[twsocket] Multiple OnDataAvailable calls when no data to read
Arno Garrels [TeamICS] wrote: Have a look at this demo, if you think it's usefull I can add it to the repository. Oh, I am looking at this and get myself full of questions. Server app is rather clear, but not the Client, it's quite complex. 1) What's the meainng of SendBinString in Server, it is never used? What for do you use PutDataInSendBuffer? 2) I see alot of code to implement a data buffer which imho does the same things that socket buffer do. Isn't it necessary to construct such sophisticated logic every time when data parsing is needed? Moreover (maybe I haven't detected) what do you do, if FRcvBuf is going to be filled? That is, FRcvBuf: [_] [_] [_] [_] [D] [D] [D] | [_] - already parsed data [D] - data to be parsed | - current pointer and there are some more bytes to be received, but buffer is over... I've found only one Move(), but it's located inside if FReceiveMode = rmLine section, but no copying is done when mode is binary. Maybe it would be a good idea to implement this buffer internally in TWSocket? Just to have a solid way to know how mush data is available now. 3) if FReceiveMode = rmLine then begin ... end; if FReceiveMode rmBinary then Exit; strange construction, concerning that FReceiveMode could be only rmLine or rmBinary... maybe if..else ? 4) while (Length(RcvdLine) 0) and (RcvdLine[Length(RcvdLine)] in [#13, #10]) do RcvdLine := Copy(RcvdLine, 1, Length(RcvdLine) - 1); while (Length(RcvdLine) 0) and (RcvdLine[Length(RcvdLine)] in [#13, #10]) do SetLength(RcvdLine, Length(RcvdLine) - 1); ? -- Best regards, Anton -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
[twsocket] Multiple OnDataAvailable calls when no data to read
Arno Garrels [TeamICS] wrote: Have a look at this demo, if you think it's usefull I can add it to the repository. Oh, I am looking at this and get myself full of questions. Server app is rather clear, but not the Client, it's quite complex. 1) What's the meainng of SendBinString in Server, it is never used? What for do you use PutDataInSendBuffer? 2) I see alot of code to implement a data buffer which imho does the same things that socket buffer do. Isn't it necessary to construct such sophisticated logic every time when data parsing is needed? Moreover (maybe I haven't detected) what do you do, if FRcvBuf is going to be filled? That is, FRcvBuf: [_] [_] [_] [_] [D] [D] [D] | [_] - already parsed data [D] - data to be parsed | - current pointer and there are some more bytes to be received, but buffer is over... I've found only one Move(), but it's located inside if FReceiveMode = rmLine section, but no copying is done when mode is binary. Maybe it would be a good idea to implement this buffer internally in TWSocket? Just to have a solid way to know how mush data is available now. 3) if FReceiveMode = rmLine then begin ... end; if FReceiveMode rmBinary then Exit; strange construction, concerning that FReceiveMode could be only rmLine or rmBinary... maybe if..else ? 4) while (Length(RcvdLine) 0) and (RcvdLine[Length(RcvdLine)] in [#13, #10]) do RcvdLine := Copy(RcvdLine, 1, Length(RcvdLine) - 1); while (Length(RcvdLine) 0) and (RcvdLine[Length(RcvdLine)] in [#13, #10]) do SetLength(RcvdLine, Length(RcvdLine) - 1); ? -- Best regards, Anton -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Multiple OnDataAvailable calls when no data to read
Anton Sviridov wrote: 1) What's the meainng of SendBinString in Server, it is never used? It's never used. What for do you use PutDataInSendBuffer? It puts data into the send buffer without actually sending the data, it's not required, however saves on internal call to socket.send. 2) I see alot of code to implement a data buffer which imho does the same things that socket buffer do. It's similar, however needs less data copies, IMO. Isn't it necessary to construct such sophisticated logic every time when data parsing is needed? Moreover (maybe I haven't detected) what do you do, if FRcvBuf is going to be filled? That is, FRcvBuf: [_] [_] [_] [_] [D] [D] [D] | [_] - already parsed data [D] - data to be parsed - current pointer and there are some more bytes to be received, but buffer is over... I've found only one Move(), but it's located inside if FReceiveMode = rmLine section, but no copying is done when mode is binary. In mode rmBinary OnBinaryReceived will trigger. Data move is left to the component user. 3) if FReceiveMode = rmLine then begin ... end; if FReceiveMode rmBinary then Exit; strange construction, concerning that FReceiveMode could be only rmLine or rmBinary... maybe if..else ? It is because after TriggerLineReceived the receive mode may have changed to rmBinary and I did not want to call ParseReceiveBuffer recursively after TriggerLineReceived, it could be optimized though. 4) while (Length(RcvdLine) 0) and (RcvdLine[Length(RcvdLine)] in [#13, #10]) do RcvdLine := Copy(RcvdLine, 1, Length(RcvdLine) - 1); while (Length(RcvdLine) 0) and (RcvdLine[Length(RcvdLine)] in [#13, #10]) do SetLength(RcvdLine, Length(RcvdLine) - 1); ? This code is from the (very old) TcpSrv demo which I did not changed. BTW: I uploaded the BinCliDemo to the SVN repository last week with a small fix in: function FindCrLf(Buf: PAnsiChar; Count: Integer): Integer; begin for Result := 0 to Count - 1 do begin if (Buf[Result] = #13) and (Result + 1 Count) and (Buf[Result + 1] = #10) then Exit; end; Result := -1; end; -- Arno Garrels [TeamICS] http://www.overbyte.be/eng/overbyte/teamics.html -- Best regards, Anton -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
[twsocket] Multiple OnDataAvailable calls when no data to read
Arno Garrels [TeamICS] wrote: AFAIK no, only if you do not read all available data OnDataAvailable will trigger again. Arno Garrels [TeamICS] wrote: Thus calling Receive multiple times in a loop in on DataAvailable would not work properly. *embarrassed* how these two statements combine? Why several Receives should cause troubles? And another question. Is TWSocket.RcvdCount value reliable, i.e. if it = 0, then there is really no data in the socket? -- Best regards, Anton -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Multiple OnDataAvailable calls when no data to read
