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import { strict as assert } from 'assert';
import {
Contributor,
Failure,
IssueActivity,
IssueNode,
MultiAssigneeIssueActivity,
ProjectPlan,
SchedulableIssue,
Schedule,
SchedulingOptions,
YouTrackIssue,
} from './api-types';
import { makeForest, traverseIssueForest } from './issue-forest';
import { assignDefined, coalesce, deepClone, OnlyOptionals, unreachableCase } from './util';
/**
* Computes and returns a schedule for the given issues.
*
* The problem of scheduling issues is transformed (“[reduced](https://en.wikipedia.org/wiki/Reduction_(complexity))”)
* to the machine-scheduling problem, which is then solved using the *list-scheduling* algorithm from project
* [fschopp/project-planning-js](https://github.com/fschopp/project-planning-js).
*
* Issues are scheduled in input order, subject to issue dependencies. Note that if an issue A depends on another
* issue B, then both A *and* its sub-issues (transitively) depend on both B and all of B’s sub-issues. Beyond that,
* parent-child relationships do *not* influence the scheduling order. That is, if both an issue and a sub-issues have
* non-zero remaining effort, then both issues’ *own* (excluding sub-issues) processing will occur in input order.
*
* Under the hood, this function introduces “dummy” jobs with size zero and zero delivery time. These dummy jobs
* (thanks to the transitive nature of dependencies) allow to “factor out” start-to-start and finish-to-finish
* dependencies (from issues to sub-issues and vice versa, respectively). Thus, the transformed machine-scheduling
* problem instance can be represented succinctly.
*
* @param issues Array of issues that need to be scheduled. The array is expected to be “closed” in the sense that a
* parent or dependency referenced by any of the issues is guaranteed to be contained in `issues`, too. That is,
* despite the name of this function, it is *not* expected that all issue are unresolved.
* @param options scheduling options
* @return promise that will be resolved with the schedule or rejected with a {@link Failure} containing a
* human-readable failure description if the problem instance is invalid (for example, has a cyclic dependency
* graph)
*/
export async function scheduleUnresolved(issues: SchedulableIssue[], options: SchedulingOptions):
Promise<Schedule> {
const actualOptions: Required<SchedulingOptions> = assignDefined(newDefaultSchedulingOptions(), options);
const {jobIdxToExtendedIssue, machineIdxToContributorIdx, schedulingInstance} =
makeSchedulingInstance(issues, actualOptions);
const machineSchedule: ProjectPlanningJs.Schedule = await ProjectPlanningJs.computeScheduleAsync(schedulingInstance);
const realTimeFactor = MINUTES_PER_WEEK_REAL_TIME / actualOptions.minutesPerWeek;
const schedule: IssueActivity[][] = issues.map(() => []);
const scheduleTimestampToEpochTime = (timestamp: number): number => Math.ceil(
actualOptions.predictionStartTimeMs + timestamp * actualOptions.resolutionMs * realTimeFactor);
for (let j = 0; j < machineSchedule.length; ++j) {
const scheduledJob: ProjectPlanningJs.ScheduledJob = machineSchedule[j];
const scheduledIssue: IssueActivity[] = schedule[jobIdxToExtendedIssue[j].issueIdx];
for (const jobFragment of scheduledJob) {
const issueActivity: IssueActivity = {
assignee: actualOptions.contributors[machineIdxToContributorIdx[jobFragment.machine]].id,
start: scheduleTimestampToEpochTime(jobFragment.start),
end: scheduleTimestampToEpochTime(jobFragment.end),
isWaiting: jobFragment.isWaiting,
};
scheduledIssue.push(issueActivity);
}
}
return schedule;
}
/**
* Appends a schedule for issues with remaining effort or wait time to a project plan.
*
* This function does not modify any of its arguments. It returns an entirely new instance that shares no mutable data
* with `projectPlan`.
*
* This function merges any issue activity in `projectPlan` that extends into an activity in `schedule` for the same
* issue and by the same contributor.
*
* @param projectPlan the project plan, typically containing only past issue activities
* @param schedule the (future) schedule for issues with remaining effort or wait time
* @param divisionTimestamp Timestamp taken as end for the project plan and as beginning for the future schedule. Any
* project-plan activities starting at or after this timestamp, and any schedule activities ending at or before this
* timestamp are omitted.
