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# groupcache
## Summary
groupcache is a caching and cache-filling library, intended as a
replacement for memcached in many cases.
For API docs and examples, see http://godoc.org/github.com/golang/groupcache
## Comparison to memcached
### **Like memcached**, groupcache:
* shards by key to select which peer is responsible for that key
### **Unlike memcached**, groupcache:
* does not require running a separate set of servers, thus massively
reducing deployment/configuration pain. groupcache is a client
library as well as a server. It connects to its own peers.
* comes with a cache filling mechanism. Whereas memcached just says
"Sorry, cache miss", often resulting in a thundering herd of
database (or whatever) loads from an unbounded number of clients
(which has resulted in several fun outages), groupcache coordinates
cache fills such that only one load in one process of an entire
replicated set of processes populates the cache, then multiplexes
the loaded value to all callers.
* does not support versioned values. If key "foo" is value "bar",
key "foo" must always be "bar". There are neither cache expiration
times, nor explicit cache evictions. Thus there is also no CAS,
nor Increment/Decrement. This also means that groupcache....
* ... supports automatic mirroring of super-hot items to multiple
processes. This prevents memcached hot spotting where a machine's
CPU and/or NIC are overloaded by very popular keys/values.
* is currently only available for Go. It's very unlikely that I
(bradfitz@) will port the code to any other language.
## Loading process
In a nutshell, a groupcache lookup of **Get("foo")** looks like:
(On machine #5 of a set of N machines running the same code)
1. Is the value of "foo" in local memory because it's super hot? If so, use it.
2. Is the value of "foo" in local memory because peer #5 (the current
peer) is the owner of it? If so, use it.
3. Amongst all the peers in my set of N, am I the owner of the key
"foo"? (e.g. does it consistent hash to 5?) If so, load it. If
other callers come in (via the same process or via RPC requests
from peers, they block waiting for the load to finish and get the
same answer). If not, RPC to the peer that's the owner and get
the answer. If the RPC fails, just load it locally (still with
local dup suppresion).
## Users
groupcache is in production use by dl.google.com (its original user),
parts of Blogger, parts of Google Code, parts of Google Fiber, parts
of Google production monitoring systems, etc.
## Presentations
See http://talks.golang.org/2013/oscon-dl.slide
## Help
Use the golang-nuts mailing list for any discussion or questions.

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/*
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 (
"bytes"
"errors"
"io"
"strings"
)
// A ByteView holds an immutable view of bytes.
// Internally it wraps either a []byte or a string,
// but that detail is invisible to callers.
//
// A ByteView is meant to be used as a value type, not
// a pointer (like a time.Time).
type ByteView struct {
// If b is non-nil, b is used, else s is used.
b []byte
s string
}
// Len returns the view's length.
func (v ByteView) Len() int {
if v.b != nil {
return len(v.b)
}
return len(v.s)
}
// ByteSlice returns a copy of the data as a byte slice.
func (v ByteView) ByteSlice() []byte {
if v.b != nil {
return cloneBytes(v.b)
}
return []byte(v.s)
}
// String returns the data as a string, making a copy if necessary.
func (v ByteView) String() string {
if v.b != nil {
return string(v.b)
}
return v.s
}
// At returns the byte at index i.
func (v ByteView) At(i int) byte {
if v.b != nil {
return v.b[i]
}
return v.s[i]
}
// Slice slices the view between the provided from and to indices.
func (v ByteView) Slice(from, to int) ByteView {
if v.b != nil {
return ByteView{b: v.b[from:to]}
}
return ByteView{s: v.s[from:to]}
}
// SliceFrom slices the view from the provided index until the end.
func (v ByteView) SliceFrom(from int) ByteView {
if v.b != nil {
return ByteView{b: v.b[from:]}
}
return ByteView{s: v.s[from:]}
}
// Copy copies b into dest and returns the number of bytes copied.
func (v ByteView) Copy(dest []byte) int {
if v.b != nil {
return copy(dest, v.b)
}
return copy(dest, v.s)
}
// Equal returns whether the bytes in b are the same as the bytes in
// b2.
func (v ByteView) Equal(b2 ByteView) bool {
if b2.b == nil {
return v.EqualString(b2.s)
}
return v.EqualBytes(b2.b)
}
// EqualString returns whether the bytes in b are the same as the bytes
// in s.
func (v ByteView) EqualString(s string) bool {
if v.b == nil {
return v.s == s
}
l := v.Len()
if len(s) != l {
return false
}
for i, bi := range v.b {
if bi != s[i] {
return false
}
}
return true
}
// EqualBytes returns whether the bytes in b are the same as the bytes
// in b2.
func (v ByteView) EqualBytes(b2 []byte) bool {
if v.b != nil {
return bytes.Equal(v.b, b2)
}
l := v.Len()
if len(b2) != l {
return false
}
for i, bi := range b2 {
if bi != v.s[i] {
return false
}
}
return true
}
// Reader returns an io.ReadSeeker for the bytes in v.
func (v ByteView) Reader() io.ReadSeeker {
if v.b != nil {
return bytes.NewReader(v.b)
}
return strings.NewReader(v.s)
}
// ReadAt implements io.ReaderAt on the bytes in v.
