task_scheduler/go/types/task.go - buildbot - Git at Google

 package types

 import (
 	"fmt"
 	"reflect"
 	"sort"
 	"strconv"
 	"strings"
 	"time"
 	"unicode/utf8"

 	"go.skia.org/infra/go/common"
 	"go.skia.org/infra/go/gitiles"
 	"go.skia.org/infra/go/sklog"
 	"go.skia.org/infra/go/util"
 )

 const (
 	// Swarming tags added by Task Scheduler.
 	SWARMING_TAG_ATTEMPT          = "sk_attempt"
 	SWARMING_TAG_DIMENSION_PREFIX = "sk_dim_"
 	SWARMING_TAG_FORCED_JOB_ID    = "sk_forced_job_id"
 	SWARMING_TAG_ID               = "sk_id"
 	SWARMING_TAG_ISSUE            = "sk_issue"
 	SWARMING_TAG_LUCI_PROJECT     = "luci_project"
 	SWARMING_TAG_MILO_HOST        = "milo_host"
 	SWARMING_TAG_NAME             = "sk_name"
 	SWARMING_TAG_PARENT_TASK_ID   = "sk_parent_task_id"
 	SWARMING_TAG_PATCHSET         = "sk_patchset"
 	SWARMING_TAG_REPO             = "sk_repo"
 	SWARMING_TAG_RETRY_OF         = "sk_retry_of"
 	SWARMING_TAG_REVISION         = "sk_revision"
 	SWARMING_TAG_SERVER           = "sk_issue_server"

 	// These two tags allow the swarming ui to point to the GoB repo
 	SWARMING_TAG_SOURCE_REVISION = "source_revision"
 	SWARMING_TAG_SOURCE_REPO     = "source_repo"

 	MILO_HOST = "https://ci.chromium.org/raw/build/%s"

 	// Types of task executors.
 	TaskExecutor_UseDefault = ""
 	TaskExecutor_Swarming   = "swarming"
 	DefaultTaskExecutor     = TaskExecutor_Swarming
 )

 var (
 	ValidTaskExecutors = []string{TaskExecutor_UseDefault, TaskExecutor_Swarming}
 )

 type TaskStatus string

 const (
 	// TASK_STATUS_PENDING indicates the task has not started. It is the empty
 	// string so that it is the zero value of TaskStatus.
 	TASK_STATUS_PENDING TaskStatus = ""
 	// TASK_STATUS_RUNNING indicates the task is in progress.
 	TASK_STATUS_RUNNING TaskStatus = "RUNNING"
 	// TASK_STATUS_SUCCESS indicates the task completed successfully.
 	TASK_STATUS_SUCCESS TaskStatus = "SUCCESS"
 	// TASK_STATUS_FAILURE indicates the task completed with failures.
 	TASK_STATUS_FAILURE TaskStatus = "FAILURE"
 	// TASK_STATUS_MISHAP indicates the task exited early with an error, died
 	// while in progress, was manually canceled, expired while waiting on the
 	// queue, or timed out before completing.
 	TASK_STATUS_MISHAP TaskStatus = "MISHAP"
 )

 // TaskKey is a struct used for identifying a Task instance. Note that more
 // than one Task may have the same TaskKey, eg. in the case of retries.
 type TaskKey struct {
 	RepoState
 	Name        string `json:"name"`
 	ForcedJobId string `json:"forcedJobId"`
 }

 // Copy returns a copy of the TaskKey.
 func (k TaskKey) Copy() TaskKey {
 	return TaskKey{
 		RepoState:   k.RepoState.Copy(),
 		Name:        k.Name,
 		ForcedJobId: k.ForcedJobId,
 	}
 }

 // Valid indicates whether or not the TaskKey is valid.
 func (k TaskKey) Valid() bool {
 	return k.RepoState.Valid() && k.Name != ""
 }

 // IsForceRun indicates whether this Task is for a forced Job, which
 // indicates that it shouldn't be de-duplicated.
 func (k TaskKey) IsForceRun() bool {
 	return k.ForcedJobId != ""
 }

 // Task describes a Swarming task generated from a TaskSpec, or a "fake" task
 // that can not be executed on Swarming, but can be added to the DB and
 // displayed as if it were a real TaskSpec.
 //
 // Task is stored as a GOB, so changes must maintain backwards compatibility.
 // See gob package documentation for details, but generally:
 //   - Ensure new fields can be initialized with their zero value.
 //   - Do not change the type of any existing field.
 //   - Leave removed fields commented out to ensure the field name is not
 //     reused.
 //   - Add any new fields to the Copy() method.
 type Task struct {
 	// Attempt is the attempt number of this task, starting with zero.
 	Attempt int `json:"attempt"`

 	// Commits are the commits which were tested in this Task. The list may
 	// change due to backfilling/bisecting.
 	Commits []string `json:"commits"`

 	// Created is the creation timestamp.
 	Created time.Time `json:"created"`

 	// DbModified is the time of the last successful call to TaskDB.PutTask/s for this
 	// Task, or zero if the task is new. It is not related to the ModifiedTs time
 	// of the associated Swarming task.
 	DbModified time.Time `json:"dbModified"`