* @return a new project plan that contains the issue activities of both `projectPlan` and `schedule`
*/
export function appendSchedule(projectPlan: ProjectPlan, schedule: Schedule, divisionTimestamp: number):
ProjectPlan | Failure {
if (projectPlan.issues.length !== schedule.length) {
return 'The given project plan and the new schedule have a different number of issues.';
}
const collator = new Intl.Collator('en');
const newProjectPlan: ProjectPlan = deepClone(projectPlan);
for (let issueIdx = 0; issueIdx < newProjectPlan.issues.length; ++issueIdx) {
const issue: YouTrackIssue = newProjectPlan.issues[issueIdx];
// The following statement means "group by assignee"
const assigneeToActivities = new Map<string, IssueActivity[]>();
const existingActivities: IssueActivity[] = [];
for (const issueActivity of issue.issueActivities) {
if (issueActivity.start < divisionTimestamp) {
issueActivity.end = Math.min(issueActivity.end, divisionTimestamp);
if (assigneeToActivities.has(issueActivity.assignee)) {
assigneeToActivities.get(issueActivity.assignee)!.push(issueActivity);
} else {
assigneeToActivities.set(issueActivity.assignee, [issueActivity]);
}
existingActivities.push(issueActivity);
}
}
issue.issueActivities = existingActivities;
const createIfAbsent = (assignee: string): IssueActivity[] => {
if (assigneeToActivities.has(assignee)) {
return assigneeToActivities.get(assignee)!;
} else {
const returnValue: IssueActivity[] = [];
assigneeToActivities.set(assignee, returnValue);
return returnValue;
}
};
for (const scheduledActivity of schedule[issueIdx]) {
if (scheduledActivity.end <= divisionTimestamp) {
continue;
}
const newActivity: IssueActivity = {
...scheduledActivity,
start: Math.max(scheduledActivity.start, divisionTimestamp),
};
const assigneeActivities: IssueActivity[] = createIfAbsent(scheduledActivity.assignee);
if (assigneeActivities.length > 0 &&
assigneeActivities[assigneeActivities.length - 1].end === newActivity.start &&
assigneeActivities[assigneeActivities.length - 1].isWaiting === newActivity.isWaiting) {
assigneeActivities[assigneeActivities.length - 1].end = newActivity.end;
} else {
assigneeActivities.push(newActivity);
issue.issueActivities.push(newActivity);
}
}
issue.issueActivities.sort((left, right) => {
const diff = left.end - right.end;
return diff !== 0
? diff
: collator.compare(left.assignee, right.assignee);
});
}
return newProjectPlan;
}
/**
* Returns the given issue activities grouped by interval and wait status.
*
* Every point in time is represented by at most two {@link MultiAssigneeIssueActivity} elements in the returned array;
* one for all assignees that are not waiting, and one for all that are. Each {@link MultiAssigneeIssueActivity} element
* has maximum length. In other words, no two {@link MultiAssigneeIssueActivity} elements could be merged into one.
*
* This function can be thought to work as follows: It first separates the activities according to wait status. Then,
* for both groups: It projects all start and end timestamps of the given activities onto a single timeline. It then
* iterates over these timestamps, and whenever the set of assignees changes:
* 1. The current {@link MultiAssigneeIssueActivity} (if any) is ended.
* 2. A new {@link MultiAssigneeIssueActivity} is added if the new set of assignees is non-empty.
* As last step, the non-waiting and waiting activities are merged (and sorted).
*
* Note that all functions in this package that return arrays of {@link IssueActivity} guarantee a “normalized” form.
* See, for instance, {@link YouTrackIssue.issueActivities}. With these extra guarantees, no activities in the array
* return by this function ever overlap.
*
* This function treats activities with empty {@link IssueActivity.assignee} in the same way as all other activities.
* That is, within this function, the empty string is a valid assignee name.
*
* @param activities The issue activities. The array does not have to be “normalized.”
* @return The array of issue activities grouped by interval and wait status. The array will be sorted by the `start`
* and then by the `isWaiting` properties. The {@link MultiAssigneeIssueActivity.assignees} property of each element
* is guaranteed to be sorted, too.
