multithreadprocs: added DoParallelNested

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@5891 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/multithreadprocs/examples/parallelloop1.lpr

@@ -54,7 +54,7 @@ begin
     Results[Index]:=-1;
     i:=Index;
     while i<List.Count-1 do begin
-      if List[i]=Value then  // hier wuerde die teure Vergleichsoperation stehen
+      if List[i]=Value then  // imagine here an expensive compare function
         Results[Index]:=i;
       inc(i,BlockCount);
     end;
@@ -72,7 +72,7 @@ begin
     BlockCount:=ProcThreadPool.MaxThreadCount;
     SetLength(Results,BlockCount);
     ProcThreadPool.DoParallel(@FindBestParallel,0,BlockCount-1,@Data);
-    // Ergebnisse zusammenfassen
+    // collect results
     Result:=-1;
     for Index:=0 to BlockCount-1 do
       if Results[Index]>=0 then
@@ -87,7 +87,7 @@ begin
   Result:=-1;
   i:=0;
   while i<List.Count do begin
-    if List[i]=Value then // hier wuerde die teure Vergleichsoperation stehen
+    if List[i]=Value then  // imagine here an expensive compare function
       Result:=i;
     inc(i);
   end;

components/multithreadprocs/examples/parallelloop_nested1.lpi

@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<CONFIG>
+  <ProjectOptions>
+    <Version Value="10"/>
+    <General>
+      <Flags>
+        <LRSInOutputDirectory Value="False"/>
+      </Flags>
+      <SessionStorage Value="InIDEConfig"/>
+      <MainUnit Value="0"/>
+      <Title Value="parallelloop_nested1"/>
+    </General>
+    <VersionInfo>
+      <StringTable ProductVersion=""/>
+    </VersionInfo>
+    <BuildModes Count="1">
+      <Item1 Name="default" Default="True"/>
+    </BuildModes>
+    <PublishOptions>
+      <Version Value="2"/>
+      <IgnoreBinaries Value="False"/>
+      <IncludeFileFilter Value="*.(pas|pp|inc|lfm|lpr|lrs|lpi|lpk|sh|xml)"/>
+      <ExcludeFileFilter Value="*.(bak|ppu|ppw|o|so);*~;backup"/>
+    </PublishOptions>
+    <RunParams>
+      <local>
+        <FormatVersion Value="1"/>
+        <LaunchingApplication PathPlusParams="/usr/X11R6/bin/xterm -T 'Lazarus Run Output' -e $(LazarusDir)/tools/runwait.sh $(TargetCmdLine)"/>
+      </local>
+    </RunParams>
+    <RequiredPackages Count="1">
+      <Item1>
+        <PackageName Value="MultiThreadProcsLaz"/>
+        <MinVersion Valid="True"/>
+        <DefaultFilename Value="../multithreadprocslaz.lpk"/>
+      </Item1>
+    </RequiredPackages>
+    <Units Count="1">
+      <Unit0>
+        <Filename Value="parallelloop_nested1.lpr"/>
+        <IsPartOfProject Value="True"/>
+      </Unit0>
+    </Units>
+  </ProjectOptions>
+  <CompilerOptions>
+    <Version Value="11"/>
+    <Parsing>
+      <SyntaxOptions>
+        <UseAnsiStrings Value="False"/>
+      </SyntaxOptions>
+    </Parsing>
+  </CompilerOptions>
+</CONFIG>

components/multithreadprocs/examples/parallelloop_nested1.lpr

@@ -0,0 +1,103 @@
+{ Example for a parallel loop with MTProcs.
+
+  Copyright (C) 2017 Mattias Gaertner mattias@freepascal.org
+
+  This library is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Library General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or (at your
+  option) any later version with the following modification:
+
+  As a special exception, the copyright holders of this library give you
+  permission to link this library with independent modules to produce an
+  executable, regardless of the license terms of these independent modules,and
+  to copy and distribute the resulting executable under terms of your choice,
+  provided that you also meet, for each linked independent module, the terms
+  and conditions of the license of that module. An independent module is a
+  module which is not derived from or based on this library. If you modify
+  this library, you may extend this exception to your version of the library,
+  but you are not obligated to do so. If you do not wish to do so, delete this
+  exception statement from your version.
+
+  This program is distributed in the hope that it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License
+  for more details.
+
+  You should have received a copy of the GNU Library General Public License
+  along with this library; if not, write to the Free Software Foundation,
+  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+}
+program parallelloop_nested1;
+
+{$mode objfpc}{$H+}
+{$ModeSwitch nestedprocvars}
+
+uses
+  {$IFDEF UNIX}
+  cthreads, cmem,
+  {$ENDIF}
+  Classes, SysUtils, Math, MTProcs;
+
+
+function FindBestParallel(aList: TList; aValue: Pointer): integer;
+var
+  BlockSize: PtrInt;
+  Results: array of integer;
+
+  procedure InParallel(Index: PtrInt; Data: Pointer; Item: TMultiThreadProcItem);
+  var
+    i, StartIndex, EndIndex: PtrInt;
+  begin
+    Results[Index]:=-1;
+    StartIndex:=Index*BlockSize;
+    EndIndex:=Min(StartIndex+BlockSize,aList.Count);
+    //if MainThreadID=GetCurrentThreadId then
+    //  writeln('FindBestParallel Index=',Index,' StartIndex=',StartIndex,' EndIndex=',EndIndex);
+    for i:=StartIndex to EndIndex-1 do begin
+      if aList[i]=aValue then  // imagine here an expensive compare function
+        Results[Index]:=i;
+    end;
+  end;
+
+var
+  Index: integer;
+  BlockCount: PtrInt;
+begin
+  ProcThreadPool.CalcBlockSize(aList.Count,BlockCount,BlockSize);
+  SetLength(Results,BlockCount);
+  //writeln('FindBestParallel BlockCount=',BlockCount,' List.Count=',aList.Count,' BlockSize=',BlockSize);
+  ProcThreadPool.DoParallelNested(@InParallel,0,BlockCount-1);
+  // collect results
+  Result:=-1;
+  for Index:=0 to BlockCount-1 do
+    if Results[Index]>=0 then
+      Result:=Results[Index];
+end;
+
+function FindBestSingleThreaded(List: TList; Value: Pointer): integer;
+var
+  i: integer;
+begin
+  Result:=-1;
+  i:=0;
+  while i<List.Count do begin
+    if List[i]=Value then  // imagine here an expensive compare function
+      Result:=i;
+    inc(i);
+  end;
+end;
+
+var
+  List: TList;
+  i: Integer;
+begin
+  List:=TList.Create;
+  for i:=0 to 100000000 do
+    List.Add(Pointer(i));
+  writeln('searching ...');
+  i:=FindBestParallel(List,Pointer(List.Count-2));
+  writeln('parallel search i=',i);
+  i:=FindBestSingleThreaded(List,Pointer(List.Count-2));
+  writeln('linear search i=',i);
+end.
+