 	// Finished is the time the task stopped running or expired from the queue, or
 	// zero if the task is pending or running.
 	Finished time.Time `json:"finished"`

 	// Id is a generated unique identifier for this Task instance. Must be
 	// URL-safe.
 	Id string `json:"id"`

 	// IsolatedOutput is the isolated hash of any outputs produced by this Task.
 	// Filled in when the task is completed. This field will not be set if the
 	// Task does not correspond to a Swarming task.
 	IsolatedOutput string `json:"isolatedOutput"`

 	// Jobs are the IDs of all Jobs which utilized this Task.
 	Jobs []string `json:"jobs"`

 	// MaxAttempts is the maximum number of attempts for this TaskSpec.
 	MaxAttempts int `json:"max_attempts"`

 	// ParentTaskIds are IDs of tasks which satisfied this task's dependencies.
 	ParentTaskIds []string `json:"parentTaskIds"`

 	// Properties contains key-value pairs from external sources. Both key and
 	// value must be UTF-8 strings. Prefer a JavaScript identifier for key. Use
 	// base64 encoding for binary data.
 	Properties map[string]string `json:"properties"`

 	// RetryOf is the ID of the task which this task is a retry of, if any.
 	RetryOf string `json:"retryOf"`

 	// Started is the time the task started running, or zero if the task is
 	// pending, or the same as Finished if the task never ran.
 	Started time.Time `json:"started"`

 	// Status is the current task status, default TASK_STATUS_PENDING.
 	Status TaskStatus `json:"status"`

 	// SwarmingBotId is the ID of the Swarming bot that ran this task. This
 	// field will not be set if the Task does not correspond to a Swarming task or
 	// if the task is still pending.
 	SwarmingBotId string `json:"swarmingBotId"`

 	// SwarmingTaskId is the Swarming task ID. This field will not be set if the
 	// Task does not correspond to a Swarming task.
 	SwarmingTaskId string `json:"swarmingTaskId"`

 	// TaskExecutor is the task executor used to run this Task.
 	TaskExecutor string `json:"taskExecutor"`

 	// TaskKey is a struct which describes aspects of the Task related
 	// to the current state of the repo when it ran, and about the Task
 	// itself.
 	TaskKey
 }

 // UpdateFromTaskResult sets or initializes t from data in s. If any changes
 // were made to t, returns true.
 //
 // Returns ErrUnknownId if the SwarmingTaskId does not match.
 //
 // If empty, sets t.Id, t.Name, t.Repo, and t.Revision from s's tags named
 // SWARMING_TAG_ID, SWARMING_TAG_NAME, SWARMING_TAG_REPO, and
 // SWARMING_TAG_REVISION, and sets t.Created from s.CreatedTs. If these fields
 // are non-empty, returns an error if they do not match.
 //
 // Always sets t.Status, t.Started, t.Finished, and t.IsolatedOutput based on s.
 func (orig *Task) UpdateFromTaskResult(res *TaskResult) (bool, error) {
 	if res == nil {
 		return false, fmt.Errorf("Missing TaskResult. %v", res)
 	}

 	// Swarming TaskId.
 	if orig.SwarmingTaskId != res.ID {
 		return false, ErrUnknownId
 	}

 	copy := orig.Copy()
 	if !reflect.DeepEqual(orig, copy) {
 		sklog.Fatalf("Task.Copy is broken; original and copy differ:\n%#v\n%#v", orig, copy)
 	}

 	// "Identity" fields stored in tags.
 	checkOrSetFromTag := func(tagName string, field *string, fieldName string) error {
 		if tagValue, ok := res.Tags[tagName]; ok {
 			if len(tagValue) != 1 {
 				return fmt.Errorf("Expected a single value for tag key %q", tagName)
 			}
 			if *field == "" {
 				*field = tagValue[0]
 			} else if *field != tagValue[0] {
 				return fmt.Errorf("%s does not match for task %s. Was %s, now %s. %v %v", fieldName, orig.Id, *field, tagValue, orig, res)
 			}
 		}
 		return nil
 	}
 	if err := checkOrSetFromTag(SWARMING_TAG_FORCED_JOB_ID, &copy.ForcedJobId, "ForcedJobId"); err != nil {
 		return false, err
 	}
 	if err := checkOrSetFromTag(SWARMING_TAG_ID, &copy.Id, "Id"); err != nil {
 		return false, err
 	}
 	if err := checkOrSetFromTag(SWARMING_TAG_NAME, &copy.Name, "Name"); err != nil {
 		return false, err
 	}
 	if err := checkOrSetFromTag(SWARMING_TAG_REPO, &copy.Repo, "Repo"); err != nil {
 		return false, err
 	}
 	if err := checkOrSetFromTag(SWARMING_TAG_RETRY_OF, &copy.RetryOf, "RetryOf"); err != nil {
 		return false, err
 	}
 	if err := checkOrSetFromTag(SWARMING_TAG_REVISION, &copy.Revision, "Revision"); err != nil {
 		return false, err
 	}
 	attempt := fmt.Sprintf("%d", copy.Attempt)
 	if err := checkOrSetFromTag(SWARMING_TAG_ATTEMPT, &attempt, "Attempt"); err != nil {
 		return false, err
 	}
 	attemptInt, err := strconv.ParseInt(attempt, 10, 32)
 	if err != nil {
 		return false, fmt.Errorf("Failed to ParseInt: %s", err)
 	}
 	copy.Attempt = int(attemptInt)
 	if orig.Attempt != 0 && copy.Attempt != orig.Attempt {
 		return false, fmt.Errorf("Attempt does not match for task %s. Was %d now %d. %v %v", orig.Id, orig.Attempt, copy.Attempt, orig, res)
 	}

