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traverse: use deque and popleft (#48353)

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Avoids a quadratic time operation. In practice it is not really felt, cause it has a tiny constant.
But maybe in very large DAGs it is.
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Harmen Stoppels 2025-01-14 09:09:57 +01:00 committed by GitHub
parent 9fa1654102
commit 53d1665a8b
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1 changed files with 9 additions and 9 deletions
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18
lib/spack/spack/traverse.py
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@ -2,7 +2,7 @@
# #
# SPDX-License-Identifier: (Apache-2.0 OR MIT) # SPDX-License-Identifier: (Apache-2.0 OR MIT)
from collections import defaultdict from collections import defaultdict, deque
from typing import ( from typing import (
Any, Any,
Callable, Callable,
@ -225,13 +225,13 @@ def get_visitor_from_args(
def with_artificial_edges(specs): def with_artificial_edges(specs):
"""Initialize a list of edges from an imaginary root node to the root specs.""" """Initialize a deque of edges from an artificial root node to the root specs."""
return [ return deque(
EdgeAndDepth( EdgeAndDepth(
edge=spack.spec.DependencySpec(parent=None, spec=s, depflag=0, virtuals=()), depth=0 edge=spack.spec.DependencySpec(parent=None, spec=s, depflag=0, virtuals=()), depth=0
) )
for s in specs for s in specs
] )
def traverse_depth_first_edges_generator(edges, visitor, post_order=False, root=True, depth=False): def traverse_depth_first_edges_generator(edges, visitor, post_order=False, root=True, depth=False):
@ -272,9 +272,9 @@ def traverse_depth_first_edges_generator(edges, visitor, post_order=False, root=
yield (edge.depth, edge.edge) if depth else edge.edge yield (edge.depth, edge.edge) if depth else edge.edge
def traverse_breadth_first_edges_generator(queue, visitor, root=True, depth=False): def traverse_breadth_first_edges_generator(queue: deque, visitor, root=True, depth=False):
while len(queue) > 0: while len(queue) > 0:
edge = queue.pop(0) edge = queue.popleft()
# If the visitor doesn't accept the node, we don't yield it nor follow its edges. # If the visitor doesn't accept the node, we don't yield it nor follow its edges.
if not visitor.accept(edge): if not visitor.accept(edge):
@ -297,7 +297,7 @@ def traverse_breadth_first_with_visitor(specs, visitor):
""" """
queue = with_artificial_edges(specs) queue = with_artificial_edges(specs)
while len(queue) > 0: while len(queue) > 0:
edge = queue.pop(0) edge = queue.popleft()
# If the visitor doesn't accept the node, we don't traverse it further. # If the visitor doesn't accept the node, we don't traverse it further.
if not visitor.accept(edge): if not visitor.accept(edge):
@ -418,10 +418,10 @@ def traverse_topo_edges_generator(edges, visitor, key=id, root=True, all_edges=F
parent_id = key(edge.parent) if edge.parent is not None else None parent_id = key(edge.parent) if edge.parent is not None else None
node_to_edges[parent_id].append(edge) node_to_edges[parent_id].append(edge)
queue = [None] queue = deque((None,))
while queue: while queue:
for edge in node_to_edges[queue.pop(0)]: for edge in node_to_edges[queue.popleft()]:
child_id = key(edge.spec) child_id = key(edge.spec)
in_edge_count[child_id] -= 1 in_edge_count[child_id] -= 1