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ref-manual: Updated the flag descriptions for shared state details

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Fixes [YOCTO 9823]

I added more details to the explanations of how shared state is
implemented.  Included a bulleted list of the various statements
of code to help explain flags and settings.

(From yocto-docs rev: 2b9db6faa0109b9001c07516c874e9935bf743e8)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Scott Rifenbark
2016-06-28 12:46:38 -07:00
committed by Richard Purdie
parent 365f85179d
commit e177680fa0
1 changed files with 118 additions and 0 deletions
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documentation/ref-manual/technical-details.xml
+118
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@@ -690,6 +690,123 @@
addtask do_deploy_setscene addtask do_deploy_setscene
do_deploy[dirs] = "${DEPLOYDIR} ${B}" do_deploy[dirs] = "${DEPLOYDIR} ${B}"
</literallayout> </literallayout>
The following list explains the previous example:
<itemizedlist>
<listitem><para>
Adding "do_deploy" to <filename>SSTATETASKS</filename>
adds some required sstate-related processing, which is
implemented in the
<link linkend='ref-classes-sstate'><filename>sstate</filename></link>
class, to before and after the
<link linkend='ref-tasks-deploy'><filename>do_deploy</filename></link>
task.
</para></listitem>
<listitem><para>
The
<filename>do_deploy[sstate-inputsdirs] = "${DEPLOYDIR}"</filename>
declares that <filename>do_deploy</filename> places its
output in <filename>${DEPLOYDIR}</filename> when run
normally (i.e. when not using the sstate cache).
This output becomes the input to the shared state cache.
</para></listitem>
<listitem><para>
The
<filename>do_deploy[sstate-outputdirs] = "${DEPLOY_DIR_IMAGE}"</filename>
line causes the contents of the shared state cache to be
copied to <filename>${DEPLOY_DIR_IMAGE}</filename>.
<note>
If <filename>do_deploy</filename> is not already in
the shared state cache or if its input checksum
(signature) has changed from when the output was
cached, the task will be run to populate the shared
state cache, after which the contents of the shared
state cache is copied to
<filename>${DEPLOY_DIR_IMAGE}</filename>.
If <filename>do_deploy</filename> is in the shared
state cache and its signature indicates that the
cached output is still valid (i.e. if no
relevant task inputs have changed), then the contents
of the shared state cache will be copied directly to
<filename>${DEPLOY_DIR_IMAGE}</filename> by the
<filename>do_deploy_setscene</filename> task instead,
skipping the <filename>do_deploy</filename> task.
</note>
</para></listitem>
<listitem><para>
The following task definition is glue logic needed to make
the previous settings effective:
<literallayout class='monospaced'>
python do_deploy_setscene () {
sstate_setscene(d)
}
addtask do_deploy_setscene
</literallayout>
<filename>sstate_setscene()</filename> takes the flags
above as input and accelerates the
<filename>do_deploy</filename> task through the
shared state cache if possible.
If the task was accelerated,
<filename>sstate_setscene()</filename> returns True.
Otherwise, it returns False, and the normal
<filename>do_deploy</filename> task runs.
For more information, see the
"<ulink url='&YOCTO_DOCS_BB_URL;#setscene'>setscene</ulink>"
section in the BitBake User Manual.
</para></listitem>
<listitem><para>
The
<filename>do_deploy[dirs] = "${DEPLOYDIR} ${B}"</filename>
line creates <filename>${DEPLOYDIR}</filename> and
<filename>${B}</filename> before the
<filename>do_deploy</filename> task runs.
For more information, see the
"<ulink url='&YOCTO_DOCS_BB_URL;#variable-flags'>Variable Flags</ulink>"
section in the BitBake User Manual.
<note>
In cases where
<filename>sstate-inputdirs</filename> and
<filename>sstate-outputdirs</filename> would be the
same, you can use
<filename>sstate-plaindirs</filename>.
For example, to preserve the
<filename>${PKGD}</filename> and
<filename>${PKGDEST}</filename> output from the
<link linkend='ref-tasks-package'><filename>do_package</filename></link>
task, use the following:
<literallayout class='monospaced'>
do_package[sstate-plaindirs] = "${PKGD} ${PKGDEST}"
</literallayout>
</note>
</para></listitem>
<listitem><para>
<filename>sstate-inputdirs</filename> and
<filename>sstate-outputdirs</filename> can also be used
with multiple directories.
For example, the following declares
<filename>PKGDESTWORK</filename> and
<filename>SHLIBWORK</filename> as shared state
input directories, which populates the shared state
cache, and <filename>PKGDATA_DIR</filename> and
<filename>SHLIBSDIR</filename> as the corresponding
shared state output directories:
<literallayout class='monospaced'>
do_package[sstate-inputdirs] = "${PKGDESTWORK} ${SHLIBSWORKDIR}"
do_package[sstate-outputdirs] = "${PKGDATA_DIR} ${SHLIBSDIR}"
</literallayout>
</para></listitem>
<listitem><para>
These methods also include the ability to take a lockfile
when manipulating shared state directory structures,
for cases where file additions or removals are sensitive:
<literallayout class='monospaced'>
do_package[sstate-lockfile] = "${PACKAGELOCK}"
</literallayout>
</para></listitem>
</itemizedlist>
</para>
<!--
<para>
In this example, we add some extra flags to the task, a name field ("deploy"), an In this example, we add some extra flags to the task, a name field ("deploy"), an
input directory where the task sends data, and the output input directory where the task sends data, and the output
directory where the data from the task should eventually be copied. directory where the data from the task should eventually be copied.
@@ -713,6 +830,7 @@
shared state directory structures since some cases are sensitive to file shared state directory structures since some cases are sensitive to file
additions or removals. additions or removals.
</para> </para>
-->
<para> <para>
Behind the scenes, the shared state code works by looking in Behind the scenes, the shared state code works by looking in