 	// Optional try job tags.
 	if err := checkOrSetFromTag(SWARMING_TAG_ISSUE, &copy.Issue, "Issue"); err != nil {
 		return false, err
 	}
 	if err := checkOrSetFromTag(SWARMING_TAG_PATCHSET, &copy.Patchset, "Patchset"); err != nil {
 		return false, err
 	}
 	if err := checkOrSetFromTag(SWARMING_TAG_SERVER, &copy.Server, "Server"); err != nil {
 		return false, err
 	}

 	// Set ParentTaskIds.
 	parentTaskIds := res.Tags[SWARMING_TAG_PARENT_TASK_ID]
 	sort.Strings(parentTaskIds)
 	copy.ParentTaskIds = parentTaskIds

 	// CreatedTs should always be present.
 	if util.TimeIsZero(copy.Created) {
 		copy.Created = res.Created
 	} else if !copy.Created.Equal(res.Created) {
 		return false, fmt.Errorf("Creation time has changed for task %s. Was %s, now %s. %v", orig.Id, orig.Created, res.Created, orig)
 	}

 	// Status.
 	copy.Status = res.Status

 	// Isolated output.
 	copy.IsolatedOutput = res.CasOutput

 	// Bot.
 	copy.SwarmingBotId = res.MachineID

 	// Timestamps.
 	maybeUpdateTime := func(newTime time.Time, field *time.Time, name string) {
 		if !util.TimeIsZero(newTime) {
 			*field = newTime
 		}
 	}

 	maybeUpdateTime(res.Started, &copy.Started, "Started")
 	maybeUpdateTime(res.Finished, &copy.Finished, "Finished")
 	if copy.Done() && util.TimeIsZero(copy.Started) {
 		copy.Started = copy.Finished
 	}

 	// TODO(benjaminwagner): SwarmingRpcsTaskResult has a ModifiedTs field that we
 	// could use to detect modifications. Unfortunately, it seems that while the
 	// task is running, ModifiedTs gets updated every 30 seconds, regardless of
 	// whether any other data actually changed. Maybe we could still use it for
 	// pending or completed tasks.
 	if !reflect.DeepEqual(orig, copy) {
 		*orig = *copy
 		return true, nil
 	}
 	return false, nil
 }

 func (t *Task) Done() bool {
 	return t.Status != TASK_STATUS_PENDING && t.Status != TASK_STATUS_RUNNING
 }

 // Fake returns whether this Task does not correspond to a Swarming task.
 func (t *Task) Fake() bool {
 	return t.SwarmingTaskId == ""
 }

 func (t *Task) Success() bool {
 	return t.Status == TASK_STATUS_SUCCESS
 }

 func (t *Task) Copy() *Task {
 	return &Task{
 		Attempt:        t.Attempt,
 		Commits:        util.CopyStringSlice(t.Commits),
 		Created:        t.Created,
 		DbModified:     t.DbModified,
 		Finished:       t.Finished,
 		Id:             t.Id,
 		IsolatedOutput: t.IsolatedOutput,
 		Jobs:           util.CopyStringSlice(t.Jobs),
 		MaxAttempts:    t.MaxAttempts,
 		ParentTaskIds:  util.CopyStringSlice(t.ParentTaskIds),
 		Properties:     util.CopyStringMap(t.Properties),
 		RetryOf:        t.RetryOf,
 		Started:        t.Started,
 		Status:         t.Status,
 		SwarmingBotId:  t.SwarmingBotId,
 		SwarmingTaskId: t.SwarmingTaskId,
 		TaskExecutor:   t.TaskExecutor,
 		TaskKey:        t.TaskKey.Copy(),
 	}
 }

