Fix crash with truetype fonts and multi threading (#9424)

distribution/changelog.txt

@@ -59,6 +59,7 @@
 - Fix: [#9324] Crash trying to remove invalid footpath scenery.
 - Fix: [#9402] Ad campaigns disappear when you save and load the game.
 - Fix: [#9411] Ad campaigns end too soon.
+- Fix: [#9424] Crash using multi threading with TrueType fonts.
 - Fix: Guests eating popcorn are drawn as if they're eating pizza.
 - Fix: The arbitrary ride type and vehicle dropdown lists are ordered case-sensitively.
 - Improved: [#6116] Expose colour scheme for track elements in the tile inspector.

src/openrct2/drawing/TTF.cpp

@@ -9,6 +9,8 @@
 
 #ifndef NO_TTF
 
+#    include <atomic>
+#    include <mutex>
 #    pragma clang diagnostic push
 #    pragma clang diagnostic ignored "-Wdocumentation"
 #    include <ft2build.h>
@@ -53,6 +55,8 @@ static int32_t _ttfGetWidthCacheCount = 0;
 static int32_t _ttfGetWidthCacheHitCount = 0;
 static int32_t _ttfGetWidthCacheMissCount = 0;
 
+static std::mutex _mutex;
+
 static TTF_Font* ttf_open_font(const utf8* fontPath, int32_t ptSize);
 static void ttf_close_font(TTF_Font* font);
 static uint32_t ttf_surface_cache_hash(TTF_Font* font, const utf8* text);
@@ -60,63 +64,111 @@ static void ttf_surface_cache_dispose(ttf_cache_entry* entry);
 static void ttf_surface_cache_dispose_all();
 static void ttf_getwidth_cache_dispose_all();
 static bool ttf_get_size(TTF_Font* font, const utf8* text, int32_t* width, int32_t* height);
+static void ttf_toggle_hinting(bool);
 static TTFSurface* ttf_render(TTF_Font* font, const utf8* text);
 
+template<typename T> class FontLockHelper
+{
+    T& _mutex;
+    const bool _enabled;
+
+public:
+    FontLockHelper(T& mutex)
+        : _mutex(mutex)
+        , _enabled(gConfigGeneral.multithreading)
+    {
+        if (_enabled)
+            _mutex.lock();
+    }
+    ~FontLockHelper()
+    {
+        if (_enabled)
+            _mutex.unlock();
+    }
+};
+
+static void ttf_toggle_hinting(bool)
+{
+    if (!LocalisationService_UseTrueTypeFont())
+    {
+        return;
+    }
+
+    for (int32_t i = 0; i < FONT_SIZE_COUNT; i++)
+    {
+        TTFFontDescriptor* fontDesc = &(gCurrentTTFFontSet->size[i]);
+        bool use_hinting = gConfigFonts.enable_hinting && fontDesc->hinting_threshold;
+        TTF_SetFontHinting(fontDesc->font, use_hinting ? 1 : 0);
+    }
+
+    if (_ttfSurfaceCacheCount)
+    {
+        ttf_surface_cache_dispose_all();
+    }
+}
+
 bool ttf_initialise()
 {
-    if (!_ttfInitialised)
+    FontLockHelper<std::mutex> lock(_mutex);
+
+    if (_ttfInitialised)
+        return true;
+
+    if (TTF_Init() != 0)
     {
-        if (TTF_Init() != 0)
+        log_error("Couldn't initialise FreeType engine");
+        return false;
+    }
+
+    for (int32_t i = 0; i < FONT_SIZE_COUNT; i++)
+    {
+        TTFFontDescriptor* fontDesc = &(gCurrentTTFFontSet->size[i]);
+
+        utf8 fontPath[MAX_PATH];
+        if (!platform_get_font_path(fontDesc, fontPath, sizeof(fontPath)))
         {
-            log_error("Couldn't initialise FreeType engine");
+            log_verbose("Unable to load font '%s'", fontDesc->font_name);
             return false;
         }
 
