cache access in ConfigurationWrapper (tdf#105575)

If we repeatedly hit a config item like this:
officecfg::Office::Common::Drawinglayer::MaximumPaperWidth::get()
the stuff in configmgr because quite a bottleneck.

So cache the access objects in ConfigurationWrapper.

This change only affects the auto-generated code we use for the
C++ officecfg:: configuration API

Change-Id: Ie2adefc2319dfb362f1ef814690120e13abae6fd
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/120866
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

2 files changed, 35 insertions, 5 deletions

diff --git a/comphelper/source/misc/configuration.cxx b/comphelper/source/misc/configuration.cxx
index a03855b41c4b..3e8bb31ebb8a 100644
--- a/comphelper/source/misc/configuration.cxx
+++ b/comphelper/source/misc/configuration.cxx
@@ -10,9 +10,12 @@
 #include <sal/config.h>
 
 #include <cassert>
+#include <map>
 #include <memory>
+#include <mutex>
 #include <string_view>
 
+#include <com/sun/star/beans/NamedValue.hpp>
 #include <com/sun/star/beans/PropertyAttribute.hpp>
 #include <com/sun/star/configuration/ReadOnlyAccess.hpp>
 #include <com/sun/star/configuration/ReadWriteAccess.hpp>
@@ -128,10 +131,36 @@ bool comphelper::detail::ConfigurationWrapper::isReadOnly(OUString const & path)
         != 0;
 }
 
-css::uno::Any comphelper::detail::ConfigurationWrapper::getPropertyValue(
-    OUString const & path) const
+css::uno::Any comphelper::detail::ConfigurationWrapper::getPropertyValue(css::uno::Reference< css::uno::XComponentContext >  const & context,
+            OUString const & path)
 {
-    return access_->getByHierarchicalName(path);
+    // Cache the configuration access, since some of the keys are used in hot code.
+    // Note that this cache is only used by the officecfg:: auto-generated code, using it for anything
+    // else would be unwise because the cache could end up containing stale entries.
+    static std::mutex gMutex;
+    static std::map<OUString, css::uno::Reference< css::container::XNameAccess >> gAccessMap;
+
+    sal_Int32 idx = path.lastIndexOf("/");
+    assert(idx!=-1);
+    OUString parentPath = path.copy(0, idx);
+    OUString childName = path.copy(idx+1);
+
+    std::scoped_lock aGuard(gMutex);
+
+    // check cache
+    auto it = gAccessMap.find(parentPath);
+    if (it != gAccessMap.end())
+        return it->second->getByName(childName);
+
+    // not in the cache, look it up
+    css::uno::Reference< css::lang::XMultiServiceFactory > provider = css::configuration::theDefaultProvider::get(
+                        context );
+    css::uno::Any arg(css::beans::NamedValue("nodepath", css::uno::Any(parentPath)));
+    css::uno::Reference< css::container::XNameAccess > access(provider->createInstanceWithArguments(
+        "com.sun.star.configuration.ConfigurationAccess",
+        { arg }), css::uno::UNO_QUERY_THROW);
+    gAccessMap.emplace(parentPath, access);
+    return access->getByName(childName);
 }
 
 void comphelper::detail::ConfigurationWrapper::setPropertyValue(
diff --git a/include/comphelper/configuration.hxx b/include/comphelper/configuration.hxx
index 1ed37dcd45c3..27344e7a3672 100644
--- a/include/comphelper/configuration.hxx
+++ b/include/comphelper/configuration.hxx
@@ -97,7 +97,8 @@ public:
 
     bool isReadOnly(OUString const & path) const;
 
-    css::uno::Any getPropertyValue(OUString const & path) const;
+    static css::uno::Any getPropertyValue(css::uno::Reference< css::uno::XComponentContext >  const & context,
+            OUString const & path);
 
     static void setPropertyValue(
         std::shared_ptr< ConfigurationChanges > const & batch,
@@ -210,7 +211,7 @@ template< typename T, typename U > struct ConfigurationProperty
         // Folding this into one statement causes a bogus error at least with
         // Red Hat GCC 4.6.2-1:
         css::uno::Any a(
-            detail::ConfigurationWrapper::get(context).getPropertyValue(
+            detail::ConfigurationWrapper::getPropertyValue(context,
                 T::path()));
         return detail::Convert< U >::fromAny(a);
     }