 // Validate returns an error if the task is not valid.
 func (task *Task) Validate() error {
 	if !task.TaskKey.Valid() {
 		return fmt.Errorf("TaskKey is not valid.")
 	}
 	if task.Fake() && !(task.IsolatedOutput == "" && task.SwarmingBotId == "" && task.SwarmingTaskId == "") {
 		return fmt.Errorf("Can not specify Swarming info for a fake task.")
 	}
 	for key, value := range task.Properties {
 		if !utf8.ValidString(key) {
 			return fmt.Errorf("Invalid property key -- must be valid UTF8: %q", key)
 		}
 		if !utf8.ValidString(value) {
 			return fmt.Errorf("Invalid property value -- must be valid UTF8 or base64-encoded: %q", value)
 		}
 	}
 	// There may be old tasks where MaxAttempts is not initialized.
 	if task.MaxAttempts == 0 {
 		if task.Attempt != 0 {
 			return fmt.Errorf("Task MaxAttempts is not initialized but Attempt is initialized to %d. %+v", task.Attempt, task)
 		}
 	} else if task.Attempt >= task.MaxAttempts {
 		return fmt.Errorf("Task Attempt %d not less than MaxAttempts %d. %+v", task.Attempt, task.MaxAttempts, task)
 	}
 	if task.Attempt < 0 {
 		return fmt.Errorf("Task Attempt is negative!! %+v", task)
 	}
 	return nil
 }

 // Valid returns true if Validate() does not return an error. Hides
 // task.TaskKey.Valid to prevent confusion.
 func (task *Task) Valid() bool {
 	return task.Validate() == nil
 }

 // TaskSummary is a subset of the information found in a Task.
 type TaskSummary struct {
 	Attempt        int        `json:"attempt"`
 	Id             string     `json:"id"`
 	MaxAttempts    int        `json:"max_attempts"`
 	Status         TaskStatus `json:"status"`
 	SwarmingTaskId string     `json:"swarmingTaskId"`
 }

 // MakeTaskSummary creates a TaskSummary from the Task instance.
 func (t *Task) MakeTaskSummary() *TaskSummary {
 	return &TaskSummary{
 		Attempt:        t.Attempt,
 		Id:             t.Id,
 		MaxAttempts:    t.MaxAttempts,
 		Status:         t.Status,
 		SwarmingTaskId: t.SwarmingTaskId,
 	}
 }

 // Copy returns a copy of the TaskSummary.
 func (t *TaskSummary) Copy() *TaskSummary {
 	return &TaskSummary{
 		Attempt:        t.Attempt,
 		Id:             t.Id,
 		MaxAttempts:    t.MaxAttempts,
 		Status:         t.Status,
 		SwarmingTaskId: t.SwarmingTaskId,
 	}
 }

 // TaskSlice implements sort.Interface. To sort tasks []*Task, use
 // sort.Sort(TaskSlice(tasks)).
 type TaskSlice []*Task

 func (s TaskSlice) Len() int { return len(s) }

 func (s TaskSlice) Less(i, j int) bool {
 	return s[i].Created.Before(s[j].Created)
 }

 func (s TaskSlice) Swap(i, j int) {
 	s[i], s[j] = s[j], s[i]
 }

 // TagsForTask returns the tags which should be set for a Task.
 func TagsForTask(name, id string, attempt int, rs RepoState, retryOf string, dimensions map[string]string, forcedJobId string, parentTaskIds []string, extraTags map[string]string) []string {
 	tags := util.CopyStringMap(extraTags)
 	if tags == nil {
 		tags = make(map[string]string, 16)
 	}
 	tags[SWARMING_TAG_ATTEMPT] = fmt.Sprintf("%d", attempt)
 	tags[SWARMING_TAG_FORCED_JOB_ID] = forcedJobId
 	tags[SWARMING_TAG_NAME] = name
 	tags[SWARMING_TAG_ID] = id
 	tags[SWARMING_TAG_LUCI_PROJECT] = common.REPO_PROJECT_MAPPING[rs.Repo]
 	tags[SWARMING_TAG_MILO_HOST] = MILO_HOST
 	tags[SWARMING_TAG_REPO] = rs.Repo
 	tags[SWARMING_TAG_RETRY_OF] = retryOf
 	tags[SWARMING_TAG_REVISION] = rs.Revision
 	tags[SWARMING_TAG_SOURCE_REVISION] = rs.Revision
 	tags[SWARMING_TAG_SOURCE_REPO] = fmt.Sprintf(gitiles.CommitURL, rs.Repo, "%s")
 	if rs.IsTryJob() {
 		tags[SWARMING_TAG_SERVER] = rs.Server
 		tags[SWARMING_TAG_ISSUE] = rs.Issue
 		tags[SWARMING_TAG_PATCHSET] = rs.Patchset
 	}

 	for k, v := range dimensions {
 		key := fmt.Sprintf("%s%s", SWARMING_TAG_DIMENSION_PREFIX, k)
 		if _, ok := tags[key]; !ok {
 			tags[key] = v
 		} else {
 			sklog.Warningf("Duplicate dimension/tag %q.", k)
 		}
 	}

 	tagsList := make([]string, 0, len(tags)+len(parentTaskIds))
 	for k, v := range tags {
 		tagsList = append(tagsList, fmt.Sprintf("%s:%s", k, v))
 	}
 	for _, id := range parentTaskIds {
 		tagsList = append(tagsList, fmt.Sprintf("%s:%s", SWARMING_TAG_PARENT_TASK_ID, id))
 	}
 	return tagsList
 }

