CCache/web/index.html - third_party/swig - Git at Google

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 <h2>ccache</h2>

 ccache is a compiler cache. It acts as a caching pre-processor to
 C/C++ compilers, using the -E compiler switch and a hash to detect
 when a compilation can be satisfied from cache. This often results in
 a 5 to 10 times speedup in common compilations.<p>

 The idea came from Erik Thiele wrote the original <a
 href="http://compilercache.sourceforge.net/">compilercache</a> program
 as a bourne shell script. ccache is a re-implementation of Erik's idea
 in C with more features and better performance.<p>

 <h2>Latest release</h2>

 The latest release is ccache 2.4.

 <ul>
 <li>Added CCACHE_READONLY option
 <li>Added CCACHE_TEMPDIR option
 <li>fixed handling of hard-linked compilers on AIX
 <li>added O_BINARY support, to try and support win32 compiles
 <li>show cache directory in stats output
 <li>fixed handling of HOME environment variable
 </ul>

 See the <a href="ccache-man.html">manual page</a> for details
 on the new options.<p>

 You can get this release from the <a href="http://ccache.samba.org/ftp/ccache/">download directory</a>

 <p>NOTE! This release changes the hash input slightly, so you will
 probably find that you will not get any hits against your existing
 cache when you upgrade.

 <h2>Why bother?</h2>

 Why bother with a compiler cache? If you ever run "make clean; make"
 then you can probably benefit from ccache. It is very common for
 developers to do a clean build of a project for a whole host of
 reasons, and this throws away all the information from your previous
 compiles.<p>

 By using ccache you can get exactly the same effect as "make clean;
 make" but much faster. It also helps a lot when doing RPM builds,
 as RPM can make doing incremental builds tricky.<p>

 I put the effort into writing ccache for 2 reasons. The first is the
 Samba build farm
 (<a href="http://build.samba.org/">http://build.samba.org/</a>)
 which constantly does clean builds of Samba on about 30 machines after each
 CVS commit. On some of those machines the build took over an hour. By
 using ccache we get the same effect as clean builds but about 6 times
 faster.<p>

 The second reason is the autobuild system I used to run for
 Quantum. That system builds our whole Linux based OS from scratch
 after every CVS commit to catch compilation problems quickly. Using
 ccache those builds are much faster.

 <h2>Is it safe?</h2>

 Yes. The most important aspect of a compiler cache is to <b>always</b>
 produce exactly the same output that the real compiler would
 produce. The includes providing exactly the same object files and
 exactly the same compiler warnings that would be produced if you use
 the real compiler. The only way you should be able to tell that you
 are using ccache is the speed.<p>

 I have coded ccache very carefully to try to provide these guarantees.

 <h2>Features</h2>

 <ul>
 <li> keeps statistics on hits/misses
 <li> automatic cache size management
 <li> can cache compiles that generate warnings
 <li> easy installation
 <li> very low overhead
 <li> uses hard links where possible to avoid copies
 </ul>

 <h2>Documentation</h2>

 See the <a href="ccache-man.html">manual page</a>


 <h2>Performance</h2>

 Here are some results for compiling Samba on my Linux laptop. I have
 also included the results of using Erik's compilercache program
 (version 1.0.10) for comparison.<p>

 <table border=1>
 <tr><th>              </th>      <th>&nbsp;&nbsp;&nbsp;&nbsp;ccache</th>     <th>&nbsp;compilercache</th>    </tr>
 <tr><td>normal        </td>      <td align=right>13m 4s     </td><td align=right>13m 4s</td> </tr>
 <tr><td>uncached      </td>      <td align=right>13m 15s     </td><td align=right>15m 41s</td> </tr>
 <tr><td>cached        </td>      <td align=right>2m 45s     </td><td align=right>4m 26s</td> </tr>
 </table>

 <h2>How to use it</h2>

 You can use ccache in two ways. The first is just to prefix your
 compile commands with "ccache". For example, you could change the
 "CC=gcc" line in your Makefile to be "CC=ccache gcc".<p>

 Alternatively, you can create symbolic links from your compilers name
 to ccache. This allows you to use ccache without any changes to your
 build system.

 <h2>Download</h2>

 You can download the latest release from the <a
 href="http://ccache.samba.org/ftp/ccache/">download directory</a>.<p>

 For the bleeding edge, you can fetch ccache via CVS or
 rsync. To fetch via cvs use the following command:

 <pre>
   cvs -d :pserver:cvs@pserver.samba.org:/cvsroot co ccache
 </pre>

 To fetch via rsync use this command:

 <pre>
   rsync -Pavz samba.org::ftp/unpacked/ccache .
 </pre>

 <h2>Related projects</h2>

 Here are some related programs you may find interesting

 <ul>
 <li> <a href="http://distcc.samba.org/">distcc</a> - a distributed compilation system
 <li> <a href="http://cachecc1.sourceforge.net/">cachecc1</a> - a gcc specific cache
 <li> <a href="http://sourceforge.net/projects/gocache/">gocache</a> - a cross platform compiler cache
 </ul>
 <p>

 <h2>Mailing list</h2>

 <p>A <a href="http://lists.samba.org/mailman/listinfo/ccache/">mailing
 list</a> is available for discussion of ccache.


