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Calling function within class.
Nov 18
Vino
Nov 18
frame
Nov 18
Vino
Nov 18
frame
Nov 18
Vino
6 days ago
frame
6 days ago
Vino
6 days ago
frame
5 days ago
Arafel
November 18
Hi All,

  Request your help on how to call a function(listFile) from another function(getFilelist) within the same class(GetDirlist), below is an example code.

Code:

class GetDirlist {

@system private auto listFile(immutable string st)
{
 auto fl = execute(["ls","-l"]);
 enforce(fl.status == 0, format("File not Found: %s", fl.status));
 return fl.output;
}

@system public auto getFilelist()
{
  Array!string amidata;
  auto flstore = Array!string("/path1/Dir1", "path2/Dir2");
  foreach(st; parallel(flstore,1)) {
     auto fltask = task!listFile(st);
     fltask.executeInNewThread();
     amidata.insert(fltask.yieldForce);
  }
  return amidata[];
}
}

void main() {
writeln(getFilelist());
}

From,
Vino.B
November 18
On Wednesday, 18 November 2020 at 15:01:53 UTC, Vino wrote:
> Hi All,
>
>   Request your help on how to call a function(listFile) from another function(getFilelist) within the same class(GetDirlist), below is an example code.

I think it's basically the same issue like that recently opened topic:

https://forum.dlang.org/thread/ddxasuvusgibppcclsop@forum.dlang.org

You need to pass your class object as argument to a static method or anonymous function.

November 18
On Wednesday, 18 November 2020 at 16:53:44 UTC, frame wrote:
> On Wednesday, 18 November 2020 at 15:01:53 UTC, Vino wrote:
>> Hi All,
>>
>>   Request your help on how to call a function(listFile) from another function(getFilelist) within the same class(GetDirlist), below is an example code.
>
> I think it's basically the same issue like that recently opened topic:
>
> https://forum.dlang.org/thread/ddxasuvusgibppcclsop@forum.dlang.org
>
> You need to pass your class object as argument to a static method or anonymous function.

Hi,

  I made the changes as below , still not working

auto fltask = task!listFile(st);
to
auto fltask = task!({listFile(st);})(this).executeInNewThread();

Error:
/DTECH/LDC/dlang/ldc-1.24.0/bin/../import/std/parallelism.d(516,34): Error: function literal __lambda2() is not callable using argument types (GetDirlist)
/DTECH/LDC/dlang/ldc-1.24.0/bin/../import/std/parallelism.d(516,34):        expected 0 argument(s), not 1
/DTECH/LDC/dlang/ldc-1.24.0/bin/../import/std/parallelism.d(842,16): Error: template instance GetDirlist.GetDirlist.getFilelist.__foreachbody2.
Task!(delegate () @system { this.listFile(st); } , GetDirlist) error instantiating instantiated from here: task!(delegate () @system { this.listFile(st); } , GetDirlist)

From,
Vino.B
November 18
On Wednesday, 18 November 2020 at 17:55:36 UTC, Vino wrote:

>
>   I made the changes as below , still not working
>
> auto fltask = task!listFile(st);
> to
> auto fltask = task!({listFile(st);})(this).executeInNewThread();

The syntax is just wrong:

auto fltask = task!({listFile(st);})(this).executeInNewThread();

Should be:

auto fltask = task!((GetDirlist obj){obj.listFile(st);})(this).executeInNewThread();

It's the anonymous function syntax in one line compressed - it's equal to:

auto fltask = task!(
  function(GetDirlist obj) {
     obj.listFile(st);
  }
)(this).executeInNewThread();


But with your context it must look like this:

auto fltask = task!(
  function(GetDirlist obj, string foo) {
     obj.listFile(foo);
  }
)(this, st);

