[CMake] Poor performance of copy_if_different

Clinton Stimpson clinton at elemtech.com
Tue Nov 6 13:41:37 EST 2012 

You could base your logic on CMAKE_CONFIGURATION_TYPES and CMAKE_BUILD TYPE.

For example:

if(CMAKE_CONFIGURATION_TYPES)
  foreach(type ${CMAKE_CONFIGURATION_TYPES})
    make_copy_rules(${type})
  endforeach()
else()
  make_copy_rules(${CMAKE_BUILD_TYPE})
endif()

On Tuesday, November 06, 2012 12:34:22 PM Robert Dailey wrote:
> I figured out the problem.
> 
> On single-configuration generators (like NMake, which I'm testing now)
> both release and debug configurations have the same binary output
> directory. Since I'm creating 1 custom target (and corresponding
> commands) per configuration, the 2nd configuration has the same
> outputs as the 1st, so the 2nd target fails because I"m adding
> different rules to the same output file. This isn't a problem with
> Visual Studio generators because my outputs go to Debug and Release.
> 
> Know any good workarounds for this?
> 
> On Tue, Nov 6, 2012 at 11:54 AM, Clinton Stimpson <clinton at elemtech.com> 
wrote:
> > Try this:
> >     add_custom_command(
> >     
> >         OUTPUT ${bin_outputs}
> >         COMMAND ${copy_commands}
> >         DEPENDS ....
> >     
> >     )
> > 
> > On Tuesday, November 06, 2012 11:50:54 AM Robert Dailey wrote:
> >> Thanks Clinton,
> >> 
> >> Here is what I have so far:
> >> 
> >> 
> >> project( copy_dlls )
> >> 
> >> set( copycmd "${CMAKE_COMMAND}" ARGS "-E" "copy_if_different" )
> >> 
> >> set( configurations debug release )
> >> foreach( config ${configurations} )
> >> 
> >>     string( TOUPPER ${config} upper_config )
> >>     
> >>     get_property( binarydirs GLOBAL PROPERTY
> >> 
> >> THIRD_PARTY_DIRS_${upper_config} ) foreach( dir ${binarydirs} )
> >> 
> >>         file( GLOB binaries "${dir}/*${CMAKE_SHARED_LIBRARY_SUFFIX}" )
> >>         
> >>         if( WIN32 AND config STREQUAL "debug" )
> >>         
> >>             file( GLOB pdbs "${dir}/*.pdb" )
> >>             list( APPEND binaries ${pdbs} )
> >>         
> >>         endif()
> >>         
> >>         foreach( bin ${binaries} )
> >>         
> >>             get_filename_component( bin_file ${bin} NAME )
> >>             
> >>             list( APPEND bin_outputs ${bin} )
> >>             list( APPEND copy_commands
> >>             
> >>                 COMMAND ${copycmd} "${bin}"
> >> 
> >> "${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${CMAKE_CFG_INTDIR}/${bin_file}"
> >> 
> >>             )
> >>         
> >>         endforeach()
> >>     
> >>     endforeach()
> >>     
> >>     add_custom_command(
> >>     
> >>         OUTPUT ${bin_outputs}
> >>         ${copy_commands}
> >>     
> >>     )
> >>     
> >>     add_custom_target( copy_dlls_${config}
> >>     
> >>         COMMENT "Copying ${config} binaries..."
> >>         DEPENDS ${bin_outputs}
> >>     
> >>     )
> >> 
> >> endforeach()
> >> 
> >> 
> >> This doesn't seem to work though, CMake tells me:
> >> 
> >> CMake Error: Attempt to add a custom rule to output
> >> "C:/Work/rdailey-hp/dpd-cmake/build-nmake-vc9/third_party/bdb/4.7.25/vc9s
> >> p1/ debug/bin/libdb47d.dll.rule" which already has a custom rule.
> >> 
> >> I'm trying to stuff all the copy commands and output files into 1
> >> custom command, and wrap that with a custom target, so I can make
> >> other targets depend on the custom target.
> >> 
> >> On Tue, Nov 6, 2012 at 11:44 AM, Clinton Stimpson <clinton at elemtech.com>
> > 
> > wrote:
> >> > add_custom_command(
> >> > 
> >> >   OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/my.dll
> >> >   COMMAND cmake -E copy ${CMAKE_CURRENT_SOURCE_DIR}/my.dll
> >> > 
> >> > ${CMAKE_CURRENT_BINARY_DIR}/my.dll
> >> > 
> >> >   DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/my.dll
> >> >   )
> >> > 
> >> > add_custom_target(copy_dll ALL DEPENDS
> >> > ${CMAKE_CURRENT_BINARY_DIR}/my.dll)
> >> > 
> >> > Whether you use 1 custom command per dll, or 1 for all dlls, is up to
> >> > you.
> >> > 
