Initial work

external/android-emugl/shared/emugl/common/smart_ptr.cpp

@@ -0,0 +1,113 @@
+// Copyright (C) 2014 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "emugl/common/smart_ptr.h"
+
+#ifdef _WIN32
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#endif
+
+namespace emugl {
+
+// Thread-safe atomic reference-counting type.
+class RefCount {
+public:
+    RefCount() : mCount(1) {}
+    ~RefCount() {}
+
+    // Technically not thread-safe, use only for testing.
+    int count() const { return (int)mCount; }
+
+    void increment() {
+#ifdef _WIN32
+        InterlockedIncrement(&mCount);
+#else
+        __sync_fetch_and_add(&mCount, 1);
+#endif
+    }
+
+    bool decrement() {
+#ifdef _WIN32
+        return InterlockedDecrement(&mCount) == 0;
+#else
+        return __sync_add_and_fetch(&mCount, -1) == 0;
+#endif
+    }
+
+private:
+#ifdef _WIN32
+    LONG mCount;
+#else
+    int mCount;
+#endif
+};
+
+
+// SmartPtrBase implementation.
+
+SmartPtrBase::SmartPtrBase(void* ptr) : mPtr(ptr), mRefCount(NULL) {
+    if (mPtr)
+        mRefCount = new RefCount();
+}
+
+
+SmartPtrBase::SmartPtrBase(const SmartPtrBase& other)
+        : mPtr(other.mPtr), mRefCount(other.mRefCount) {
+    if (mRefCount)
+        mRefCount->increment();
+}
+
+
+int SmartPtrBase::getRefCount() const {
+    return mRefCount ? mRefCount->count() : 0;
+}
+
+
+void SmartPtrBase::addRef() {
+    if (mRefCount)
+        mRefCount->increment();
+}
+
+
+void* SmartPtrBase::copyFrom(const SmartPtrBase& other) {
+    void* old_ptr = release();
+
+    mPtr = other.mPtr;
+    mRefCount = other.mRefCount;
+    if (mRefCount)
+        mRefCount->increment();
+
+    return old_ptr;
+}
+
+
+void* SmartPtrBase::release() {
+    void* old_ptr = mPtr;
+    RefCount* old_refcount = mRefCount;
+
+    if (old_refcount) {
+        mPtr = NULL;
+        mRefCount = NULL;
+
+        if (old_refcount->decrement()) {
+          delete old_refcount;
+          return old_ptr;
+        }
+    }
+
+    return NULL;
+}
+
+}  // namespace emugl