Command to clean reprovider queue

[hsanjuan]

Checklist

• My issue is specific & actionable.
• I am not suggesting a protocol enhancement.
• I have searched on the issue tracker for my issue.

Description

In a situation in which:

• One has a huge reprovider queue that has been stored to disk
• One decides to update the reprovider strategy

There is no way to clean the existing queue. It would be nice to have.

[guillaumemichel]

Let's implement this feature directly on the new reprovider module once it lands libp2p/go-libp2p-kad-dht#1082

[hsanjuan]

Triage:

• Additionally: at least a warning in the docs that if strategy is changed, the clean command should be run. But better to have it AUTOMATIC.
• Clean the queue for the current reprovide code: boxo/provider. Need to store last-known strategy when implementing automatic cleanup.
• DHT new provide code: there is functionality to reset and should be plugged in to this command.

[guillaumemichel]

As mentioned in the initial description, there are 2 use cases:

1. Clear the provide queue
2. Update the KeyChanFunc, which gives all the keys that should be reprovided.

Concerning 2:

If we are fine with updating the reprovide strategy only on reboot, then both the old and new provide clients should be fine. If we want to change the strategy while kubo is running then, we need to update the KeyChanFunc on the provide clients (light change). IMO it should be fine to restart kubo when changing the reprovide strategy.

Concerning 1:

There is currently no mechanism in the (old) boxo/provider package to clear the provide queue. We could implement it if it seems low effort, but since we eventually want to deprecate this package it doesn't seem worth it to spend too much time on it.

For the (new) go-libp2p-kad-dht/provider package, I plan to implement a feature to drop the queue of pending provides, but keep reproviding them, if they match the reprovide policy.