forked from TrueCloudLab/frostfs-api-go
[#372] object: Add object notification attributes
Also, add functions for parsing and setting object notifications. Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
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@ -1,5 +1,11 @@
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package object
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import (
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"errors"
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"fmt"
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"strconv"
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)
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// SysAttributePrefix is a prefix of key to system attribute.
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const SysAttributePrefix = "__NEOFS__"
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@ -9,4 +15,155 @@ const (
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// SysAttributeExpEpoch tells GC to delete object after that epoch.
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SysAttributeExpEpoch = SysAttributePrefix + "EXPIRATION_EPOCH"
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// SysAttributeTickEpoch defines what epoch must produce object
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// notification.
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SysAttributeTickEpoch = SysAttributePrefix + "TICK_EPOCH"
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// SysAttributeTickTopic defines what topic object notification
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// must be sent to.
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SysAttributeTickTopic = SysAttributePrefix + "TICK_TOPIC"
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)
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// NotificationInfo groups information about object notification
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// that can be written to object.
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//
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// Topic is an optional field.
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type NotificationInfo struct {
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epoch uint64
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topic string
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}
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// Epoch returns object notification tick
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// epoch.
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func (n NotificationInfo) Epoch() uint64 {
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return n.epoch
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}
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// SetEpoch sets object notification tick
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// epoch.
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func (n *NotificationInfo) SetEpoch(epoch uint64) {
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n.epoch = epoch
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}
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// Topic return optional object notification
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// topic.
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func (n NotificationInfo) Topic() string {
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return n.topic
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}
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// SetTopic sets optional object notification
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// topic.
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func (n *NotificationInfo) SetTopic(topic string) {
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n.topic = topic
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}
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// WriteNotificationInfo writes NotificationInfo to the Object via attributes. Object must not be nil.
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//
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// Existing notification attributes are expected to be key-unique, otherwise undefined behavior.
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func WriteNotificationInfo(o *Object, ni NotificationInfo) {
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h := o.GetHeader()
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if h == nil {
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h = new(Header)
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o.SetHeader(h)
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}
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var (
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attrs = h.GetAttributes()
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epoch = strconv.FormatUint(ni.Epoch(), 10)
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topic = ni.Topic()
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changedEpoch bool
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changedTopic bool
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deleteIndex = -1
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)
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for i := range attrs {
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switch attrs[i].GetKey() {
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case SysAttributeTickEpoch:
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attrs[i].SetValue(epoch)
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changedEpoch = true
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case SysAttributeTickTopic:
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changedTopic = true
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if topic == "" {
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deleteIndex = i
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break
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}
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attrs[i].SetValue(topic)
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}
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if changedEpoch && changedTopic {
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break
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}
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}
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if deleteIndex != -1 {
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// approach without allocation/waste
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// coping works since the attributes
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// order is not important
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attrs[deleteIndex] = attrs[len(attrs)-1]
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attrs = attrs[:len(attrs)-1]
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}
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notifyAttrs := make([]*Attribute, 0, 2)
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if !changedEpoch {
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eAttr := new(Attribute)
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eAttr.SetKey(SysAttributeTickEpoch)
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eAttr.SetValue(epoch)
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notifyAttrs = append(notifyAttrs, eAttr)
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}
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if !changedTopic && topic != "" {
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tAttr := new(Attribute)
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tAttr.SetKey(SysAttributeTickTopic)
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tAttr.SetValue(topic)
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notifyAttrs = append(notifyAttrs, tAttr)
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}
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attrs = append(attrs, notifyAttrs...)
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h.SetAttributes(attrs)
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}
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// ErrNotificationNotSet means that object does not have notification.
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var ErrNotificationNotSet = errors.New("notification for object is not set")
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// GetNotificationInfo looks for object notification attributes. Object must not be nil.
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// Returns ErrNotificationNotSet if no corresponding attributes
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// were found.
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//
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// Existing notification attributes are expected to be key-unique, otherwise undefined behavior.
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func GetNotificationInfo(o *Object) (*NotificationInfo, error) {
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var (
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foundEpoch bool
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ni = new(NotificationInfo)
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)
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for _, attr := range o.GetHeader().GetAttributes() {
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switch key := attr.GetKey(); key {
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case SysAttributeTickEpoch:
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epoch, err := strconv.ParseUint(attr.GetValue(), 10, 64)
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if err != nil {
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return nil, fmt.Errorf("could not parse epoch: %w", err)
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}
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ni.SetEpoch(epoch)
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foundEpoch = true
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case SysAttributeTickTopic:
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ni.SetTopic(attr.GetValue())
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}
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}
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if !foundEpoch {
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return nil, ErrNotificationNotSet
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}
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return ni, nil
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}
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