5161347efd
Allow Zuul to process circular dependencies between changes. Gating of circular dependencies must be explicitly enabled on a per tenant or project basis. In case Zuul detects a dependency cycle it will make sure that every change also include all other changes that are part of the cycle. However each change will still be a normal item in the queue with its own jobs. When it comes to reporting, all items in the cycle are treated as one unit that determines the success/failure of those changes. Changes with cross-repo circular dependencies are required to share the same change queue. Depends-On: https://review.opendev.org/#/c/643309/ Change-Id: Ic121b2d8d057a7dc4448ae70045853347f265c6c
61 lines
1.9 KiB
Python
61 lines
1.9 KiB
Python
# Algorithm from http://www.logarithmic.net/pfh/blog/01208083168
|
|
# License: public domain
|
|
# Authors: Dr. Paul Harrison / Dries Verdegem
|
|
|
|
|
|
def strongly_connected_components(graph):
|
|
"""
|
|
Tarjan's Algorithm (named for its discoverer, Robert Tarjan) is a graph
|
|
theory algorithm for finding the strongly connected components of a graph.
|
|
|
|
Based on:
|
|
http://en.wikipedia.org/wiki/Tarjan%27s_strongly_connected_components_algorithm
|
|
"""
|
|
|
|
index_counter = [0]
|
|
stack = []
|
|
lowlinks = {}
|
|
index = {}
|
|
result = []
|
|
|
|
def strongconnect(node):
|
|
# set the depth index for this node to the smallest unused index
|
|
index[node] = index_counter[0]
|
|
lowlinks[node] = index_counter[0]
|
|
index_counter[0] += 1
|
|
stack.append(node)
|
|
|
|
# Consider successors of `node`
|
|
try:
|
|
successors = graph[node]
|
|
except KeyError:
|
|
successors = []
|
|
for successor in successors:
|
|
if successor not in lowlinks:
|
|
# Successor has not yet been visited; recurse on it
|
|
strongconnect(successor)
|
|
lowlinks[node] = min(lowlinks[node], lowlinks[successor])
|
|
elif successor in stack:
|
|
# the successor is in the stack and hence in the current
|
|
# strongly connected component (SCC)
|
|
lowlinks[node] = min(lowlinks[node], index[successor])
|
|
|
|
# If 'node' is a root node, pop the stack and generate an SCC
|
|
if lowlinks[node] == index[node]:
|
|
connected_component = []
|
|
|
|
while True:
|
|
successor = stack.pop()
|
|
connected_component.append(successor)
|
|
if successor == node:
|
|
break
|
|
component = tuple(connected_component)
|
|
# storing the result
|
|
result.append(component)
|
|
|
|
for node in graph:
|
|
if node not in lowlinks:
|
|
strongconnect(node)
|
|
|
|
return result
|