Convert ImplFontCache to use o3tl::lru_map

We still do our own cleanup of the LRU map, as we can't drop
any fonts in use.

Change-Id: I8ec5c6ce8f80893635621357e9085950e7010f5b
Reviewed-on: https://gerrit.libreoffice.org/61455
Tested-by: Jenkins
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>

include/o3tl/lru_map.hxx

@@ -31,7 +31,7 @@ namespace o3tl
  * for most of the operations with a combination unordered map and linked list.
  *
  **/
-template<typename Key, typename Value, class KeyHash = std::hash<Key>>
+template<typename Key, typename Value, class KeyHash = std::hash<Key>, class KeyEqual = std::equal_to<Key>>
 class lru_map final
 {
 public:
@@ -42,7 +42,7 @@ private:
     typedef typename list_t::iterator list_iterator_t;
     typedef typename list_t::const_iterator list_const_iterator_t;
 
-    typedef std::unordered_map<Key, list_iterator_t, KeyHash> map_t;
+    typedef std::unordered_map<Key, list_iterator_t, KeyHash, KeyEqual> map_t;
     typedef typename map_t::iterator map_iterator_t;
     typedef typename map_t::const_iterator map_const_iterator_t;
 
@@ -65,8 +65,9 @@ public:
     typedef list_iterator_t iterator;
     typedef list_const_iterator_t const_iterator;
 
+    // a size of 0 effectively disables the LRU cleanup code
     lru_map(size_t nMaxSize)
-        : mMaxSize(nMaxSize)
+        : mMaxSize(nMaxSize ? nMaxSize : std::min(mLruMap.max_size(), mLruList.max_size()))
     {}
 
     void insert(key_value_pair_t& rPair)

o3tl/qa/test-lru_map.cxx

@@ -28,6 +28,7 @@ public:
     void testLruRemoval();
     void testCustomHash();
     void testRemoveIf();
+    void testNoAutoCleanup();
 
     CPPUNIT_TEST_SUITE(lru_map_test);
     CPPUNIT_TEST(testBaseUsage);
@@ -36,6 +37,7 @@ public:
     CPPUNIT_TEST(testLruRemoval);
     CPPUNIT_TEST(testCustomHash);
     CPPUNIT_TEST(testRemoveIf);
+    CPPUNIT_TEST(testNoAutoCleanup);
     CPPUNIT_TEST_SUITE_END();
 };
 
@@ -289,6 +291,24 @@ void lru_map_test::testRemoveIf()
     CPPUNIT_ASSERT_EQUAL(size_t(0), lru.size());
 }
 
+void lru_map_test::testNoAutoCleanup()
+{
+    o3tl::lru_map<int, int> lru(0);
+    CPPUNIT_ASSERT_EQUAL(size_t(0), lru.size());
+    lru.insert({0,0});
+    lru.insert({1,1});
+    CPPUNIT_ASSERT_EQUAL(size_t(2), lru.size());
+    lru.insert({0,0});
+    CPPUNIT_ASSERT_EQUAL(size_t(2), lru.size());
+
+    int i = 0;
+    for (auto &rPair : lru)
+    {
+        CPPUNIT_ASSERT_EQUAL(i, rPair.first);
+        ++i;
+    }
+}
+
 CPPUNIT_TEST_SUITE_REGISTRATION(lru_map_test);
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

vcl/inc/impfontcache.hxx

@@ -69,7 +69,8 @@ private:
     // cache of recently used font instances
     struct IFSD_Equal { bool operator()( const FontSelectPattern&, const FontSelectPattern& ) const; };
     struct IFSD_Hash { size_t operator()( const FontSelectPattern& ) const; };
-    typedef std::unordered_map<FontSelectPattern, rtl::Reference<LogicalFontInstance>, IFSD_Hash, IFSD_Equal> FontInstanceList;
+    typedef o3tl::lru_map<FontSelectPattern, rtl::Reference<LogicalFontInstance>, IFSD_Hash, IFSD_Equal> FontInstanceList;
+    typedef FontInstanceList::key_value_pair_t FontInstanceListPair;
 
