ghatem, single-threaded attempt

Author: georges-hatem

entries/ghatem/src/FileReader.pas

@@ -0,0 +1,90 @@
+unit FileReader;
+
+interface
+
+uses
+  System.Classes, System.SysUtils, System.Types,
+  Winapi.Windows;
+
+type
+  TInputReader = class
+    class procedure MMF(const AFilename: string; var aOut: TArray<AnsiChar>);
+  end;
+
+implementation
+
+
+class procedure TInputReader.MMF (const AFilename: string; var aOut: TArray<AnsiChar>);
+// procedure found online while searching for memory-mappped files
+
+// PROBLEM-1: GetFileSize was returning ~3.9B, which is incorrect.
+//            GetFileSizeEx was correctly returning 16B instead.
+// PROBLEM-2: CreateFileMapping only accepts Cardinals, which are not enough to fit 16B,
+//            thus RangeCheck error.
+// One way would be to call CreateFileMapping in chunks of acceptable size,
+// but a chunk of 3.9B was taking ~1.7 seconds to load.
+// so 4 times that was pretty slow, especially that it is a single-threaded operation
+var
+  hFile: THandle;
+  hFileMap: THandle;
+  hiSize: Int64;
+  loSize: Int64;
+  view: pointer;
+begin
+  if AFilename = '' then
+    Exit;
+  if not FileExists(AFilename) then
+    Exit;
+  {Open the file}
+  hFile := CreateFile(
+    PChar(AFilename), GENERIC_READ, FILE_SHARE_READ, nil,
+    OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0
+  );
+  if hFile <> INVALID_HANDLE_VALUE then
+  begin
+    loSize := GetFileSize(hFile, @hiSize);
+    {File was opened successfully, now map it:}
+    hFileMap := CreateFileMapping(
+      hFile, nil, PAGE_READONLY, hiSize, loSize, 'TextForString'
+    );
+    if (hFileMap <> 0) then
+    begin
+      if (GetLastError() = ERROR_ALREADY_EXISTS) then
+      begin
+        Writeln('Mapping already exists - not created.');
+        CloseHandle(hFileMap)
+      end
+      else
+      begin
+        view := nil;
+        try
+          {File mapped successfully, now map a view of the file into the
+          address space:}
+          view := MapViewOfFile(hFileMap, FILE_MAP_READ, 0, 0, 0);
+          if (view <> nil) then
+          begin {View mapped successfully}
+            {Close file handle - as long is view is open it will persist}
+            CloseHandle(hFile);
+            SetLength(aOut, loSize);
+            Move(view^, aOut[0], loSize);
+          end
+          else
+            WriteLn('Unable to map view of file.');
+        finally
+          UnmapViewOfFile(view);  {Close view}
+          CloseHandle(hFileMap);  {Close mapping}
+        end
+      end
+    end
+    else
+    begin
+      WriteLn('Unable to create file mapping.');
+    end;
+  end
+  else
+  begin
+    WriteLn('Unable to open file.');
+  end;
+end;
+
+end.

entries/ghatem/src/GHatemOneBRC.dpr

@@ -0,0 +1,69 @@
+program GHatemOneBRC;
+
+{$APPTYPE CONSOLE}
+
+{$R *.res}
+
+{$IFDEF RELEASE}
+{$INLINE ON}
+{$OPTIMIZATION ON}
+{$ASSERTIONS OFF}
+{$OVERFLOWCHECKS OFF}
+{$RANGECHECKS OFF}
+{$ENDIF}
+
+uses
+  OneBRC in 'OneBRC.pas',
+  Utils in 'Utils.pas',
+  console in 'console.pas';
+
+//const
+//  cInput: string = 'C:\DelphiLabs\1BRC2\data\measurements_1m.txt';
+//  cInput: string = 'C:\DelphiLabs\1BRC2\data\measurements_100m.txt';
+//  cInput: string = 'C:\DelphiLabs\1BRC2\data\measurements_1b.txt';
+
+var
+  vOneBRC: TOneBRC;
+  vFileName: string;
+begin
+  if ParseCmdLineParams (vFileName) then begin
+
+    vOneBRC := TOneBRC.Create;
+    try
+      vOneBRC.mORMotMMF (vFileName);
+      vOneBRC.SingleThread;
+      vOneBRC.GenerateOutput;
+    finally
+      vOneBRC.Free;
+    end;
+
+{$REGION 'debug'}
+//    Timer ('read mmfile',
+//      procedure
+//      begin
+//
+//      end
+//    );
+//
+//    for I := 0 to 4 do begin
+//      Timer ('process single thread',
+//        procedure
+//        begin
+//
+//        end
+//      );
+//
+//      Timer ('generate output',
+//        procedure
+//        begin
+//
+//        end
+//      );
+//    end;
+//
+//    WriteLn ('DONE!');
+//    Readln;
+{$ENDREGION}
+
+  end;
+end.