SNMP-Walk應用_多工簡單化 : async & await

參考資料 : http://www.codeproject.com/Articles/660482/Insides-Of-Async-Await 

在一個 async Methard ( )  中，程式會在 await 中等待新的線程完成，但主線程不阻塞。

該 async Methard ( ) 可多次進入，產生多個線程同時執行。

/* 主線程 */

private async void ThreadMathed()

        {

            txtAnalysisResult.Text = "Please wait while analysing the population.";

            try

            {

                int result = await new AnalysisEngine().AnalyzePopulationAsync();

                txtAnalysisResult.Text = result.ToString();

            }

            catch (System.Exception exp)

            {

                txtAnalysisResult.Text = exp.Message + Thread.CurrentThread.Name;

            }

        }

/* 子線程 Class */

class AnalysisEngine

    {

        public Task<int> AnalyzePopulationAsync()

        {

            Task<int> task = new Task<int>(AnalyzePopulation);

            task.Start();

            return task;

        }

        public int AnalyzePopulation()

        {

            //Sleep is used to simulate the time consuming activity.

            Thread.Sleep(10000);

            return new Random().Next(1, 5000);

        }

    }

 

運用到多線程 SNMP Walk : (該程式需使用 SnmpSharpNet.dll )

/* 主線程 */

        private async void button2_Click(object sender, EventArgs e)

        {

            Text = cnt++.ToString();

            NmsDevice dev = new NmsDevice();

            dev.IP = txtIP.Text;

            dev = await Pulling(dev, textBox1.Text);

            txtAnalysisResult.Text += dev.PullingOidResult + Environment.NewLine;

        }

        private async Task<NmsDevice> Pulling(NmsDevice dev, string oid)

        {

            NmsDevice Dev = new NmsDevice();

            try

            {

                Dev = await new SNMP_Walk(dev, oid).OidPullingAsync();

            }

            catch (System.Exception exp)

            {

                //txtAnalysisResult.Text = exp.Message + Thread.CurrentThread.Name;

                Dev.PullingOidResult = string.Format("No response received from SNMP agent.{0}", Environment.NewLine);

            }

            return Dev;

        }

子線程物件:

public class SNMP_Walk

 {

     /* 建構式 */

     public SNMP_Walk(NmsDevice dev, string oid)

     {

         mDevice = dev;

         OID = oid;

     }

     /* 屬性 */

     private NmsDevice mDevice = new NmsDevice();

     private string OID { get; set; }

     /* 方法 */

     public Task<NmsDevice> OidPullingAsync()

     {

         /* 一般程式寫法 */

         //Task<NmsDevice> task = new Task<NmsDevice>(SnmpWalk);

         //task.Start();

         /* 黏巴達 語法 */

         //Task<NmsDevice> task = Task<NmsDevice>.Factory.StartNew(() => { return SnmpWalk(); });

         //return task;

         /* 匿名方式 黏巴達 語法*/

         return Task<NmsDevice>.Factory.StartNew(() => { return SnmpWalk(); });

     }

     private NmsDevice SnmpWalk()

     {

         string IP = mDevice.IP;

         List<string> list = new List<string>();

         list = SnmpWalkList(IP, OID);

         /* 串接回傳值 */

         mDevice.PullingOidResult = "";

         foreach (string ss in list)

         {

             mDevice.PullingOidResult += string.Format("{0}{1}", ss, Environment.NewLine);

         }

         return mDevice;

     }

     private List<string> SnmpWalkList(string IP, string oid)

     {

         List<string> list = new List<string>();

         try

         {

             // SNMP community name

             OctetString community = new OctetString("public");

             // Define agent parameters class

             AgentParameters param = new AgentParameters(community);

             // Set SNMP version to 1

             param.Version = SnmpVersion.Ver1;

             // Construct the agent address object

             // IpAddress class is easy to use here because

             //  it will try to resolve constructor parameter if it doesn't

             //  parse to an IP address

             IpAddress agent = new IpAddress(IP);

             // Construct target

             UdpTarget target = new UdpTarget((IPAddress)agent, 161, 2000, 1);

             // Define Oid that is the root of the MIB

             //  tree you wish to retrieve

             Oid rootOid = new Oid(oid.Replace("\"", "")); // ifDescr

             // This Oid represents last Oid returned by

             //  the SNMP agent

             Oid lastOid = (Oid)rootOid.Clone();

             // Pdu class used for all requests

             Pdu pdu = new Pdu(PduType.GetNext);

             #region Loop through results

             while (lastOid != null)

             {

                 // When Pdu class is first constructed, RequestId is set to a random value

                 // that needs to be incremented on subsequent requests made using the

                 // same instance of the Pdu class.

                 if (pdu.RequestId != 0)

                 {

                     pdu.RequestId += 1;

                 }

                 // Clear Oids from the Pdu class.

                 pdu.VbList.Clear();

                 // Initialize request PDU with the last retrieved Oid

                 pdu.VbList.Add(lastOid);

                 // Make SNMP request

                 SnmpV1Packet result = (SnmpV1Packet)target.Request(pdu, param);

                 // You should catch exceptions in the Request if using in real application.

                 // If result is null then agent didn't reply or we couldn't parse the reply.

                 if (result != null)

                 {

                     // ErrorStatus other then 0 is an error returned by 

                     // the Agent - see SnmpConstants for error definitions

                     if (result.Pdu.ErrorStatus != 0)

                     {

                         // agent reported an error with the request

                         Console.WriteLine(string.Format("Error in SNMP reply. Error {0} index {1}",

                             result.Pdu.ErrorStatus,

                             result.Pdu.ErrorIndex));

                         lastOid = null;

                         break;

                     }

                     else

                     {

                         // Walk through returned variable bindings

                         foreach (Vb v in result.Pdu.VbList)

                         {

                             // Check that retrieved Oid is "child" of the root OID

                             if (rootOid.IsRootOf(v.Oid))

                             {

                                 //listBox1.Items.Add(string.Format("{0} ({1}): {2}",

                                 //    v.Oid.ToString(),

                                 //    SnmpConstants.GetTypeName(v.Value.Type),

                                 //    v.Value.ToString()) );

                                 list.Add(string.Format("{0}{1}", v.Value.ToString(), Environment.NewLine));

                                 lastOid = v.Oid;

                             }

                             else

                             {

                                 // we have reached the end of the requested

                                 // MIB tree. Set lastOid to null and exit loop

                                 lastOid = null;

                             }

                         }

                     }

                 }

                 else

                 {

                     list.Add(string.Format("No response received from SNMP agent.{0}", Environment.NewLine));

                 }

             }

             #endregion

             target.Close();

             return list;

         }

         catch (Exception ex)

         {

             list.Add(string.Format("No response received from SNMP agent.{0}", Environment.NewLine));

             return list;

         }

     }

 }