Hello Anton, *embarrassed* how these two statements combine? Why several Receives should cause troubles? it is by design, only 1 receive call in the event. And another question. Is TWSocket.RcvdCount value reliable, i.e. if it = 0, then there is really no data in the socket? Microsoft reports that the RcvdCount is not always reliable. Even if null then beste is to try to receive. See4 ReceiveStr as excmple. --- Rgds, Wilfried [TeamICS] http://www.overbyte.be/eng/overbyte/teamics.html http://www.mestdagh.biz -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
[twsocket] Multiple OnDataAvailable calls when no data to read
I'm now implementing a server on the base of TWSocketServer. In the client app I send some message to the server app, which receives it inside ServerIn_ClientDataAvailable procedure. Receiving is realized step by step to find a signature of message - i.e., there are several client.Receive in the method. I faced with strange thing: after whole message is read (and no data is sent yet), client's OnDataAvailable is executed some more times. TMsgReceiveSocket(Sender).RcvdCount returns 0, and Receive returns -1 with error code Would block. So the question: why OnDataAvailable is executed when there is actually no data to be read? -- Best regards, Anton -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Multiple OnDataAvailable calls when no data to read
Hello Anton, Don't worry. You don't have to do anything on the 'would block' winsock error. TWSocket deals with it. when OnDataAvailable fires, just try to receive all data. When Receive return 0 or -1 then just exit the event handler. -1 is error (don't worry), and 0 is if the peer has closed. --- Rgds, Wilfried [TeamICS] http://www.overbyte.be/eng/overbyte/teamics.html http://www.mestdagh.biz Tuesday, November 25, 2008, 15:29, Anton Sviridov wrote: I'm now implementing a server on the base of TWSocketServer. In the client app I send some message to the server app, which receives it inside ServerIn_ClientDataAvailable procedure. Receiving is realized step by step to find a signature of message - i.e., there are several client.Receive in the method. I faced with strange thing: after whole message is read (and no data is sent yet), client's OnDataAvailable is executed some more times. TMsgReceiveSocket(Sender).RcvdCount returns 0, and Receive returns -1 with error code Would block. So the question: why OnDataAvailable is executed when there is actually no data to be read? -- Best regards, Anton -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Multiple OnDataAvailable calls when no data to read
Wilfried Mestdagh wrote: Hello Anton, Don't worry. You don't have to do anything on the 'would block' winsock error. TWSocket deals with it. when OnDataAvailable fires, just try to receive all data. When Receive return 0 or -1 then just exit the event handler. -1 is error (don't worry), and 0 is if the peer has closed. As I understand the OP calls receive multiple times in OnDataAvailable which is not a good idea. -- Arno Garrels [TeamICS] http://www.overbyte.be/eng/overbyte/teamics.html --- Rgds, Wilfried [TeamICS] http://www.overbyte.be/eng/overbyte/teamics.html http://www.mestdagh.biz Tuesday, November 25, 2008, 15:29, Anton Sviridov wrote: I'm now implementing a server on the base of TWSocketServer. In the client app I send some message to the server app, which receives it inside ServerIn_ClientDataAvailable procedure. Receiving is realized step by step to find a signature of message - i.e., there are several client.Receive in the method. I faced with strange thing: after whole message is read (and no data is sent yet), client's OnDataAvailable is executed some more times. TMsgReceiveSocket(Sender).RcvdCount returns 0, and Receive returns -1 with error code Would block. So the question: why OnDataAvailable is executed when there is actually no data to be read? -- Best regards, Anton -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
[twsocket] Multiple OnDataAvailable calls when no data to read
Hello, Wilfried! You have calmed me :) Arno Garrels [TeamICS] wrote: As I understand the OP calls receive multiple times in OnDataAvailable which is not a good idea. So, each Recv launches one more OnDataAvail in the future? If so, can I easily read from socket block-by-block? Here's what i do for now: ... // look for first byte of message start signature repeat res := Receive(@tmpC,SizeOf(tmpC)) until (res=0) or (tmpC=MsgBeg[1]); if res = 0 then Exit; // check if the following bytes are really message start for tmpI := 2 to Length(MsgBeg) do if (Receive(@tmpC,SizeOf(tmpC))=0) or (tmpC MsgBeg[tmpI]) then Exit; // get message type res := Receive(@tmpI,SizeOf(tmpI)); // all OK, start receiving message FMsgType := TMsgType(tmpI); FInsideMsg := True; FBytesToRead := MsgLengths[FMsgType]; end Should I create a state variable and do every receive in separate execution of OnDataAvail ? -- Best regards, Anton -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
Re: [twsocket] Multiple OnDataAvailable calls when no data to read
Anton Sviridov wrote: Hello, Wilfried! You have calmed me :) Arno Garrels [TeamICS] wrote: As I understand the OP calls receive multiple times in OnDataAvailable which is not a good idea. So, each Recv launches one more OnDataAvail in the future? AFAIK no, only if you do not read all available data OnDataAvailable will trigger again. If so, can I easily read from socket block-by-block? Here's what i do for now: You should read from the socket once in OnDataAvailable. OnDataAvailable will trigger again when new data is available or in case you did not read everything. ICS uses asynchron sockets which requires messages being processed. Thus calling Receive multiple times in a loop in on DataAvailable would not work properly. -- Arno Garrels -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
