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key_space.go
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key_space.go
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package consumer
import (
"github.com/LiveRamp/gazette/v2/pkg/allocator"
"github.com/LiveRamp/gazette/v2/pkg/keyspace"
pb "github.com/LiveRamp/gazette/v2/pkg/protocol"
"github.com/coreos/etcd/mvcc/mvccpb"
)
// NewKeySpace returns a KeySpace suitable for use with an Allocator.
// It decodes allocator Items as ShardSpec messages, Members as ConsumerSpecs,
// and Assignments as RecoveryStatus enums.
func NewKeySpace(prefix string) *keyspace.KeySpace {
return allocator.NewAllocatorKeySpace(prefix, decoder{})
}
// decoder is an instance of allocator.Decoder. Much like broker.decoder, it
// strictly enforces that ShardSpec.Id matches the Id implied by the Spec's Etcd
// key. Conceptually, the Etcd key is source-of-truth regarding entity naming,
// but it's helpful to carry these identifiers within the specs themselves,
// making them a stand-alone representation and allowing for content-addressing
// of a spec into its appropriate Etcd key. This decoder behavior provides an
// assertion that these identifiers never diverge.
type decoder struct{}
func (d decoder) DecodeItem(id string, raw *mvccpb.KeyValue) (allocator.ItemValue, error) {
var s = new(ShardSpec)
if err := s.Unmarshal(raw.Value); err != nil {
return nil, err
} else if err = s.Validate(); err != nil {
return nil, err
} else if s.Id.String() != id {
return nil, pb.NewValidationError("ShardSpec ID doesn't match Item ID (%+v vs %+v)", s.Id, id)
}
return s, nil
}
func (d decoder) DecodeMember(zone, suffix string, raw *mvccpb.KeyValue) (allocator.MemberValue, error) {
var s = new(ConsumerSpec)
if err := s.Unmarshal(raw.Value); err != nil {
return nil, err
} else if err = s.Validate(); err != nil {
return nil, err
} else if s.Id.Zone != zone {
return nil, pb.NewValidationError("ConsumerSpec Zone doesn't match Member Zone (%+v vs %+v)", s.Id.Zone, zone)
} else if s.Id.Suffix != suffix {
return nil, pb.NewValidationError("ConsumerSpec Suffix doesn't match Member Suffix (%+v vs %+v)", s.Id.Suffix, suffix)
}
return s, nil
}
func (d decoder) DecodeAssignment(itemID, memberZone, memberSuffix string, slot int, raw *mvccpb.KeyValue) (allocator.AssignmentValue, error) {
var s = new(ReplicaStatus)
if err := s.Unmarshal(raw.Value); err != nil {
return nil, err
} else if err = s.Validate(); err != nil {
return nil, err
}
return s, nil
}