Databases
StackOverflow2013
Postsdbo
POHow to detect a timeout when using asynchronous Socket.BeginReceive?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHow to detect a timeout when using asynchronous Socket.BeginReceive?
    primarykey
    data
    text
    <p>Writing an asynchronous Ping using Raw Sockets in F#, to enable parallel requests using as few threads as possible. Not using "System.Net.NetworkInformation.Ping", because it appears to allocate one thread per request. Am also interested in using F# async workflows.</p> <p>The synchronous version below correctly times out when the target host does not exist/respond, but the asynchronous version hangs. Both work when the host does respond. Not sure if this is a .NET issue, or an F# one...</p> <p>Any ideas?</p> <p>(note: the process must run as Admin to allow Raw Socket access)</p> <p>This throws a timeout:</p> <pre><code>let result = Ping.Ping ( IPAddress.Parse( "192.168.33.22" ), 1000 ) </code></pre> <p>However, this hangs:</p> <pre><code>let result = Ping.AsyncPing ( IPAddress.Parse( "192.168.33.22" ), 1000 ) |&gt; Async.RunSynchronously </code></pre> <p>Here's the code...</p> <pre><code>module Ping open System open System.Net open System.Net.Sockets open System.Threading //---- ICMP Packet Classes type IcmpMessage (t : byte) = let mutable m_type = t let mutable m_code = 0uy let mutable m_checksum = 0us member this.Type with get() = m_type member this.Code with get() = m_code member this.Checksum = m_checksum abstract Bytes : byte array default this.Bytes with get() = [| m_type m_code byte(m_checksum) byte(m_checksum &gt;&gt;&gt; 8) |] member this.GetChecksum() = let mutable sum = 0ul let bytes = this.Bytes let mutable i = 0 // Sum up uint16s while i &lt; bytes.Length - 1 do sum &lt;- sum + uint32(BitConverter.ToUInt16( bytes, i )) i &lt;- i + 2 // Add in last byte, if an odd size buffer if i &lt;&gt; bytes.Length then sum &lt;- sum + uint32(bytes.[i]) // Shuffle the bits sum &lt;- (sum &gt;&gt;&gt; 16) + (sum &amp;&amp;&amp; 0xFFFFul) sum &lt;- sum + (sum &gt;&gt;&gt; 16) sum &lt;- ~~~sum uint16(sum) member this.UpdateChecksum() = m_checksum &lt;- this.GetChecksum() type InformationMessage (t : byte) = inherit IcmpMessage(t) let mutable m_identifier = 0us let mutable m_sequenceNumber = 0us member this.Identifier = m_identifier member this.SequenceNumber = m_sequenceNumber override this.Bytes with get() = Array.append (base.Bytes) [| byte(m_identifier) byte(m_identifier &gt;&gt;&gt; 8) byte(m_sequenceNumber) byte(m_sequenceNumber &gt;&gt;&gt; 8) |] type EchoMessage() = inherit InformationMessage( 8uy ) let mutable m_data = Array.create 32 32uy do base.UpdateChecksum() member this.Data with get() = m_data and set(d) = m_data &lt;- d this.UpdateChecksum() override this.Bytes with get() = Array.append (base.Bytes) (this.Data) //---- Synchronous Ping let Ping (host : IPAddress, timeout : int ) = let mutable ep = new IPEndPoint( host, 0 ) let socket = new Socket( AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout ) let packet = EchoMessage() let mutable buffer = packet.Bytes try if socket.SendTo( buffer, ep ) &lt;= 0 then raise (SocketException()) buffer &lt;- Array.create (buffer.Length + 20) 0uy let mutable epr = ep :&gt; EndPoint if socket.ReceiveFrom( buffer, &amp;epr ) &lt;= 0 then raise (SocketException()) finally socket.Close() buffer //---- Entensions to the F# Async class to allow up to 5 paramters (not just 3) type Async with static member FromBeginEnd(arg1,arg2,arg3,arg4,beginAction,endAction,?cancelAction): Async&lt;'T&gt; = Async.FromBeginEnd((fun (iar,state) -&gt; beginAction(arg1,arg2,arg3,arg4,iar,state)), endAction, ?cancelAction=cancelAction) static member FromBeginEnd(arg1,arg2,arg3,arg4,arg5,beginAction,endAction,?cancelAction): Async&lt;'T&gt; = Async.FromBeginEnd((fun (iar,state) -&gt; beginAction(arg1,arg2,arg3,arg4,arg5,iar,state)), endAction, ?cancelAction=cancelAction) //---- Extensions to the Socket class to provide async SendTo and ReceiveFrom type System.Net.Sockets.Socket with member this.AsyncSendTo( buffer, offset, size, socketFlags, remoteEP ) = Async.FromBeginEnd( buffer, offset, size, socketFlags, remoteEP, this.BeginSendTo, this.EndSendTo ) member this.AsyncReceiveFrom( buffer, offset, size, socketFlags, remoteEP ) = Async.FromBeginEnd( buffer, offset, size, socketFlags, remoteEP, this.BeginReceiveFrom, (fun asyncResult -&gt; this.EndReceiveFrom(asyncResult, remoteEP) ) ) //---- Asynchronous Ping let AsyncPing (host : IPAddress, timeout : int ) = async { let ep = IPEndPoint( host, 0 ) use socket = new Socket( AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout ) let packet = EchoMessage() let outbuffer = packet.Bytes try let! result = socket.AsyncSendTo( outbuffer, 0, outbuffer.Length, SocketFlags.None, ep ) if result &lt;= 0 then raise (SocketException()) let epr = ref (ep :&gt; EndPoint) let inbuffer = Array.create (outbuffer.Length + 256) 0uy let! result = socket.AsyncReceiveFrom( inbuffer, 0, inbuffer.Length, SocketFlags.None, epr ) if result &lt;= 0 then raise (SocketException()) return inbuffer finally socket.Close() } </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USJames Hugard
    1. USJames Hugard
    plurals
    1. This table or related slice is empty.
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POHow to detect a timeout when using asynchronous Socket.BeginReceive?
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POHow to detect a timeout when using asynchronous Socket.BeginReceive?
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POHow to detect a timeout when using asynchronous Socket.BeginReceive?
      1. USCameron Taggart
      1. VTFavorite
    1. COIs there any particular reason you want to re-invent System.Net.NetworkInformation.Ping.SendAsync()? It already supports timeouts.
      singulars
      1. POHow to detect a timeout when using asynchronous Socket.BeginReceive?
      1. USHans Passant
    2. COSendAsync/SendToAsync is not the same as the AsyncSendTo above... the former do not integrate with F# asynchronous workflows (which greatly simplify writing async code).
      singulars
      1. POHow to detect a timeout when using asynchronous Socket.BeginReceive?
      1. USJames Hugard
    3. COErm, the point is that you don't have to write it.
      singulars
      1. POHow to detect a timeout when using asynchronous Socket.BeginReceive?
      1. USHans Passant
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload