RuntimeHelpers.cs source code in C# .NET

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                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / clr / src / BCL / System / Runtime / CompilerServices / RuntimeHelpers.cs / 2 / RuntimeHelpers.cs
                        

                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
////////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////// 
// 
// RuntimeHelpers
//	This class defines a set of static methods that provide support for compilers. 
//
// Date: April 2000
//
namespace System.Runtime.CompilerServices { 

    using System; 
    using System.Runtime.CompilerServices; 
    using System.Runtime.InteropServices;
    using System.Runtime.ConstrainedExecution; 
    using System.Security.Permissions;
    using System.Threading;

    public static class RuntimeHelpers 
    {
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        public static extern void InitializeArray(Array array,RuntimeFieldHandle fldHandle); 

        // GetObjectValue is intended to allow value classes to be manipulated as 'Object' 
        // but have aliasing behavior of a value class.  The intent is that you would use
        // this function just before an assignment to a variable of type 'Object'.  If the
        // value being assigned is a mutable value class, then a shallow copy is returned
        // (because value classes have copy semantics), but otherwise the object itself 
        // is returned.
        // 
        // Note: VB calls this method when they're about to assign to an Object 
        // or pass it as a parameter.  The goal is to make sure that boxed
        // value types work identical to unboxed value types - ie, they get 
        // cloned when you pass them around, and are always passed by value.
        // Of course, reference types are not cloned.
        //
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        public static extern Object GetObjectValue(Object obj);
 
 	    // RunClassConstructor causes the class constructor for the given type to be triggered 
	    // in the current domain.  After this call returns, the class constructor is guaranteed to
	    // have at least been started by some thread.  In the absence of class constructor 
        // deadlock conditions, the call is further guaranteed to have completed.
        //
        // This call will generate an exception if the specified class constructor threw an
        // exception when it ran. 

        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        private static extern void _RunClassConstructor(IntPtr type); 
        public static void RunClassConstructor(RuntimeTypeHandle type)
        { 
            _RunClassConstructor(type.Value);
        }

	    // RunModuleConstructor causes the module constructor for the given type to be triggered 
 	    // in the current domain.  After this call returns, the module constructor is guaranteed to
	    // have at least been started by some thread.  In the absence of module constructor 
        // deadlock conditions, the call is further guaranteed to have completed. 
        //
        // This call will generate an exception if the specified module constructor threw an 
        // exception when it ran.

        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        private static extern void _RunModuleConstructor(IntPtr module); 

        public static void RunModuleConstructor(ModuleHandle module) 
        { 
 	        unsafe {
               _RunModuleConstructor(new IntPtr(module.Value)); 
            }
        }

        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        private static extern void _PrepareMethod(IntPtr method, RuntimeTypeHandle[] instantiation);
 
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        internal static extern void _CompileMethod(IntPtr method);
 
        // Simple (instantiation not required) method.
        [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode=true)]
        public static void PrepareMethod(RuntimeMethodHandle method)
        { 
            _PrepareMethod(method.Value, null);
        } 
 
        // Generic method or method with generic class with specific instantiation.
        [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode=true)] 
        public static void PrepareMethod(RuntimeMethodHandle method, RuntimeTypeHandle[] instantiation)
        {
            _PrepareMethod(method.Value, instantiation);
        } 

        // This method triggers a given delegate to be prepared.  This involves preparing the 
        // delegate's Invoke method and preparing the target of that Invoke.  In the case of 
        // a multi-cast delegate, we rely on the fact that each individual component was prepared
        // prior to the Combine.  In other words, this service does not navigate through the 
        // entire multicasting list.
        // If our own reliable event sinks perform the Combine (for example AppDomain.DomainUnload),
        // then the result is fully prepared.  But if a client calls Combine himself and then
        // then adds that combination to e.g. AppDomain.DomainUnload, then the client is responsible 
        // for his own preparation.
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode=true)] 
        public static extern void PrepareDelegate(Delegate d);
 
        public static int GetHashCode(Object o)
        {
            return Object.InternalGetHashCode(o);
        } 

        public new static bool Equals(Object o1, Object o2) 
        { 
            return Object.InternalEquals(o1, o2);
        } 

        public static int OffsetToStringData
        {
            get { 
                // Number of bytes from the address pointed to by a reference to
                // a String to the first 16-bit character in the String.  Skip 
                // over the MethodTable pointer, String capacity, & String 
                // length.  Of course, the String reference points to the memory
                // after the sync block, so don't count that. 
                // This property allows C#'s fixed statement to work on Strings.
                // On 64 bit platforms, this should be 16.
#if WIN32
                return 12; 
#else
                return 16; 
#endif 
            }
        } 