func (v ByteView) ReadAt(p []byte, off int64) (n int, err error) {
if off < 0 {
return 0, errors.New("view: invalid offset")
}
if off >= int64(v.Len()) {
return 0, io.EOF
}
n = v.SliceFrom(int(off)).Copy(p)
if n < len(p) {
err = io.EOF
}
return
}

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/*
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 (
"fmt"
"io"
"io/ioutil"
"testing"
)
func TestByteView(t *testing.T) {
for _, s := range []string{"", "x", "yy"} {
for _, v := range []ByteView{of([]byte(s)), of(s)} {
name := fmt.Sprintf("string %q, view %+v", s, v)
if v.Len() != len(s) {
t.Errorf("%s: Len = %d; want %d", name, v.Len(), len(s))
}
if v.String() != s {
t.Errorf("%s: String = %q; want %q", name, v.String(), s)
}
var longDest [3]byte
if n := v.Copy(longDest[:]); n != len(s) {
t.Errorf("%s: long Copy = %d; want %d", name, n, len(s))
}
var shortDest [1]byte
if n := v.Copy(shortDest[:]); n != min(len(s), 1) {
t.Errorf("%s: short Copy = %d; want %d", name, n, min(len(s), 1))
}
if got, err := ioutil.ReadAll(v.Reader()); err != nil || string(got) != s {
t.Errorf("%s: Reader = %q, %v; want %q", name, got, err, s)
}
if got, err := ioutil.ReadAll(io.NewSectionReader(v, 0, int64(len(s)))); err != nil || string(got) != s {
t.Errorf("%s: SectionReader of ReaderAt = %q, %v; want %q", name, got, err, s)
}
}
}
}
// of returns a byte view of the []byte or string in x.
func of(x interface{}) ByteView {
if bytes, ok := x.([]byte); ok {
return ByteView{b: bytes}
}
return ByteView{s: x.(string)}
}
func TestByteViewEqual(t *testing.T) {
tests := []struct {
a interface{} // string or []byte
b interface{} // string or []byte
want bool
}{
{"x", "x", true},
{"x", "y", false},
{"x", "yy", false},
{[]byte("x"), []byte("x"), true},
{[]byte("x"), []byte("y"), false},
{[]byte("x"), []byte("yy"), false},
{[]byte("x"), "x", true},
{[]byte("x"), "y", false},
{[]byte("x"), "yy", false},
{"x", []byte("x"), true},
{"x", []byte("y"), false},
{"x", []byte("yy"), false},
}
for i, tt := range tests {
va := of(tt.a)
if bytes, ok := tt.b.([]byte); ok {
if got := va.EqualBytes(bytes); got != tt.want {
t.Errorf("%d. EqualBytes = %v; want %v", i, got, tt.want)
}
} else {
if got := va.EqualString(tt.b.(string)); got != tt.want {
t.Errorf("%d. EqualString = %v; want %v", i, got, tt.want)
}
}
if got := va.Equal(of(tt.b)); got != tt.want {
t.Errorf("%d. Equal = %v; want %v", i, got, tt.want)
}
}
}
func TestByteViewSlice(t *testing.T) {
tests := []struct {
in string
from int
to interface{} // nil to mean the end (SliceFrom); else int
want string
}{
{
in: "abc",
from: 1,
to: 2,
want: "b",
},
{
in: "abc",
from: 1,
want: "bc",
},
{
in: "abc",
to: 2,
want: "ab",
},
}
for i, tt := range tests {
for _, v := range []ByteView{of([]byte(tt.in)), of(tt.in)} {
name := fmt.Sprintf("test %d, view %+v", i, v)
if tt.to != nil {
v = v.Slice(tt.from, tt.to.(int))
} else {
v = v.SliceFrom(tt.from)
}
if v.String() != tt.want {
t.Errorf("%s: got %q; want %q", name, v.String(), tt.want)
}
}
}
}
func min(a, b int) int {
if a < b {
return a
}
return b
}

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/*
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 provides a data loading mechanism with caching
// and de-duplication that works across a set of peer processes.
//
// Each data Get first consults its local cache, otherwise delegates
// to the requested key's canonical owner, which then checks its cache
// or finally gets the data. In the common case, many concurrent
// cache misses across a set of peers for the same key result in just
// one cache fill.
package groupcache
import (
"errors"
"math/rand"
"strconv"
"sync"
"sync/atomic"
pb "github.com/golang/groupcache/groupcachepb"
"github.com/golang/groupcache/lru"
"github.com/golang/groupcache/singleflight"
)
// A Getter loads data for a key.
type Getter interface {
// Get returns the value identified by key, populating dest.
//
// The returned data must be unversioned. That is, key must
// uniquely describe the loaded data, without an implicit
// current time, and without relying on cache expiration
// mechanisms.
Get(ctx Context, key string, dest Sink) error
}
// A GetterFunc implements Getter with a function.
type GetterFunc func(ctx Context, key string, dest Sink) error
func (f GetterFunc) Get(ctx Context, key string, dest Sink) error {
return f(ctx, key, dest)
}
var (
mu sync.RWMutex
groups = make(map[string]*Group)
initPeerServerOnce sync.Once
initPeerServer func()
)
// GetGroup returns the named group previously created with NewGroup, or
// nil if there's no such group.
func GetGroup(name string) *Group {
mu.RLock()
g := groups[name]
mu.RUnlock()
return g
}
// NewGroup creates a coordinated group-aware Getter from a Getter.
//
// The returned Getter tries (but does not guarantee) to run only one
// Get call at once for a given key across an entire set of peer
// processes. Concurrent callers both in the local process and in
// other processes receive copies of the answer once the original Get
// completes.