 // DimensionsFromTags returns a set of dimensions based on the given tags.
 func DimensionsFromTags(tags map[string][]string) []string {
 	rv := make([]string, 0, len(tags))
 	for key, values := range tags {
 		if strings.HasPrefix(key, SWARMING_TAG_DIMENSION_PREFIX) {
 			dimKey := key[len(SWARMING_TAG_DIMENSION_PREFIX):]
 			for _, dimVal := range values {
 				rv = append(rv, fmt.Sprintf("%s:%s", dimKey, dimVal))
 			}
 		}
 	}
 	return rv
 }
	package types

	import (
	"fmt"
	"reflect"
	"sort"
	"strconv"
	"strings"
	"time"
	"unicode/utf8"

	"go.skia.org/infra/go/common"
	"go.skia.org/infra/go/gitiles"
	"go.skia.org/infra/go/sklog"
	"go.skia.org/infra/go/util"
	)

	const (
	// Swarming tags added by Task Scheduler.
	SWARMING_TAG_ATTEMPT = "sk_attempt"
	SWARMING_TAG_DIMENSION_PREFIX = "sk_dim_"
	SWARMING_TAG_FORCED_JOB_ID = "sk_forced_job_id"
	SWARMING_TAG_ID = "sk_id"
	SWARMING_TAG_ISSUE = "sk_issue"
	SWARMING_TAG_LUCI_PROJECT = "luci_project"
	SWARMING_TAG_MILO_HOST = "milo_host"
	SWARMING_TAG_NAME = "sk_name"
	SWARMING_TAG_PARENT_TASK_ID = "sk_parent_task_id"
	SWARMING_TAG_PATCHSET = "sk_patchset"
	SWARMING_TAG_REPO = "sk_repo"
	SWARMING_TAG_RETRY_OF = "sk_retry_of"
	SWARMING_TAG_REVISION = "sk_revision"
	SWARMING_TAG_SERVER = "sk_issue_server"

	// These two tags allow the swarming ui to point to the GoB repo
	SWARMING_TAG_SOURCE_REVISION = "source_revision"
	SWARMING_TAG_SOURCE_REPO = "source_repo"

	MILO_HOST = "https://ci.chromium.org/raw/build/%s"

	// Types of task executors.
	TaskExecutor_UseDefault = ""
	TaskExecutor_Swarming = "swarming"
	DefaultTaskExecutor = TaskExecutor_Swarming
	)

	var (
	ValidTaskExecutors = []string{TaskExecutor_UseDefault, TaskExecutor_Swarming}
	)

	type TaskStatus string

	const (
	// TASK_STATUS_PENDING indicates the task has not started. It is the empty
	// string so that it is the zero value of TaskStatus.
	TASK_STATUS_PENDING TaskStatus = ""
	// TASK_STATUS_RUNNING indicates the task is in progress.
	TASK_STATUS_RUNNING TaskStatus = "RUNNING"
	// TASK_STATUS_SUCCESS indicates the task completed successfully.
	TASK_STATUS_SUCCESS TaskStatus = "SUCCESS"
	// TASK_STATUS_FAILURE indicates the task completed with failures.
	TASK_STATUS_FAILURE TaskStatus = "FAILURE"
	// TASK_STATUS_MISHAP indicates the task exited early with an error, died
	// while in progress, was manually canceled, expired while waiting on the
	// queue, or timed out before completing.
	TASK_STATUS_MISHAP TaskStatus = "MISHAP"
	)

	// TaskKey is a struct used for identifying a Task instance. Note that more
	// than one Task may have the same TaskKey, eg. in the case of retries.
	type TaskKey struct {
	RepoState
	Name string `json:"name"`
	ForcedJobId string `json:"forcedJobId"`
	}

	// Copy returns a copy of the TaskKey.
	func (k TaskKey) Copy() TaskKey {
	return TaskKey{
	RepoState: k.RepoState.Copy(),
	Name: k.Name,
	ForcedJobId: k.ForcedJobId,
	}
	}

	// Valid indicates whether or not the TaskKey is valid.
	func (k TaskKey) Valid() bool {
	return k.RepoState.Valid() && k.Name != ""
	}

	// IsForceRun indicates whether this Task is for a forced Job, which
	// indicates that it shouldn't be de-duplicated.
	func (k TaskKey) IsForceRun() bool {
	return k.ForcedJobId != ""
	}

	// Task describes a Swarming task generated from a TaskSpec, or a "fake" task
	// that can not be executed on Swarming, but can be added to the DB and
	// displayed as if it were a real TaskSpec.
	//
	// Task is stored as a GOB, so changes must maintain backwards compatibility.
	// See gob package documentation for details, but generally:
	// - Ensure new fields can be initialized with their zero value.
	// - Do not change the type of any existing field.
	// - Leave removed fields commented out to ensure the field name is not
	// reused.
	// - Add any new fields to the Copy() method.
	type Task struct {
	// Attempt is the attempt number of this task, starting with zero.
	Attempt int `json:"attempt"`

	// Commits are the commits which were tested in this Task. The list may
	// change due to backfilling/bisecting.
	Commits []string `json:"commits"`