        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode=true)]
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)] 
        public static extern void ProbeForSufficientStack();
 
        // This method is a marker placed immediately before a try clause to mark the corresponding catch and finally blocks as 
        // constrained. There's no code here other than the probe because most of the work is done at JIT time when we spot a call to this routine.
        [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode=true)] 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
        public static void PrepareConstrainedRegions()
        {
            ProbeForSufficientStack(); 
        }
 
        // When we detect a CER with no calls, we can point the JIT to this non-probing version instead 
        // as we don't need to probe.
        [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode=true)] 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
        public static void PrepareConstrainedRegionsNoOP()
        {
        } 

        public delegate void TryCode(Object userData); 
 
        public delegate void CleanupCode(Object userData, bool exceptionThrown);
 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode=true)]
        public static extern void ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData);
 
        [PrePrepareMethod]
        internal static void ExecuteBackoutCodeHelper(Object backoutCode, Object userData, bool exceptionThrown) 
        { 
            ((CleanupCode)backoutCode)(userData, exceptionThrown);
        } 

        // Roughly equivalent to a CER try/finally that will take a lock, run
        // the try code, and in the finally block, release the lock.  Calls
        // ExecuteCodeWithGuaranteedCleanup to ensure this will work w.r.t. 
        // stack overflows.
        // We should consider making this public. 
        [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode=true)] 
        [HostProtection(Synchronization=true)]
        internal static void ExecuteCodeWithLock(Object lockObject, TryCode code, object userState) 
        {
            ExecuteWithLockHelper execHelper = new ExecuteWithLockHelper(lockObject, code, userState);
            ExecuteCodeWithGuaranteedCleanup(s_EnterMonitor, s_ExitMonitor, execHelper);
        } 

        private static TryCode s_EnterMonitor = new TryCode(EnterMonitorAndTryCode); 
        private static CleanupCode s_ExitMonitor = new CleanupCode(ExitMonitorOnBackout); 

        private static void EnterMonitorAndTryCode(Object helper) 
        {
            ExecuteWithLockHelper execHelper = (ExecuteWithLockHelper) helper;
            BCLDebug.Assert(execHelper != null, "ExecuteWithLockHelper is null");
            BCLDebug.Assert(execHelper.m_lockObject != null, "LockObject is null"); 
            BCLDebug.Assert(execHelper.m_userCode != null, "UserCode is null");
 
            Monitor.ReliableEnter(execHelper.m_lockObject, ref execHelper.m_tookLock); 
            execHelper.m_userCode(execHelper.m_userState);
        } 

        [PrePrepareMethod]
        private static void ExitMonitorOnBackout(Object helper, bool exceptionThrown)
        { 
            ExecuteWithLockHelper execHelper = (ExecuteWithLockHelper) helper;
            BCLDebug.Assert(execHelper != null, "ExecuteWithLockHelper is null"); 
            BCLDebug.Assert(execHelper.m_lockObject != null, "LockObject is null"); 

            if (execHelper.m_tookLock) 
                Monitor.Exit(execHelper.m_lockObject);
        }

        class ExecuteWithLockHelper 
        {
            internal Object m_lockObject; 
            internal bool   m_tookLock; 
            internal TryCode m_userCode;
            internal object m_userState; 

            internal ExecuteWithLockHelper(Object lockObject, TryCode userCode, object userState)
            {
                m_lockObject = lockObject; 
                m_userCode = userCode;
                m_userState = userState; 
            } 

        } 
    }
}

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