Initial checkin of gRPC to third_party/

third_party/grpc/src/csharp/Grpc.Core/Internal/AtomicCounter.cs

Index: third_party/grpc/src/csharp/Grpc.Core/Internal/AtomicCounter.cs
diff --git a/third_party/protobuf/csharp/src/Google.Protobuf/Reflection/PackageDescriptor.cs b/third_party/grpc/src/csharp/Grpc.Core/Internal/AtomicCounter.cs
similarity index 59%
copy from third_party/protobuf/csharp/src/Google.Protobuf/Reflection/PackageDescriptor.cs
copy to third_party/grpc/src/csharp/Grpc.Core/Internal/AtomicCounter.cs
index e547d834986de8d80703504469e9c39b3d8ae93d..63bea44e0e98161f9c51845dfb02dd1fb653f23a 100644
--- a/third_party/protobuf/csharp/src/Google.Protobuf/Reflection/PackageDescriptor.cs
+++ b/third_party/grpc/src/csharp/Grpc.Core/Internal/AtomicCounter.cs
@@ -1,7 +1,7 @@
 #region Copyright notice and license
-// Protocol Buffers - Google's data interchange format
-// Copyright 2008 Google Inc.  All rights reserved.
-// https://developers.google.com/protocol-buffers/
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
@@ -28,41 +28,59 @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 #endregion
 
-namespace Google.Protobuf.Reflection
+using System;
+using System.Threading;
+
+namespace Grpc.Core.Internal
 {
-    /// <summary>
-    /// Represents a package in the symbol table.  We use PackageDescriptors
-    /// just as placeholders so that someone cannot define, say, a message type
-    /// that has the same name as an existing package.
-    /// </summary>
-    internal sealed class PackageDescriptor : IDescriptor
+    internal class AtomicCounter
     {
-        private readonly string name;
-        private readonly string fullName;
-        private readonly FileDescriptor file;
+        long counter = 0;
+
+        public AtomicCounter(long initialCount = 0)
+        {
+            this.counter = initialCount;
+        }
 
-        internal PackageDescriptor(string name, string fullName, FileDescriptor file)
+        public long Increment()
         {
-            this.file = file;
-            this.fullName = fullName;
-            this.name = name;
+            return Interlocked.Increment(ref counter);
         }
 
-        public string Name
+        public void IncrementIfNonzero(ref bool success)
         {
-            get { return name; }
+            long origValue = counter;
+            while (true)
+            {
+                if (origValue == 0)
+                {
+                    success = false;
+                    return;
+                }
+                long result = Interlocked.CompareExchange(ref counter, origValue + 1, origValue);
+                if (result == origValue)
+                {
+                    success = true;
+                    return;
+                };
+                origValue = result;
+            }
         }
 
-        public string FullName
+        public long Decrement()
         {
-            get { return fullName; }
+            return Interlocked.Decrement(ref counter);
         }
 
-        public FileDescriptor File
+        public long Count
         {
-            get { return file; }
+            get
+            {
+                return counter;
+            }
         }
     }
-}
+}