Skip to content
Permalink
Branch: master
Find file Copy path
Find file Copy path
4 contributors

Users who have contributed to this file

@dsymonds @okdave @davidsansome @jtzwu
542 lines (485 sloc) 16.8 KB
// Copyright 2011 Google Inc. All rights reserved.
// Use of this source code is governed by the Apache 2.0
// license that can be found in the LICENSE file.
/*
Package taskqueue provides a client for App Engine's taskqueue service.
Using this service, applications may perform work outside a user's request.
A Task may be constructed manually; alternatively, since the most common
taskqueue operation is to add a single POST task, NewPOSTTask makes it easy.
t := taskqueue.NewPOSTTask("/worker", url.Values{
"key": {key},
})
taskqueue.Add(c, t, "") // add t to the default queue
*/
package taskqueue // import "google.golang.org/appengine/taskqueue"
import (
"errors"
"fmt"
"net/http"
"net/url"
"strconv"
"time"
"github.com/golang/protobuf/proto"
"golang.org/x/net/context"
"google.golang.org/appengine"
"google.golang.org/appengine/internal"
dspb "google.golang.org/appengine/internal/datastore"
pb "google.golang.org/appengine/internal/taskqueue"
)
var (
// ErrTaskAlreadyAdded is the error returned by Add and AddMulti when a task has already been added with a particular name.
ErrTaskAlreadyAdded = errors.New("taskqueue: task has already been added")
)
// RetryOptions let you control whether to retry a task and the backoff intervals between tries.
type RetryOptions struct {
// Number of tries/leases after which the task fails permanently and is deleted.
// If AgeLimit is also set, both limits must be exceeded for the task to fail permanently.
RetryLimit int32
// Maximum time allowed since the task's first try before the task fails permanently and is deleted (only for push tasks).
// If RetryLimit is also set, both limits must be exceeded for the task to fail permanently.
AgeLimit time.Duration
// Minimum time between successive tries (only for push tasks).
MinBackoff time.Duration
// Maximum time between successive tries (only for push tasks).
MaxBackoff time.Duration
// Maximum number of times to double the interval between successive tries before the intervals increase linearly (only for push tasks).
MaxDoublings int32
// If MaxDoublings is zero, set ApplyZeroMaxDoublings to true to override the default non-zero value.
// Otherwise a zero MaxDoublings is ignored and the default is used.
ApplyZeroMaxDoublings bool
}
// toRetryParameter converts RetryOptions to pb.TaskQueueRetryParameters.
func (opt *RetryOptions) toRetryParameters() *pb.TaskQueueRetryParameters {
params := &pb.TaskQueueRetryParameters{}
if opt.RetryLimit > 0 {
params.RetryLimit = proto.Int32(opt.RetryLimit)
}
if opt.AgeLimit > 0 {
params.AgeLimitSec = proto.Int64(int64(opt.AgeLimit.Seconds()))
}
if opt.MinBackoff > 0 {
params.MinBackoffSec = proto.Float64(opt.MinBackoff.Seconds())
}
if opt.MaxBackoff > 0 {
params.MaxBackoffSec = proto.Float64(opt.MaxBackoff.Seconds())
}
if opt.MaxDoublings > 0 || (opt.MaxDoublings == 0 && opt.ApplyZeroMaxDoublings) {
params.MaxDoublings = proto.Int32(opt.MaxDoublings)
}
return params
}
// A Task represents a task to be executed.
type Task struct {
// Path is the worker URL for the task.
// If unset, it will default to /_ah/queue/<queue_name>.
Path string
// Payload is the data for the task.
// This will be delivered as the HTTP request body.
// It is only used when Method is POST, PUT or PULL.
// url.Values' Encode method may be used to generate this for POST requests.
Payload []byte
// Additional HTTP headers to pass at the task's execution time.
// To schedule the task to be run with an alternate app version
// or backend, set the "Host" header.
Header http.Header
// Method is the HTTP method for the task ("GET", "POST", etc.),
// or "PULL" if this is task is destined for a pull-based queue.
// If empty, this defaults to "POST".
Method string
// A name for the task.
// If empty, a name will be chosen.
Name string
// Delay specifies the duration the task queue service must wait
// before executing the task.
// Either Delay or ETA may be set, but not both.
Delay time.Duration
// ETA specifies the earliest time a task may be executed (push queues)
// or leased (pull queues).
// Either Delay or ETA may be set, but not both.
ETA time.Time
// The number of times the task has been dispatched or leased.
RetryCount int32
// Tag for the task. Only used when Method is PULL.
Tag string
// Retry options for this task. May be nil.