//
// The group name must be unique for each getter.
func NewGroup(name string, cacheBytes int64, getter Getter) *Group {
return newGroup(name, cacheBytes, getter, nil)
}
// If peers is nil, the peerPicker is called via a sync.Once to initialize it.
func newGroup(name string, cacheBytes int64, getter Getter, peers PeerPicker) *Group {
if getter == nil {
panic("nil Getter")
}
mu.Lock()
defer mu.Unlock()
initPeerServerOnce.Do(callInitPeerServer)
if _, dup := groups[name]; dup {
panic("duplicate registration of group " + name)
}
g := &Group{
name: name,
getter: getter,
peers: peers,
cacheBytes: cacheBytes,
}
if fn := newGroupHook; fn != nil {
fn(g)
}
groups[name] = g
return g
}
// newGroupHook, if non-nil, is called right after a new group is created.
var newGroupHook func(*Group)
// RegisterNewGroupHook registers a hook that is run each time
// a group is created.
func RegisterNewGroupHook(fn func(*Group)) {
if newGroupHook != nil {
panic("RegisterNewGroupHook called more than once")
}
newGroupHook = fn
}
// RegisterServerStart registers a hook that is run when the first
// group is created.
func RegisterServerStart(fn func()) {
if initPeerServer != nil {
panic("RegisterServerStart called more than once")
}
initPeerServer = fn
}
func callInitPeerServer() {
if initPeerServer != nil {
initPeerServer()
}
}
// A Group is a cache namespace and associated data loaded spread over
// a group of 1 or more machines.
type Group struct {
name string
getter Getter
peersOnce sync.Once
peers PeerPicker
cacheBytes int64 // limit for sum of mainCache and hotCache size
// mainCache is a cache of the keys for which this process
// (amongst its peers) is authorative. That is, this cache
// contains keys which consistent hash on to this process's
// peer number.
mainCache cache
// hotCache contains keys/values for which this peer is not
// authorative (otherwise they would be in mainCache), but
// are popular enough to warrant mirroring in this process to
// avoid going over the network to fetch from a peer. Having
// a hotCache avoids network hotspotting, where a peer's
// network card could become the bottleneck on a popular key.
// This cache is used sparingly to maximize the total number
// of key/value pairs that can stored globally.
hotCache cache
// loadGroup ensures that each key is only fetched once
// (either locally or remotely), regardless of the number of
// concurrent callers.
loadGroup singleflight.Group
// Stats are statistics on the group.
Stats Stats
}
// Stats are per-group statistics.
type Stats struct {
Gets AtomicInt // any Get request, including from peers
CacheHits AtomicInt // either cache was good
PeerLoads AtomicInt // either remote load or remote cache hit (not an error)
PeerErrors AtomicInt
Loads AtomicInt // (gets - cacheHits)
LoadsDeduped AtomicInt // after singleflight
LocalLoads AtomicInt // total good local loads
LocalLoadErrs AtomicInt // total bad local loads
ServerRequests AtomicInt // gets that came over the network from peers
}
// Name returns the name of the group.
func (g *Group) Name() string {
return g.name
}
func (g *Group) initPeers() {
if g.peers == nil {
g.peers = getPeers()
}
}
func (g *Group) Get(ctx Context, key string, dest Sink) error {
g.peersOnce.Do(g.initPeers)
g.Stats.Gets.Add(1)
if dest == nil {
return errors.New("groupcache: nil dest Sink")
}
value, cacheHit := g.lookupCache(key)
if cacheHit {
g.Stats.CacheHits.Add(1)
return setSinkView(dest, value)
}
// Optimization to avoid double unmarshalling or copying: keep
// track of whether the dest was already populated. One caller
// (if local) will set this; the losers will not. The common
// case will likely be one caller.
destPopulated := false
value, destPopulated, err := g.load(ctx, key, dest)
if err != nil {
return err
}
if destPopulated {
return nil
}
return setSinkView(dest, value)
}
// load loads key either by invoking the getter locally or by sending it to another machine.
func (g *Group) load(ctx Context, key string, dest Sink) (value ByteView, destPopulated bool, err error) {
g.Stats.Loads.Add(1)
viewi, err := g.loadGroup.Do(key, func() (interface{}, error) {
g.Stats.LoadsDeduped.Add(1)
var value ByteView
var err error
if peer, ok := g.peers.PickPeer(key); ok {
value, err = g.getFromPeer(ctx, peer, key)
if err == nil {
g.Stats.PeerLoads.Add(1)
return value, nil
}
g.Stats.PeerErrors.Add(1)
// TODO(bradfitz): log the peer's error? keep
// log of the past few for /groupcachez? It's
// probably boring (normal task movement), so not
// worth logging I imagine.
}
value, err = g.getLocally(ctx, key, dest)
if err != nil {
g.Stats.LocalLoadErrs.Add(1)
return nil, err
}
g.Stats.LocalLoads.Add(1)
destPopulated = true // only one caller of load gets this return value
g.populateCache(key, value, &g.mainCache)
return value, nil
})
if err == nil {
value = viewi.(ByteView)
}
return
}
func (g *Group) getLocally(ctx Context, key string, dest Sink) (ByteView, error) {
err := g.getter.Get(ctx, key, dest)
if err != nil {
return ByteView{}, err
}
return dest.view()
}
func (g *Group) getFromPeer(ctx Context, peer ProtoGetter, key string) (ByteView, error) {
req := &pb.GetRequest{
Group: &g.name,
Key: &key,
}
res := &pb.GetResponse{}
err := peer.Get(ctx, req, res)
if err != nil {
return ByteView{}, err
}
value := ByteView{b: res.Value}
// TODO(bradfitz): use res.MinuteQps or something smart to
// conditionally populate hotCache. For now just do it some
// percentage of the time.
if rand.Intn(10) == 0 {
g.populateCache(key, value, &g.hotCache)
}
return value, nil
}
func (g *Group) lookupCache(key string) (value ByteView, ok bool) {
if g.cacheBytes <= 0 {
return
}
value, ok = g.mainCache.get(key)
if ok {
return
}
value, ok = g.hotCache.get(key)
return
}
func (g *Group) populateCache(key string, value ByteView, cache *cache) {
if g.cacheBytes <= 0 {
return
}
cache.add(key, value)
// Evict items from cache(s) if necessary.
for {
mainBytes := g.mainCache.bytes()
hotBytes := g.hotCache.bytes()
if mainBytes+hotBytes <= g.cacheBytes {
return
}
// TODO(bradfitz): this is good-enough-for-now logic.
// It should be something based on measurements and/or
// respecting the costs of different resources.
victim := &g.mainCache
if hotBytes > mainBytes/8 {
victim = &g.hotCache
}
victim.removeOldest()
}
}
// CacheType represents a type of cache.
type CacheType int
const (
// The MainCache is the cache for items that this peer is the
// owner for.
