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comparison lib/swig/swigwin-2.0.11/CCache/debian/README.Debian @ 1899:b3009adc0e2f
Adding swig, gitignore, hgignore
| author | Nomad |
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| date | Mon, 21 Oct 2013 10:42:27 +0200 |
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| 1867:eb580660bbbb | 1899:b3009adc0e2f |
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| 1 Installing ccache | |
| 2 ----------------- | |
| 3 | |
| 4 The recommended way to use this with Debian is to either create "cc" | |
| 5 and "gcc" symlinks to /usr/bin/ccache in your private bin directory | |
| 6 (which must be before the real cc and gcc in your path), or use | |
| 7 CC="ccache gcc" on the make command line. | |
| 8 | |
| 9 Another option is to just prepend /usr/lib/ccache in your PATH | |
| 10 environment variable, like | |
| 11 | |
| 12 export PATH="/usr/lib/ccache:$PATH" | |
| 13 | |
| 14 Note that ccache works with both native and cross compilers. | |
| 15 | |
| 16 Ignoring whitespace | |
| 17 ------------------- | |
| 18 | |
| 19 If you wish to set up ccache so that it ignores blank lines, have a | |
| 20 look at the CCACHE_UNIFY option. However, please note that this | |
| 21 option is off by default since the reported line numbers may not | |
| 22 match the source files anymore. | |
| 23 | |
| 24 | |
| 25 NFS Issues | |
| 26 ---------- | |
| 27 | |
| 28 (from John Coiner <john.coiner@amd.com> on the ccache mailing list) | |
| 29 | |
| 30 When CCache creates a hardlinked output file, it calls utime() to update | |
| 31 the timestamp on the object, so that Make realizes that the object has | |
| 32 changed. | |
| 33 | |
| 34 On NFS, utime() has no coherency guarantee, AFAIK. When utime() runs on | |
| 35 host A, and our parallel implementation of Make is running on host B, | |
| 36 sometimes Make doesn't see the new timestamp soon enough -- and neglects | |
| 37 to relink the final binary. That's a one-way ticket to Silent Mysterious | |
| 38 Failure Town. | |
| 39 | |
| 40 Instead of relying on the object file timestamp, we create a dummy file | |
| 41 with a reliable timestamp: | |
| 42 | |
| 43 objs/foo.o objs/foo.o.built : | |
| 44 if ( ccache gcc -o foo.o -c foo.c ) ; \ | |
| 45 then touch objs/foo.o.built ; \ | |
| 46 else exit 1; \ | |
| 47 fi | |
| 48 | |
| 49 binary : objs/foo.o.built | |
| 50 gcc -o binary objs/foo.o | |
| 51 | |
| 52 NFS does make a coherency guarantee, that if a file is written and | |
| 53 close()d on host A, and subsequently open()ed on host B, that the second | |
| 54 open() will reflect all modifications and attributes from the close(). | |
| 55 Since Make does open() when checking timestamps, and the dummy file is | |
| 56 close()d when it's created, the binary will always relink after the | |
| 57 object is recompiled. | |
| 58 | |
| 59 -- Francois Marier <francois@debian.org> Sun, 20 May 2007 17:35:36 +1200 |