Modernize SkMutex and SkSemaphore.

include/private/SkMutex.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkMutex_DEFINED
 #define SkMutex_DEFINED
 
-// This file is not part of the public Skia API.
 #include "../private/SkSemaphore.h"
+#include "../private/SkThreadID.h"
 #include "SkTypes.h"
 
-#ifdef SK_DEBUG
-    #include "../private/SkThreadID.h"
-#endif
+#define SK_DECLARE_STATIC_MUTEX(name) static SkBaseMutex name;
 
-#define SK_MUTEX_SEMAPHORE_INIT {1, {0}}
+class SkBaseMutex {
+public:
+    constexpr SkBaseMutex() = default;
 
-#ifdef SK_DEBUG
-    #define SK_BASE_MUTEX_INIT {SK_MUTEX_SEMAPHORE_INIT, 0}
-#else
-    #define SK_BASE_MUTEX_INIT {SK_MUTEX_SEMAPHORE_INIT}
-#endif
-
-// Using POD-style initialization prevents the generation of a static initializer.
-//
-// Without magic statics there are no thread safety guarantees on initialization
-// of local statics (even POD). As a result, it is illegal to use
-// SK_DECLARE_STATIC_MUTEX in a function.
-//
-// Because SkBaseMutex is not a primitive, a static SkBaseMutex cannot be
-// initialized in a class with this macro.
-#define SK_DECLARE_STATIC_MUTEX(name) namespace {} static SkBaseMutex name = SK_BASE_MUTEX_INIT;
-
-struct SkBaseMutex {
     void acquire() {
         fSemaphore.wait();
         SkDEBUGCODE(fOwner = SkGetThreadID();)
     }
 
     void release() {
         this->assertHeld();
         SkDEBUGCODE(fOwner = kIllegalThreadID;)
         fSemaphore.signal();
     }
 
     void assertHeld() {
         SkASSERT(fOwner == SkGetThreadID());
     }
 
-    SkBaseSemaphore fSemaphore;
-    SkDEBUGCODE(SkThreadID fOwner;)
+protected:
+    SkBaseSemaphore fSemaphore{1};
+    SkDEBUGCODE(SkThreadID fOwner{kIllegalThreadID};)
 };
 
-// This needs to use subclassing instead of encapsulation to make SkAutoMutexAcquire to work.
 class SkMutex : public SkBaseMutex {
 public:
-    SkMutex () {
-        fSemaphore = SK_MUTEX_SEMAPHORE_INIT;
-        SkDEBUGCODE(fOwner = kIllegalThreadID);
-    }
-    ~SkMutex () { fSemaphore.deleteSemaphore(); }
-    SkMutex(const SkMutex&) = delete;
-    SkMutex& operator=(const SkMutex&) = delete;
+    using SkBaseMutex::SkBaseMutex;
+    ~SkMutex() { fSemaphore.cleanup(); }
 };
 
 template <typename Lock>
 class SkAutoTAcquire : SkNoncopyable {
 public:
     explicit SkAutoTAcquire(Lock& mutex) : fMutex(&mutex) {
         SkASSERT(fMutex != nullptr);
         mutex.acquire();
     }
 
@@ skipping 39 matching lines @@
     Lock &fLock;
 };
 
 typedef SkAutoTAcquire<SkBaseMutex> SkAutoMutexAcquire;
 #define SkAutoMutexAcquire(...) SK_REQUIRE_LOCAL_VAR(SkAutoMutexAcquire)
 
 typedef SkAutoTExclusive<SkBaseMutex> SkAutoMutexExclusive;
 #define SkAutoMutexExclusive(...) SK_REQUIRE_LOCAL_VAR(SkAutoMutexExclusive)
 
 #endif//SkMutex_DEFINED