> >> >  If they usually change together, then you could have fewer custom
> >> > 
> >> > commands.  In that case, the OUTPUT would have multiple files and both
> >> > DEPENDS would have multiple files.
> >> > 
> >> > Another alternative is to use add_custom_command(TARGET POST_BUILD ...)
> >> > if
> >> > these are dlls that you compile yourself and need to copy after the
> >> > build
> >> > step.
> >> > 
> >> > On Tuesday, November 06, 2012 11:23:03 AM Robert Dailey wrote:
> >> >> Also, is it safe to add 1 custom command for each DLL copy? Or would
> >> >> you somehow only use 1 custom command and copy them all with it? Also
> >> >> would I add the custom commands to the custom target?
> >> >> 
> >> >> On Tue, Nov 6, 2012 at 11:11 AM, Clinton Stimpson
> >> >> <clinton at elemtech.com>
> >> > 
> >> > wrote:
> >> >> > On Tuesday, November 06, 2012 11:06:45 AM Robert Dailey wrote:
> >> >> >> I use ${CMAKE_COMMAND} -E copy_if_different to copy DLL files to my
> >> >> >> binary output directory. The custom target runs this command about
> >> >> >> 50-100 times (for that many files).
> >> >> >> 
> >> >> >> I notice that when all files are already copied, the commands still
> >> >> >> run extremely slowly. It takes just as long to copy all the files
> >> >> >> as
> >> >> >> it does to copy none of them.
> >> >> >> 
> >> >> >> I used the Sysinternals tool called Process Monitor to see what
> >> >> >> CMake
> >> >> >> is doing as it runs copy_if_different. It's opening the full file
> >> >> >> and
> >> >> >> seems to be comparing actual contents instead of something simple,
> >> >> >> such as timestamp.
> >> >> >> 
> >> >> >> I do not need such a thorough check, I simply want the check to see
> >> >> >> which timestamp is higher and copy if the source is newer than the
> >> >> >> target.
> >> >> >> 
> >> >> >> Any reason why copy_if_different is so slow? Is my assumption
> >> >> >> correct?
> >> >> >> How can I make it faster?
> >> >> > 
> >> >> > How about using plain "cmake -E copy ..." and rely on the timestamp
> >> >> > check
> >> >> > done by a custom command (add_custom_command()).
> >> >> > You need to make sure the input/ouput parts of the custom command
> >> >> > are
> >> >> > set
> >> >> > correctly so it can do a timestamp check.
> >> >> > 
> >> >> > --
> >> >> > Clinton Stimpson
> >> >> > Elemental Technologies, Inc
> >> >> > Computational Simulation Software, LLC
> >> >> > www.csimsoft.com
> >> >> > --
> >> >> > 
> >> >> > Powered by www.kitware.com
> >> >> > 
> >> >> > Visit other Kitware open-source projects at
> >> >> > http://www.kitware.com/opensource/opensource.html
> >> >> > 
> >> >> > Please keep messages on-topic and check the CMake FAQ at:
> >> >> > http://www.cmake.org/Wiki/CMake_FAQ
> >> >> > 
> >> >> > Follow this link to subscribe/unsubscribe:
> >> >> > http://www.cmake.org/mailman/listinfo/cmake
> >> > 
> >> > --
> >> > Clinton Stimpson
> >> > Elemental Technologies, Inc
> >> > Computational Simulation Software, LLC
> >> > www.csimsoft.com
> >> > --
> >> > 
> >> > Powered by www.kitware.com
> >> > 
> >> > Visit other Kitware open-source projects at
> >> > http://www.kitware.com/opensource/opensource.html
> >> > 
> >> > Please keep messages on-topic and check the CMake FAQ at:
> >> > http://www.cmake.org/Wiki/CMake_FAQ
> >> > 
> >> > Follow this link to subscribe/unsubscribe:
> >> > http://www.cmake.org/mailman/listinfo/cmake
> > 
> > --
> > Clinton Stimpson
> > Elemental Technologies, Inc
> > Computational Simulation Software, LLC
> > www.csimsoft.com
> > --
> > 
> > Powered by www.kitware.com
> > 
> > Visit other Kitware open-source projects at
> > http://www.kitware.com/opensource/opensource.html
> > 
> > Please keep messages on-topic and check the CMake FAQ at:
> > http://www.cmake.org/Wiki/CMake_FAQ
> > 
> > Follow this link to subscribe/unsubscribe:
> > http://www.cmake.org/mailman/listinfo/cmake
-- 
Clinton Stimpson
Elemental Technologies, Inc
Computational Simulation Software, LLC
www.csimsoft.com

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