MainCache CacheType = iota + 1
// The HotCache is the cache for items that seem popular
// enough to replicate to this node, even though it's not the
// owner.
HotCache
)
// CacheStats returns stats about the provided cache within the group.
func (g *Group) CacheStats(which CacheType) CacheStats {
switch which {
case MainCache:
return g.mainCache.stats()
case HotCache:
return g.hotCache.stats()
default:
return CacheStats{}
}
}
// cache is a wrapper around an *lru.Cache that adds synchronization,
// makes values always be ByteView, and counts the size of all keys and
// values.
type cache struct {
mu sync.RWMutex
nbytes int64 // of all keys and values
lru *lru.Cache
nhit, nget int64
nevict int64 // number of evictions
}
func (c *cache) stats() CacheStats {
c.mu.RLock()
defer c.mu.RUnlock()
return CacheStats{
Bytes: c.nbytes,
Items: c.itemsLocked(),
Gets: c.nget,
Hits: c.nhit,
Evictions: c.nevict,
}
}
func (c *cache) add(key string, value ByteView) {
c.mu.Lock()
defer c.mu.Unlock()
if c.lru == nil {
c.lru = &lru.Cache{
OnEvicted: func(key lru.Key, value interface{}) {
val := value.(ByteView)
c.nbytes -= int64(len(key.(string))) + int64(val.Len())
c.nevict++
},
}
}
c.lru.Add(key, value)
c.nbytes += int64(len(key)) + int64(value.Len())
}
func (c *cache) get(key string) (value ByteView, ok bool) {
c.mu.Lock()
defer c.mu.Unlock()
c.nget++
if c.lru == nil {
return
}
vi, ok := c.lru.Get(key)
if !ok {
return
}
c.nhit++
return vi.(ByteView), true
}
func (c *cache) removeOldest() {
c.mu.Lock()
defer c.mu.Unlock()
if c.lru != nil {
c.lru.RemoveOldest()
}
}
func (c *cache) bytes() int64 {
c.mu.RLock()
defer c.mu.RUnlock()
return c.nbytes
}
func (c *cache) items() int64 {
c.mu.RLock()
defer c.mu.RUnlock()
return c.itemsLocked()
}
func (c *cache) itemsLocked() int64 {
if c.lru == nil {
return 0
}
return int64(c.lru.Len())
}
// An AtomicInt is an int64 to be accessed atomically.
type AtomicInt int64
// Add atomically adds n to i.
func (i *AtomicInt) Add(n int64) {
atomic.AddInt64((*int64)(i), n)
}
// Get atomically gets the value of i.
func (i *AtomicInt) Get() int64 {
return atomic.LoadInt64((*int64)(i))
}
func (i *AtomicInt) String() string {
return strconv.FormatInt(i.Get(), 10)
}
// CacheStats are returned by stats accessors on Group.
type CacheStats struct {
Bytes int64
Items int64
Gets int64
Hits int64
Evictions int64
}

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// Code generated by protoc-gen-go.
// source: groupcache.proto
// DO NOT EDIT!
package groupcache
import proto "code.google.com/p/goprotobuf/proto"
import json "encoding/json"
import math "math"
// Reference proto, json, and math imports to suppress error if they are not otherwise used.
var _ = proto.Marshal
var _ = &json.SyntaxError{}
var _ = math.Inf
type GetRequest struct {
Group *string `protobuf:"bytes,1,req,name=group" json:"group,omitempty"`
Key *string `protobuf:"bytes,2,req,name=key" json:"key,omitempty"`
XXX_unrecognized []byte `json:"-"`
}
func (m *GetRequest) Reset() { *m = GetRequest{} }
func (m *GetRequest) String() string { return proto.CompactTextString(m) }
func (*GetRequest) ProtoMessage() {}
func (m *GetRequest) GetGroup() string {
if m != nil && m.Group != nil {
return *m.Group
}
return ""
}
func (m *GetRequest) GetKey() string {
if m != nil && m.Key != nil {
return *m.Key
}
return ""
}
type GetResponse struct {
Value []byte `protobuf:"bytes,1,opt,name=value" json:"value,omitempty"`
MinuteQps *float64 `protobuf:"fixed64,2,opt,name=minute_qps" json:"minute_qps,omitempty"`
XXX_unrecognized []byte `json:"-"`
}
func (m *GetResponse) Reset() { *m = GetResponse{} }
func (m *GetResponse) String() string { return proto.CompactTextString(m) }
func (*GetResponse) ProtoMessage() {}
func (m *GetResponse) GetValue() []byte {
if m != nil {
return m.Value
}
return nil
}
func (m *GetResponse) GetMinuteQps() float64 {
if m != nil && m.MinuteQps != nil {
return *m.MinuteQps
}
return 0
}
func init() {
}

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/*
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.
*/
// Tests for groupcache.
package groupcache
import (
"errors"
"fmt"
"hash/crc32"
"math/rand"
"reflect"
"sync"
"testing"
"time"
"code.google.com/p/goprotobuf/proto"
pb "github.com/golang/groupcache/groupcachepb"
testpb "github.com/golang/groupcache/testpb"
)
var (
once sync.Once
stringGroup, protoGroup Getter
stringc = make(chan string)
dummyCtx Context
// cacheFills is the number of times stringGroup or
// protoGroup's Getter have been called. Read using the
// cacheFills function.
