Interlocked.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Threading / Interlocked.cs / 1305376 / Interlocked.cs
                        

                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
//
// [....] 
namespace System.Threading 
{
    using System; 
    using System.Security.Permissions;
    using System.Runtime.CompilerServices;
    using System.Runtime.ConstrainedExecution;
    using System.Runtime.Versioning; 
    using System.Runtime;
 
    // After much discussion, we decided the Interlocked class doesn't need 
    // any HPA's for synchronization or external threading.  They hurt C#'s
    // codegen for the yield keyword, and arguably they didn't protect much. 
    // Instead, they penalized people (and compilers) for writing threadsafe
    // code.
    [System.Security.SecuritySafeCritical]  // auto-generated
    public static class Interlocked 
    {
        /****************************** 
         * Increment 
         *   Implemented: int
         *                        long 
         *****************************/

        [ResourceExposure(ResourceScope.None)]
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
#if !FEATURE_CORECLR
        [TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")] 
#endif 
        public static int Increment(ref int location)
        { 
            return Add(ref location, 1);
        }

        [ResourceExposure(ResourceScope.None)] 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
#if !FEATURE_CORECLR 
        [TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")] 
#endif
        public static long Increment(ref long location) 
        {
            return Add(ref location, 1);
        }
 
        /******************************
         * Decrement 
         *   Implemented: int 
         *                        long
         *****************************/ 

        [ResourceExposure(ResourceScope.None)]
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
#if !FEATURE_CORECLR 
        [TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
#endif 
        public static int Decrement(ref int location) 
        {
            return Add(ref location, -1); 
        }

        [ResourceExposure(ResourceScope.None)]
#if !FEATURE_CORECLR 
        [TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
#endif 
        public static long Decrement(ref long location) 
        {
            return Add(ref location, -1); 
        }

        /******************************
         * Exchange 
         *   Implemented: int
         *                        long 
         *                        float 
         *                        double
         *                        Object 
         *                        IntPtr
         *****************************/

        [ResourceExposure(ResourceScope.None)] 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
        public static extern int Exchange(ref int location1, int value); 

        [ResourceExposure(ResourceScope.None)] 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        public static extern long Exchange(ref long location1, long value);

        [ResourceExposure(ResourceScope.None)] 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        public static extern float Exchange(ref float location1, float value); 
 
        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        public static extern double Exchange(ref double location1, double value);

        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        public static extern Object Exchange(ref Object location1, Object value); 
 
        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        public static extern IntPtr Exchange(ref IntPtr location1, IntPtr value);

        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
        [System.Runtime.InteropServices.ComVisible(false)]
        public static T Exchange(ref T location1, T value) where T : class 
        { 
            _Exchange(__makeref(location1), __makeref(value));
            //Since value is a local we use trash its data on return 
            //  The Exchange replaces the data with new data
            //  so after the return "value" contains the original location1
            //See ExchangeGeneric for more details
            return value; 
        }
 
        [ResourceExposure(ResourceScope.None)] 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
        private static extern void _Exchange(TypedReference location1, TypedReference value);

        /******************************
         * CompareExchange 
         *    Implemented: int
         *                         long 
         *                         float 
         *                         double
         *                         Object 
         *                         IntPtr
         *****************************/

        [ResourceExposure(ResourceScope.None)] 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
        public static extern int CompareExchange(ref int location1, int value, int comparand); 

        [ResourceExposure(ResourceScope.None)] 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        public static extern long CompareExchange(ref long location1, long value, long comparand);

        [ResourceExposure(ResourceScope.None)] 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        public static extern float CompareExchange(ref float location1, float value, float comparand); 
 
        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        public static extern double CompareExchange(ref double location1, double value, double comparand);

        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        public static extern Object CompareExchange(ref Object location1, Object value, Object comparand); 
 
        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        public static extern IntPtr CompareExchange(ref IntPtr location1, IntPtr value, IntPtr comparand);

        /****************************************************************** 
         * CompareExchange
         * 
         * Notice how CompareExchange() uses the __makeref keyword 
         * to create two TypedReferences before calling _CompareExchange().
         * This is horribly slow. Ideally we would like CompareExchange() 
         * to simply call CompareExchange(ref Object, Object, Object);
         * however, this would require casting a "ref T" into a "ref Object",
         * which is not legal in C#.
         * 
         * Thus we opted to cheat, and hacked to JIT so that when it reads
         * the method body for CompareExchange() it gets back the 
         * following IL: 
         *
         *     ldarg.0 
         *     ldarg.1
         *     ldarg.2
         *     call System.Threading.Interlocked::CompareExchange(ref Object, Object, Object)
         *     ret 
         *
         * See getILIntrinsicImplementationForInterlocked() in VM\JitInterface.cpp 
         * for details. 
         *****************************************************************/
 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        [System.Runtime.InteropServices.ComVisible(false)]
        public static T CompareExchange(ref T location1, T value, T comparand) where T : class
        { 
            // _CompareExchange() passes back the value read from location1 via local named 'value'
            _CompareExchange(__makeref(location1), __makeref(value), comparand); 
            return value; 
        }
 
        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        private static extern void _CompareExchange(TypedReference location1, TypedReference value, Object comparand); 

        // BCL-internal overload that returns success via a ref bool param, useful for reliable spin locks. 
        [ResourceExposure(ResourceScope.None)] 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
        internal static extern int CompareExchange(ref int location1, int value, int comparand, ref bool succeeded);

        /******************************
         * Add 
         *    Implemented: int
         *                         long 
         *****************************/ 

        [ResourceExposure(ResourceScope.None)] 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        internal static extern int ExchangeAdd(ref int location1, int value);
 
        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        internal static extern long ExchangeAdd(ref long location1, long value); 

        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
#if !FEATURE_CORECLR
        [TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
#endif
        public static int Add(ref int location1, int value) 
        {
            return ExchangeAdd(ref location1, value) + value; 
        } 

        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
#if !FEATURE_CORECLR
        [TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
#endif
        public static long Add(ref long location1, long value) 
        {
            return ExchangeAdd(ref location1, value) + value; 
        } 

        /****************************** 
         * Read
         *****************************/
        public static long Read(ref long location)
        { 
            return Interlocked.CompareExchange(ref location,0,0);
        } 
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

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