RetryOptions *RetryOptions
}
func (t *Task) method() string {
if t.Method == "" {
return "POST"
}
return t.Method
}
// NewPOSTTask creates a Task that will POST to a path with the given form data.
func NewPOSTTask(path string, params url.Values) *Task {
h := make(http.Header)
h.Set("Content-Type", "application/x-www-form-urlencoded")
return &Task{
Path: path,
Payload: []byte(params.Encode()),
Header: h,
Method: "POST",
}
}
// RequestHeaders are the special HTTP request headers available to push task
// HTTP request handlers. These headers are set internally by App Engine.
// See https://cloud.google.com/appengine/docs/standard/go/taskqueue/push/creating-handlers#reading_request_headers
// for a description of the fields.
type RequestHeaders struct {
QueueName string
TaskName string
TaskRetryCount int64
TaskExecutionCount int64
TaskETA time.Time
TaskPreviousResponse int
TaskRetryReason string
FailFast bool
}
// ParseRequestHeaders parses the special HTTP request headers available to push
// task request handlers. This function silently ignores values of the wrong
// format.
func ParseRequestHeaders(h http.Header) *RequestHeaders {
ret := &RequestHeaders{
QueueName: h.Get("X-AppEngine-QueueName"),
TaskName: h.Get("X-AppEngine-TaskName"),
}
ret.TaskRetryCount, _ = strconv.ParseInt(h.Get("X-AppEngine-TaskRetryCount"), 10, 64)
ret.TaskExecutionCount, _ = strconv.ParseInt(h.Get("X-AppEngine-TaskExecutionCount"), 10, 64)
etaSecs, _ := strconv.ParseInt(h.Get("X-AppEngine-TaskETA"), 10, 64)
if etaSecs != 0 {
ret.TaskETA = time.Unix(etaSecs, 0)
}
ret.TaskPreviousResponse, _ = strconv.Atoi(h.Get("X-AppEngine-TaskPreviousResponse"))
ret.TaskRetryReason = h.Get("X-AppEngine-TaskRetryReason")
if h.Get("X-AppEngine-FailFast") != "" {
ret.FailFast = true
}
return ret
}
var (
currentNamespace = http.CanonicalHeaderKey("X-AppEngine-Current-Namespace")
defaultNamespace = http.CanonicalHeaderKey("X-AppEngine-Default-Namespace")
)
func getDefaultNamespace(ctx context.Context) string {
return internal.IncomingHeaders(ctx).Get(defaultNamespace)
}
func newAddReq(c context.Context, task *Task, queueName string) (*pb.TaskQueueAddRequest, error) {
if queueName == "" {
queueName = "default"
}
path := task.Path
if path == "" {
path = "/_ah/queue/" + queueName
}
eta := task.ETA
if eta.IsZero() {
eta = time.Now().Add(task.Delay)
} else if task.Delay != 0 {
panic("taskqueue: both Delay and ETA are set")
}
req := &pb.TaskQueueAddRequest{
QueueName: []byte(queueName),
TaskName: []byte(task.Name),
EtaUsec: proto.Int64(eta.UnixNano() / 1e3),
}
method := task.method()
if method == "PULL" {
// Pull-based task
req.Body = task.Payload
req.Mode = pb.TaskQueueMode_PULL.Enum()
if task.Tag != "" {
req.Tag = []byte(task.Tag)
}
} else {
// HTTP-based task
if v, ok := pb.TaskQueueAddRequest_RequestMethod_value[method]; ok {
req.Method = pb.TaskQueueAddRequest_RequestMethod(v).Enum()
} else {
return nil, fmt.Errorf("taskqueue: bad method %q", method)
}
req.Url = []byte(path)
for k, vs := range task.Header {
for _, v := range vs {
req.Header = append(req.Header, &pb.TaskQueueAddRequest_Header{
Key: []byte(k),
Value: []byte(v),
})
}
}
if method == "POST" || method == "PUT" {
req.Body = task.Payload
}
// Namespace headers.
if _, ok := task.Header[currentNamespace]; !ok {
// Fetch the current namespace of this request.
ns := internal.NamespaceFromContext(c)
req.Header = append(req.Header, &pb.TaskQueueAddRequest_Header{
Key: []byte(currentNamespace),
Value: []byte(ns),
})
}
if _, ok := task.Header[defaultNamespace]; !ok {
// Fetch the X-AppEngine-Default-Namespace header of this request.
if ns := getDefaultNamespace(c); ns != "" {
req.Header = append(req.Header, &pb.TaskQueueAddRequest_Header{
Key: []byte(defaultNamespace),
Value: []byte(ns),
})
}
}
}
if task.RetryOptions != nil {
req.RetryParameters = task.RetryOptions.toRetryParameters()
}
return req, nil
}
var alreadyAddedErrors = map[pb.TaskQueueServiceError_ErrorCode]bool{
pb.TaskQueueServiceError_TASK_ALREADY_EXISTS: true,
pb.TaskQueueServiceError_TOMBSTONED_TASK: true,
}
// Add adds the task to a named queue.
