[fpc-pascal] ShortString still relevant today?

[Guillermo Martínez Jiménez]

Hi,

I'm not sure but I think that CPU caches (L1, L2...) have some impact
on this example.  Also I think PChar assignation should use string
copy instead (Strings.strcopy).  Not time to do my own tests right now
though u_u) .

Regards,
Guillermo "Ñuño" Martínez

El Tue, 4 Jul 2023 11:46:42 +0700
Hairy Pixels via fpc-pascal <fpc-pascal at lists.freepascal.org> escribió:
> Here is my test unit I'm playing with. It's crude but can anyone
> suggest what other things I could test? 
> 
> I'm playing with a string pointer also to see how ref
> counting/finalization plays in. Making your own managed typed using
> management operators is not tested but I'm sure it will be terrible
> compared to everything else.
> 
> * test_short_string time: 143ms
> * test_ansi_string time: 115ms
> * test_mem_string time: 115ms
> 
> * test_short_string_record time: 165ms
> * test_ansi_string_record time: 75ms
> * test_mem_string_record time: 47ms
> 
> * test_short_string_mutate time: 203ms
> * test_ansi_string_mutate time: 181ms
> 
> =======================================================================================
> 
> {$mode objfpc}
> 
> program string_test;
> uses
>   SysUtils, DateUtils;
> 
> const
>   ITERATIONS = 1000 * 1000;
>   TEST_STRING = 'Lorem ipsum dolor sit amet, consectetur adipiscing
> elit';
> 
> type
>   TTestProc = procedure;
> 
> procedure test_mem_string;
> 
>   procedure do_pass(const s: PString; len: Integer);
>   var
>     c: Char;
>     i: Integer;
>   begin
>     for i := 0 to len - 1 do
>       c := s^[i];
>   end;
> 
> var
>   s: PString;
>   i, len: Integer;
> begin
>   for i := 0 to ITERATIONS - 1 do
>     begin
>       len := Length(TEST_STRING);
>       s := GetMem(len);
>       s^ := TEST_STRING;
>       do_pass(s, len);
>       FreeMem(s);
>     end;
> end;
> 
> procedure test_short_string;
> 
>   procedure do_pass(const s: ShortString);
>   var
>     c: Char;
>     i: Integer;
>   begin
>     for i := 0 to length(s) - 1 do
>       c := s[i];
>   end;
> 
> var
>   s: Shortstring;
>   i: Integer;
> begin
>   for i := 0 to ITERATIONS - 1 do
>     begin
>       s := TEST_STRING;
>       do_pass(s);
>     end;
> end;
> 
> procedure test_ansi_string;
> 
>   procedure ansi_string_pass(const s: AnsiString);
>   var
>     c: Char;
>     i: Integer;
>   begin
>     for i := 0 to length(s) - 1 do
>       c := s[i];
>   end;
> 
> var
>   s: AnsiString;
>   i: Integer;
> begin
>   for i := 0 to ITERATIONS - 1 do
>     begin
>       s := TEST_STRING;
>       ansi_string_pass(s);
>     end;
> end;
> 
> procedure test_ansi_string_mutate;
> var
>   i, j: Integer;
>   s1, s2: AnsiString;
> begin
>   for i := 0 to ITERATIONS - 1 do
>     begin
>       s1 := TEST_STRING;
>       s2 := s1 + IntToStr(i);
>       for j := 1 to length(s2) - 1 do
>         s2[j] := 'x';
>     end;
> end;
> 
> procedure test_short_string_mutate;
> var
>   i, j: Integer;
>   s1, s2: ShortString;
> begin
>   for i := 0 to ITERATIONS - 1 do
>     begin
>       s1 := TEST_STRING;
>       s2 := s1 + IntToStr(i);
>       for j := 1 to length(s2) - 1 do
>         s2[j] := 'x';
>     end;
> end;
> 
> procedure test_short_string_record;
> 
> type
>   TMyRecord = record
>     a: ShortString;
>     b: ShortString;
>     c: ShortString;
>   end;
> 
> function do_pass(rec: TMyRecord): TMyRecord;
> begin
>   result := rec;
> end;
> 
> var
>   i: Integer;
>   r: TMyRecord;
> begin
>   for i := 0 to ITERATIONS - 1 do
>     begin
>       r.a := TEST_STRING;
>       r.b := TEST_STRING;
>       r.c := TEST_STRING;
>       do_pass(r);
>     end;
> end;
> 
> 
> procedure test_ansi_string_record;
> 
> type
>   TMyRecord = record
>     a: AnsiString;
>     b: AnsiString;
>     c: AnsiString;
>   end;
> 
> function do_pass(rec: TMyRecord): TMyRecord;
> begin
>   result := rec;
> end;
> 
> var
>   i: Integer;
>   r: TMyRecord;
> begin
>   for i := 0 to ITERATIONS - 1 do
>     begin
>       r.a := TEST_STRING;
>       r.b := TEST_STRING;
>       r.c := TEST_STRING;
> 
>       do_pass(r);
>     end;
> end;
> 
> procedure test_mem_string_record;
> 
> type
>   TMyRecord = record
>     a: PString;
>     b: PString;
>     c: PString;
>   end;
> 
> function do_pass(rec: TMyRecord): TMyRecord;
> begin
>   result := rec;
> end;
> 
> var
>   i: Integer;
>   r: TMyRecord;
>   len: Integer;
> begin
>   len := Length(TEST_STRING);
> 
>   for i := 0 to ITERATIONS - 1 do
>     begin
>       r.a := GetMem(len);
>       r.b := GetMem(len);
>       r.c := GetMem(len);
> 
>       r.a^ := TEST_STRING;
>       r.b^ := TEST_STRING;
>       r.c^ := TEST_STRING;
> 
>       do_pass(r);
>     end;
> end;
> 
> 
> procedure run_test(name: String; test: TTestProc);
> var
>   startTime: Double;
> begin
>   startTime := Now;
>   test;
>   writeln('* ', name,' time: ', MilliSecondsBetween(Now, StartTime),
> 'ms'); end;
> 
> begin
>   run_test('test_short_string', @test_short_string);
>   run_test('test_ansi_string', @test_ansi_string);
>   run_test('test_mem_string', @test_ansi_string);
> 
>   run_test('test_short_string_record', @test_short_string_record);
>   run_test('test_ansi_string_record', @test_ansi_string_record);
>   run_test('test_mem_string_record', @test_mem_string_record);
> 
>   run_test('test_short_string_mutate', @test_short_string_mutate);
>   run_test('test_ansi_string_mutate', @test_ansi_string_mutate);
> end.
> 
> Regards,
> Ryan Joseph
> 
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