*/
export function groupByIntervalAndWaitStatus(activities: IssueActivity[]): MultiAssigneeIssueActivity[] {
enum IssueEventType {
ADDED = 0,
REMOVED = 1,
}
interface IssueEvent {
type: IssueEventType;
assignee: string;
timestamp: number;
isWaiting: boolean;
}
const result: MultiAssigneeIssueActivity[] = [];
for (const isWaiting of [false, true]) {
const events: IssueEvent[] = [];
for (const activity of filter(activities, (filterActivity) => filterActivity.isWaiting === isWaiting)) {
const assignee = activity.assignee;
events.push(
{type: IssueEventType.ADDED, assignee, timestamp: activity.start, isWaiting},
{type: IssueEventType.REMOVED, assignee, timestamp: activity.end, isWaiting}
);
}
events.sort((first, second) => first.timestamp - second.timestamp);
let lastActivity: MultiAssigneeIssueActivity = {
assignees: [],
start: Number.MIN_SAFE_INTEGER,
end: Number.MAX_SAFE_INTEGER,
isWaiting: false,
};
let lastTimestamp: number = Number.MIN_SAFE_INTEGER;
const assigneeToActivityCount = new Map<string, number>();
for (const event of events) {
if (event.timestamp > lastTimestamp) {
lastActivity = timePassed(lastActivity, lastTimestamp, assigneeToActivityCount, result, isWaiting);
}
let assigneeActiveCount: number = coalesce(assigneeToActivityCount.get(event.assignee), 0);
if (event.type === IssueEventType.REMOVED) {
--assigneeActiveCount;
} else {
++assigneeActiveCount;
}
assert(assigneeActiveCount >= 0, 'count cannot become negative');
assigneeToActivityCount.set(event.assignee, assigneeActiveCount);
lastTimestamp = event.timestamp;
}
timePassed(lastActivity, lastTimestamp, assigneeToActivityCount, result, isWaiting);
}
result.sort((first, second) => first.start === second.start
? (+first.isWaiting) - (+second.isWaiting)
: first.start - second.start);
return result;
}
/**
* Mapping between an issue and (either one or two) jobs in the machine scheduling problem.
*/
interface ExtendedIssue extends Required<SchedulableIssue> {
/**
* Index of this issue in the original (flat) array that was used to create this extended issue.
*/
issueIdx: number;
/**
* Index of the “main” (machine-scheduling) job corresponding to the current issue.
*
* This job has a size computed from {@link SchedulableIssue.remainingEffortMs}, etc.
*/
jobIdx: number;
/**
* Index of the “dummy” (machine-scheduling) job that the main job and all jobs corresponding to direct sub-issues of
* the current issue depend on.
*
* This dummy job (with size zero and zero delivery time) ensures a start-to-start dependency from the current issue
* to its sub-issues. It is this job that depends on the jobs corresponding to dependencies of the current issue.
*
* If the current issue has no sub-issues, this will be the same as {@link jobIdx}.
*/
startToStartDummyJobIdx: number;
/**
* Index of the “dummy” (machine-scheduling) job that depends on the main job and all jobs corresponding to direct
* sub-issues of the current issue.
*
* This dummy job (with size zero and zero delivery time) ensures a finish-to-finish dependency from the current
* issue’s sub-issues to itself. It is this job that the jobs corresponding to dependents of the current issue depend
* on.
*
* If the current issue has no sub-issues, this will be the same as {@link jobIdx}.
*/
asDependencyJobIdx: number;
}
/**
* The kind of a machine-scheduling job created for an issue.
*/
enum JobType {
MAIN,
START_TO_START,
FINISH_TO_FINISH,
}
/**
* A job descriptor that will be converted into a `Job`.
*/
type JobDescriptor = [IssueNode<ExtendedIssue>, JobType];
/**
* The number of minutes per week, in real time.
*/
const MINUTES_PER_WEEK_REAL_TIME: number = 7 * 24 * 60;
const NO_INDEX: number = -1;
/**
* Returns a new object with values for the optional properties of {@link SchedulableIssue}.
*/
function newDefaultSchedulableIssue(): OnlyOptionals<SchedulableIssue> {
return {
remainingWaitTimeMs: 0,
parent: '',
splittable: false,
dependencies: [],
assignee: '',
};
}
/**
* Returns a new object with values for the optional properties of {@link SchedulingOptions}.
*/
function newDefaultSchedulingOptions(): OnlyOptionals<SchedulingOptions> {
return {
minutesPerWeek: 5 * 8 * 60,
resolutionMs: 60 * 60 * 1000,
minActivityDuration: 1,
predictionStartTimeMs: Date.now(),
};
}
/**
* Returns a machine-scheduling problem instance for the given issues, thereby “reducing” the problem to a another one
* for that a solver already exists.
