[Soc-2017-dev] Weekly Report #08 - Package Manager

[Ellwood Zwovic]

Here's my report from the wiki for this week: 
https://wiki.blender.org/index.php/User:Gandalf3/GSoC_2017/Reports#Week_8

== Week 8 ==

What I did this week:

* Added tracking of installed packages, and an uninstall operator.
* Added installation/setup instructions to the 
[https://developer.blender.org/diffusion/BPMA/browse/master/README.md 
readme].
* Put a package repository containing blender's official addons up on 
http://blendermonkey.com/bpkg/ for testing.

To try it out:

<ol>
<li>Clone blender and checkout the 
[https://developer.blender.org/diffusion/B/browse/soc-2017-package_manager/ 
soc-2017-package_manager branch].</li>

<pre>
git clone git://git.blender.org/blender.git
cd blender
git checkout soc-2017-package_manager
</pre>

<li>[https://wiki.blender.org/index.php/Dev:Doc/Building_Blender 
Build].</li>
<li>Clone the [https://developer.blender.org/diffusion/BPMA/repository 
package manager addon repository]:</li>

<pre> git clone git://git.blender.org/blender-package-manager-addon.git 
</pre>

<li>Install the addon. Copy (or symlink) the package_manager directory 
contained within the cloned repository into 
/path/to/blender/build/bin/2.78/scripts/addons/</li>
<li>Run blender</li>
<li>Open the user preferences, enable the addon and set the repository</li>
<li>Refresh, and switch to the "Packages" section.</li>
</ol>

The default repository can currently be changed in the addon's preferences
section (currently only accessible in the "Addons" section).

A local repository can be generated with the generate_repository script 
found
in the addon repository. Example usage:

   ./generate_repository /path/to/packages --baseurl 'http://localhost/'

This will produce a repo.json file in the current directory, which can then
be copied to the server.  The baseurl is prepended to the filename of each
package to form the package's url (so for example, 
http://localhost/node_wrangler.py).

=== Questions ===

* I'm not sure how best to disable asynchronous operators while they are 
running. The trick is, I want to allow multiple instances same operator 
to be run at once, but not with the same parameters. This is so that a 
user can click install on multiple different packages without waiting 
for any one to complete, but double-clicking on one will not spawn two 
install processes. I believe operators are only instantiated when they 
are executed, so I can't store an instance variable to track the running 
state. I thought of adding a class variable which holds a list of the 
parameters of running operators. The operator poll() method could then 
perform a check to see if the current operator's parameters are present 
in this list, and if so, return false. However, surely there's a better way?

* Putting the package manager addon in a python package puts the addon 
itself under a subdirectory, so blender won't recognize it when the 
whole repository is placed in a submodule in scripts/addons. The blender 
cloud addon also seems to have the same issue, how was this solved there?

* ideasman42: I was directed to ask you regarding this, but I haven't 
managed to catch you in irc.. How do info header progress bars work? The 
only thing I've found which seems connected to them is this 
[https://docs.blender.org/api/blender_python_api_2_78_3/bpy.types.UILayout.html#bpy.types.UILayout.template_running_jobs 
undocumented `template_running_jobs()`] method.

* I noticed that my `bpkg` subpackage isn't getting reloaded when 
pressing F8, despite getting passed to `importlib.reload()`. Does anyone 
know why this might be?

=== Plans for next week ===

* More code cleanup.
* Add addon preferences, enabling/disabling, and more filtering.
* Multiple repository support.

Continued from last week:
* Improve responsiveness/add progress displays, listen for abort signals 
on longer-running subprocesses.
* Prevent subprocesses operators from being started multiple times.