mirror of https://codeberg.org/pzp/pzp-goals.git
279 lines
7.2 KiB
JavaScript
279 lines
7.2 KiB
JavaScript
// @ts-ignore
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const Obz = require('obz')
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// @ts-ignore
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const multicb = require('multicb')
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/**
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* @typedef {ReturnType<import('ppppp-db').init>} PPPPPDB
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* @typedef {ReturnType<import('ppppp-record').init>} PPPPPRecord
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* @typedef {import('ppppp-db').RecPresent} RecPresent
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* @typedef {import('ppppp-db').Tangle} Tangle
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* @typedef {ReturnType<PPPPPDB['getTangle']>} DBTangle
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* @typedef {string} MsgID
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* @typedef {'none'|'all'|`newest-${number}`|'record'|'set'} GoalDSL
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* @typedef {'none'|'all'|'newest'|'record'|'set'} GoalType
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* @typedef {[number, number]} Range
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* @typedef {{ id: string, type: GoalType, count: number }} Goal
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*/
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/**
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* @template T
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* @typedef {(...args: [Error] | [null, T]) => void } CB
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*/
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/**
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* @template T
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* @typedef {(args?: CB<Array<T>>) => any} Multicb
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*/
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/**
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* A *purpose* is a tag that explains why a msg exists in the database.
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* - "none" means the msg has no purpose, and should not exist in the database.
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* - "ghost" means the msg has no purpose, should not exist in the database, but
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* we should still register it as a ghost so that we don't accidentally
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* re-request it during replication.
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* - "trail" means the msg does not meet any goal, but it is required to be in
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* the database because it is along the path of goalful msgs to the root of the
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* tangle. See "Lipmaa certificate pool" concept from Bamboo.
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* - "goal" means the msg perfectly meets the requirements of some goal.
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*
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* These tags are ordered, "none" < "ghost" < "trail" < "goal", meaning that a
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* msg with purpose "goal" may *also* fulfill the purpose of "trail", and a
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* "trail" also prevents accidental re-request like "ghost" does.
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* @typedef {'none' | 'ghost' | 'trail' | 'goal'} Purpose
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*/
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/**
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* @param {{ db: PPPPPDB | null }} peer
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* @returns {asserts peer is { db: PPPPPDB }}
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*/
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function assertDBPlugin(peer) {
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if (!peer.db) throw new Error('goals plugin requires ppppp-db plugin')
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}
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/**
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* @param {{ record: PPPPPRecord | null }} peer
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* @returns {asserts peer is { record: PPPPPRecord }}
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*/
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function assertRecordPlugin(peer) {
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if (!peer.record) throw new Error('goals plugin requires ppppp-record plugin')
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}
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/**
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* @implements {Goal}
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*/
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class GoalImpl {
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/** @type {string} */
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#id
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/** @type {GoalType} */
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#type
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/** @type {number} */
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#count
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/**
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* @param {string} tangleID
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* @param {GoalDSL} goalDSL
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* @returns
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*/
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constructor(tangleID, goalDSL) {
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this.#id = tangleID
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if (goalDSL === 'none') {
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this.#type = 'none'
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this.#count = 0
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return
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}
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if (goalDSL === 'all') {
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this.#type = 'all'
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this.#count = Infinity
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return
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}
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if (goalDSL === 'set') {
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this.#type = 'set'
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this.#count = Infinity
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return
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}
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if (goalDSL === 'record') {
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this.#type = 'record'
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this.#count = Infinity
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return
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}
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const matchN = goalDSL.match(/^newest-(\d+)$/)
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if (matchN) {
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this.#type = 'newest'
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this.#count = Number(matchN[1])
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return
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}
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throw new Error(`Unrecognized goal DSL: ${goalDSL}`)
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}
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get id() {
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return this.#id
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}
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get type() {
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return this.#type
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}
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get count() {
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return this.#count
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}
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}
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/**
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* @param {{ db: PPPPPDB | null, record: PPPPPRecord | null }} peer
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* @param {unknown} config
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*/
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function initGoals(peer, config) {
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assertDBPlugin(peer)
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// Constants:
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const EMPTY_RANGE = /** @type {Range} */ ([1, 0])
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// State:
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const goals = /** @type {Map<string, Goal>} */ (new Map())
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const listen = Obz()
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/**
