IntroductionIn Multi threaded application, it is essential to have thread safe collection. Provided below the SafeDictionary class built over Dictionary object.
Note: To iterate each item in collection, avoid "For each" loop & use "CopyTo", so that the collection values will be moved to another array & you can loop that array.
SafeDictionary.vb
Public Class SafeDictionary(Of TKey, TValue)
Implements IDictionary(Of TKey, TValue)
Private _rwLock As New Threading.ReaderWriterLockSlim
Private _dict As New Generic.Dictionary(Of TKey, TValue)
Private Class AcquireWriteLock
Implements IDisposable
Private _rwLock As New Threading.ReaderWriterLockSlim
Public Sub New(ByVal rwLock As Threading.ReaderWriterLockSlim)
_rwLock = rwLock
_rwLock.EnterWriteLock()
End Sub
Private disposedValue As Boolean = False ' To detect redundant calls
' IDisposable
Protected Overridable Sub Dispose(ByVal disposing As Boolean)
If Not Me.disposedValue Then
If disposing Then
' TODO: free other state (managed objects).
_rwLock.ExitWriteLock()
End If
' TODO: free your own state (unmanaged objects).
' TODO: set large fields to null.
End If
Me.disposedValue = True
End Sub
#Region " IDisposable Support "
' This code added by Visual Basic to correctly implement the disposable pattern.
Public Sub Dispose() Implements IDisposable.Dispose
' Do not change this code. Put cleanup code in Dispose(ByVal disposing As Boolean) above.
Dispose(True)
GC.SuppressFinalize(Me)
End Sub
#End Region
End Class
Private Class AcquireReadLock
Implements IDisposable
Private _rwLock As New Threading.ReaderWriterLockSlim
Public Sub New(ByVal rwLock As Threading.ReaderWriterLockSlim)
_rwLock = rwLock
_rwLock.EnterReadLock()
End Sub
Private disposedValue As Boolean = False ' To detect redundant calls
' IDisposable
Protected Overridable Sub Dispose(ByVal disposing As Boolean)
If Not Me.disposedValue Then
If disposing Then
' TODO: free other state (managed objects).
_rwLock.ExitReadLock()
End If
' TODO: free your own state (unmanaged objects).
' TODO: set large fields to null.
End If
Me.disposedValue = True
End Sub
#Region " IDisposable Support "
' This code added by Visual Basic to correctly implement the disposable pattern.
Public Sub Dispose() Implements IDisposable.Dispose
' Do not change this code. Put cleanup code in Dispose(ByVal disposing As Boolean) above.
Dispose(True)
GC.SuppressFinalize(Me)
End Sub
#End Region
End Class
Public Sub Add(ByVal item As System.Collections.Generic.KeyValuePair(Of TKey, TValue)) Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).Add
Using New AcquireWriteLock(_rwLock)
_dict(item.Key) = item.Value
End Using
End Sub
Public Sub Clear() Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).Clear
Using New AcquireWriteLock(_rwLock)
_dict.Clear()
End Using
End Sub
Public Function Contains(ByVal item As System.Collections.Generic.KeyValuePair(Of TKey, TValue)) As Boolean Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).Contains
Using New AcquireReadLock(_rwLock)
Return _dict.Contains(item)
End Using
End Function
Public Sub CopyTo(ByVal array() As System.Collections.Generic.KeyValuePair(Of TKey, TValue), ByVal arrayIndex As Integer) Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).CopyTo
Using New AcquireReadLock(_rwLock)
_dict.ToArray.CopyTo(array, arrayIndex)
End Using
End Sub
Public ReadOnly Property Count() As Integer Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).Count
Get
Using New AcquireReadLock(_rwLock)
Return _dict.Count
End Using
End Get
End Property
Public ReadOnly Property IsReadOnly() As Boolean Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).IsReadOnly
Get
Return False
End Get
End Property
Public Function Remove(ByVal item As System.Collections.Generic.KeyValuePair(Of TKey, TValue)) As Boolean Implements System.Collections.Generic.ICollection(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).Remove
Using New AcquireWriteLock(_rwLock)
Return _dict.Remove(item.Key)
End Using
End Function
Public Sub Add(ByVal key As TKey, ByVal value As TValue) Implements System.Collections.Generic.IDictionary(Of TKey, TValue).Add
Using New AcquireWriteLock(_rwLock)
_dict(key) = value
End Using
End Sub
Public Function ContainsKey(ByVal key As TKey) As Boolean Implements System.Collections.Generic.IDictionary(Of TKey, TValue).ContainsKey
Using New AcquireReadLock(_rwLock)
Return _dict.ContainsKey(key)
End Using
End Function
Default Public Property Item(ByVal key As TKey) As TValue Implements System.Collections.Generic.IDictionary(Of TKey, TValue).Item
Get
Using New AcquireReadLock(_rwLock)
Return _dict(key)
End Using
End Get
Set(ByVal value As TValue)
Using New AcquireWriteLock(_rwLock)
_dict(key) = value
End Using
End Set
End Property
Public ReadOnly Property Keys() As System.Collections.Generic.ICollection(Of TKey) Implements System.Collections.Generic.IDictionary(Of TKey, TValue).Keys
Get
Using New AcquireReadLock(_rwLock)
Return _dict.Keys
End Using
End Get
End Property
Public Function Remove(ByVal key As TKey) As Boolean Implements System.Collections.Generic.IDictionary(Of TKey, TValue).Remove
Using New AcquireWriteLock(_rwLock)
Return _dict.Remove(key)
End Using
End Function
Public Function TryGetValue(ByVal key As TKey, ByRef value As TValue) As Boolean Implements System.Collections.Generic.IDictionary(Of TKey, TValue).TryGetValue
Using New AcquireReadLock(_rwLock)
Return _dict.TryGetValue(key, value)
End Using
End Function
Public ReadOnly Property Values() As System.Collections.Generic.ICollection(Of TValue) Implements System.Collections.Generic.IDictionary(Of TKey, TValue).Values
Get
Using New AcquireReadLock(_rwLock)
Return _dict.Values
End Using
End Get
End Property
Public Function GetEnumeratorGeneric() As System.Collections.Generic.IEnumerator(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)) Implements System.Collections.Generic.IEnumerable(Of System.Collections.Generic.KeyValuePair(Of TKey, TValue)).GetEnumerator
Using New AcquireReadLock(_rwLock)
Return _dict.GetEnumerator
End Using
End Function
Public Function GetEnumerator() As System.Collections.IEnumerator Implements System.Collections.IEnumerable.GetEnumerator
Using New AcquireReadLock(_rwLock)
Return _dict.GetEnumerator
End Using
End Function
End Class
Happy Coding!
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