 <hr>
 <tiny>
 <a href="http://samba.org/~tridge/">Andrew Tridgell</a><br>
 <a href="mailto:bugs@ccache.samba.org">bugs@ccache.samba.org</a>
 </tiny>

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	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
	<HTML>
	<HEAD>
	<TITLE>ccache</TITLE>
	</HEAD>
	<BODY BGCOLOR="#ffffff" TEXT="#000000" VLINK="#292555" LINK="#292555" ALINK="#cc0033">
	<h2>ccache</h2>

	ccache is a compiler cache. It acts as a caching pre-processor to
	C/C++ compilers, using the -E compiler switch and a hash to detect
	when a compilation can be satisfied from cache. This often results in
	a 5 to 10 times speedup in common compilations.<p>

	The idea came from Erik Thiele wrote the original <a
	href="http://compilercache.sourceforge.net/">compilercache</a> program
	as a bourne shell script. ccache is a re-implementation of Erik's idea
	in C with more features and better performance.<p>

	<h2>Latest release</h2>

	The latest release is ccache 2.4.

	<ul>
	<li>Added CCACHE_READONLY option
	<li>Added CCACHE_TEMPDIR option
	<li>fixed handling of hard-linked compilers on AIX
	<li>added O_BINARY support, to try and support win32 compiles
	<li>show cache directory in stats output
	<li>fixed handling of HOME environment variable
	</ul>

	See the <a href="ccache-man.html">manual page</a> for details
	on the new options.<p>

	You can get this release from the <a href="http://ccache.samba.org/ftp/ccache/">download directory</a>

	<p>NOTE! This release changes the hash input slightly, so you will
	probably find that you will not get any hits against your existing
	cache when you upgrade.

	<h2>Why bother?</h2>

	Why bother with a compiler cache? If you ever run "make clean; make"
	then you can probably benefit from ccache. It is very common for
	developers to do a clean build of a project for a whole host of
	reasons, and this throws away all the information from your previous
	compiles.<p>

	By using ccache you can get exactly the same effect as "make clean;
	make" but much faster. It also helps a lot when doing RPM builds,
	as RPM can make doing incremental builds tricky.<p>

	I put the effort into writing ccache for 2 reasons. The first is the
	Samba build farm
	(<a href="http://build.samba.org/">http://build.samba.org/</a>)
	which constantly does clean builds of Samba on about 30 machines after each
	CVS commit. On some of those machines the build took over an hour. By
	using ccache we get the same effect as clean builds but about 6 times
	faster.<p>

	The second reason is the autobuild system I used to run for
	Quantum. That system builds our whole Linux based OS from scratch
	after every CVS commit to catch compilation problems quickly. Using
	ccache those builds are much faster.

	<h2>Is it safe?</h2>

	Yes. The most important aspect of a compiler cache is to <b>always</b>
	produce exactly the same output that the real compiler would
	produce. The includes providing exactly the same object files and
	exactly the same compiler warnings that would be produced if you use
	the real compiler. The only way you should be able to tell that you
	are using ccache is the speed.<p>

	I have coded ccache very carefully to try to provide these guarantees.

	<h2>Features</h2>

	<ul>
	<li> keeps statistics on hits/misses
	<li> automatic cache size management
	<li> can cache compiles that generate warnings
	<li> easy installation
	<li> very low overhead
	<li> uses hard links where possible to avoid copies
	</ul>

	<h2>Documentation</h2>

	See the <a href="ccache-man.html">manual page</a>


	<h2>Performance</h2>

	Here are some results for compiling Samba on my Linux laptop. I have
	also included the results of using Erik's compilercache program
	(version 1.0.10) for comparison.<p>

	<table border=1>
	<tr><th> </th> <th>    ccache</th> <th> compilercache</th> </tr>
	<tr><td>normal </td> <td align=right>13m 4s </td><td align=right>13m 4s</td> </tr>
	<tr><td>uncached </td> <td align=right>13m 15s </td><td align=right>15m 41s</td> </tr>
	<tr><td>cached </td> <td align=right>2m 45s </td><td align=right>4m 26s</td> </tr>
	</table>

	<h2>How to use it</h2>

	You can use ccache in two ways. The first is just to prefix your
	compile commands with "ccache". For example, you could change the
	"CC=gcc" line in your Makefile to be "CC=ccache gcc".<p>

	Alternatively, you can create symbolic links from your compilers name
	to ccache. This allows you to use ccache without any changes to your
	build system.

	<h2>Download</h2>

	You can download the latest release from the <a
	href="http://ccache.samba.org/ftp/ccache/">download directory</a>.<p>

	For the bleeding edge, you can fetch ccache via CVS or
	rsync. To fetch via cvs use the following command:

	<pre>
	cvs -d :pserver:cvs@pserver.samba.org:/cvsroot co ccache
	</pre>

	To fetch via rsync use this command:

	<pre>
	rsync -Pavz samba.org::ftp/unpacked/ccache .
	</pre>

	<h2>Related projects</h2>

	Here are some related programs you may find interesting

	<ul>
	<li> <a href="http://distcc.samba.org/">distcc</a> - a distributed compilation system
	<li> <a href="http://cachecc1.sourceforge.net/">cachecc1</a> - a gcc specific cache
	<li> <a href="http://sourceforge.net/projects/gocache/">gocache</a> - a cross platform compiler cache
	</ul>
	<p>

	<h2>Mailing list</h2>

	<p>A <a href="http://lists.samba.org/mailman/listinfo/ccache/">mailing
	list</a> is available for discussion of ccache.


	<hr>
	<tiny>
	<a href="http://samba.org/~tridge/">Andrew Tridgell</a><br>
	<a href="mailto:bugs@ccache.samba.org">bugs@ccache.samba.org</a>
	</tiny>

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	</HTML>