*
* For every parent issue P, this function creates two dummy jobs with size zero and zero delivery time:
* 1. A job that depends on all direct sub-issues.
* 2. A job that all direct sub-issues depend on.
*/
function makeSchedulingInstance(issues: SchedulableIssue[], actualOptions: Required<SchedulingOptions>):
{
jobIdxToExtendedIssue: ExtendedIssue[];
machineIdxToContributorIdx: number[];
schedulingInstance: ProjectPlanningJs.SchedulingInstance;
} {
const jobIdxToExtendedIssue: ExtendedIssue[] = [];
const machineIdxToContributorIdx: number[] = [];
// Invariant: n === machineIdxToContributorIdx.length === schedulingInstance.machineSpeeds.length
let n: number = 0;
const assigneeToContributorIdx = new Map<string, number>();
const schedulingInstance: ProjectPlanningJs.SchedulingInstance = {
machineSpeeds: [],
jobs: [],
minFragmentSize: actualOptions.minActivityDuration * actualOptions.minutesPerWeek,
};
for (let i = 0; i < actualOptions.contributors.length; ++i) {
const contributor: Contributor = actualOptions.contributors[i];
assigneeToContributorIdx.set(contributor.id, i);
const numMembers: number = coalesce(contributor.numMembers, 1);
machineIdxToContributorIdx.length = n + numMembers;
machineIdxToContributorIdx.fill(i, n, n + numMembers);
schedulingInstance.machineSpeeds.length = n + numMembers;
schedulingInstance.machineSpeeds.fill(contributor.minutesPerWeek, n, n + numMembers);
n += numMembers;
}
// From the intermediate representation as job descriptors, create the actual machine-scheduling jobs. This cannot be
// done directly (without the job descriptors), because dependency information is required.
for (const [node, jobType] of makeJobDescriptors(issues)) {
let job: ProjectPlanningJs.Job;
const issue: ExtendedIssue = node.issue;
const size: number = 0;
const dependencies: number[] = node.parent !== undefined
? [node.parent.issue.startToStartDummyJobIdx]
: [];
switch (jobType) {
case JobType.START_TO_START:
dependencies.push(...node.dependencies.map((dependencyNode) => dependencyNode.issue.asDependencyJobIdx));
job = {size, dependencies};
break;
case JobType.FINISH_TO_FINISH:
job = {
size,
dependencies: node.children
.map((childNode) => childNode.issue.asDependencyJobIdx)
.concat(node.issue.jobIdx),
};
break;
case JobType.MAIN:
if (node.children.length === 0) {
// There is no start-to-start job for this issue.
dependencies.push(...node.dependencies.map((dependencyNode) => dependencyNode.issue.asDependencyJobIdx));
}
job = {
size: Math.ceil(issue.remainingEffortMs / actualOptions.resolutionMs) * actualOptions.minutesPerWeek,
deliveryTime: Math.ceil(issue.remainingWaitTimeMs / actualOptions.resolutionMs),
splitting: issue.splittable
? ProjectPlanningJs.JobSplitting.MULTIPLE_MACHINES
: ProjectPlanningJs.JobSplitting.PREEMPTION,
dependencies,
preAssignment: issue.assignee.length > 0
? assigneeToContributorIdx.get(issue.assignee)
: undefined,
};
break;
/* istanbul ignore next */
default: return unreachableCase(jobType);
}
jobIdxToExtendedIssue.push(node.issue);
schedulingInstance.jobs.push(job);
}
return {jobIdxToExtendedIssue, machineIdxToContributorIdx, schedulingInstance};
}
function makeJobDescriptors(issues: SchedulableIssue[]): JobDescriptor[] {
// 1. Augment the given issues with extra information (some of which we'll have to fill in later).
const extendedIssues: ExtendedIssue[] = issues.map((issue, issueIdx) => ({
...assignDefined(newDefaultSchedulableIssue(), issue),
issueIdx,
// The job indices will be updated later!
jobIdx: NO_INDEX,
startToStartDummyJobIdx: NO_INDEX,
asDependencyJobIdx: NO_INDEX,
}));
const nodes: IssueNode<ExtendedIssue>[] = [];
nodes.length = extendedIssues.length;
const jobDescriptors: JobDescriptor[] = [];
// 2. Build tree. Also, for each issue, create 1 (if the issue has no sub-issues) or 3 (otherwise) machine-scheduling
// jobs. Note that the dummy jobs come first, because they need higher priority than all the main jobs. The reason is
// that no otherwise ready main job should ever wait for a dummy job.
