Initial checkin of gRPC to third_party/

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

 #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
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 // copyright notice, this list of conditions and the following disclaimer
 // in the documentation and/or other materials provided with the
 // distribution.
 //     * Neither the name of Google Inc. nor the names of its
 // contributors may be used to endorse or promote products derived from
 // this software without specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // 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;
 
-        internal PackageDescriptor(string name, string fullName, FileDescriptor file)
+        public AtomicCounter(long initialCount = 0)
         {
-            this.file = file;
-            this.fullName = fullName;
-            this.name = name;
+            this.counter = initialCount;
         }
 
-        public string Name
+        public long Increment()
         {
-            get { return name; }
+            return Interlocked.Increment(ref counter);
         }
 
-        public string FullName
+        public void IncrementIfNonzero(ref bool success)
         {
-            get { return fullName; }
+            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 FileDescriptor File
+        public long Decrement()
         {
-            get { return file; }
+            return Interlocked.Decrement(ref counter);
+        }
+
+        public long Count
+        {
+            get
+            {
+                return counter;
+            }
         }
     }
-}
+}