Still your code need to be fixed at lot to get working.
November 18
On Wednesday, 18 November 2020 at 18:24:59 UTC, frame wrote:
> On Wednesday, 18 November 2020 at 17:55:36 UTC, Vino wrote:
>
>>
>>   I made the changes as below , still not working
>>
>> auto fltask = task!listFile(st);
>> to
>> auto fltask = task!({listFile(st);})(this).executeInNewThread();
>
> The syntax is just wrong:
>
> auto fltask = task!({listFile(st);})(this).executeInNewThread();
>
> Should be:
>
> auto fltask = task!((GetDirlist obj){obj.listFile(st);})(this).executeInNewThread();
>
> It's the anonymous function syntax in one line compressed - it's equal to:
>
> auto fltask = task!(
>   function(GetDirlist obj) {
>      obj.listFile(st);
>   }
> )(this).executeInNewThread();
>
>
> But with your context it must look like this:
>
> auto fltask = task!(
>   function(GetDirlist obj, string foo) {
>      obj.listFile(foo);
>   }
> )(this, st);
>
> Still your code need to be fixed at lot to get working.

Hi,

  The above code is a sample code, but the logic is same, correct me if my understanding is wrong, in the above code "obj" is a an object for the class GetDirlist, so we are accessing the class member using "obj.listFile(st)" , so why do we need the "(this)" and also why is this so complicated in D where as in PHP it is simple like below

PHP Code:
class PHPclass {
      function test1 ($st) { return $st; }
      function test2 ()  { return $this->test1("Test"); }
}

$obj = new PHPclass();
print_r($obj->test2());





November 18
On 11/18/20 11:25 AM, Vino wrote:

> why is this
> so complicated in D where as in PHP it is simple like below
>
> PHP Code:
> class PHPclass {
>        function test1 ($st) { return $st; }
>        function test2 ()  { return $this->test1("Test"); }
> }
>
> $obj = new PHPclass();
> print_r($obj->test2());

It is so similar in D that one can say they are the same:

class PHPclass {
  auto test1(T)(T st) { return st; }
  auto test2()  { return this.test1("Test"); }
}

import std.stdio;

void main() {
  auto obj = new PHPclass();
  writeln(obj.test2());
}

Ali

November 18
On 11/18/20 7:01 AM, Vino wrote:

>    Request your help on how to call a function(listFile) from another
> function(getFilelist) within the same class(GetDirlist), below is an
> example code.

That code looks unnecessarily complex to me. First of all, parallel() already executes the loop body in separate threads, so I don't see any reason for Task in that code.

std.parallel will appear during my DConf presentation on Saturday. The following program applies ideas from some of my slides and just works in parallel:

import std.process;
import std.exception;
import std.format;
import std.parallelism;
import std.stdio;

class GetDirlist {

  @system private auto listFile(immutable string st)
  {
    auto fl = execute(["ls","-l"]);
    enforce(fl.status == 0, format("File not Found: %s", fl.status));
    return fl.output;
  }

  @system public auto getFilelist()
  {
    // I am using D dynamic arrays for simpliticy
    auto flstore = [ "/path1/Dir1", "path2/Dir2" ];

    // Note preallocated slot for each result:
    auto amidata = new string[flstore.length];

    // Taking advantage of automatic loop counter
    foreach(i, st; parallel(flstore,1)) {
      // Each execution assigns to its own slot
      amidata[i] = listFile(st);
    }
    return amidata[];
  }
}

void main() {
  // Need an object to call a non-static member function:
  auto g = new GetDirlist();
  writeln(g.getFilelist());
}

Ali

6 days ago
On Wednesday, 18 November 2020 at 19:25:06 UTC, Vino wrote:

>   The above code is a sample code, but the logic is same, correct me if my understanding is wrong, in the above code "obj" is a an object for the class GetDirlist, so we are accessing the class member using "obj.listFile(st)" , so why do we need the "(this)" and also why is this so complicated in D where as in PHP it is simple like below

You need to understand that you cannot use "this" in a function that you call in a new thread but task! starts a kind of new thread. That's not allowed by the runtime.