cacheFills AtomicInt
)
const (
stringGroupName = "string-group"
protoGroupName = "proto-group"
testMessageType = "google3/net/groupcache/go/test_proto.TestMessage"
fromChan = "from-chan"
cacheSize = 1 << 20
)
func testSetup() {
stringGroup = NewGroup(stringGroupName, cacheSize, GetterFunc(func(_ Context, key string, dest Sink) error {
if key == fromChan {
key = <-stringc
}
cacheFills.Add(1)
return dest.SetString("ECHO:" + key)
}))
protoGroup = NewGroup(protoGroupName, cacheSize, GetterFunc(func(_ Context, key string, dest Sink) error {
if key == fromChan {
key = <-stringc
}
cacheFills.Add(1)
return dest.SetProto(&testpb.TestMessage{
Name: proto.String("ECHO:" + key),
City: proto.String("SOME-CITY"),
})
}))
}
// tests that a Getter's Get method is only called once with two
// outstanding callers. This is the string variant.
func TestGetDupSuppressString(t *testing.T) {
once.Do(testSetup)
// Start two getters. The first should block (waiting reading
// from stringc) and the second should latch on to the first
// one.
resc := make(chan string, 2)
for i := 0; i < 2; i++ {
go func() {
var s string
if err := stringGroup.Get(dummyCtx, fromChan, StringSink(&s)); err != nil {
resc <- "ERROR:" + err.Error()
return
}
resc <- s
}()
}
// Wait a bit so both goroutines get merged together via
// singleflight.
// TODO(bradfitz): decide whether there are any non-offensive
// debug/test hooks that could be added to singleflight to
// make a sleep here unnecessary.
time.Sleep(250 * time.Millisecond)
// Unblock the first getter, which should unblock the second
// as well.
stringc <- "foo"
for i := 0; i < 2; i++ {
select {
case v := <-resc:
if v != "ECHO:foo" {
t.Errorf("got %q; want %q", v, "ECHO:foo")
}
case <-time.After(5 * time.Second):
t.Errorf("timeout waiting on getter #%d of 2", i+1)
}
}
}
// tests that a Getter's Get method is only called once with two
// outstanding callers. This is the proto variant.
func TestGetDupSuppressProto(t *testing.T) {
once.Do(testSetup)
// Start two getters. The first should block (waiting reading
// from stringc) and the second should latch on to the first
// one.
resc := make(chan *testpb.TestMessage, 2)
for i := 0; i < 2; i++ {
go func() {
tm := new(testpb.TestMessage)
if err := protoGroup.Get(dummyCtx, fromChan, ProtoSink(tm)); err != nil {
tm.Name = proto.String("ERROR:" + err.Error())
}
resc <- tm
}()
}
// Wait a bit so both goroutines get merged together via
// singleflight.
// TODO(bradfitz): decide whether there are any non-offensive
// debug/test hooks that could be added to singleflight to
// make a sleep here unnecessary.
time.Sleep(250 * time.Millisecond)
// Unblock the first getter, which should unblock the second
// as well.
stringc <- "Fluffy"
want := &testpb.TestMessage{
Name: proto.String("ECHO:Fluffy"),
City: proto.String("SOME-CITY"),
}
for i := 0; i < 2; i++ {
select {
case v := <-resc:
if !reflect.DeepEqual(v, want) {
t.Errorf(" Got: %v\nWant: %v", proto.CompactTextString(v), proto.CompactTextString(want))
}
case <-time.After(5 * time.Second):
t.Errorf("timeout waiting on getter #%d of 2", i+1)
}
}
}
func countFills(f func()) int64 {
fills0 := cacheFills.Get()
f()
return cacheFills.Get() - fills0
}
func TestCaching(t *testing.T) {
once.Do(testSetup)
fills := countFills(func() {
for i := 0; i < 10; i++ {
var s string
if err := stringGroup.Get(dummyCtx, "TestCaching-key", StringSink(&s)); err != nil {
t.Fatal(err)
}
}
})
if fills != 1 {
t.Errorf("expected 1 cache fill; got %d", fills)
}
}
func TestCacheEviction(t *testing.T) {
once.Do(testSetup)
testKey := "TestCacheEviction-key"
getTestKey := func() {
var res string
for i := 0; i < 10; i++ {
if err := stringGroup.Get(dummyCtx, testKey, StringSink(&res)); err != nil {
t.Fatal(err)
}
}
}
fills := countFills(getTestKey)
if fills != 1 {
t.Fatalf("expected 1 cache fill; got %d", fills)
}
g := stringGroup.(*Group)
evict0 := g.mainCache.nevict
// Trash the cache with other keys.
var bytesFlooded int64
// cacheSize/len(testKey) is approximate
for bytesFlooded < cacheSize+1024 {
var res string
key := fmt.Sprintf("dummy-key-%d", bytesFlooded)
stringGroup.Get(dummyCtx, key, StringSink(&res))
bytesFlooded += int64(len(key) + len(res))
}
evicts := g.mainCache.nevict - evict0
if evicts <= 0 {
t.Errorf("evicts = %v; want more than 0", evicts)
}
// Test that the key is gone.
fills = countFills(getTestKey)
if fills != 1 {
t.Fatalf("expected 1 cache fill after cache trashing; got %d", fills)
}
}
type fakePeer struct {
hits int
fail bool
}
func (p *fakePeer) Get(_ Context, in *pb.GetRequest, out *pb.GetResponse) error {
p.hits++
if p.fail {
return errors.New("simulated error from peer")
}
out.Value = []byte("got:" + in.GetKey())
return nil
}
type fakePeers []ProtoGetter
func (p fakePeers) PickPeer(key string) (peer ProtoGetter, ok bool) {
if len(p) == 0 {
return
}
n := crc32.Checksum([]byte(key), crc32.IEEETable) % uint32(len(p))
return p[n], p[n] != nil
}
// tests that peers (virtual, in-process) are hit, and how much.
