ServiceMemoryGates.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / WCF / WCF / 3.5.30729.1 / untmp / Orcas / SP / ndp / cdf / src / WCF / ServiceModel / System / ServiceModel / Activation / ServiceMemoryGates.cs / 1 / ServiceMemoryGates.cs
                        

                        
                            //---------------------------------------------------------------------------- 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//---------------------------------------------------------------------------
namespace System.ServiceModel.Activation
{ 
    using System.Collections.Generic;
    using System.ServiceModel.Channels; 
    using System.Runtime.InteropServices; 
    using System.ComponentModel;
    using System.Threading; 
    using System.Runtime.CompilerServices;
    using System.Security;

    static class ServiceMemoryGates 
    {
        ///  
        /// Critical - uses SecurityCritical helper methods to check memory status 
        ///          - allocates unmanaged resources, can only be called with admin-specified value
        ///  
        [SecurityCritical]
        internal static void Check(int minFreeMemoryPercentage)
        {
            // Boundary check percentage, if out of bounds Gate is turned off. 
            // 0 is defined as disabled. Configuration defines 99 as max allowed so we disable
            // if we receive something out of range 
            if (minFreeMemoryPercentage < 1 || minFreeMemoryPercentage > 99) 
            {
                return; 
            }

            UnsafeNativeMethods.MEMORYSTATUSEX memoryStatus = new UnsafeNativeMethods.MEMORYSTATUSEX();
            GetGlobalMemoryStatus(ref memoryStatus); 

            ulong threshold = memoryStatus.ullTotalPageFile / 100 * (ulong)minFreeMemoryPercentage; 
            if (memoryStatus.ullAvailPageFile < threshold) 
            {
                // Yield this thread -- this will also ensure that we have a full time slice when we 
                // do our alloc/free
                Thread.Sleep(0);

                // Commit 1.5 times of the threshold. This should force the page file to grow, if 
                // possible. (GlobalMemoryStatusEx only returns information about the current pagefile,
                // not about the maximum pagefile.) 
                uint sizeToAlloc = 0; 
                if (threshold < (ulong)int.MaxValue)
                { 
                    sizeToAlloc = (uint)threshold / 2 * 3;
                }

                if (sizeToAlloc > 0) 
                {
                    ForcePageFileToGrow(sizeToAlloc); 
 
                    GetGlobalMemoryStatus(ref memoryStatus);
                    threshold = memoryStatus.ullTotalPageFile / 100 * (ulong)minFreeMemoryPercentage; 
                }

                if (memoryStatus.ullAvailPageFile < threshold)
                { 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InsufficientMemoryException(
                        SR.GetString(SR.Hosting_MemoryGatesCheckFailed, memoryStatus.ullAvailPageFile, 
                        minFreeMemoryPercentage))); 
                }
            } 
        }

        /// 
        /// Critical - Uses UnsafeNativeMethods, caller must guard parameter 
        /// 
        [SecurityCritical] 
        static void ForcePageFileToGrow(uint sizeToAlloc) 
        {
            RuntimeHelpers.PrepareConstrainedRegions(); 
            try
            {}
            finally
            { 
                // We don't care if this actually succeeds or not, we are just trying to grow the page
                // file. 
#pragma warning suppress 56523 // [....], we don't care whether this actually succeeds 
                IntPtr ptr = UnsafeNativeMethods.VirtualAlloc(IntPtr.Zero, (UIntPtr)sizeToAlloc, UnsafeNativeMethods.MEM_COMMIT,
                    (uint)UnsafeNativeMethods.PAGE_READWRITE); 

                if (ptr != IntPtr.Zero)
                {
#pragma warning suppress 56523 // [....], we don't care whether this actually succeeds 
                    UnsafeNativeMethods.VirtualFree(ptr, (UIntPtr)sizeToAlloc, UnsafeNativeMethods.MEM_DECOMMIT);
                } 
            } 
        }
 
        /// 
        /// Critical - Uses UnsafeNativeMethods to fetch memory status structure, caller must not leak it
        /// 
        [SecurityCritical] 
        static void GetGlobalMemoryStatus(ref UnsafeNativeMethods.MEMORYSTATUSEX memoryStatus)
        { 
            memoryStatus.dwLength = (uint)Marshal.SizeOf(typeof(UnsafeNativeMethods.MEMORYSTATUSEX)); 

            if (!UnsafeNativeMethods.GlobalMemoryStatusEx(ref memoryStatus)) 
            {
                int error = Marshal.GetLastWin32Error();
                // Treat as the worst case.
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError( 
                    new InvalidOperationException(SR.GetString(SR.Hosting_GetGlobalMemoryFailed),
                    new Win32Exception(error))); 
            } 
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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