File: autoconf.info,  Node: Cache Checkpointing,  Prev: Cache Files,  Up: Caching Results

7.4.3 Cache Checkpointing
-------------------------

If your configure script, or a macro called from ‘configure.ac’, happens
to abort the configure process, it may be useful to checkpoint the cache
a few times at key points using ‘AC_CACHE_SAVE’.  Doing so reduces the
amount of time it takes to rerun the configure script with (hopefully)
the error that caused the previous abort corrected.

 -- Macro: AC_CACHE_LOAD
     Loads values from existing cache file, or creates a new cache file
     if a cache file is not found.  Called automatically from ‘AC_INIT’.

 -- Macro: AC_CACHE_SAVE
     Flushes all cached values to the cache file.  Called automatically
     from ‘AC_OUTPUT’, but it can be quite useful to call
     ‘AC_CACHE_SAVE’ at key points in ‘configure.ac’.

   For instance:

      ... AC_INIT, etc. ...
     # Checks for programs.
     AC_PROG_CC
     AC_PROG_AWK
      ... more program checks ...
     AC_CACHE_SAVE

     # Checks for libraries.
     AC_CHECK_LIB([nsl], [gethostbyname])
     AC_CHECK_LIB([socket], [connect])
      ... more lib checks ...
     AC_CACHE_SAVE

     # Might abort...
     AM_PATH_GTK([1.0.2], [], [AC_MSG_ERROR([GTK not in path])])
     AM_PATH_GTKMM([0.9.5], [], [AC_MSG_ERROR([GTK not in path])])
      ... AC_OUTPUT, etc. ...