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author | Scott Rifenbark <scott.m.rifenbark@intel.com> | 2012-12-11 12:07:58 -0600 |
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committer | Richard Purdie <richard.purdie@linuxfoundation.org> | 2013-01-07 14:43:25 +0000 |
commit | ed0a240e1632682ec4c33341f3e24ad71773cdfc (patch) | |
tree | 201557f498b77b9f51fad7e12a6009f74aca4c65 /documentation/ref-manual/eclipse/html/poky-ref-manual/invalidating-shared-state.html | |
parent | af19d889ef320f9625aae42eed6688b5cc739793 (diff) | |
download | poky-ed0a240e1632682ec4c33341f3e24ad71773cdfc.tar.gz |
documentation: Rename of poky-ref-manual folder to ref-manual.
Changing the folder that holds the YP Reference Manual to be
"ref-manual". This will help with confustion over the manual's
intended purpose.
(From yocto-docs rev: 1106442964b5080cb0b6b3bd3af32e9407c0f7c1)
Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'documentation/ref-manual/eclipse/html/poky-ref-manual/invalidating-shared-state.html')
-rw-r--r-- | documentation/ref-manual/eclipse/html/poky-ref-manual/invalidating-shared-state.html | 53 |
1 files changed, 53 insertions, 0 deletions
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1 | <html> | ||
2 | <head> | ||
3 | <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> | ||
4 | <title>3.2.4.2. Invalidating Shared State</title> | ||
5 | <link rel="stylesheet" type="text/css" href="../book.css"> | ||
6 | <meta name="generator" content="DocBook XSL Stylesheets V1.76.1"> | ||
7 | <link rel="home" href="index.html" title="The Yocto Project Reference Manual"> | ||
8 | <link rel="up" href="tips-and-tricks.html" title="3.2.4. Tips and Tricks"> | ||
9 | <link rel="prev" href="debugging.html" title="3.2.4.1. Debugging"> | ||
10 | <link rel="next" href="x32.html" title="3.3. x32"> | ||
11 | </head> | ||
12 | <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="section" title="3.2.4.2. Invalidating Shared State"> | ||
13 | <div class="titlepage"><div><div><h4 class="title"> | ||
14 | <a name="invalidating-shared-state"></a>3.2.4.2. Invalidating Shared State</h4></div></div></div> | ||
15 | <p> | ||
16 | The shared state code uses checksums and shared state | ||
17 | cache to avoid unnecessarily rebuilding tasks. | ||
18 | As with all schemes, this one has some drawbacks. | ||
19 | It is possible that you could make implicit changes that are not factored | ||
20 | into the checksum calculation, but do affect a task's output. | ||
21 | A good example is perhaps when a tool changes its output. | ||
22 | Let's say that the output of <code class="filename">rpmdeps</code> needed to change. | ||
23 | The result of the change should be that all the "package", "package_write_rpm", | ||
24 | and "package_deploy-rpm" shared state cache items would become invalid. | ||
25 | But, because this is a change that is external to the code and therefore implicit, | ||
26 | the associated shared state cache items do not become invalidated. | ||
27 | In this case, the build process would use the cached items rather than running the | ||
28 | task again. | ||
29 | Obviously, these types of implicit changes can cause problems. | ||
30 | </p> | ||
31 | <p> | ||
32 | To avoid these problems during the build, you need to understand the effects of any | ||
33 | change you make. | ||
34 | Note that any changes you make directly to a function automatically are factored into | ||
35 | the checksum calculation and thus, will invalidate the associated area of sstate cache. | ||
36 | You need to be aware of any implicit changes that are not obvious changes to the | ||
37 | code and could affect the output of a given task. | ||
38 | Once you are aware of such a change, you can take steps to invalidate the cache | ||
39 | and force the task to run. | ||
40 | The step to take is as simple as changing a function's comments in the source code. | ||
41 | For example, to invalidate package shared state files, change the comment statements | ||
42 | of <code class="filename">do_package</code> or the comments of one of the functions it calls. | ||
43 | The change is purely cosmetic, but it causes the checksum to be recalculated and | ||
44 | forces the task to be run again. | ||
45 | </p> | ||
46 | <div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"> | ||
47 | <h3 class="title">Note</h3> | ||
48 | For an example of a commit that makes a cosmetic change to invalidate | ||
49 | a shared state, see this | ||
50 | <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/poky/commit/meta/classes/package.bbclass?id=737f8bbb4f27b4837047cb9b4fbfe01dfde36d54" target="_self">commit</a>. | ||
51 | </div> | ||
52 | </div></body> | ||
53 | </html> | ||