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dkounal

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Posts posted by dkounal

  1. Posted

    Using TThreadedQueue<T> in Delphi 10.4.1, I have a couple of computers with windows 10 running an application of mine that have an Access violation error in line 7917 of system.generics.collections as reported by Eurekalog.

    it is the line: "TMonitor.Enter(FQueueLock);" It is not random. It happens all the time the first time it is used.

    Can you think of a reason? 

    function TThreadedQueue<T>.PushItem(const AItem: T; var AQueueSize: Integer): TWaitResult;
begin
  TMonitor.Enter(FQueueLock);
  try
    Result := wrSignaled;
    while (Result = wrSignaled) and (FQueueSize = Length(FQueue)) and not FShutDown do
      if not TMonitor.Wait(FQueueNotFull, FQueueLock, FPushTimeout) then
        Result := wrTimeout;

    if FShutDown or (Result <> wrSignaled) then
      Exit;

    FQueue[(FQueueOffset + FQueueSize) mod Length(FQueue)] := AItem;
    Inc(FQueueSize);
    Inc(FTotalItemsPushed);

  finally
    AQueueSize := FQueueSize;
    TMonitor.Exit(FQueueLock);
  end;

  TMonitor.Pulse(FQueueNotEmpty);
end;

     

  2. Posted · Edited by dkounal

    That's a good solution too, for many other situations.

    Agreed and thank you.

    One day, the limit arrives to this solution, too. I have 3 to 5 letters dirs, but installation programs still change path in updates and add again the path they want.....

    Not all the components are used at the same time. I can not afford to install and de-install them, to go behind each update to see what happened.

    I needed something else. Now the limit is the IDE itself.

  3. Posted

    I can not afford any more the "Can not load package" error message after installations that use DCC command line.

    I have a long library path with many components installed and an error like the following is presented again: 

    warning MSB6002: The command-line for the "DCC" task is too long. 
Command-lines longer than 32000 characters are likely to fail. 
Try reducing the length of the command-line by breaking down the call to "DCC" into multiple calls with fewer parameters per call.

    this mean that I should remove paths from library path in the IDE and try to compile again and return them back.... a bit annoying....

    Also, I hate to go to every combobox selection to add a path.

    The attached program reads registry and allows you to enable or disable library paths, add paths to all configs or remove from all configs.

    When saving it produces an .ini file with all paths (even these that are not enabled) to be used in the next time it runs

     

    No responsibility for anything, use it at your own risk, keep a backup of 'CurrentUser\SOFTWARE\Embarcadero\BDS\xxx\Library\' before using it, source at request, have a nice day!

    LibManager.zip

  4. Posted

    To be honest I usually use the above rec2J to log records with the Codesite express.

    Now, I need to transfer different type of records in JSON through mqtt protocol. So, I was investigating the J2rec.

    The idea of using BSON for the mqtt seems also better. Thank you a lot

    1 hour ago, mvanrijnen said:

    I like this one a lot: Efficient and easy-to-use JSON and BSON library – grijjy blog

     

     

  6. Posted · Edited by dkounal

    I need to serialize and de-serialize different records types.

    I wrote the following code that works ok only for the serialization and to be honest, I have not tested having records with class objects.

    The opposite, the de-serialization gives me an error " Internal: Cannot instantiate type .... " when calling the TJson.JsonToObject. I believe it has to do with the initialization of the new object but I can not understand the problem

    Any ideas? Thank you in advance

    The code is: 

    type Trec4Json<T>=class
   private
     fbv:T;
   public
     class Function rec2J(a: T):string;
     class Function J2rec(const a: string; var c:T):boolean;
     property bv:T read fbv write fbv;
end;


implementation
uses rest.json;

{ Trec4Json<T> }

class function Trec4Json<T>.rec2J(a: T): string;   // Record to Json String
var
  b: Trec4Json<T>;
begin
  b := Trec4Json<T>.create;
  b.bv := a;
  try
    result := TJson.ObjectToJsonString(b);
  finally
    b.free;
  end;
end;

class function Trec4Json<T>.J2rec(const a: string; var c: T): boolean;   // Json String to Record
var
  b: Trec4Json<T>;
begin
  try
    b := TJson.JsonToObject < Trec4Json < T >> (a);
    c := b.bv;
    b.free;
    result := true;
  except
    result := false;
  end;
end;

     

  7. Posted

    37 minutes ago, Dmitry Arefiev said:

    http://docwiki.embarcadero.com/RADStudio/Sydney/en/Local_SQL_(FireDAC)

    Thank you very much for your response

    I have seen this documentation and I have already used TFDlocalSQL with TFDMemTables ONLY

    The question is: In an existing TFDConnection fot SQLite with TFDTables and TFDQueries attached to it, can I add also a TFDLocalSQL and attach TFDMemTables?