func TestPeers(t *testing.T) {
once.Do(testSetup)
rand.Seed(123)
peer0 := &fakePeer{}
peer1 := &fakePeer{}
peer2 := &fakePeer{}
peerList := fakePeers([]ProtoGetter{peer0, peer1, peer2, nil})
const cacheSize = 0 // disabled
localHits := 0
getter := func(_ Context, key string, dest Sink) error {
localHits++
return dest.SetString("got:" + key)
}
testGroup := newGroup("TestPeers-group", cacheSize, GetterFunc(getter), peerList)
run := func(name string, n int, wantSummary string) {
// Reset counters
localHits = 0
for _, p := range []*fakePeer{peer0, peer1, peer2} {
p.hits = 0
}
for i := 0; i < n; i++ {
key := fmt.Sprintf("key-%d", i)
want := "got:" + key
var got string
err := testGroup.Get(dummyCtx, key, StringSink(&got))
if err != nil {
t.Errorf("%s: error on key %q: %v", name, key, err)
continue
}
if got != want {
t.Errorf("%s: for key %q, got %q; want %q", name, key, got, want)
}
}
summary := func() string {
return fmt.Sprintf("localHits = %d, peers = %d %d %d", localHits, peer0.hits, peer1.hits, peer2.hits)
}
if got := summary(); got != wantSummary {
t.Errorf("%s: got %q; want %q", name, got, wantSummary)
}
}
resetCacheSize := func(maxBytes int64) {
g := testGroup
g.cacheBytes = maxBytes
g.mainCache = cache{}
g.hotCache = cache{}
}
// Base case; peers all up, with no problems.
resetCacheSize(1 << 20)
run("base", 200, "localHits = 49, peers = 51 49 51")
// Verify cache was hit. All localHits are gone, and some of
// the peer hits (the ones randomly selected to be maybe hot)
run("cached_base", 200, "localHits = 0, peers = 49 47 48")
resetCacheSize(0)
// With one of the peers being down.
// TODO(bradfitz): on a peer number being unavailable, the
// consistent hashing should maybe keep trying others to
// spread the load out. Currently it fails back to local
// execution if the first consistent-hash slot is unavailable.
peerList[0] = nil
run("one_peer_down", 200, "localHits = 100, peers = 0 49 51")
// Failing peer
peerList[0] = peer0
peer0.fail = true
run("peer0_failing", 200, "localHits = 100, peers = 51 49 51")
}
func TestTruncatingByteSliceTarget(t *testing.T) {
var buf [100]byte
s := buf[:]
if err := stringGroup.Get(dummyCtx, "short", TruncatingByteSliceSink(&s)); err != nil {
t.Fatal(err)
}
if want := "ECHO:short"; string(s) != want {
t.Errorf("short key got %q; want %q", s, want)
}
s = buf[:6]
if err := stringGroup.Get(dummyCtx, "truncated", TruncatingByteSliceSink(&s)); err != nil {
t.Fatal(err)
}
if want := "ECHO:t"; string(s) != want {
t.Errorf("truncated key got %q; want %q", s, want)
}
}
func TestAllocatingByteSliceTarget(t *testing.T) {
var dst []byte
sink := AllocatingByteSliceSink(&dst)
inBytes := []byte("some bytes")
sink.SetBytes(inBytes)
if want := "some bytes"; string(dst) != want {
t.Errorf("SetBytes resulted in %q; want %q", dst, want)
}
v, err := sink.view()
if err != nil {
t.Fatalf("view after SetBytes failed: %v", err)
}
if &inBytes[0] == &dst[0] {
t.Error("inBytes and dst share memory")
}
if &inBytes[0] == &v.b[0] {
t.Error("inBytes and view share memory")
}
if &dst[0] == &v.b[0] {
t.Error("dst and view share memory")
}
}
// TODO(bradfitz): port the Google-internal full integration test into here,
// using HTTP requests instead of our RPC system.

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// Code generated by protoc-gen-go.
// source: groupcache.proto
// DO NOT EDIT!
package groupcachepb
import proto "code.google.com/p/goprotobuf/proto"
import json "encoding/json"
import math "math"
// Reference proto, json, and math imports to suppress error if they are not otherwise used.
var _ = proto.Marshal
var _ = &json.SyntaxError{}
var _ = math.Inf
type GetRequest struct {
Group *string `protobuf:"bytes,1,req,name=group" json:"group,omitempty"`
Key *string `protobuf:"bytes,2,req,name=key" json:"key,omitempty"`
XXX_unrecognized []byte `json:"-"`
}
func (m *GetRequest) Reset() { *m = GetRequest{} }
func (m *GetRequest) String() string { return proto.CompactTextString(m) }
func (*GetRequest) ProtoMessage() {}
func (m *GetRequest) GetGroup() string {
if m != nil && m.Group != nil {
return *m.Group
}
return ""
}
func (m *GetRequest) GetKey() string {
if m != nil && m.Key != nil {
return *m.Key
}
return ""
}
type GetResponse struct {
Value []byte `protobuf:"bytes,1,opt,name=value" json:"value,omitempty"`
MinuteQps *float64 `protobuf:"fixed64,2,opt,name=minute_qps" json:"minute_qps,omitempty"`
XXX_unrecognized []byte `json:"-"`
}
func (m *GetResponse) Reset() { *m = GetResponse{} }
func (m *GetResponse) String() string { return proto.CompactTextString(m) }
func (*GetResponse) ProtoMessage() {}
func (m *GetResponse) GetValue() []byte {
if m != nil {
return m.Value
}
return nil
}
func (m *GetResponse) GetMinuteQps() float64 {
if m != nil && m.MinuteQps != nil {
return *m.MinuteQps
}
return 0
}
func init() {
}

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/*
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 groupcachepb;
message GetRequest {
required string group = 1;
required string key = 2; // not actually required/guaranteed to be UTF-8
}
message GetResponse {
optional bytes value = 1;
optional double minute_qps = 2;
}
service GroupCache {
rpc Get(GetRequest) returns (GetResponse) {
};
}

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/*
Copyright 2013 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 lru implements an LRU cache.
package lru
import "container/list"
// Cache is an LRU cache. It is not safe for concurrent access.
type Cache struct {
// MaxEntries is the maximum number of cache entries before
// an item is evicted. Zero means no limit.