     LogicalFontInstance* mpLastHitCacheEntry; ///< keeps the last hit cache entry
     FontInstanceList maFontInstanceList;

vcl/source/font/fontcache.cxx

@@ -85,13 +85,14 @@ bool ImplFontCache::IFSD_Equal::operator()(const FontSelectPattern& rA, const Fo
 
 ImplFontCache::ImplFontCache()
     : mpLastHitCacheEntry( nullptr )
+    , maFontInstanceList(0)
     // The cache limit is set by the rough number of characters needed to read your average Asian newspaper.
     , m_aBoundRectCache(3000)
 {}
 
 ImplFontCache::~ImplFontCache()
 {
-    for (auto & rLFI : maFontInstanceList)
+    for (const auto & rLFI : maFontInstanceList)
         rLFI.second->mpFontCache = nullptr;
 }
 
@@ -115,7 +116,7 @@ rtl::Reference<LogicalFontInstance> ImplFontCache::GetFontInstance( PhysicalFont
         pFontInstance = mpLastHitCacheEntry;
     else
     {
-        FontInstanceList::iterator it = maFontInstanceList.find( aFontSelData );
+        FontInstanceList::const_iterator it = maFontInstanceList.find( aFontSelData );
         if( it != maFontInstanceList.end() )
             pFontInstance = (*it).second;
     }
@@ -130,7 +131,7 @@ rtl::Reference<LogicalFontInstance> ImplFontCache::GetFontInstance( PhysicalFont
             aFontSelData.maSearchName = pFontFamily->GetSearchName();
 
             // check if an indirectly matching logical font instance is already cached
-            FontInstanceList::iterator it = maFontInstanceList.find( aFontSelData );
+            FontInstanceList::const_iterator it = maFontInstanceList.find( aFontSelData );
             if( it != maFontInstanceList.end() )
                 pFontInstance = (*it).second;
         }
@@ -168,25 +169,24 @@ rtl::Reference<LogicalFontInstance> ImplFontCache::GetFontInstance( PhysicalFont
 
         if (maFontInstanceList.size() >= FONTCACHE_MAX)
         {
-            // remove entries from font instance cache that are only referenced by the cache
-            FontInstanceList::iterator it_next = maFontInstanceList.begin();
-            while( it_next != maFontInstanceList.end() )
+            struct limit_exception : public std::exception {};
+            try
             {
-                LogicalFontInstance* pFontEntry = (*it_next).second.get();
-                if( pFontEntry->m_nCount > 1 )
-                {
-                    ++it_next;
-                    continue;
-                }
-                m_aBoundRectCache.remove_if([&pFontEntry] (GlpyhBoundRectCachePair const& rPair)
-                    { return rPair.first.m_pFont == pFontEntry; } );
-
-                maFontInstanceList.erase(it_next);
-                if (mpLastHitCacheEntry == pFontEntry)
-                    mpLastHitCacheEntry = nullptr;
-                // just remove one entry, which will bring us back under FONTCACHE_MAX size again
-                break;
+                maFontInstanceList.remove_if([this] (FontInstanceListPair const& rFontPair)
+                    {
+                        if (maFontInstanceList.size() < FONTCACHE_MAX)
+                            throw limit_exception();
+                        LogicalFontInstance* pFontEntry = rFontPair.second.get();
+                        if (pFontEntry->m_nCount > 1)
+                            return false;
+                        m_aBoundRectCache.remove_if([&pFontEntry] (GlpyhBoundRectCachePair const& rGlyphPair)
+                            { return rGlyphPair.first.m_pFont == pFontEntry; });
+                        if (mpLastHitCacheEntry == pFontEntry)
+                            mpLastHitCacheEntry = nullptr;
+                        return true;
+                    });
             }
+            catch (limit_exception) {}
         }
 
         assert(pFontInstance);