VB.NET语言 分布式系统中的数据一致性处理

Public Class RedisLock
Private _redis As IDatabase
Private _lockKey As String
Private _lockValue As String

Public Sub New(redis As IDatabase, lockKey As String, lockValue As String)
_redis = redis
_lockKey = lockKey
_lockValue = lockValue
End Sub

Public Function AcquireLock(timeout As TimeSpan) As Boolean
Dim lockResult As Boolean = False
Dim start As DateTime = DateTime.Now

While Not lockResult AndAlso (DateTime.Now - start) < timeout
lockResult = _redis.StringSetIf(_lockKey, _lockValue, TimeSpan.FromSeconds(10))
End While

Return lockResult
End Function

Public Class ZookeeperLock
Private _zk As ZooKeeper
Private _lockPath As String

Public Sub New(zk As ZooKeeper, lockPath As String)
_zk = zk
_lockPath = lockPath
End Sub

Public Function AcquireLock() As Boolean
Dim lockNode As String = _lockPath + "/lock"
Dim lockData As byte() = Encoding.UTF8.GetBytes("lock")

Try
Dim stat As Stat = _zk.create(lockNode, lockData, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL)
Dim sequence As Long = Convert.ToInt64(stat.EphemeralSequential.ToString.Substring(stat.EphemeralSequential.ToString.LastIndexOf("/") + 1))

Dim siblings As List(Of String) = _zk.getChildren(_lockPath, False).Children.ToList()
Dim currentSequence As Long = sequence

While currentSequence = siblings.Max(Function(s) Convert.ToInt64(s.Substring(s.LastIndexOf("/") + 1)))
Dim children As List(Of String) = _zk.getChildren(_lockPath, False).Children.ToList()
Dim minSequence As Long = children.Min(Function(s) Convert.ToInt64(s.Substring(s.LastIndexOf("/") + 1)))

If minSequence = currentSequence Then
Return True
End If

Thread.Sleep(1000)
End While
Catch ex As KeeperException
Return False
End Try

Return False
End Function

Public Sub ExecuteDistributedTransaction()
Using scope As New TransactionScope(TransactionScopeOption.Required, New TransactionOptions() With {
.IsolationLevel = IsolationLevel.ReadCommitted,
.Timeout = TimeSpan.FromSeconds(30)
})
' 执行分布式事务中的操作
' ...

Public Class DistributedTransaction
Private _userTransactionManager As UserTransactionManager

Public Sub New()
_userTransactionManager = UserTransactionManager.getInstance()
End Sub

Public Function BeginTransaction() As Xid
Dim xid As Xid = _userTransactionManager.getTransaction()
xid.begin()
Return xid
End Function

Public Sub CommitTransaction(xid As Xid)
xid.commit()
_userTransactionManager.commit(xid)
End Sub

Public Class EventBus
Private _channel As IModel
Private _queueName As String

Public Sub New(queueName As String)
Dim factory As IConnectionFactory = New ConnectionFactory() With {
.HostName = "localhost"
}
_channel = factory.CreateConnection().CreateModel()
_channel.QueueDeclare(queueName, False, False, False, Nothing)
_queueName = queueName
End Sub

Public Sub Publish(message As String)
Dim properties As BasicProperties = New BasicProperties() With {
.ContentType = "text/plain",
.DeliveryMode = 2
}
_channel.BasicPublish("", _queueName, properties, Encoding.UTF8.GetBytes(message))
End Sub

Public Sub Subscribe()
Dim consumer As EventingBasicConsumer = New EventingBasicConsumer(_channel)
AddHandler consumer.Received, AddressOf Consumer_Received
_channel.BasicConsume(_queueName, False, consumer)
End Sub

Public Class MessageQueue
Private _channel As IModel
Private _queueName As String

Public Sub New(queueName As String)
Dim factory As IConnectionFactory = New ConnectionFactory() With {
.HostName = "localhost"
}
_channel = factory.CreateConnection().CreateModel()
_channel.QueueDeclare(queueName, False, False, False, Nothing)
_queueName = queueName
End Sub

Public Sub Send(message As String)
Dim properties As BasicProperties = New BasicProperties() With {
.ContentType = "text/plain",
.DeliveryMode = 2
}
_channel.BasicPublish("", _queueName, properties, Encoding.UTF8.GetBytes(message))
End Sub

Public Sub Receive()
Dim consumer As EventingBasicConsumer = New EventingBasicConsumer(_channel)
AddHandler consumer.Received, AddressOf Consumer_Received
_channel.BasicConsume(_queueName, False, consumer)
End Sub