Clean up SkFontConfigInterface implementation.

src/ports/SkFontConfigInterface_direct.cpp

 /*
  * Copyright 2009-2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /* migrated from chrome/src/skia/ext/SkFontHost_fontconfig_direct.cpp */
 
 #include "SkBuffer.h"
 #include "SkDataTable.h"
 #include "SkFixed.h"
 #include "SkFontConfigInterface_direct.h"
 #include "SkFontStyle.h"
 #include "SkMutex.h"
 #include "SkStream.h"
 #include "SkString.h"
 #include "SkTArray.h"
 #include "SkTDArray.h"
 #include "SkTemplates.h"
 #include "SkTypeface.h"
 #include "SkTypes.h"
 
 #include <fontconfig/fontconfig.h>
 #include <unistd.h>
 
+#ifdef SK_DEBUG
+#    include "SkTLS.h"
+#endif
+
+namespace {
+
+// Fontconfig is not threadsafe before 2.10.91. Before that, we lock with a global mutex.
+// See https://bug.skia.org/1497 for background.
+SK_DECLARE_STATIC_MUTEX(gFCMutex);
+
+#ifdef SK_DEBUG
+void* CreateThreadFcLocked() { return new bool(false); }
+void DeleteThreadFcLocked(void* v) { delete static_cast<bool*>(v); }
+#   define THREAD_FC_LOCKED \
+        static_cast<bool*>(SkTLS::Get(CreateThreadFcLocked, DeleteThreadFcLocked))
+#endif
+
+struct FCLocker {
+    // Assume FcGetVersion() has always been thread safe.
+
+    FCLocker() {
+        if (FcGetVersion() < 21091) {
+            gFCMutex.acquire();
+        } else {
+            SkDEBUGCODE(bool* threadLocked = THREAD_FC_LOCKED);
+            SkASSERT(false == *threadLocked);
+            SkDEBUGCODE(*threadLocked = true);
+        }
+    }
+
+    ~FCLocker() {
+        AssertHeld();
+        if (FcGetVersion() < 21091) {
+            gFCMutex.release();
+        } else {
+            SkDEBUGCODE(*THREAD_FC_LOCKED = false);
+        }
+    }
+
+    static void AssertHeld() { SkDEBUGCODE(
+        if (FcGetVersion() < 21091) {
+            gFCMutex.assertHeld();
+        } else {
+            SkASSERT(true == *THREAD_FC_LOCKED);
+        }
+    ) }
+};
+
+} // namespace
+
 size_t SkFontConfigInterface::FontIdentity::writeToMemory(void* addr) const {
     size_t size = sizeof(fID) + sizeof(fTTCIndex);
     size += sizeof(int32_t) + sizeof(int32_t) + sizeof(uint8_t); // weight, width, italic
     size += sizeof(int32_t) + fString.size();    // store length+data
     if (addr) {
         SkWBuffer buffer(addr, size);
 
         buffer.write32(fID);
         buffer.write32(fTTCIndex);
         buffer.write32(fString.size());
@@ skipping 404 matching lines @@
     FcPatternAddInteger(pattern, FC_SLANT , slant);
 }
 
 }  // anonymous namespace
 
 ///////////////////////////////////////////////////////////////////////////////
 
 #define kMaxFontFamilyLength    2048
 
 SkFontConfigInterfaceDirect::SkFontConfigInterfaceDirect() {
-    SkAutoMutexAcquire ac(mutex_);
+    FCLocker lock;
 
     FcInit();
 
     SkDEBUGCODE(fontconfiginterface_unittest();)
 }
 
 SkFontConfigInterfaceDirect::~SkFontConfigInterfaceDirect() {
 }
 
 bool SkFontConfigInterfaceDirect::isAccessible(const char* filename) {
@@ skipping 63 matching lines @@
 bool SkFontConfigInterfaceDirect::matchFamilyName(const char familyName[],
                                                   SkFontStyle style,
                                                   FontIdentity* outIdentity,
                                                   SkString* outFamilyName,
                                                   SkFontStyle* outStyle) {
     SkString familyStr(familyName ? familyName : "");
     if (familyStr.size() > kMaxFontFamilyLength) {
         return false;
     }
 
-    SkAutoMutexAcquire ac(mutex_);
+    FCLocker lock;
 
     FcPattern* pattern = FcPatternCreate();
 
     if (familyName) {
         FcPatternAddString(pattern, FC_FAMILY, (FcChar8*)familyName);
     }
     fcpattern_from_skfontstyle(style, pattern);
 
     FcPatternAddBool(pattern, FC_SCALABLE, FcTrue);
 
@@ skipping 96 matching lines @@
     int count = list.count();
     for (int i = 0; i < count; ++i) {
         if (!strcmp(list[i], str)) {
             return true;
         }
     }
     return false;
 }
 
 SkDataTable* SkFontConfigInterfaceDirect::getFamilyNames() {
-    SkAutoMutexAcquire ac(mutex_);
+    FCLocker lock;
 
     FcPattern* pat = FcPatternCreate();
     SkAutoTCallVProc<FcPattern, FcPatternDestroy> autoDestroyPat(pat);
     if (nullptr == pat) {
         return nullptr;
     }
 
     FcObjectSet* os = FcObjectSetBuild(FC_FAMILY, (char *)0);
     SkAutoTCallVProc<FcObjectSet, FcObjectSetDestroy> autoDestroyOs(os);
     if (nullptr == os) {
@@ skipping 13 matching lines @@
         const char* famName = get_name(match, FC_FAMILY);
         if (famName && !find_name(names, famName)) {
             *names.append() = famName;
             *sizes.append() = strlen(famName) + 1;
         }
     }
 
     return SkDataTable::NewCopyArrays((const void*const*)names.begin(),
                                       sizes.begin(), names.count());
 }