	// Created is the creation timestamp.
	Created time.Time `json:"created"`

	// DbModified is the time of the last successful call to TaskDB.PutTask/s for this
	// Task, or zero if the task is new. It is not related to the ModifiedTs time
	// of the associated Swarming task.
	DbModified time.Time `json:"dbModified"`

	// Finished is the time the task stopped running or expired from the queue, or
	// zero if the task is pending or running.
	Finished time.Time `json:"finished"`

	// Id is a generated unique identifier for this Task instance. Must be
	// URL-safe.
	Id string `json:"id"`

	// IsolatedOutput is the isolated hash of any outputs produced by this Task.
	// Filled in when the task is completed. This field will not be set if the
	// Task does not correspond to a Swarming task.
	IsolatedOutput string `json:"isolatedOutput"`

	// Jobs are the IDs of all Jobs which utilized this Task.
	Jobs []string `json:"jobs"`

	// MaxAttempts is the maximum number of attempts for this TaskSpec.
	MaxAttempts int `json:"max_attempts"`

	// ParentTaskIds are IDs of tasks which satisfied this task's dependencies.
	ParentTaskIds []string `json:"parentTaskIds"`

	// Properties contains key-value pairs from external sources. Both key and
	// value must be UTF-8 strings. Prefer a JavaScript identifier for key. Use
	// base64 encoding for binary data.
	Properties map[string]string `json:"properties"`

	// RetryOf is the ID of the task which this task is a retry of, if any.
	RetryOf string `json:"retryOf"`

	// Started is the time the task started running, or zero if the task is
	// pending, or the same as Finished if the task never ran.
	Started time.Time `json:"started"`

	// Status is the current task status, default TASK_STATUS_PENDING.
	Status TaskStatus `json:"status"`

	// SwarmingBotId is the ID of the Swarming bot that ran this task. This
	// field will not be set if the Task does not correspond to a Swarming task or
	// if the task is still pending.
	SwarmingBotId string `json:"swarmingBotId"`

	// SwarmingTaskId is the Swarming task ID. This field will not be set if the
	// Task does not correspond to a Swarming task.
	SwarmingTaskId string `json:"swarmingTaskId"`

	// TaskExecutor is the task executor used to run this Task.
	TaskExecutor string `json:"taskExecutor"`

	// TaskKey is a struct which describes aspects of the Task related
	// to the current state of the repo when it ran, and about the Task
	// itself.
	TaskKey
	}

	// UpdateFromTaskResult sets or initializes t from data in s. If any changes
	// were made to t, returns true.
	//
	// Returns ErrUnknownId if the SwarmingTaskId does not match.
	//
	// If empty, sets t.Id, t.Name, t.Repo, and t.Revision from s's tags named
	// SWARMING_TAG_ID, SWARMING_TAG_NAME, SWARMING_TAG_REPO, and
	// SWARMING_TAG_REVISION, and sets t.Created from s.CreatedTs. If these fields
	// are non-empty, returns an error if they do not match.
	//
	// Always sets t.Status, t.Started, t.Finished, and t.IsolatedOutput based on s.
	func (orig Task) UpdateFromTaskResult(res TaskResult) (bool, error) {
	if res == nil {
	return false, fmt.Errorf("Missing TaskResult. %v", res)
	}

	// Swarming TaskId.
	if orig.SwarmingTaskId != res.ID {
	return false, ErrUnknownId
	}

	copy := orig.Copy()
	if !reflect.DeepEqual(orig, copy) {
	sklog.Fatalf("Task.Copy is broken; original and copy differ:\n%#v\n%#v", orig, copy)
	}

	// "Identity" fields stored in tags.
	checkOrSetFromTag := func(tagName string, field *string, fieldName string) error {
	if tagValue, ok := res.Tags[tagName]; ok {
	if len(tagValue) != 1 {
	return fmt.Errorf("Expected a single value for tag key %q", tagName)
	}
	if *field == "" {
	*field = tagValue[0]
	} else if *field != tagValue[0] {
	return fmt.Errorf("%s does not match for task %s. Was %s, now %s. %v %v", fieldName, orig.Id, *field, tagValue, orig, res)
	}
	}
	return nil
	}
	if err := checkOrSetFromTag(SWARMING_TAG_FORCED_JOB_ID, &copy.ForcedJobId, "ForcedJobId"); err != nil {
	return false, err
	}
	if err := checkOrSetFromTag(SWARMING_TAG_ID, &copy.Id, "Id"); err != nil {
	return false, err
	}
	if err := checkOrSetFromTag(SWARMING_TAG_NAME, &copy.Name, "Name"); err != nil {
	return false, err
	}
	if err := checkOrSetFromTag(SWARMING_TAG_REPO, &copy.Repo, "Repo"); err != nil {
	return false, err
	}
	if err := checkOrSetFromTag(SWARMING_TAG_RETRY_OF, &copy.RetryOf, "RetryOf"); err != nil {
	return false, err
	}
	if err := checkOrSetFromTag(SWARMING_TAG_REVISION, &copy.Revision, "Revision"); err != nil {
	return false, err
	}
	attempt := fmt.Sprintf("%d", copy.Attempt)
	if err := checkOrSetFromTag(SWARMING_TAG_ATTEMPT, &attempt, "Attempt"); err != nil {
	return false, err
	}
	attemptInt, err := strconv.ParseInt(attempt, 10, 32)
	if err != nil {
	return false, fmt.Errorf("Failed to ParseInt: %s", err)
	}
	copy.Attempt = int(attemptInt)
	if orig.Attempt != 0 && copy.Attempt != orig.Attempt {
	return false, fmt.Errorf("Attempt does not match for task %s. Was %d now %d. %v %v", orig.Id, orig.Attempt, copy.Attempt, orig, res)
	}

