1 files changed, 57 insertions, 0 deletions
diff --git a/src/deps/skia/include/private/SkSpinlock.h b/src/deps/skia/include/private/SkSpinlock.h
new file mode 100644
index 000000000..e1d501168
--- /dev/null
+++ b/src/deps/skia/include/private/SkSpinlock.h
@@ -0,0 +1,57 @@
+/*
+ * 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 SkSpinlock_DEFINED
+#define SkSpinlock_DEFINED
+
+#include "include/core/SkTypes.h"
+#include "include/private/SkThreadAnnotations.h"
+#include <atomic>
+
+class SK_CAPABILITY("mutex") SkSpinlock {
+public:
+    constexpr SkSpinlock() = default;
+
+    void acquire() SK_ACQUIRE() {
+        // To act as a mutex, we need an acquire barrier when we acquire the lock.
+        if (fLocked.exchange(true, std::memory_order_acquire)) {
+            // Lock was contended.  Fall back to an out-of-line spin loop.
+            this->contendedAcquire();
+        }
+    }
+
+    // Acquire the lock or fail (quickly). Lets the caller decide to do something other than wait.
+    bool tryAcquire() SK_TRY_ACQUIRE(true) {
+        // To act as a mutex, we need an acquire barrier when we acquire the lock.
+        if (fLocked.exchange(true, std::memory_order_acquire)) {
+            // Lock was contended. Let the caller decide what to do.
+            return false;
+        }
+        return true;
+    }
+
+    void release() SK_RELEASE_CAPABILITY() {
+        // To act as a mutex, we need a release barrier when we release the lock.
+        fLocked.store(false, std::memory_order_release);
+    }
+
+private:
+    SK_API void contendedAcquire();
+
+    std::atomic<bool> fLocked{false};
+};
+
+class SK_SCOPED_CAPABILITY SkAutoSpinlock {
+public:
+    SkAutoSpinlock(SkSpinlock& mutex) SK_ACQUIRE(mutex) : fSpinlock(mutex) { fSpinlock.acquire(); }
+    ~SkAutoSpinlock() SK_RELEASE_CAPABILITY() { fSpinlock.release(); }
+
+private:
+    SkSpinlock& fSpinlock;
+};
+
+#endif//SkSpinlock_DEFINED