[graph] Add possibility to set a specific cacheDir in the mg scene

[Alxiice]

Description

Add possibility to set a specific cache folder in the mg scene

• In meshroom_batch a new option enables saving the scene with a specific cache folder.
• a _explicitCacheDir parameter in the Graph tracks the explicit path we set (can be absolute or relative)
• functions were added to set the default cache path or a custom one

About the Meshroom file :

• graphIO : a CacheDir key was added to the serialized format. Serialization is designed to save the cacheDir inside the .mg file
• graph : the deserialization is designed to load the explicit cache folder if we get one, and if we don't to select the default path (./MeshroomCache)
• the serialized cacheDir can be a list, and in this case when deserialized we will iterate over elements and take the first one whose folder exists.

We can see the custom cache directory on the status bar :

Tests

Here is a command that can be used to set a new cache directory in a meshroom file

ROOT="..."
MG_FILE_IN="$ROOT/scene.mg"
MG_FILE_OUT="$MG_FILE_IN"
CACHE_DIR="$ROOT/MeshroomCache-v001"
meshroom_batch -p $MG_FILE_IN -s $MG_FILE_OUT --compute no --overrideCacheDir $CACHE_DIR

The following steps can test this feature :

1. Create a new meshroom scene
2. Compute the graph
3. Close it
4. Follow above script to set a new custom cache
5. Open the scene
6. You should see that the nodes are considered not computed (because we changed the cache to an empty folder). The new cache folder is set and can be seen on the status bar (at the bottom)
7. Empty the previous cache folder (MeshroomCache)
8. Launch the process on the current (new) scene
9. It doesn't affect the original cache folder but the new cache is filled with the current scene nodes computation data

[codecov]

Codecov Report

❌ Patch coverage is 77.90698% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.93%. Comparing base (9a19925) to head (2a75c68).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
meshroom/core/graph.py	70.31%	19 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3077      +/-   ##
===========================================
- Coverage    83.98%   83.93%   -0.06%     
===========================================
  Files           83       83              
  Lines        10829    10910      +81     
===========================================
+ Hits          9095     9157      +62     
- Misses        1734     1753      +19     

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[sonarqubecloud]

Quality Gate passed

Issues
6 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[cbentejac]

It'd be nice to add some tests on the serialization/deserialization of graphs with a specific cache directory to ensure we're covering all cases.

The test that's currently part of the PR only checks that the setExplicitCacheDir works as expected.

Otherwise, it all looks good to me!

[Alxiice]

I added another system following @fcastan recommendations :
We can have a list as the explicit cacheDir

We browse the list fist-to-last and we check for existence :

If none of the elements in the list is found then it fallsback to the default location (./MeshroomCache)

Outdated change request.