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rework version_string logic - only write the file if the git commit (not timestamp) changes

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Mark Pictor 2015-01-26 21:24:14 -05:00
parent 2216cf47d3
commit 6ec39b58aa
1 changed files with 18 additions and 5 deletions
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23
cmake/sc_version_string.cmake
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@ -1,11 +1,16 @@
# creates sc_version_string.h, which defines sc_version()
# sc_version() returns a pretty commit description and a build timestamp.
# only update the file if the git commit has changed, because whenever the file is updated files including the header must rebuild
# parallel rebuilds can result in race conditions and failures, particularly when running ctest in parallel
# http://stackoverflow.com/questions/3780667
# http://www.cmake.org/pipermail/cmake/2009-February/027014.html
set(SC_IS_SUBBUILD "@SC_IS_SUBBUILD@")
set(SC_VERSION_HEADER "${BINARY_DIR}/include/sc_version_string.h")
#---------- find commit id ------------------
#use git for a pretty commit id
#uses 'git describe --tags', so tags are required in the repo
@ -69,11 +74,19 @@ set(header_string "/* sc_version_string.h - written by cmake. Changes will be lo
"#endif\n"
)
file(WRITE sc_version_string.h.txt ${header_string})
# copy the file to the final header only if the version changes
# reduces needless rebuilds
execute_process(COMMAND ${CMAKE_COMMAND} -E copy_if_different
sc_version_string.h.txt ${BINARY_DIR}/include/sc_version_string.h)
#compare the new and old commit versions, don't update the file if only the timestamp differs
if(EXISTS ${SC_VERSION_HEADER})
file(READ ${SC_VERSION_HEADER} OLD_VER_STRING LIMIT 600) #file is ~586 bytes
string(FIND "${OLD_VER_STRING}" "git commit id: ${GIT_COMMIT_ID}" COMMIT_MATCH )
# ${COMMIT_MATCH} == -1 if no match
else()
set(COMMIT_MATCH -1)
endif(EXISTS ${SC_VERSION_HEADER})
if(${COMMIT_MATCH} LESS 1 )
file(WRITE ${SC_VERSION_HEADER} ${header_string})
endif(${COMMIT_MATCH} LESS 1)
if(NOT SC_IS_SUBBUILD)
message("-- sc_version_string.h is up-to-date.")
endif(NOT SC_IS_SUBBUILD)