traverseIssueForest(makeForest(extendedIssues), (node) => {
nodes[node.index] = node;
if (node.children.length > 0) {
jobDescriptors.push([node, JobType.START_TO_START], [node, JobType.FINISH_TO_FINISH]);
}
});
// reduce() does *not* call callbackfn for empty slots, so the assert is reasonable:
// https://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.21
assert(nodes.reduce((count) => count + 1, 0) === extendedIssues.length, 'Traversal must have visited all issues');
for (const node of nodes) {
const issue: ExtendedIssue = node.issue;
// Initialize the jobs indices. The dummy job indices may be updated again below.
issue.startToStartDummyJobIdx = issue.asDependencyJobIdx = issue.jobIdx = jobDescriptors.length;
jobDescriptors.push([node, JobType.MAIN]);
}
// 3. Now that we know what machine-scheduling jobs will be created (and what issue each corresponds to), complete the
// reverse mapping from issue to job indices.
outer: for (let i = 0; i < jobDescriptors.length; ++i) {
const [node, jobType] = jobDescriptors[i];
const issue: ExtendedIssue = node.issue;
switch (jobType) {
case JobType.START_TO_START: issue.startToStartDummyJobIdx = i; break;
case JobType.FINISH_TO_FINISH: issue.asDependencyJobIdx = i; break;
case JobType.MAIN: break outer;
/* istanbul ignore next */
default: return unreachableCase(jobType);
}
}
return jobDescriptors;
}
/**
* Commits the last issue activity if the set of assignees changed at the last timestamp.
*
* This function is called because time progressed from `lastTimestamp` to `x`, so the interval between `lastTimestamp`
* and `x` becomes “settled.”
*
* Note that there are 3 logical timestamps of relevance here:
* 1. The timestamp when `lastActivity` started. This is simply `lastActivity.start`.
* 2. The timestamp of the last event prior to the current time. This is `lastTimestamp`.
* 3. The current time. This function does not need an exact value, so it may be an arbitrary value
* `x > lastTimestamp`.
*
* @param lastActivity The activity that is known to have lasted (at least) until timestamp `lastTimestamp`. That is,
* `lastActivity.assignees` contains the set of assignees between timestamps `lastActivity.start` and
* `lastTimestamp`.
* @param lastTimestamp The timestamp of the last event (prior to the current time `x`). It holds that
* `lastTimestamp < x`. If the set of assignees changed at `lastTimestamp`, then this function updates
* `lastActivity` and adds it to `result` (assuming there was at least one assignee between timestamps
* `lastActivity.start` and `lastTimestamp`).
* @param currentAssignees The set of assignees between timestamp `lastTimestamp` and `x`.
* @param result The array of activities that `lastActivity` will be added to if the set of assignees changed at
* timestamp `lastTimestamp`.
* @param isWaiting If this function returns a new activity (starting at `lastTimestamp`), the value for the
* `isWaiting` property.
* @return The current activity that is known to have lasted (at least) until timestamp `x`.
*/
function timePassed(lastActivity: MultiAssigneeIssueActivity, lastTimestamp: number,
currentAssignees: Map<string, number>, result: MultiAssigneeIssueActivity[], isWaiting: boolean):
MultiAssigneeIssueActivity {
let assigneesChanged: boolean = false;
for (const assignee of lastActivity.assignees) {
if (coalesce(currentAssignees.get(assignee), 0) <= 0) {
assigneesChanged = true;
break;
}
}
const assignees: string[] = [];
for (const [assignee, activeCount] of currentAssignees.entries()) {
if (activeCount > 0) {
assignees.push(assignee);
}
}
assigneesChanged = assigneesChanged || lastActivity.assignees.length !== assignees.length;
if (assigneesChanged) {
if (lastActivity.assignees.length > 0) {
lastActivity.end = lastTimestamp;
result.push(lastActivity);
}
assignees.sort();
return {
assignees,
start: lastTimestamp,
end: Number.MAX_SAFE_INTEGER,
isWaiting,
};
} else {
return lastActivity;
}
}
function* filter<T>(iterable: Iterable<T>, predicate: (val: T) => boolean): Iterable<T> {
for (const value of iterable) {
if (predicate(value)) {
yield value;
}
}
}
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