starred/netbox
1
0
Fork 0
mirror of https://github.com/netbox-community/netbox.git synced 2026-01-13 13:53:31 +01:00
Code Issues 273 Packages Projects Releases 10 Wiki Activity

[PR #3897] [CLOSED] Fixes #3782: Prevent power loops #12688

New Issue
Closed
opened 2025-12-29 22:23:03 +01:00 by adam · 0 comments
adam commented 2025-12-29 22:23:03 +01:00
Owner
Copy Link

📋 Pull Request Information

Original PR: https://github.com/netbox-community/netbox/pull/3897
Author: @hSaria
Created: 1/12/2020
Status: ❌ Closed

Base: develop ← Head: 3782-disallow-power-loops

📝 Commits (1)

📊 Changes

3 files changed (+68 additions, -0 deletions)

View changed files

📝 docs/release-notes/version-2.6.md (+1 -0)
📝 netbox/dcim/models.py (+37 -0)
📝 netbox/dcim/tests/test_models.py (+30 -0)

📄 Description

Fixes: #3782

Prevent power loops from being created. It ended up being a derivative of the Bellman–Ford algorithm, though it didn't start as one.

Please note that this is not necessarily something we'd want to do; I'm not the expert on power so I don't know if loops inherently exist out there. I created this PR as a potential solution to the ticket, but apart from #3377, it makes no difference if a loop is preset (AFAIK), so it might be worth to continue allowing power loops and just figure out a different way to solve #3377. To be honest, I'd like to keep power loops in case someone needs them.

It runs in a ring-like structure (like the rings on a piece of wood), expanding on every iteration. The ring starts with the source node (i.e. termination_a.device of the new connection). On the second iteration, it will include devices on hop away from those processed in the iteration before. It will stop once all vertices (power cables in this case) that connect to the source node (directly or indirectly) have been scanned, or when a loop gets detected (an iteration containing the destination node termination_b.device).

1st iteration/ring:    A -)- B --- C --- D
2nd iteration/ring:    A --- B -)- C --- D
3rd iteration/ring:    A --- B --- C -)- D

I did my best to in-line document the operation and to keep it as simple as I could, though a cup of coffee when reading it would definitely ease your experience.

Some notes:

  • You should probably look at the tests first to understand specifically what this is preventing against.
  • Relating to the number of the database operations, this implementation has an upper bound of O(2n), where n is the longest number of hops involving the source node.
  • A vertex between the nodes must be of type power outlet; there's an in-line explanation for this (tldr; it is always one end of the cable what would cause a power loop). Because of this and how power is modelled, power feeds improve the search by acting as boundaries.
  • Existing power loops will be ignored, but new ones will be prevented.
  • Going back to the algorithm, an alternative solution would be to use recursive queries which would have a O(1) time complexity from the perspective of the ORM. However, I didn't go with that implementation because I'm not all too comfortable with it as it'll involve a raw query, but I'm open to refactoring the code to use that instead.

🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.

## 📋 Pull Request Information **Original PR:** https://github.com/netbox-community/netbox/pull/3897 **Author:** [@hSaria](https://github.com/hSaria) **Created:** 1/12/2020 **Status:** ❌ Closed **Base:** `develop` ← **Head:** `3782-disallow-power-loops` --- ### 📝 Commits (1) - [`cce99f7`](https://github.com/netbox-community/netbox/commit/cce99f77ea31e14a680f9b774de8751a04417eb9) Fixes #3782: Prevent power loops ### 📊 Changes **3 files changed** (+68 additions, -0 deletions) <details> <summary>View changed files</summary> 📝 `docs/release-notes/version-2.6.md` (+1 -0) 📝 `netbox/dcim/models.py` (+37 -0) 📝 `netbox/dcim/tests/test_models.py` (+30 -0) </details> ### 📄 Description ### Fixes: #3782 Prevent power loops from being created. It ended up being a derivative of the Bellman–Ford algorithm, though it didn't start as one. > Please note that this is not necessarily something we'd want to do; I'm not the expert on power so I don't know if loops inherently exist out there. I created this PR as a potential solution to the ticket, but apart from #3377, it makes no difference if a loop is preset (AFAIK), so it might be worth to continue allowing power loops and just figure out a different way to solve #3377. To be honest, I'd like to keep power loops in case someone needs them. It runs in a ring-like structure (like the rings on a piece of wood), expanding on every iteration. The ring starts with the source node (i.e. `termination_a.device` of the new connection). On the second iteration, it will include devices on hop away from those processed in the iteration before. It will stop once all vertices (power cables in this case) that connect to the source node (directly or indirectly) have been scanned, or when a loop gets detected (an iteration containing the destination node `termination_b.device`). ``` 1st iteration/ring: A -)- B --- C --- D 2nd iteration/ring: A --- B -)- C --- D 3rd iteration/ring: A --- B --- C -)- D ``` > I did my best to in-line document the operation and to keep it as simple as I could, though a cup of coffee when reading it would definitely ease your experience. Some notes: * You should probably look at the tests first to understand specifically what this is preventing against. * _Relating to the number of the database operations_, this implementation has an upper bound of _O(2n)_, where _n_ is the longest number of hops involving the source node. * A vertex between the nodes must be of type power outlet; there's an in-line explanation for this (tldr; it is __always__ one end of the cable what would cause a power loop). Because of this and how power is modelled, power feeds improve the search by acting as boundaries. * Existing power loops will be ignored, but new ones will be prevented. * Going back to the algorithm, an alternative solution would be to use recursive queries which would have a O(1) time complexity from the perspective of the ORM. However, I didn't go with that implementation because I'm not all too comfortable with it as it'll involve a raw query, but I'm open to refactoring the code to use that instead. --- <sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>
adam added the pull-request label 2025-12-29 22:23:03 +01:00
adam closed this issue 2025-12-29 22:23:03 +01:00
Sign in to join this conversation.
No Branch/Tag Specified
Branches Tags
Labels
Clear labels
beta
breaking change
complexity: high
complexity: low
complexity: medium
needs milestone
netbox
pending closure
plugin candidate
pull-request
Mirrored from GitHub Pull Request
 severity: high
severity: low
severity: medium
status: accepted
status: backlog
status: blocked
status: duplicate
status: needs owner
status: needs triage
status: revisions needed
status: under review
topic: GraphQL
topic: Internationalization
topic: OpenAPI
topic: UI/UX
topic: cabling
topic: event rules
topic: htmx navigation
topic: industrialization
topic: migrations
topic: plugins
topic: scripts
topic: templating
topic: testing
type: bug
type: deprecation
type: documentation
type: feature
type: housekeeping
type: translation
No Label pull-request
Milestone
No items
No Milestone
Projects
Clear projects
No project
Assignees
Clear assignees
adam
No Assignees
1 Participants
Notifications
Due Date
No due date set.
Dependencies

No dependencies set.

Reference: starred/netbox#12688
Delete Branch "%!s()"

Deleting a branch is permanent. Although the deleted branch may continue to exist for a short time before it actually gets removed, it CANNOT be undone in most cases. Continue?