Your PHP code does not show any threading and PHP does not support threading without extensions. Also PHP does not allow $this for real threading extensions like parallel.

For D that means...

// before that statement you can call "this" - it points to your GetDirlist class.

auto fltask = task!(

   // this function is called in the new thread
   // and it's enclosed in the body of task! but could be also just a pointer to another
   // function. This is valid as long as the compiler do not need to access outside
   // variables/scope. "this" would also access the outside scope.

   function(GetDirlist obj, string st) {
            obj.listFile(st);
   }

   // end of function and thread
)

// after that statement you can call "this" again
// so we pass "this" (your object) as argument to the function that cannot access "this"
// and the string that the function is expecting

(this, "foo");


6 days ago
On Wednesday, 18 November 2020 at 21:33:58 UTC, Ali Çehreli wrote:
> On 11/18/20 7:01 AM, Vino wrote:
>
> >    Request your help on how to call a function(listFile) from
> another
> > function(getFilelist) within the same class(GetDirlist),
> below is an
> > example code.
>
> That code looks unnecessarily complex to me. First of all, parallel() already executes the loop body in separate threads, so I don't see any reason for Task in that code.
>
> std.parallel will appear during my DConf presentation on Saturday. The following program applies ideas from some of my slides and just works in parallel:
>
> import std.process;
> import std.exception;
> import std.format;
> import std.parallelism;
> import std.stdio;
>
> class GetDirlist {
>
>   @system private auto listFile(immutable string st)
>   {
>     auto fl = execute(["ls","-l"]);
>     enforce(fl.status == 0, format("File not Found: %s", fl.status));
>     return fl.output;
>   }
>
>   @system public auto getFilelist()
>   {
>     // I am using D dynamic arrays for simpliticy
>     auto flstore = [ "/path1/Dir1", "path2/Dir2" ];
>
>     // Note preallocated slot for each result:
>     auto amidata = new string[flstore.length];
>
>     // Taking advantage of automatic loop counter
>     foreach(i, st; parallel(flstore,1)) {
>       // Each execution assigns to its own slot
>       amidata[i] = listFile(st);
>     }
>     return amidata[];
>   }
> }
>
> void main() {
>   // Need an object to call a non-static member function:
>   auto g = new GetDirlist();
>   writeln(g.getFilelist());
> }
>
> Ali

Hi Ali,

Thank you very much, your solution works for my example, but it does not work for the main goal, let me explain what we are trying to perform.

Nut shell: Try to execute an aws command on sever accounts in parallel to get some data.

Noe: each account has as separate username and password store in a database table(encrypted).

Cod Logic
Fetch the username/ password from the table for each account.

Get the “awssecrete” key and “accesskey” for each account by calling an aws api using the above username/password.

Set the fetched key’s as an environment variable.

Execute the aws command and get the data for each of the account

  As we have many accounts what we are trying is to get the data in parallel(execute the aws command in parallel for each account and store the result in a array). At present our code is working fine(without parallel), the moment we enable parallelism, it is throwing an error on the SQL part (Fetch the username/ password from the table for each account), as it could not execute the SQL query in parallel for different account. If there is any other logic please do let me know will give it a try. Below is the SQL code.

@trusted public auto getAwsconf(immutable string account)
{
 auto con = new GetConnections();
 Statement stmt = con.db.prepare("SELECT username,AES_DECRYPT(b.userpass,b.key,b.vector) AS passwd FROM config WHERE account = :account");
 stmt.setParameter("account", account);
 RowSet awsaccount = stmt.query();
 scope(exit) con.db.close();
 return awsaccount;
}

From,
Vino.B
6 days ago
On Thursday, 19 November 2020 at 19:51:24 UTC, Vino wrote:
the moment we enable
> parallelism, it is throwing an error on the SQL part (Fetch the username/ password from the table for each account), as it could not execute the SQL query in parallel for different account.

I see no reason for a SELECT call (UPDATE/INSERT could cause locks...). Which error do you get?

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