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* @private
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* @param {Goal} goal
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* @param {Tangle} tangle
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* @returns {Range}
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*/
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function crossGoalWithTangle(goal, tangle) {
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const maxDepth = tangle.maxDepth
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switch (goal.type) {
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case 'newest':
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const start = Math.max(0, maxDepth - goal.count + 1)
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return [start, maxDepth]
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case 'all':
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case 'set':
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return [0, maxDepth]
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case 'record':
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assertRecordPlugin(peer)
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const minDepth = peer.record.getMinRequiredDepth(goal.id)
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return [minDepth, maxDepth]
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case 'none':
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return EMPTY_RANGE
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default:
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throw new Error(`Unrecognized goal type: ${goal.type}`)
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}
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}
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/**
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* @public
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* @param {string} tangleID
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* @param {GoalDSL} goalDSL
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* @returns {void}
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*/
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function set(tangleID, goalDSL) {
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const goal = new GoalImpl(tangleID, goalDSL)
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goals.set(tangleID, goal)
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listen.set(goal)
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}
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/**
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* @public
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* @param {string} tangleID
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* @returns {Goal | null}
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*/
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function get(tangleID) {
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return goals.get(tangleID) ?? null
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}
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/**
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* @public
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* @param {RecPresent} rec
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* @returns {Purpose}
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*/
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function getRecordPurpose(rec) {
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assertDBPlugin(peer)
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let servesAsTrail = false
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// Check whether this record is a goalful root of some tangle:
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asRoot: if (goals.has(rec.id)) {
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const goal = /** @type {GoalImpl} */ (goals.get(rec.id))
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if (goal.type === 'none') break asRoot
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const tangle = peer.db.getTangle(rec.id)
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if (!tangle) break asRoot
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const [min, max] = crossGoalWithTangle(goal, tangle)
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if (min > max) break asRoot
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if (min === 0) return 'goal'
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if (min > 0) servesAsTrail = true
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}
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// Check whether this record is a goalful affix of some tangle:
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const validTangles =
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/** @type {Array<[DBTangle, number, number, number, GoalType]>} */ ([])
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asAffix: for (const tangleID in rec.msg.metadata.tangles) {
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if (!goals.has(tangleID)) continue asAffix
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const goal = /** @type {GoalImpl} */ (goals.get(tangleID))
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if (goal.type === 'none') continue asAffix
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const tangle = peer.db.getTangle(tangleID)
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if (!tangle) continue asAffix
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const [min, max] = crossGoalWithTangle(goal, tangle)
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if (min > max) continue asAffix
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const recDepth = tangle.getDepth(rec.id)
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if (recDepth < 0) continue asAffix
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validTangles.push([tangle, min, max, recDepth, goal.type])
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}
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// (Loop over once without heavy computations and maybe return early:)
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for (const [, min, max, recDepth] of validTangles) {
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if (min <= recDepth && recDepth <= max) return 'goal'
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}
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// At this point we know that the record *cannot* serve as 'goal',
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// so if it serves as trail, that'll do:
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if (servesAsTrail) return 'trail'
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// Check whether this record is a trail affix of some tangle:
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// (Loop again with heavy computations now that it's inevitable:)
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for (const [tangle, min] of validTangles) {
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const minMsgIDs = tangle
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.topoSort()
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.filter((msgID) => tangle.getDepth(msgID) === min)
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const { erasables } = tangle.getDeletablesAndErasables(...minMsgIDs)
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if (erasables.has(rec.id)) return 'trail'
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}
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// Check whether this record is a ghost affix of some tangle:
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for (const [tangle, , , , goalType] of validTangles) {
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if (goalType === 'record') {
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assertRecordPlugin(peer)
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if (peer.record.isGhostable(rec.id, tangle.id)) {
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return 'ghost'
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}
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}
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}
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return 'none'
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}
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/**
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* @public
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* @returns {IterableIterator<Goal>}
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*/
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function list() {
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return goals.values()
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}
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return {
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set,
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get,
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getRecordPurpose,
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list,
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listen,
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}
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}
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exports.name = 'goals'
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exports.init = initGoals
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