopeGuard<FlagRestorationGuard_Impl>
     {
     public:
         FlagRestorationGuard( bool& i_flagRef, bool i_temporaryValue )
-            : ScopeGuard(RestoreFlag(i_flagRef))
+            : ScopeGuard(FlagRestorationGuard_Impl(i_flagRef))
         {
             i_flagRef = i_temporaryValue;
         }
-
-        ~FlagRestorationGuard();
-
-    private:
-        // note: can't store the originalValue in a FlagRestorationGuard member,
-        // because it will be used from base class dtor
-        struct RestoreFlag
-        {
-            bool & rFlag;
-            bool const originalValue;
-            RestoreFlag(bool & i_flagRef)
-                : rFlag(i_flagRef), originalValue(i_flagRef) {}
-            void operator()()
-            {
-                rFlag = originalValue;
-            }
-        };
     };
 
 
     //= FlagGuard
 
-    class COMPHELPER_DLLPUBLIC FlagGuard : public ScopeGuard
+    // Guarantees that the flag is true within the scope of the guard, and is set to false after
+    // its destruction, regardless of initial flag value
+    class FlagGuard : public FlagRestorationGuard
     {
     public:
-        explicit FlagGuard( bool& i_flagRef )
-            : ScopeGuard( [&i_flagRef] () { i_flagRef = false; } )
+        // Set flag to false before passing its reference to base class ctor, so that it would be
+        // reset back to false in base class dtor
+        explicit FlagGuard(bool& i_flagRef)
+            : FlagRestorationGuard((i_flagRef = false), true)
         {
-            i_flagRef = true;
         }
-
-        ~FlagGuard();
     };
 
 
diff --git a/include/comphelper/scopeguard.hxx b/include/comphelper/scopeguard.hxx
index cfe012acf340..60836a7661c7 100644
--- a/include/comphelper/scopeguard.hxx
+++ b/include/comphelper/scopeguard.hxx
@@ -21,34 +21,50 @@
 #define INCLUDED_COMPHELPER_SCOPEGUARD_HXX
 
 #include <comphelper/comphelperdllapi.h>
-
-#include <functional>
+#include <sal/log.hxx>
+#include <com/sun/star/uno/Exception.hpp>
 
 namespace comphelper {
 
 /** ScopeGuard to ease writing exception-safe code.
  */
-class COMPHELPER_DLLPUBLIC ScopeGuard
+template <class Func> class ScopeGuard
 {
 public:
     /** @param func function object to be executed in dtor
     */
-    template <typename func_type>
-    explicit ScopeGuard( func_type const & func ) : m_func( func ) {}
+    explicit ScopeGuard( Func && func ) : m_func( std::move(func) ) {}
 
-    ~ScopeGuard();
+    ~ScopeGuard()
+    {
+        if (m_bDismissed)
+            return;
+        try
+        {
+            m_func();
+        }
+        catch (css::uno::Exception& exc)
+        {
+            SAL_WARN("comphelper", "UNO exception occurred: " << exc);
+        }
+        catch (...)
+        {
+            SAL_WARN("comphelper", "unknown exception occurred!");
+        }
+    }
 
     /** Dismisses the scope guard, i.e. the function won't
         be executed.
     */
-    void dismiss();
+    void dismiss() { m_bDismissed = true; }
 
 private:
     // noncopyable until we have good reasons...
     ScopeGuard(const ScopeGuard&) = delete;
     ScopeGuard& operator=(const ScopeGuard&) = delete;
 
-    ::std::function<void ()> m_func;
+    Func m_func;
+    bool m_bDismissed = false;
 };
 
 } // namespace comphelper