	// Optional try job tags.
	if err := checkOrSetFromTag(SWARMING_TAG_ISSUE, &copy.Issue, "Issue"); err != nil {
	return false, err
	}
	if err := checkOrSetFromTag(SWARMING_TAG_PATCHSET, &copy.Patchset, "Patchset"); err != nil {
	return false, err
	}
	if err := checkOrSetFromTag(SWARMING_TAG_SERVER, &copy.Server, "Server"); err != nil {
	return false, err
	}

	// Set ParentTaskIds.
	parentTaskIds := res.Tags[SWARMING_TAG_PARENT_TASK_ID]
	sort.Strings(parentTaskIds)
	copy.ParentTaskIds = parentTaskIds

	// CreatedTs should always be present.
	if util.TimeIsZero(copy.Created) {
	copy.Created = res.Created
	} else if !copy.Created.Equal(res.Created) {
	return false, fmt.Errorf("Creation time has changed for task %s. Was %s, now %s. %v", orig.Id, orig.Created, res.Created, orig)
	}

	// Status.
	copy.Status = res.Status

	// Isolated output.
	copy.IsolatedOutput = res.CasOutput

	// Bot.
	copy.SwarmingBotId = res.MachineID

	// Timestamps.
	maybeUpdateTime := func(newTime time.Time, field *time.Time, name string) {
	if !util.TimeIsZero(newTime) {
	*field = newTime
	}
	}

	maybeUpdateTime(res.Started, &copy.Started, "Started")
	maybeUpdateTime(res.Finished, &copy.Finished, "Finished")
	if copy.Done() && util.TimeIsZero(copy.Started) {
	copy.Started = copy.Finished
	}

	// TODO(benjaminwagner): SwarmingRpcsTaskResult has a ModifiedTs field that we
	// could use to detect modifications. Unfortunately, it seems that while the
	// task is running, ModifiedTs gets updated every 30 seconds, regardless of
	// whether any other data actually changed. Maybe we could still use it for
	// pending or completed tasks.
	if !reflect.DeepEqual(orig, copy) {
	orig = copy
	return true, nil
	}
	return false, nil
	}

	func (t *Task) Done() bool {
	return t.Status != TASK_STATUS_PENDING && t.Status != TASK_STATUS_RUNNING
	}

	// Fake returns whether this Task does not correspond to a Swarming task.
	func (t *Task) Fake() bool {
	return t.SwarmingTaskId == ""
	}

	func (t *Task) Success() bool {
	return t.Status == TASK_STATUS_SUCCESS
	}

	func (t Task) Copy() Task {
	return &Task{
	Attempt: t.Attempt,
	Commits: util.CopyStringSlice(t.Commits),
	Created: t.Created,
	DbModified: t.DbModified,
	Finished: t.Finished,
	Id: t.Id,
	IsolatedOutput: t.IsolatedOutput,
	Jobs: util.CopyStringSlice(t.Jobs),
	MaxAttempts: t.MaxAttempts,
	ParentTaskIds: util.CopyStringSlice(t.ParentTaskIds),
	Properties: util.CopyStringMap(t.Properties),
	RetryOf: t.RetryOf,
	Started: t.Started,
	Status: t.Status,
	SwarmingBotId: t.SwarmingBotId,
	SwarmingTaskId: t.SwarmingTaskId,
	TaskExecutor: t.TaskExecutor,
	TaskKey: t.TaskKey.Copy(),
	}
	}

	// Validate returns an error if the task is not valid.
	func (task *Task) Validate() error {
	if !task.TaskKey.Valid() {
	return fmt.Errorf("TaskKey is not valid.")
	}
	if task.Fake() && !(task.IsolatedOutput == "" && task.SwarmingBotId == "" && task.SwarmingTaskId == "") {
	return fmt.Errorf("Can not specify Swarming info for a fake task.")
	}
	for key, value := range task.Properties {
	if !utf8.ValidString(key) {
	return fmt.Errorf("Invalid property key -- must be valid UTF8: %q", key)
	}
	if !utf8.ValidString(value) {
	return fmt.Errorf("Invalid property value -- must be valid UTF8 or base64-encoded: %q", value)
	}
	}
	// There may be old tasks where MaxAttempts is not initialized.
	if task.MaxAttempts == 0 {
	if task.Attempt != 0 {
	return fmt.Errorf("Task MaxAttempts is not initialized but Attempt is initialized to %d. %+v", task.Attempt, task)
	}
	} else if task.Attempt >= task.MaxAttempts {
	return fmt.Errorf("Task Attempt %d not less than MaxAttempts %d. %+v", task.Attempt, task.MaxAttempts, task)
	}
	if task.Attempt < 0 {
	return fmt.Errorf("Task Attempt is negative!! %+v", task)
	}
	return nil
	}

