Add a flag --skip-cached to skip already-downloaded models and collections

[khaledgabr77]

🎉 New feature

Closes #150

Summary

This PR introduces a --skip-cached flag option to gz-fuel-tools10 (available through the gz fuel download command).
When the flag is set, any models that already exist in the local cache are skipped instead of downloaded again, saving time.

Both individual model downloads and collection downloads now respect this flag.

Behaviour before this PR

Every time running of gz fuel download re-download of all models, even if they were already present locally.

Behaviour after this PR

With --skip-cached, the CLI first checks the local cache and only downloads the models that are missing.

Test it

1. Start a large collection download and interrupt it Press Ctrl+C partway through

gz fuel download -j 4  -u "https://fuel.gazebosim.org/1.0/openrobotics/collections/Gazebo classic model database"

2. Resume with the new flag – already-downloaded models are skipped

gz fuel download -j 4 --skip-cached -u "https://fuel.gazebosim.org/1.0/openrobotics/collections/Gazebo classic model database"

You can repeat the same steps with an individual model URL too.

gz fuel download -u https://fuel.gazebosim.org/1.0/OpenRobotics/models/Ambulance -v 4

gz fuel download -u --skip-cached https://fuel.gazebosim.org/1.0/OpenRobotics/models/Ambulance -v 4

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[ahcorde]

You have introduced many changes which are not related with this PR, do you mind to restore them

[ahcorde]

Suggested change

	'skip_cached' => 'false'
	'skip_cached' => false

[ahcorde]

Suggested change

	options['skip_cached'] = 'true'
	options['skip_cached'] = true

[ahcorde]

Suggested change

	Importer.extern 'int downloadUrl(const char *, const char *, const char *, const char *, unsigned int, const char *)'
	Importer.extern 'int downloadUrl(const char *, const char *, const char *, const char *, unsigned int, bool)'

[khaledgabr77]

Hi @ahcorde
I followed the changes you suggested and updated both gz.cc and gz.hh to accept a bool parameter. However, when I tried to compile and run the code, I encountered the following issue:

Library error: Problem running [download]() from /root/gz_ws/install/lib/libgz-fuel_tools10.so.10.0.1

I need to determine whether this issue came from the Ruby script or the C++ implementation. Previously, when reading the file, I noticed that char was used to represent boolean values, so I followed the same approach. However, now I plan to recheck the full code to understand exactly where the issue is coming from.

[khaledgabr77]

You have introduced many changes which are not related with this PR, do you mind to restore them

You're right — I forgot to mention that the changes are related to running ament_uncrustify --reformat. After I finished working on each C++ file, I applied the reformatting using that command.
Do you still want me to revert the changes?

[ahcorde]

You have introduced many changes which are not related with this PR, do you mind to restore them

You're right — I forgot to mention that the changes are related to running ament_uncrustify --reformat. After I finished working on each C++ file, I applied the reformatting using that command. Do you still want me to revert the changes?

we are not using uncrustify in gazebo. Yes, restore the changes

[khaledgabr77]

You have introduced many changes which are not related with this PR, do you mind to restore them

You're right — I forgot to mention that the changes are related to running ament_uncrustify --reformat. After I finished working on each C++ file, I applied the reformatting using that command. Do you still want me to revert the changes?

we are not using uncrustify in gazebo. Yes, restore the changes

I'm sorry for that, i restore changes now.

[khaledgabr77]

I’ve restored the changes and will review the updates you requested later tomorrow.

[ahcorde]

some linters are failing

  /github/workspace/src/gz.cc:468:  Lines should be <= 80 characters long  [whitespace/line_length] [2]
  /github/workspace/src/gz.cc:515:  If/else bodies with multiple statements require braces  [readability/braces] [4]
  /github/workspace/src/gz.cc:516:  Lines should be <= 80 characters long  [whitespace/line_length] [2]
  /github/workspace/src/gz.cc:559:  If/else bodies with multiple statements require braces  [readability/braces] [4]
  /github/workspace/src/gz.cc:560:  Lines should be <= 80 characters long  [whitespace/line_length] [2]
  /github/workspace/src/gz.cc:658:  Lines should be <= 80 characters long  [whitespace/line_length] [2]
  /github/workspace/src/gz.hh:65:  Lines should be <= 80 characters long  [whitespace/line_length] [2]

[azeey]

Hi @khaledgabr77, there are some review comments that are still not addressed. Do you think you'll have time to get to them before the Jetty code freeze (see https://discourse.openrobotics.org/t/feature-freeze-for-gazebo-jetty/48187/3?u=azeey)

[azeey]

Thanks for the great contribution, but since there hasn't been any updates for a while, I'll remove it from the Jetty milestone. But please don't let this stop you from pushing on this PR. Once the initial feature freeze window is over, we'll be able to merge this.