first go at a timeline memory store
first to use in unit tests for persister later also to use in production when idb is not available
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Bruno Windels
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1 changed files with 220 additions and 0 deletions
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src/matrix/storage/memory/stores/RoomTimelineStore.js
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src/matrix/storage/memory/stores/RoomTimelineStore.js
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import SortKey from "../sortkey.js";
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import sortedIndex from "../../../utils/sortedIndex.js";
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function compareKeys(key, entry) {
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if (key.roomId === entry.roomId) {
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return key.sortKey.compare(entry.sortKey);
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} else {
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return key.roomId < entry.roomId ? -1 : 1;
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}
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}
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class Range {
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constructor(timeline, lower, upper, lowerOpen, upperOpen) {
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this._timeline = timeline;
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this._lower = lower;
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this._upper = upper;
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this._lowerOpen = lowerOpen;
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this._upperOpen = upperOpen;
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}
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/** projects the range onto the timeline array */
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project(roomId, maxCount = Number.MAX_SAFE_INTEGER) {
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// determine lowest and highest allowed index.
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// Important not to bleed into other roomIds here.
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const lowerKey = {roomId, sortKey: this._lower || SortKey.minKey };
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// apply lower key being open (excludes given key)
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let minIndex = sortedIndex(this._timeline, lowerKey, compareKeys);
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if (this._lowerOpen && minIndex < this._timeline.length && compareKeys(lowerKey, this._timeline[minIndex]) === 0) {
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minIndex += 1;
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}
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const upperKey = {roomId, sortKey: this._upper || SortKey.maxKey };
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// apply upper key being open (excludes given key)
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let maxIndex = sortedIndex(this._timeline, upperKey, compareKeys);
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if (this._upperOpen && maxIndex < this._timeline.length && compareKeys(upperKey, this._timeline[maxIndex]) === 0) {
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maxIndex -= 1;
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}
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// find out from which edge we should grow
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// if upper or lower bound
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// again, important not to go below minIndex or above maxIndex
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// to avoid bleeding into other rooms
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let startIndex, endIndex;
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if (!this._lower && this._upper) {
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startIndex = Math.max(minIndex, maxIndex - maxCount);
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endIndex = maxIndex;
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} else if (this._lower && !this._upper) {
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startIndex = minIndex;
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endIndex = Math.min(maxIndex, minIndex + maxCount);
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} else {
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startIndex = minIndex;
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endIndex = maxIndex;
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}
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// if startIndex is out of range, make range empty
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if (startIndex === this._timeline.length) {
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startIndex = endIndex = 0;
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}
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const count = endIndex - startIndex;
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return {startIndex, count};
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}
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select(roomId, maxCount) {
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const {startIndex, count} = this.project(roomId, this._timeline, maxCount);
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return this._timeline.slice(startIndex, startIndex + count);
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}
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}
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export default class RoomTimelineStore {
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constructor(initialTimeline = []) {
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this._timeline = initialTimeline;
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}
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/** Creates a range that only includes the given key
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* @param {SortKey} sortKey the key
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* @return {Range} the created range
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*/
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onlyRange(sortKey) {
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return new Range(this._timeline, sortKey, sortKey);
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}
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/** Creates a range that includes all keys before sortKey, and optionally also the key itself.
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* @param {SortKey} sortKey the key
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* @param {boolean} [open=false] whether the key is included (false) or excluded (true) from the range at the upper end.
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* @return {Range} the created range
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*/
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upperBoundRange(sortKey, open=false) {
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return new Range(this._timeline, undefined, sortKey, undefined, open);
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}
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/** Creates a range that includes all keys after sortKey, and optionally also the key itself.
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* @param {SortKey} sortKey the key
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* @param {boolean} [open=false] whether the key is included (false) or excluded (true) from the range at the lower end.
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* @return {Range} the created range
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*/
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lowerBoundRange(sortKey, open=false) {
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return new Range(this._timeline, sortKey, undefined, open);
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}
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/** Creates a range that includes all keys between `lower` and `upper`, and optionally the given keys as well.
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* @param {SortKey} lower the lower key
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* @param {SortKey} upper the upper key
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* @param {boolean} [lowerOpen=false] whether the lower key is included (false) or excluded (true) from the range.
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* @param {boolean} [upperOpen=false] whether the upper key is included (false) or excluded (true) from the range.
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* @return {Range} the created range
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*/
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boundRange(lower, upper, lowerOpen=false, upperOpen=false) {
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return new Range(this._timeline, lower, upper, lowerOpen, upperOpen);
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}
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/** Looks up the last `amount` entries in the timeline for `roomId`.
