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genieacs/lib/gpn-heuristic.ts
T

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TypeScript

import Path from "./common/path";
/**
* Copyright 2013-2019 GenieACS Inc.
*
* This file is part of GenieACS.
*
* GenieACS is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* GenieACS is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with GenieACS. If not, see <http://www.gnu.org/licenses/>.
*/
const WILDCARD_MULTIPLIER = 2;
const UNDISCOVERED_DEPTH = 7;
// Simple heuristic to estimate GPN count given a set of patterns to be
// discovered. Used to decide whether to use nextLevel = false in GPN.
// gpnPatterns is [pattern, flags]
// pattern is a path (array)
// flags is an int where its bits mark the segments in the pattern that
// need refreshing. Leading 0s indicate that the pattern up to that
// point has been discovered.
export function estimateGpnCount(
gpnPatterns: [Path, number][],
depth: number = 0
): number {
const children: { [segment: string]: [Path, number][] } = {};
const wildcardChildren: [Path, number][] = [];
let wildcardDiscovered = false;
let gpnCount = 0;
for (const pattern of gpnPatterns) {
const path = pattern[0];
const flags = pattern[1] >> depth;
const k = path.segments[depth] as string;
if (!k) {
if (flags & 1) gpnCount = 1;
continue;
}
if (flags & 1) {
gpnCount = 1;
if (depth > UNDISCOVERED_DEPTH) continue;
} else if (k === "*") {
wildcardDiscovered = true;
}
if (k === "*") {
wildcardChildren.push(pattern);
} else {
children[k] = children[k] || [];
children[k].push(pattern);
}
}
let wildcardGpnCount = 0;
if (!wildcardDiscovered && wildcardChildren.length) {
wildcardGpnCount +=
estimateGpnCount(wildcardChildren, depth + 1) * WILDCARD_MULTIPLIER;
}
for (const k of Object.keys(children)) {
const c = estimateGpnCount(children[k].concat(wildcardChildren), depth + 1);
wildcardGpnCount -= c;
gpnCount += c;
}
gpnCount += Math.max(0, wildcardGpnCount);
return gpnCount;
}