85 lines
3.3 KiB
Go
85 lines
3.3 KiB
Go
// Mgmt
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// Copyright (C) 2013-2024+ James Shubin and the project contributors
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// Written by James Shubin <james@shubin.ca> and the project contributors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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//
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// Additional permission under GNU GPL version 3 section 7
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//
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// If you modify this program, or any covered work, by linking or combining it
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// with embedded mcl code and modules (and that the embedded mcl code and
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// modules which link with this program, contain a copy of their source code in
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// the authoritative form) containing parts covered by the terms of any other
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// license, the licensors of this program grant you additional permission to
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// convey the resulting work. Furthermore, the licensors of this program grant
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// the original author, James Shubin, additional permission to update this
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// additional permission if he deems it necessary to achieve the goals of this
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// additional permission.
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package autogroup
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import (
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"github.com/purpleidea/mgmt/pgraph"
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"github.com/purpleidea/mgmt/util/errwrap"
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)
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// NonReachabilityGrouper is the most straight-forward algorithm for grouping.
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// TODO: this algorithm may not be correct in all cases. replace if needed!
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type NonReachabilityGrouper struct {
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baseGrouper // "inherit" what we want, and reimplement the rest
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}
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// Name returns the name for the grouper algorithm.
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func (ag *NonReachabilityGrouper) Name() string {
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return "NonReachabilityGrouper"
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}
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// VertexNext iteratively finds vertex pairs with simple graph reachability...
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// This algorithm relies on the observation that if there's a path from a to b,
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// then they *can't* be merged (b/c of the existing dependency) so therefore we
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// merge anything that *doesn't* satisfy this condition or that of the reverse!
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func (ag *NonReachabilityGrouper) VertexNext() (v1, v2 pgraph.Vertex, err error) {
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for {
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v1, v2, err = ag.baseGrouper.VertexNext() // get all iterable pairs
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if err != nil {
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return nil, nil, errwrap.Wrapf(err, "error running autoGroup(vertexNext)")
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}
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// ignore self cmp early (perf optimization)
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if v1 != v2 && v1 != nil && v2 != nil {
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// if NOT reachable, they're viable...
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out1, e1 := ag.graph.Reachability(v1, v2)
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if e1 != nil {
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return nil, nil, e1
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}
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out2, e2 := ag.graph.Reachability(v2, v1)
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if e2 != nil {
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return nil, nil, e2
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}
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if len(out1) == 0 && len(out2) == 0 {
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return // return v1 and v2, they're viable
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}
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}
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// if we got here, it means we're skipping over this candidate!
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if ok, err := ag.baseGrouper.VertexTest(false); err != nil {
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return nil, nil, errwrap.Wrapf(err, "error running autoGroup(vertexTest)")
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} else if !ok {
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return nil, nil, nil // done!
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}
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// the vertexTest passed, so loop and try with a new pair...
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}
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}
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