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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 2287 | - | 1 | #if !MONO && !PocketPC |
| 2 | #define UseFastResourceLock |
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| 3 | #endif |
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| 4 | |||
| 5 | namespace GMap.NET.Internals |
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| 6 | { |
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| 7 | using System; |
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| 8 | using System.Threading; |
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| 9 | #if !MONO |
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| 10 | using System.Runtime.InteropServices; |
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| 11 | #endif |
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| 12 | |||
| 13 | /// <summary> |
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| 14 | /// custom ReaderWriterLock |
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| 15 | /// in Vista and later uses integrated Slim Reader/Writer (SRW) Lock |
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| 16 | /// http://msdn.microsoft.com/en-us/library/aa904937(VS.85).aspx |
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| 17 | /// http://msdn.microsoft.com/en-us/magazine/cc163405.aspx#S2 |
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| 18 | /// </summary> |
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| 19 | public sealed class FastReaderWriterLock : IDisposable |
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| 20 | { |
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| 21 | #if !MONO && !PocketPC |
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| 22 | private static class NativeMethods |
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| 23 | { |
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| 24 | // Methods |
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| 25 | [DllImport("Kernel32", ExactSpelling = true)] |
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| 26 | internal static extern void AcquireSRWLockExclusive(ref IntPtr srw); |
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| 27 | [DllImport("Kernel32", ExactSpelling = true)] |
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| 28 | internal static extern void AcquireSRWLockShared(ref IntPtr srw); |
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| 29 | [DllImport("Kernel32", ExactSpelling = true)] |
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| 30 | internal static extern void InitializeSRWLock(out IntPtr srw); |
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| 31 | [DllImport("Kernel32", ExactSpelling = true)] |
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| 32 | internal static extern void ReleaseSRWLockExclusive(ref IntPtr srw); |
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| 33 | [DllImport("Kernel32", ExactSpelling = true)] |
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| 34 | internal static extern void ReleaseSRWLockShared(ref IntPtr srw); |
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| 35 | } |
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| 36 | |||
| 37 | IntPtr LockSRW = IntPtr.Zero; |
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| 38 | |||
| 39 | public FastReaderWriterLock() |
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| 40 | { |
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| 41 | if (UseNativeSRWLock) |
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| 42 | { |
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| 43 | NativeMethods.InitializeSRWLock(out this.LockSRW); |
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| 44 | } |
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| 45 | else |
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| 46 | { |
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| 47 | #if UseFastResourceLock |
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| 48 | pLock = new FastResourceLock(); |
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| 49 | #endif |
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| 50 | } |
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| 51 | } |
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| 52 | |||
| 53 | #if UseFastResourceLock |
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| 54 | ~FastReaderWriterLock() |
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| 55 | { |
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| 56 | Dispose(false); |
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| 57 | } |
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| 58 | |||
| 59 | void Dispose(bool disposing) |
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| 60 | { |
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| 61 | if (pLock != null) |
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| 62 | { |
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| 63 | pLock.Dispose(); |
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| 64 | pLock = null; |
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| 65 | } |
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| 66 | } |
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| 67 | |||
| 68 | FastResourceLock pLock; |
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| 69 | #endif |
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| 70 | |||
| 71 | static readonly bool UseNativeSRWLock = Stuff.IsRunningOnVistaOrLater() && IntPtr.Size == 4; // works only in 32-bit mode, any ideas on native 64-bit support? |
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| 72 | |||
| 73 | #endif |
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| 74 | |||
| 75 | #if !UseFastResourceLock |
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| 76 | Int32 busy = 0; |
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| 77 | Int32 readCount = 0; |
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| 78 | #endif |
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| 79 | |||
| 80 | public void AcquireReaderLock() |
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| 81 | { |
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| 82 | #if !MONO && !PocketPC |
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| 83 | if (UseNativeSRWLock) |
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| 84 | { |
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| 85 | NativeMethods.AcquireSRWLockShared(ref LockSRW); |
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| 86 | } |
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| 87 | else |
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| 88 | #endif |
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| 89 | { |
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| 90 | #if UseFastResourceLock |
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| 91 | pLock.AcquireShared(); |
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| 92 | #else |
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| 93 | Thread.BeginCriticalRegion(); |
