[Cmake-commits] [cmake-commits] alex committed cmDepends.cxx 1.18 1.19

[cmake-commits at cmake.org]

Update of /cvsroot/CMake/CMake/Source
In directory public:/mounts/ram/cvs-serv26367

Modified Files:
	cmDepends.cxx 
Log Message:
Minor optimization in dependency checking.

When reading the depend.internal file, check only once for every depender
whether it exists, instead of repeatedly in a loop for each dependee. Within 
that function it can only change of the depender is removed. This is taken
care of.
This reduces the number of access() calls in kdelibs/khtml from 180000 to
90000 (i.e. 50%), and reduces the time for that (without the actual
scanning) from 0.3 s to 0.21 s on my system.

Alex


Index: cmDepends.cxx
===================================================================
RCS file: /cvsroot/CMake/CMake/Source/cmDepends.cxx,v
retrieving revision 1.18
retrieving revision 1.19
diff -C 2 -d -r1.18 -r1.19
*** cmDepends.cxx	8 May 2008 14:09:14 -0000	1.18
--- cmDepends.cxx	19 Sep 2009 17:02:12 -0000	1.19
***************
*** 153,156 ****
--- 153,157 ----
    // regenerated.
    bool okay = true;
+   bool dependerExists = false;
    while(internalDepends.getline(this->Dependee, this->MaxPath))
      {
***************
*** 169,172 ****
--- 170,178 ----
        {
        memcpy(this->Depender, this->Dependee, len+1);
+       // Calling FileExists() for the depender here saves in many cases 50%
+       // of the calls to FileExists() further down in the loop. E.g. for
+       // kdelibs/khtml this reduces the number of calls from 184k down to 92k,
+       // or the time for cmake -E cmake_depends from 0.3 s down to 0.21 s.
+       dependerExists = cmSystemTools::FileExists(this->Depender);
        continue;
        }
***************
*** 199,203 ****
          }
        }
!     else if(cmSystemTools::FileExists(depender))
        {
        // The dependee and depender both exist.  Compare file times.
--- 205,209 ----
          }
        }
!     else if(dependerExists)
        {
        // The dependee and depender both exist.  Compare file times.
***************
*** 226,230 ****
  
        // Remove the depender to be sure it is rebuilt.
!       cmSystemTools::RemoveFile(depender);
        }
      }
--- 232,240 ----
  
        // Remove the depender to be sure it is rebuilt.
!       if (dependerExists)
!         {
!         cmSystemTools::RemoveFile(depender);
!         dependerExists = false;
!         }
        }
      }