    I notice for example that multiple results are not supported that "If the application is using base datasets and local datasets connected to the same SQLite connection, the connection must be enabled explicitly before any dataset on this connection is opened/executed/prepared. Otherwise, an exception is raised."

    I am not having the Enterprise version and I am a bit blind to use it in many cases, like the TFDDatSRow object that is not explained anywhere neither in the book of Jensen.

    I have also find that in the above link, the examples at the end of the page goes to a Not Found http error

    Thank you again in advance

  11. Posted

    I have to update an application that has 20 threads running at the same time and each thread is requesting an XML through an http connection. In order to process the received XML, each thread has to use data from 14 TFDMemtables. The Threads are the same running all the time and the TFDMemtables they use are also the same, The TFDMemTables' data are static, received from an external database when application starts, not need to be updated/edited as the application runs.

    I read that with TFDMemTable you can use clonecursor and have different TFDMemTable object instances with the same data. I though that I could create such a TFDMemTable for each thread before threads start to use them.

     

    My question: Can different threads use TFDMemTables object instances (created with data from clonecursor) from an initial TFDMemTable? Is this threadsafe?

     

    Thank you in advace

  13. Posted

    7 minutes ago, Marat1961 said:

    You just need to configure the auto format according to the formatting standard.

    This format is usually the default.

     

    If you think a little, then the following conclusion follows from here:
    Delphi has only one correct coding standard, and all the others are wrong.

     

    Delphi IDE 10.4.1 -> Tools -> Options -> Language ->Formatter ->select profile "Formater Default config" -> Apply.

    The code remains the same after Right Click->Format Source

    Am I missing something? Thank you in advance for your help

  16. Posted · Edited by dkounal
    better presentation of code

    I need to run a piece of code in TTask threads using a thread pool, that runs in every platform and get the results in the main UI thread in a thread safe message object without checking with a timer.
    Inspired by a post from Remy Lebeau in the Lazarus forum I wrote the following.
    Comments, suggestions, errors in the code welcome.
      
    interface

type
TTaskdata < T >= class
  type mydataP = ^T;
  mytaskproctyp =procedure(a: mydataP) of object;
private
  Data: T;
  ProcessData: mytaskproctyp;
  procedure DoProcess;
public
  procedure queue(datatyp: T; taskproc: mytaskproctyp);
  end;

implementation

procedure TTaskdata<T>.queue(datatyp: T; taskproc: mytaskproctyp);
begin
  Data := datatyp;
  ProcessData := taskproc;
  TThread.queue(nil, DoProcess);
end;

procedure TTaskdata<T>.DoProcess;
begin
  ProcessData(@Data);
end;
    In an other/main Tform Unit 
    type
  Dsoup = record
    nam: string;
    i: integer;
  end; // a sample record for send and receiving data to Ttask routine

  ReturnProc = procedure(mypointer: Ttaskdata<Dsoup>.mydataP) of object;

var
  FCustomPool: TThreadPool;
  // the theadpool to be used for reusing threads, it should initialiazed in Tform's constructor

procedure TForm1.Button1Click(Sender: TObject);
// the initial route that will prepare data for Ttask and run it
var
  soup: Dsoup;
begin
  { set in Dsoup all data to send in TTask routine }
  TTask.Run(dowork(soup, getresults), FCustomPool);
end;

function TForm1.dowork(const a: Dsoup; p: ReturnProc): tproc;
begin
  Result := // anonymous function to run by Ttask
      procedure
    var
      ff: Ttaskdata<Dsoup>;
    begin
      ff := Ttaskdata<Dsoup>.create;
      try
        { do all the task job here }
        ff.queue(a, p); // add result data to be sent with Thread.queue
      except
        ff.free;
      end;
    end;
end;

procedure TForm1.getresults(p: Ttaskdata<Dsoup>.mydataP);
begin
  { here come the results from TTask in the main UI thread }
end;

     

     
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