MaxEntries int
// OnEvicted optionally specificies a callback function to be
// executed when an entry is purged from the cache.
OnEvicted func(key Key, value interface{})
ll *list.List
cache map[interface{}]*list.Element
}
// A Key may be any value that is comparable. See http://golang.org/ref/spec#Comparison_operators
type Key interface{}
type entry struct {
key Key
value interface{}
}
// New creates a new Cache.
// If maxEntries is zero, the cache has no limit and it's assumed
// that eviction is done by the caller.
func New(maxEntries int) *Cache {
return &Cache{
MaxEntries: maxEntries,
ll: list.New(),
cache: make(map[interface{}]*list.Element),
}
}
// Add adds a value to the cache.
func (c *Cache) Add(key Key, value interface{}) {
if c.cache == nil {
c.cache = make(map[interface{}]*list.Element)
c.ll = list.New()
}
if ee, ok := c.cache[key]; ok {
c.ll.MoveToFront(ee)
ee.Value.(*entry).value = value
return
}
ele := c.ll.PushFront(&entry{key, value})
c.cache[key] = ele
if c.MaxEntries != 0 && c.ll.Len() > c.MaxEntries {
c.RemoveOldest()
}
}
// Get looks up a key's value from the cache.
func (c *Cache) Get(key Key) (value interface{}, ok bool) {
if c.cache == nil {
return
}
if ele, hit := c.cache[key]; hit {
c.ll.MoveToFront(ele)
return ele.Value.(*entry).value, true
}
return
}
// Remove removes the provided key from the cache.
func (c *Cache) Remove(key Key) {
if c.cache == nil {
return
}
if ele, hit := c.cache[key]; hit {
c.removeElement(ele)
}
}
// RemoveOldest removes the oldest item from the cache.
func (c *Cache) RemoveOldest() {
if c.cache == nil {
return
}
ele := c.ll.Back()
if ele != nil {
c.removeElement(ele)
}
}
func (c *Cache) removeElement(e *list.Element) {
c.ll.Remove(e)
kv := e.Value.(*entry)
delete(c.cache, kv.key)
if c.OnEvicted != nil {
c.OnEvicted(kv.key, kv.value)
}
}
// Len returns the number of items in the cache.
func (c *Cache) Len() int {
if c.cache == nil {
return 0
}
return c.ll.Len()
}

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/*
Copyright 2013 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 lru
import (
"testing"
)
type simpleStruct struct {
int
string
}
type complexStruct struct {
int
simpleStruct
}
var getTests = []struct {
name string
keyToAdd interface{}
keyToGet interface{}
expectedOk bool
}{
{"string_hit", "myKey", "myKey", true},
{"string_miss", "myKey", "nonsense", false},
{"simple_struct_hit", simpleStruct{1, "two"}, simpleStruct{1, "two"}, true},
{"simeple_struct_miss", simpleStruct{1, "two"}, simpleStruct{0, "noway"}, false},
{"complex_struct_hit", complexStruct{1, simpleStruct{2, "three"}},
complexStruct{1, simpleStruct{2, "three"}}, true},
}
func TestGet(t *testing.T) {
for _, tt := range getTests {
lru := New(0)
lru.Add(tt.keyToAdd, 1234)
val, ok := lru.Get(tt.keyToGet)
if ok != tt.expectedOk {
t.Fatalf("%s: cache hit = %v; want %v", tt.name, ok, !ok)
} else if ok && val != 1234 {
t.Fatalf("%s expected get to return 1234 but got %v", tt.name, val)
}
}
}
func TestRemove(t *testing.T) {
lru := New(0)
lru.Add("myKey", 1234)
if val, ok := lru.Get("myKey"); !ok {
t.Fatal("TestRemove returned no match")
} else if val != 1234 {
t.Fatalf("TestRemove failed. Expected %d, got %v", 1234, val)
}
lru.Remove("myKey")
if _, ok := lru.Get("myKey"); ok {
t.Fatal("TestRemove returned a removed entry")
}
}

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/*
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.
*/
// peers.go defines how processes find and communicate with their peers.
package groupcache
import (
pb "github.com/golang/groupcache/groupcachepb"
)
// Context is an opaque value passed through calls to the
// ProtoGetter. It may be nil if your ProtoGetter implementation does
// not require a context.
type Context interface{}
// ProtoGetter is the interface that must be implemented by a peer.
type ProtoGetter interface {
Get(context Context, in *pb.GetRequest, out *pb.GetResponse) error
}
// PeerPicker is the interface that must be implemented to locate
// the peer that owns a specific key.
type PeerPicker interface {
PickPeer(key string) (peer ProtoGetter, ok bool)
}
// NoPeers is an implementation of PeerPicker that never finds a peer.
type NoPeers struct{}
func (NoPeers) PickPeer(key string) (peer ProtoGetter, ok bool) { return }
var (
portPicker func() PeerPicker
)
// RegisterInitPeers registers the peer initialization function.