// An empty queue name means that the default queue will be used.
// Add returns an equivalent Task with defaults filled in, including setting
// the task's Name field to the chosen name if the original was empty.
func Add(c context.Context, task *Task, queueName string) (*Task, error) {
req, err := newAddReq(c, task, queueName)
if err != nil {
return nil, err
}
res := &pb.TaskQueueAddResponse{}
if err := internal.Call(c, "taskqueue", "Add", req, res); err != nil {
apiErr, ok := err.(*internal.APIError)
if ok && alreadyAddedErrors[pb.TaskQueueServiceError_ErrorCode(apiErr.Code)] {
return nil, ErrTaskAlreadyAdded
}
return nil, err
}
resultTask := *task
resultTask.Method = task.method()
if task.Name == "" {
resultTask.Name = string(res.ChosenTaskName)
}
return &resultTask, nil
}
// AddMulti adds multiple tasks to a named queue.
// An empty queue name means that the default queue will be used.
// AddMulti returns a slice of equivalent tasks with defaults filled in, including setting
// each task's Name field to the chosen name if the original was empty.
// If a given task is badly formed or could not be added, an appengine.MultiError is returned.
func AddMulti(c context.Context, tasks []*Task, queueName string) ([]*Task, error) {
req := &pb.TaskQueueBulkAddRequest{
AddRequest: make([]*pb.TaskQueueAddRequest, len(tasks)),
}
me, any := make(appengine.MultiError, len(tasks)), false
for i, t := range tasks {
req.AddRequest[i], me[i] = newAddReq(c, t, queueName)
any = any || me[i] != nil
}
if any {
return nil, me
}
res := &pb.TaskQueueBulkAddResponse{}
if err := internal.Call(c, "taskqueue", "BulkAdd", req, res); err != nil {
return nil, err
}
if len(res.Taskresult) != len(tasks) {
return nil, errors.New("taskqueue: server error")
}
tasksOut := make([]*Task, len(tasks))
for i, tr := range res.Taskresult {
tasksOut[i] = new(Task)
*tasksOut[i] = *tasks[i]
tasksOut[i].Method = tasksOut[i].method()
if tasksOut[i].Name == "" {
tasksOut[i].Name = string(tr.ChosenTaskName)
}
if *tr.Result != pb.TaskQueueServiceError_OK {
if alreadyAddedErrors[*tr.Result] {
me[i] = ErrTaskAlreadyAdded
} else {
me[i] = &internal.APIError{
Service: "taskqueue",
Code: int32(*tr.Result),
}
}
any = true
}
}
if any {
return tasksOut, me
}
return tasksOut, nil
}
// Delete deletes a task from a named queue.
func Delete(c context.Context, task *Task, queueName string) error {
err := DeleteMulti(c, []*Task{task}, queueName)
if me, ok := err.(appengine.MultiError); ok {
return me[0]
}
return err
}
// DeleteMulti deletes multiple tasks from a named queue.
// If a given task could not be deleted, an appengine.MultiError is returned.
// Each task is deleted independently; one may fail to delete while the others
// are sucessfully deleted.
func DeleteMulti(c context.Context, tasks []*Task, queueName string) error {
taskNames := make([][]byte, len(tasks))
for i, t := range tasks {
taskNames[i] = []byte(t.Name)
}
if queueName == "" {
queueName = "default"
}
req := &pb.TaskQueueDeleteRequest{
QueueName: []byte(queueName),
TaskName: taskNames,
}
res := &pb.TaskQueueDeleteResponse{}
if err := internal.Call(c, "taskqueue", "Delete", req, res); err != nil {
return err
}
if a, b := len(req.TaskName), len(res.Result); a != b {
return fmt.Errorf("taskqueue: internal error: requested deletion of %d tasks, got %d results", a, b)
}
me, any := make(appengine.MultiError, len(res.Result)), false
for i, ec := range res.Result {
if ec != pb.TaskQueueServiceError_OK {
me[i] = &internal.APIError{
Service: "taskqueue",
Code: int32(ec),
}
any = true
}
}
if any {
return me
}
return nil
}
func lease(c context.Context, maxTasks int, queueName string, leaseTime int, groupByTag bool, tag []byte) ([]*Task, error) {
if queueName == "" {
queueName = "default"
}
req := &pb.TaskQueueQueryAndOwnTasksRequest{
QueueName: []byte(queueName),
LeaseSeconds: proto.Float64(float64(leaseTime)),
MaxTasks: proto.Int64(int64(maxTasks)),
GroupByTag: proto.Bool(groupByTag),
Tag: tag,
}
res := &pb.TaskQueueQueryAndOwnTasksResponse{}
if err := internal.Call(c, "taskqueue", "QueryAndOwnTasks", req, res); err != nil {
return nil, err
}
tasks := make([]*Task, len(res.Task))
for i, t := range res.Task {
tasks[i] = &Task{
Payload: t.Body,
Name: string(t.TaskName),
Method: "PULL",
ETA: time.Unix(0, *t.EtaUsec*1e3),
RetryCount: *t.RetryCount,
Tag: string(t.Tag),
}
}
return tasks, nil
}
// Lease leases tasks from a queue.