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* @param {string} roomId
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* @param {number} amount
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* @return {Promise<Entry[]>} a promise resolving to an array with 0 or more entries, in ascending order.
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*/
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lastEvents(roomId, amount) {
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return this.eventsBefore(roomId, SortKey.maxKey, amount);
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}
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/** Looks up the first `amount` entries in the timeline for `roomId`.
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* @param {string} roomId
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* @param {number} amount
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* @return {Promise<Entry[]>} a promise resolving to an array with 0 or more entries, in ascending order.
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*/
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firstEvents(roomId, amount) {
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return this.eventsAfter(roomId, SortKey.minKey, amount);
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}
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/** Looks up `amount` entries after `sortKey` in the timeline for `roomId`.
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* The entry for `sortKey` is not included.
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* @param {string} roomId
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* @param {SortKey} sortKey
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* @param {number} amount
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* @return {Promise<Entry[]>} a promise resolving to an array with 0 or more entries, in ascending order.
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*/
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eventsAfter(roomId, sortKey, amount) {
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const events = this.lowerBoundRange(sortKey, true).select(roomId, amount);
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return Promise.resolve(events);
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}
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/** Looks up `amount` entries before `sortKey` in the timeline for `roomId`.
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* The entry for `sortKey` is not included.
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* @param {string} roomId
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* @param {SortKey} sortKey
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* @param {number} amount
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* @return {Promise<Entry[]>} a promise resolving to an array with 0 or more entries, in ascending order.
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*/
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eventsBefore(roomId, sortKey, amount) {
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const events = this.upperBoundRange(sortKey, true).select(roomId, amount);
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return Promise.resolve(events);
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}
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/** Looks up the first, if any, event entry (so excluding gap entries) after `sortKey`.
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* @param {string} roomId
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* @param {SortKey} sortKey
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* @return {Promise<(?Entry)>} a promise resolving to entry, if any.
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*/
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nextEvent(roomId, sortKey) {
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const searchSpace = this.lowerBoundRange(sortKey, true).select(roomId);
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const event = searchSpace.find(entry => !!entry.event);
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return Promise.resolve(event);
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}
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/** Looks up the first, if any, event entry (so excluding gap entries) before `sortKey`.
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* @param {string} roomId
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* @param {SortKey} sortKey
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* @return {Promise<(?Entry)>} a promise resolving to entry, if any.
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*/
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previousEvent(roomId, sortKey) {
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const searchSpace = this.upperBoundRange(sortKey, true).select(roomId);
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const event = searchSpace.reverse().find(entry => !!entry.event);
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return Promise.resolve(event);
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}
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/** Inserts a new entry into the store. The combination of roomId and sortKey should not exist yet, or an error is thrown.
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* @param {Entry} entry the entry to insert
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* @return {Promise<>} a promise resolving to undefined if the operation was successful, or a StorageError if not.
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* @throws {StorageError} ...
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*/
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insert(entry) {
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const insertIndex = sortedIndex(this._timeline, entry, compareKeys);
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if (insertIndex < this._timeline.length) {
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const existingEntry = this._timeline[insertIndex];
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if (compareKeys(entry, existingEntry) === 0) {
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return Promise.reject(new Error("entry already exists"));
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}
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}
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this._timeline.splice(insertIndex, 0, entry);
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return Promise.resolve();
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}
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/** Updates the entry into the store with the given [roomId, sortKey] combination.
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* If not yet present, will insert. Might be slower than add.
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* @param {Entry} entry the entry to update.
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* @return {Promise<>} a promise resolving to undefined if the operation was successful, or a StorageError if not.
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*/
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update(entry) {
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let update = false;
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const updateIndex = sortedIndex(this._timeline, entry, compareKeys);
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if (updateIndex < this._timeline.length) {
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const existingEntry = this._timeline[updateIndex];
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if (compareKeys(entry, existingEntry) === 0) {
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update = true;
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}
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}
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this._timeline.splice(updateIndex, update ? 1 : 0, entry);
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return Promise.resolve();
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}
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get(roomId, sortKey) {
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const range = this.onlyRange(sortKey);
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const {startIndex, count} = range.project(roomId);
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const event = count ? this._timeline[startIndex] : undefined;
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return Promise.resolve(event);
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}
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removeRange(roomId, range) {
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const {startIndex, count} = range.project(roomId);
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const removedEntries = this._timeline.splice(startIndex, count);
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return Promise.resolve(removedEntries);
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}
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}
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