d_cache_miss.go

package gossipcache

import (
	"context"
	"errors"
	"github.com/golang/protobuf/proto"
)

type Getter interface {
	Get(ctx context.Context, key string, dest Sink) error
}

type GetterFunc func(ctx context.Context, key string, dest Sink) error

func (f GetterFunc) Get(ctx context.Context, key string, dest Sink) error {
	return f(ctx, key, dest)
}

// ----------------------------------------------

type Sink interface {
	// SetString sets the value to s.
	SetString(s string) error

	// SetBytes sets the value to the contents of v.
	// The caller retains ownership of v.
	SetBytes(v []byte) error

	// SetProto sets the value to the encoded version of m.
	// The caller retains ownership of m.
	SetProto(m proto.Message) error

	// view returns a frozen view of the bytes for caching.
	view() (ByteView, error)
}

type allocBytesSink struct {
	dst *[]byte
	v   ByteView
}

func AllocatingByteSliceSink(dst *[]byte) Sink {
	return &allocBytesSink{dst: dst}
}

func (s *allocBytesSink) SetString(v string) error {
	if s.dst == nil {
		return errors.New("nil AllocatingByteSliceSink *[]byte dst")
	}
	*s.dst = []byte(v)
	s.v.b = nil
	s.v.s = v
	return nil
}
func (s *allocBytesSink) view() (ByteView, error) {
	return s.v, nil
}

func (s *allocBytesSink) setView(v ByteView) error {
	if v.b != nil {
		*s.dst = cloneBytes(v.b)
	} else {
		*s.dst = []byte(v.s)
	}
	s.v = v
	return nil
}

func (s *allocBytesSink) SetProto(m proto.Message) error {
	b, err := proto.Marshal(m)
	if err != nil {
		return err
	}
	return s.setBytesOwned(b)
}

func (s *allocBytesSink) SetBytes(b []byte) error {
	return s.setBytesOwned(cloneBytes(b))
}

func (s *allocBytesSink) setBytesOwned(b []byte) error {
	if s.dst == nil {
		return errors.New("nil AllocatingByteSliceSink *[]byte dst")
	}
	*s.dst = cloneBytes(b) // another copy, protecting the read-only s.v.b view
	s.v.b = b
	s.v.s = ""
	return nil
}