-        for (int32_t i = 0; i < FONT_SIZE_COUNT; i++)
+        fontDesc->font = ttf_open_font(fontPath, fontDesc->ptSize);
+        if (fontDesc->font == nullptr)
         {
-            TTFFontDescriptor* fontDesc = &(gCurrentTTFFontSet->size[i]);
-
-            utf8 fontPath[MAX_PATH];
-            if (!platform_get_font_path(fontDesc, fontPath, sizeof(fontPath)))
-            {
-                log_verbose("Unable to load font '%s'", fontDesc->font_name);
-                return false;
-            }
-
-            fontDesc->font = ttf_open_font(fontPath, fontDesc->ptSize);
-            if (fontDesc->font == nullptr)
-            {
-                log_verbose("Unable to load '%s'", fontPath);
-                return false;
-            }
+            log_verbose("Unable to load '%s'", fontPath);
+            return false;
         }
-
-        ttf_toggle_hinting();
-        _ttfInitialised = true;
     }
+
+    ttf_toggle_hinting(true);
+
+    _ttfInitialised = true;
+
     return true;
 }
 
 void ttf_dispose()
 {
-    if (_ttfInitialised)
+    FontLockHelper<std::mutex> lock(_mutex);
+
+    if (!_ttfInitialised)
+        return;
+
+    ttf_surface_cache_dispose_all();
+    ttf_getwidth_cache_dispose_all();
+
+    for (int32_t i = 0; i < FONT_SIZE_COUNT; i++)
     {
-        ttf_surface_cache_dispose_all();
-        ttf_getwidth_cache_dispose_all();
-
-        for (int32_t i = 0; i < FONT_SIZE_COUNT; i++)
+        TTFFontDescriptor* fontDesc = &(gCurrentTTFFontSet->size[i]);
+        if (fontDesc->font != nullptr)
         {
-            TTFFontDescriptor* fontDesc = &(gCurrentTTFFontSet->size[i]);
-            if (fontDesc->font != nullptr)
-            {
-                ttf_close_font(fontDesc->font);
-                fontDesc->font = nullptr;
-            }
+            ttf_close_font(fontDesc->font);
+            fontDesc->font = nullptr;
         }
-
-        TTF_Quit();
-        _ttfInitialised = false;
     }
+
+    TTF_Quit();
+
+    _ttfInitialised = false;
 }
 
 static TTF_Font* ttf_open_font(const utf8* fontPath, int32_t ptSize)
@@ -163,22 +215,8 @@ static void ttf_surface_cache_dispose_all()
 
 void ttf_toggle_hinting()
 {
-    if (!LocalisationService_UseTrueTypeFont())
-    {
-        return;
-    }
-
-    for (int32_t i = 0; i < FONT_SIZE_COUNT; i++)
-    {
-        TTFFontDescriptor* fontDesc = &(gCurrentTTFFontSet->size[i]);
-        bool use_hinting = gConfigFonts.enable_hinting && fontDesc->hinting_threshold;
-        TTF_SetFontHinting(fontDesc->font, use_hinting ? 1 : 0);
-    }
-
-    if (_ttfSurfaceCacheCount)
-    {
-        ttf_surface_cache_dispose_all();
-    }
+    FontLockHelper<std::mutex> lock(_mutex);
+    ttf_toggle_hinting(true);
 }
 
 TTFSurface* ttf_surface_cache_get_or_add(TTF_Font* font, const utf8* text)
@@ -187,6 +225,9 @@ TTFSurface* ttf_surface_cache_get_or_add(TTF_Font* font, const utf8* text)
 
     uint32_t hash = ttf_surface_cache_hash(font, text);
     int32_t index = hash % TTF_SURFACE_CACHE_SIZE;
+
+    FontLockHelper<std::mutex> lock(_mutex);
+
     for (int32_t i = 0; i < TTF_SURFACE_CACHE_SIZE; i++)
     {
         entry = &_ttfSurfaceCache[index];
@@ -260,6 +301,9 @@ uint32_t ttf_getwidth_cache_get_or_add(TTF_Font* font, const utf8* text)
 
     uint32_t hash = ttf_surface_cache_hash(font, text);
     int32_t index = hash % TTF_GETWIDTH_CACHE_SIZE;
+
+    FontLockHelper<std::mutex> lock(_mutex);
+
     for (int32_t i = 0; i < TTF_GETWIDTH_CACHE_SIZE; i++)
     {
         entry = &_ttfGetWidthCache[index];
@@ -304,6 +348,7 @@ uint32_t ttf_getwidth_cache_get_or_add(TTF_Font* font, const utf8* text)
 
 TTFFontDescriptor* ttf_get_font_from_sprite_base(uint16_t spriteBase)
 {
+    FontLockHelper<std::mutex> lock(_mutex);
     return &gCurrentTTFFontSet->size[font_get_size_from_sprite_base(spriteBase)];
 }