// leaseTime is in seconds.
// The number of tasks fetched will be at most maxTasks.
func Lease(c context.Context, maxTasks int, queueName string, leaseTime int) ([]*Task, error) {
return lease(c, maxTasks, queueName, leaseTime, false, nil)
}
// LeaseByTag leases tasks from a queue, grouped by tag.
// If tag is empty, then the returned tasks are grouped by the tag of the task with earliest ETA.
// leaseTime is in seconds.
// The number of tasks fetched will be at most maxTasks.
func LeaseByTag(c context.Context, maxTasks int, queueName string, leaseTime int, tag string) ([]*Task, error) {
return lease(c, maxTasks, queueName, leaseTime, true, []byte(tag))
}
// Purge removes all tasks from a queue.
func Purge(c context.Context, queueName string) error {
if queueName == "" {
queueName = "default"
}
req := &pb.TaskQueuePurgeQueueRequest{
QueueName: []byte(queueName),
}
res := &pb.TaskQueuePurgeQueueResponse{}
return internal.Call(c, "taskqueue", "PurgeQueue", req, res)
}
// ModifyLease modifies the lease of a task.
// Used to request more processing time, or to abandon processing.
// leaseTime is in seconds and must not be negative.
func ModifyLease(c context.Context, task *Task, queueName string, leaseTime int) error {
if queueName == "" {
queueName = "default"
}
req := &pb.TaskQueueModifyTaskLeaseRequest{
QueueName: []byte(queueName),
TaskName: []byte(task.Name),
EtaUsec: proto.Int64(task.ETA.UnixNano() / 1e3), // Used to verify ownership.
LeaseSeconds: proto.Float64(float64(leaseTime)),
}
res := &pb.TaskQueueModifyTaskLeaseResponse{}
if err := internal.Call(c, "taskqueue", "ModifyTaskLease", req, res); err != nil {
return err
}
task.ETA = time.Unix(0, *res.UpdatedEtaUsec*1e3)
return nil
}
// QueueStatistics represents statistics about a single task queue.
type QueueStatistics struct {
Tasks int // may be an approximation
OldestETA time.Time // zero if there are no pending tasks
Executed1Minute int // tasks executed in the last minute
InFlight int // tasks executing now
EnforcedRate float64 // requests per second
}
// QueueStats retrieves statistics about queues.
func QueueStats(c context.Context, queueNames []string) ([]QueueStatistics, error) {
req := &pb.TaskQueueFetchQueueStatsRequest{
QueueName: make([][]byte, len(queueNames)),
}
for i, q := range queueNames {
if q == "" {
q = "default"
}
req.QueueName[i] = []byte(q)
}
res := &pb.TaskQueueFetchQueueStatsResponse{}
if err := internal.Call(c, "taskqueue", "FetchQueueStats", req, res); err != nil {
return nil, err
}
qs := make([]QueueStatistics, len(res.Queuestats))
for i, qsg := range res.Queuestats {
qs[i] = QueueStatistics{
Tasks: int(*qsg.NumTasks),
}
if eta := *qsg.OldestEtaUsec; eta > -1 {
qs[i].OldestETA = time.Unix(0, eta*1e3)
}
if si := qsg.ScannerInfo; si != nil {
qs[i].Executed1Minute = int(*si.ExecutedLastMinute)
qs[i].InFlight = int(si.GetRequestsInFlight())
qs[i].EnforcedRate = si.GetEnforcedRate()
}
}
return qs, nil
}
func setTransaction(x *pb.TaskQueueAddRequest, t *dspb.Transaction) {
x.Transaction = t
}
func init() {
internal.RegisterErrorCodeMap("taskqueue", pb.TaskQueueServiceError_ErrorCode_name)
// Datastore error codes are shifted by DATASTORE_ERROR when presented through taskqueue.
dsCode := int32(pb.TaskQueueServiceError_DATASTORE_ERROR) + int32(dspb.Error_TIMEOUT)
internal.RegisterTimeoutErrorCode("taskqueue", dsCode)
// Transaction registration.
internal.RegisterTransactionSetter(setTransaction)
internal.RegisterTransactionSetter(func(x *pb.TaskQueueBulkAddRequest, t *dspb.Transaction) {
for _, req := range x.AddRequest {
setTransaction(req, t)
}
})
}
You can’t perform that action at this time.