	// Valid returns true if Validate() does not return an error. Hides
	// task.TaskKey.Valid to prevent confusion.
	func (task *Task) Valid() bool {
	return task.Validate() == nil
	}

	// TaskSummary is a subset of the information found in a Task.
	type TaskSummary struct {
	Attempt int `json:"attempt"`
	Id string `json:"id"`
	MaxAttempts int `json:"max_attempts"`
	Status TaskStatus `json:"status"`
	SwarmingTaskId string `json:"swarmingTaskId"`
	}

	// MakeTaskSummary creates a TaskSummary from the Task instance.
	func (t Task) MakeTaskSummary() TaskSummary {
	return &TaskSummary{
	Attempt: t.Attempt,
	Id: t.Id,
	MaxAttempts: t.MaxAttempts,
	Status: t.Status,
	SwarmingTaskId: t.SwarmingTaskId,
	}
	}

	// Copy returns a copy of the TaskSummary.
	func (t TaskSummary) Copy() TaskSummary {
	return &TaskSummary{
	Attempt: t.Attempt,
	Id: t.Id,
	MaxAttempts: t.MaxAttempts,
	Status: t.Status,
	SwarmingTaskId: t.SwarmingTaskId,
	}
	}

	// TaskSlice implements sort.Interface. To sort tasks []*Task, use
	// sort.Sort(TaskSlice(tasks)).
	type TaskSlice []*Task

	func (s TaskSlice) Len() int { return len(s) }

	func (s TaskSlice) Less(i, j int) bool {
	return s[i].Created.Before(s[j].Created)
	}

	func (s TaskSlice) Swap(i, j int) {
	s[i], s[j] = s[j], s[i]
	}

	// TagsForTask returns the tags which should be set for a Task.
	func TagsForTask(name, id string, attempt int, rs RepoState, retryOf string, dimensions map[string]string, forcedJobId string, parentTaskIds []string, extraTags map[string]string) []string {
	tags := util.CopyStringMap(extraTags)
	if tags == nil {
	tags = make(map[string]string, 16)
	}
	tags[SWARMING_TAG_ATTEMPT] = fmt.Sprintf("%d", attempt)
	tags[SWARMING_TAG_FORCED_JOB_ID] = forcedJobId
	tags[SWARMING_TAG_NAME] = name
	tags[SWARMING_TAG_ID] = id
	tags[SWARMING_TAG_LUCI_PROJECT] = common.REPO_PROJECT_MAPPING[rs.Repo]
	tags[SWARMING_TAG_MILO_HOST] = MILO_HOST
	tags[SWARMING_TAG_REPO] = rs.Repo
	tags[SWARMING_TAG_RETRY_OF] = retryOf
	tags[SWARMING_TAG_REVISION] = rs.Revision
	tags[SWARMING_TAG_SOURCE_REVISION] = rs.Revision
	tags[SWARMING_TAG_SOURCE_REPO] = fmt.Sprintf(gitiles.CommitURL, rs.Repo, "%s")
	if rs.IsTryJob() {
	tags[SWARMING_TAG_SERVER] = rs.Server
	tags[SWARMING_TAG_ISSUE] = rs.Issue
	tags[SWARMING_TAG_PATCHSET] = rs.Patchset
	}

	for k, v := range dimensions {
	key := fmt.Sprintf("%s%s", SWARMING_TAG_DIMENSION_PREFIX, k)
	if _, ok := tags[key]; !ok {
	tags[key] = v
	} else {
	sklog.Warningf("Duplicate dimension/tag %q.", k)
	}
	}

	tagsList := make([]string, 0, len(tags)+len(parentTaskIds))
	for k, v := range tags {
	tagsList = append(tagsList, fmt.Sprintf("%s:%s", k, v))
	}
	for _, id := range parentTaskIds {
	tagsList = append(tagsList, fmt.Sprintf("%s:%s", SWARMING_TAG_PARENT_TASK_ID, id))
	}
	return tagsList
	}

	// DimensionsFromTags returns a set of dimensions based on the given tags.
	func DimensionsFromTags(tags map[string][]string) []string {
	rv := make([]string, 0, len(tags))
	for key, values := range tags {
	if strings.HasPrefix(key, SWARMING_TAG_DIMENSION_PREFIX) {
	dimKey := key[len(SWARMING_TAG_DIMENSION_PREFIX):]
	for _, dimVal := range values {
	rv = append(rv, fmt.Sprintf("%s:%s", dimKey, dimVal))
	}
	}
	}
	return rv
	}