Make leak counters thread-safe

include/core/SkInstCnt.h

Index: include/core/SkInstCnt.h
diff --git a/include/core/SkInstCnt.h b/include/core/SkInstCnt.h
index 89bbfa1126d12017b6a77486421baa8ad22f4b46..7e5b454b15d67f4ad7c082a5b2b3af17e1073af5 100644
--- a/include/core/SkInstCnt.h
+++ b/include/core/SkInstCnt.h
@@ -20,9 +20,16 @@
 #include "SkTypes.h"
 
 #if SK_ENABLE_INST_COUNT
+// Static variables inside member functions below may be defined multiple times
+// if Skia is being used as a dynamic library. Instance counting should be on
+// only for static builds. See bug skia:2058.
+#if defined(SKIA_DLL)
+#error Instance counting works only when Skia is built as a static library.
+#endif
+
+#include "SkOnce.h"
 #include "SkTArray.h"
 #include "SkThread.h"
-
 extern bool gPrintInstCount;
 
 // The non-root classes just register themselves with their parent
@@ -38,17 +45,16 @@ extern bool gPrintInstCount;
 #define SK_DECLARE_INST_COUNT_INTERNAL(className, initStep)                 \
     class SkInstanceCountHelper {                                           \
     public:                                                                 \
-        typedef int (*PFCheckInstCnt)(int level, bool cleanUp);             \
         SkInstanceCountHelper() {                                           \
-            static bool gInited;                                            \
-            if (!gInited) {                                                 \
-                initStep                                                    \
-                GetChildren() = new SkTArray<PFCheckInstCnt>;               \
-                gInited = true;                                             \
-            }                                                               \
+            SK_DECLARE_STATIC_ONCE(once);                                   \
+            SkOnce(&once, init, 0);                                         \
             sk_atomic_inc(GetInstanceCountPtr());                           \
         }                                                                   \
                                                                             \
+        static void init(int) {                                             \
+            initStep                                                        \
+        }                                                                   \
+                                                                            \
         SkInstanceCountHelper(const SkInstanceCountHelper&) {               \
             sk_atomic_inc(GetInstanceCountPtr());                           \
         }                                                                   \
@@ -62,11 +68,16 @@ extern bool gPrintInstCount;
             return &gInstanceCount;                                         \
         }                                                                   \
                                                                             \
-        static SkTArray<PFCheckInstCnt>*& GetChildren() {                   \
-            static SkTArray<PFCheckInstCnt>* gChildren;                     \
+        static SkTArray<int (*)(int, bool)>*& GetChildren() {               \
+            static SkTArray<int (*)(int, bool)>* gChildren;                 \
             return gChildren;                                               \
         }                                                                   \
                                                                             \
+        static SkBaseMutex& GetChildrenMutex() {                            \
+            SK_DECLARE_STATIC_MUTEX(childrenMutex);                         \
+            return childrenMutex;                                           \
+        }                                                                   \
+                                                                            \
     } fInstanceCountHelper;                                                 \
                                                                             \
     static int32_t GetInstanceCount() {                                     \
@@ -86,7 +97,7 @@ extern bool gPrintInstCount;
         if (NULL == SkInstanceCountHelper::GetChildren()) {                 \
             return GetInstanceCount();                                      \
         }                                                                   \
-        SkTArray<int (*)(int, bool)>* children =                            \
+        SkTArray<int (*)(int, bool)>* children = \
             SkInstanceCountHelper::GetChildren();                           \
         int childCount = children->count();                                 \
         int count = GetInstanceCount();                                     \
@@ -105,8 +116,12 @@ extern bool gPrintInstCount;
     }                                                                       \
                                                                             \
     static void AddInstChild(int (*childCheckInstCnt)(int, bool)) {         \
-        if (CheckInstanceCount != childCheckInstCnt &&                      \
-            NULL != SkInstanceCountHelper::GetChildren()) {                 \
+        if (CheckInstanceCount != childCheckInstCnt) {                      \
+            SkAutoMutexAcquire ama(SkInstanceCountHelper::GetChildrenMutex()); \
+            if (NULL == SkInstanceCountHelper::GetChildren()) {             \
+                SkInstanceCountHelper::GetChildren() =                      \
+                    new SkTArray<int (*)(int, bool)>;                       \
+            }                                                               \
             SkInstanceCountHelper::GetChildren()->push_back(childCheckInstCnt); \
         }                                                                   \
     }