1 files changed, 322 insertions, 0 deletions
diff --git a/vendor/github.com/golang/groupcache/sinks.go b/vendor/github.com/golang/groupcache/sinks.go
new file mode 100644
index 000000000..cb42b41b4
--- /dev/null
+++ b/vendor/github.com/golang/groupcache/sinks.go
@@ -0,0 +1,322 @@
+/*
+Copyright 2012 Google Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package groupcache
+
+import (
+	"errors"
+
+	"github.com/golang/protobuf/proto"
+)
+
+// A Sink receives data from a Get call.
+//
+// Implementation of Getter must call exactly one of the Set methods
+// on success.
+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)
+}
+
+func cloneBytes(b []byte) []byte {
+	c := make([]byte, len(b))
+	copy(c, b)
+	return c
+}
+
+func setSinkView(s Sink, v ByteView) error {
+	// A viewSetter is a Sink that can also receive its value from
+	// a ByteView. This is a fast path to minimize copies when the
+	// item was already cached locally in memory (where it's
+	// cached as a ByteView)
+	type viewSetter interface {
+		setView(v ByteView) error
+	}
+	if vs, ok := s.(viewSetter); ok {
+		return vs.setView(v)
+	}
+	if v.b != nil {
+		return s.SetBytes(v.b)
+	}
+	return s.SetString(v.s)
+}
+
+// StringSink returns a Sink that populates the provided string pointer.
+func StringSink(sp *string) Sink {
+	return &stringSink{sp: sp}
+}
+
+type stringSink struct {
+	sp *string
+	v  ByteView
+	// TODO(bradfitz): track whether any Sets were called.
+}
+
+func (s *stringSink) view() (ByteView, error) {
+	// TODO(bradfitz): return an error if no Set was called
+	return s.v, nil
+}
+
+func (s *stringSink) SetString(v string) error {
+	s.v.b = nil
+	s.v.s = v
+	*s.sp = v
+	return nil
+}
+
+func (s *stringSink) SetBytes(v []byte) error {
+	return s.SetString(string(v))
+}
+
+func (s *stringSink) SetProto(m proto.Message) error {
+	b, err := proto.Marshal(m)
+	if err != nil {
+		return err
+	}
+	s.v.b = b
+	*s.sp = string(b)
+	return nil
+}
+
+// ByteViewSink returns a Sink that populates a ByteView.
+func ByteViewSink(dst *ByteView) Sink {
+	if dst == nil {
+		panic("nil dst")
+	}
+	return &byteViewSink{dst: dst}
+}
+
+type byteViewSink struct {
+	dst *ByteView
+
+	// if this code ever ends up tracking that at least one set*
+	// method was called, don't make it an error to call set
+	// methods multiple times. Lorry's payload.go does that, and
+	// it makes sense. The comment at the top of this file about
+	// "exactly one of the Set methods" is overly strict. We
+	// really care about at least once (in a handler), but if
+	// multiple handlers fail (or multiple functions in a program
+	// using a Sink), it's okay to re-use the same one.
+}
+
+func (s *byteViewSink) setView(v ByteView) error {
+	*s.dst = v
+	return nil
+}
+
+func (s *byteViewSink) view() (ByteView, error) {
+	return *s.dst, nil
+}
+
+func (s *byteViewSink) SetProto(m proto.Message) error {
+	b, err := proto.Marshal(m)
+	if err != nil {
+		return err
+	}
+	*s.dst = ByteView{b: b}
+	return nil
+}
+
+func (s *byteViewSink) SetBytes(b []byte) error {
+	*s.dst = ByteView{b: cloneBytes(b)}
+	return nil
+}
+
+func (s *byteViewSink) SetString(v string) error {
+	*s.dst = ByteView{s: v}
+	return nil
+}
+
+// ProtoSink returns a sink that unmarshals binary proto values into m.
+func ProtoSink(m proto.Message) Sink {
+	return &protoSink{
+		dst: m,
+	}
+}
+
+type protoSink struct {
+	dst proto.Message // authorative value
+	typ string
+
+	v ByteView // encoded
+}
+
+func (s *protoSink) view() (ByteView, error) {
+	return s.v, nil
+}
+
+func (s *protoSink) SetBytes(b []byte) error {
+	err := proto.Unmarshal(b, s.dst)
+	if err != nil {
+		return err
+	}
+	s.v.b = cloneBytes(b)
+	s.v.s = ""
+	return nil
+}
+
+func (s *protoSink) SetString(v string) error {
+	b := []byte(v)
+	err := proto.Unmarshal(b, s.dst)
+	if err != nil {
+		return err
+	}
+	s.v.b = b
+	s.v.s = ""
+	return nil
+}
+
+func (s *protoSink) SetProto(m proto.Message) error {
+	b, err := proto.Marshal(m)
+	if err != nil {
+		return err
+	}
+	// TODO(bradfitz): optimize for same-task case more and write
+	// right through? would need to document ownership rules at
+	// the same time. but then we could just assign *dst = *m
+	// here. This works for now:
+	err = proto.Unmarshal(b, s.dst)
+	if err != nil {
+		return err
+	}
+	s.v.b = b
+	s.v.s = ""
+	return nil
+}
+
+// AllocatingByteSliceSink returns a Sink that allocates
+// a byte slice to hold the received value and assigns
+// it to *dst. The memory is not retained by groupcache.
+func AllocatingByteSliceSink(dst *[]byte) Sink {
+	return &allocBytesSink{dst: dst}
+}
+
+type allocBytesSink struct {
+	dst *[]byte
+	v   ByteView
+}
+
+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
+}
+
+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
+}
+
+// TruncatingByteSliceSink returns a Sink that writes up to len(*dst)
+// bytes to *dst. If more bytes are available, they're silently
+// truncated. If fewer bytes are available than len(*dst), *dst
+// is shrunk to fit the number of bytes available.
+func TruncatingByteSliceSink(dst *[]byte) Sink {
+	return &truncBytesSink{dst: dst}
+}
+
+type truncBytesSink struct {
+	dst *[]byte
+	v   ByteView
+}
+
+func (s *truncBytesSink) view() (ByteView, error) {
+	return s.v, nil
+}
+
+func (s *truncBytesSink) SetProto(m proto.Message) error {
+	b, err := proto.Marshal(m)
+	if err != nil {
+		return err
+	}
+	return s.setBytesOwned(b)
+}
+
+func (s *truncBytesSink) SetBytes(b []byte) error {
+	return s.setBytesOwned(cloneBytes(b))
+}
+
+func (s *truncBytesSink) setBytesOwned(b []byte) error {
+	if s.dst == nil {
+		return errors.New("nil TruncatingByteSliceSink *[]byte dst")
+	}
+	n := copy(*s.dst, b)
+	if n < len(*s.dst) {
+		*s.dst = (*s.dst)[:n]
+	}
+	s.v.b = b
+	s.v.s = ""
+	return nil
+}
+
+func (s *truncBytesSink) SetString(v string) error {
+	if s.dst == nil {
+		return errors.New("nil TruncatingByteSliceSink *[]byte dst")
+	}
+	n := copy(*s.dst, v)
+	if n < len(*s.dst) {
+		*s.dst = (*s.dst)[:n]
+	}
+	s.v.b = nil
+	s.v.s = v
+	return nil
+}