{{Header}}
{{Title|
title=How-to: Install PyLRU in {{project_name_long}}
}}
{{#seo:
|description=PyLRU python library
|image=Py123123.png
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[[image:Py123123.png|thumb]]
{{intro|
PyLRU python library
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__FORCETOC__
= Introduction =

PyLRU is: <ref>https://pypi.org/project/pylru/</ref>
<blockquote>...a true LRU cache along with several support classes. The cache is efficient and written in pure Python. It works with Python 2.6+ including the 3.x series. Basic operations (lookup, insert, delete) all run in a constant amount of time. Pylru provides a cache class with a simple dict interface. It also provides classes to wrap any object that has a dict interface with a cache. Both write-through and write-back semantics are supported. Pylru also provides classes to wrap functions in a similar way, including a function decorator.</blockquote>

= PyLRU Setup =

{{mbox
| type    = notice
| image   = [[File:Ambox_notice.png|40px|alt=Info]]
| text    = Perform the following procedure in {{project_name_workstation_long}} ([[Qubes|{{q_project_name_long}}]]: <code>{{project_name_workstation_vm}}</code> App Qube).
}}

== Download ==

Acquire the [https://github.com/jlhutch/pylru PyLRU] source code by Jay Hutchinson ([https://github.com/jlhutch <code>jlhutch</code> on GitHub]).

{{CodeSelect|code=
git clone https://github.com/jlhutch/pylru ~/pylru
}}

== Digital Signature Verification ==

{{mbox
| type    = notice
| image   = [[File:Ambox_notice.png|40px|alt=Info]]
| text    = This section is optional, but provides better security.
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{{Box|text=
'''1.''' Import Jay Hutchinson signing key. <ref>
* https://github.com/jlhutch/pylru/issues/33
* https://web.archive.org/web/20231219165732/https://api.github.com/users/jlhutch/gpg_keys
</ref>

Note: File name and URL might change in the future from <code>.gpg</code> to <code>.asc</code> in the future as per [https://github.com/jlhutch/pylru/issues/33 PyLRU github issue: please upload your OpenPGP / gpg public key].

{{gpg key
|url=scurl-download https://github.com/jlhutch.gpg
|source_filename=jlhutch.gpg
|fingerprint=1E0B4C97BD81966B3BDCF84D2FF6B00325E9519C
|gpg_fingerprint_output=
In late-2023, the output is identical to the following.

      Key fingerprint = 1E0B 4C97 BD81 966B 3BDC  F84D 2FF6 B003 25E9 519C
}}

'''2.''' Enter the repository.
{{CodeSelect|code=
cd ~/pylru
}}

'''3.''' Perform digital signature verification. <ref>
Alternative command:

{{CodeSelect|code=
git log -1 --show-signature
}}
}}
</ref>

{{CodeSelect|code=
git verify-commit HEAD
}}

{{GnuPG-Success}}

{{GnuPG-Warning}}
}}

== Installation ==

{{Box|text=
'''1.''' Create folder <code>/usr/local/lib/python3.11/dist-packages/</code>.

{{CodeSelect|code=
sudo mkdir -p /usr/local/lib/python3.11/dist-packages/
}}

'''2.''' Install <code>pylru.py</code> in folder <code>/usr/local/lib/python3.11/dist-packages/</code>.

{{CodeSelect|code=
sudo cp ~/pylru/pylru.py /usr/local/lib/python3.11/dist-packages/
}}

'''3.''' Done.

PyLRU installation is now complete.
}}

= Troubleshooting =
<pre>
electrumx_server[]: PermissionError: [Errno 13] Permission denied: '/usr/local/lib/python3.11/dist-pa...pylru.py'
</pre>

'''Permission fix.'''

Required in some build versions of {{project_name_long}}. <ref>
The issue is the read permission for "<code>others</code>" than root were not set during file creation.

Related issue: [https://github.com/Kicksecure/security-misc/issues/185 Restrict umask to 027 except for sudo/root broken]
</ref>

{{CodeSelect|code=
sudo chmod --recursive o+r /usr/local/lib/python3.11/dist-packages
}}

= Footnotes =

{{reflist|close=1}}

{{Footer}}

[[Category:Documentation]]