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| 94 | |||
| 95 | while(Interlocked.CompareExchange(ref busy, 1, 0) != 0) |
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| 96 | { |
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| 97 | Thread.Sleep(1); |
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| 98 | } |
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| 99 | |||
| 100 | Interlocked.Increment(ref readCount); |
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| 101 | |||
| 102 | // somehow this fix deadlock on heavy reads |
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| 103 | Thread.Sleep(0); |
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| 104 | Thread.Sleep(0); |
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| 105 | Thread.Sleep(0); |
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| 106 | Thread.Sleep(0); |
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| 107 | Thread.Sleep(0); |
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| 108 | Thread.Sleep(0); |
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| 109 | Thread.Sleep(0); |
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| 110 | |||
| 111 | Interlocked.Exchange(ref busy, 0); |
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| 112 | #endif |
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| 113 | } |
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| 114 | } |
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| 115 | |||
| 116 | public void ReleaseReaderLock() |
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| 117 | { |
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| 118 | #if !MONO && !PocketPC |
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| 119 | if (UseNativeSRWLock) |
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| 120 | { |
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| 121 | NativeMethods.ReleaseSRWLockShared(ref LockSRW); |
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| 122 | } |
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| 123 | else |
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| 124 | #endif |
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| 125 | { |
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| 126 | #if UseFastResourceLock |
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| 127 | pLock.ReleaseShared(); |
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| 128 | #else |
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| 129 | Interlocked.Decrement(ref readCount); |
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| 130 | Thread.EndCriticalRegion(); |
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| 131 | #endif |
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| 132 | } |
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| 133 | } |
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| 134 | |||
| 135 | public void AcquireWriterLock() |
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| 136 | { |
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| 137 | #if !MONO && !PocketPC |
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| 138 | if (UseNativeSRWLock) |
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| 139 | { |
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| 140 | NativeMethods.AcquireSRWLockExclusive(ref LockSRW); |
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| 141 | } |
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| 142 | else |
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| 143 | #endif |
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| 144 | { |
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| 145 | #if UseFastResourceLock |
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| 146 | pLock.AcquireExclusive(); |
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| 147 | #else |
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| 148 | Thread.BeginCriticalRegion(); |
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| 149 | |||
| 150 | while(Interlocked.CompareExchange(ref busy, 1, 0) != 0) |
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| 151 | { |
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| 152 | Thread.Sleep(1); |
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| 153 | } |
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| 154 | |||
| 155 | while(Interlocked.CompareExchange(ref readCount, 0, 0) != 0) |
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| 156 | { |
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| 157 | Thread.Sleep(1); |
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| 158 | } |
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| 159 | #endif |
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| 160 | } |
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| 161 | } |
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| 162 | |||
| 163 | public void ReleaseWriterLock() |
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| 164 | { |
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| 165 | #if !MONO && !PocketPC |
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| 166 | if (UseNativeSRWLock) |
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| 167 | { |
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| 168 | NativeMethods.ReleaseSRWLockExclusive(ref LockSRW); |
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| 169 | } |
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| 170 | else |
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| 171 | #endif |
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| 172 | { |
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| 173 | #if UseFastResourceLock |
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| 174 | pLock.ReleaseExclusive(); |
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| 175 | #else |
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| 176 | Interlocked.Exchange(ref busy, 0); |
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| 177 | Thread.EndCriticalRegion(); |
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| 178 | #endif |
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| 179 | } |
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| 180 | } |
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| 181 | |||
| 182 | #region IDisposable Members |
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| 183 | |||
| 184 | public void Dispose() |
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| 185 | { |
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| 186 | #if UseFastResourceLock |
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| 187 | this.Dispose(true); |
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| 188 | GC.SuppressFinalize(this); |
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| 189 | #endif |
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| 190 | } |
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| 191 | |||
| 192 | #endregion |
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| 193 | } |
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| 194 | } |