// It is called once, when the first group is created.
func RegisterPeerPicker(fn func() PeerPicker) {
if portPicker != nil {
panic("RegisterInitPeers called more than once")
}
portPicker = fn
}
func getPeers() PeerPicker {
if portPicker == nil {
return NoPeers{}
}
pk := portPicker()
if pk == nil {
pk = NoPeers{}
}
return pk
}

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/*
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 singleflight provides a duplicate function call suppression
// mechanism.
package singleflight
import "sync"
// call is an in-flight or completed Do call
type call struct {
wg sync.WaitGroup
val interface{}
err error
}
// Group represents a class of work and forms a namespace in which
// units of work can be executed with duplicate suppression.
type Group struct {
mu sync.Mutex // protects m
m map[string]*call // lazily initialized
}
// Do executes and returns the results of the given function, making
// sure that only one execution is in-flight for a given key at a
// time. If a duplicate comes in, the duplicate caller waits for the
// original to complete and receives the same results.
func (g *Group) Do(key string, fn func() (interface{}, error)) (interface{}, error) {
g.mu.Lock()
if g.m == nil {
g.m = make(map[string]*call)
}
if c, ok := g.m[key]; ok {
g.mu.Unlock()
c.wg.Wait()
return c.val, c.err
}
c := new(call)
c.wg.Add(1)
g.m[key] = c
g.mu.Unlock()
c.val, c.err = fn()
c.wg.Done()
g.mu.Lock()
delete(g.m, key)
g.mu.Unlock()
return c.val, c.err
}

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/*
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 singleflight
import (
"errors"
"fmt"
"sync"
"sync/atomic"
"testing"
"time"
)
func TestDo(t *testing.T) {
var g Group
v, err := g.Do("key", func() (interface{}, error) {
return "bar", nil
})
if got, want := fmt.Sprintf("%v (%T)", v, v), "bar (string)"; got != want {
t.Errorf("Do = %v; want %v", got, want)
}
if err != nil {
t.Errorf("Do error = %v", err)
}
}
func TestDoErr(t *testing.T) {
var g Group
someErr := errors.New("Some error")
v, err := g.Do("key", func() (interface{}, error) {
return nil, someErr
})
if err != someErr {
t.Errorf("Do error = %v; want someErr", err, someErr)
}
if v != nil {
t.Errorf("unexpected non-nil value %#v", v)
}
}
func TestDoDupSuppress(t *testing.T) {
var g Group
c := make(chan string)
var calls int32
fn := func() (interface{}, error) {
atomic.AddInt32(&calls, 1)
return <-c, nil
}
const n = 10
var wg sync.WaitGroup
for i := 0; i < n; i++ {
wg.Add(1)
go func() {
v, err := g.Do("key", fn)
if err != nil {
t.Errorf("Do error: %v", err)
}
if v.(string) != "bar" {
t.Errorf("got %q; want %q", v, "bar")
}
wg.Done()
}()
}
time.Sleep(100 * time.Millisecond) // let goroutines above block
c <- "bar"
wg.Wait()
if got := atomic.LoadInt32(&calls); got != 1 {
t.Errorf("number of calls = %d; want 1", got)
}
}

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/*
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"
"code.google.com/p/goprotobuf/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
}

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// Code generated by protoc-gen-go.
// source: test.proto
// DO NOT EDIT!
package testpb
import proto "code.google.com/p/goprotobuf/proto"
import json "encoding/json"
import math "math"
// Reference proto, json, and math imports to suppress error if they are not otherwise used.
var _ = proto.Marshal
var _ = &json.SyntaxError{}
var _ = math.Inf
type TestMessage struct {
Name *string `protobuf:"bytes,1,opt,name=name" json:"name,omitempty"`
City *string `protobuf:"bytes,2,opt,name=city" json:"city,omitempty"`
XXX_unrecognized []byte `json:"-"`
}
func (m *TestMessage) Reset() { *m = TestMessage{} }
func (m *TestMessage) String() string { return proto.CompactTextString(m) }
func (*TestMessage) ProtoMessage() {}
func (m *TestMessage) GetName() string {
if m != nil && m.Name != nil {
return *m.Name
}
return ""
}
func (m *TestMessage) GetCity() string {
if m != nil && m.City != nil {
return *m.City
}
return ""
}
type TestRequest struct {
Lower *string `protobuf:"bytes,1,req,name=lower" json:"lower,omitempty"`
RepeatCount *int32 `protobuf:"varint,2,opt,name=repeat_count,def=1" json:"repeat_count,omitempty"`
XXX_unrecognized []byte `json:"-"`
}
func (m *TestRequest) Reset() { *m = TestRequest{} }
func (m *TestRequest) String() string { return proto.CompactTextString(m) }
func (*TestRequest) ProtoMessage() {}
const Default_TestRequest_RepeatCount int32 = 1
func (m *TestRequest) GetLower() string {
if m != nil && m.Lower != nil {
return *m.Lower
}
return ""
}
func (m *TestRequest) GetRepeatCount() int32 {
if m != nil && m.RepeatCount != nil {
return *m.RepeatCount
}
return Default_TestRequest_RepeatCount
}
type TestResponse struct {
Value *string `protobuf:"bytes,1,opt,name=value" json:"value,omitempty"`
XXX_unrecognized []byte `json:"-"`
}
func (m *TestResponse) Reset() { *m = TestResponse{} }
func (m *TestResponse) String() string { return proto.CompactTextString(m) }
func (*TestResponse) ProtoMessage() {}
func (m *TestResponse) GetValue() string {
if m != nil && m.Value != nil {
return *m.Value
}
return ""
}
type CacheStats struct {
Items *int64 `protobuf:"varint,1,opt,name=items" json:"items,omitempty"`
Bytes *int64 `protobuf:"varint,2,opt,name=bytes" json:"bytes,omitempty"`
Gets *int64 `protobuf:"varint,3,opt,name=gets" json:"gets,omitempty"`
Hits *int64 `protobuf:"varint,4,opt,name=hits" json:"hits,omitempty"`
Evicts *int64 `protobuf:"varint,5,opt,name=evicts" json:"evicts,omitempty"`
XXX_unrecognized []byte `json:"-"`
}
func (m *CacheStats) Reset() { *m = CacheStats{} }
func (m *CacheStats) String() string { return proto.CompactTextString(m) }
func (*CacheStats) ProtoMessage() {}
func (m *CacheStats) GetItems() int64 {
if m != nil && m.Items != nil {
return *m.Items
}
return 0
}
func (m *CacheStats) GetBytes() int64 {
if m != nil && m.Bytes != nil {
return *m.Bytes
}
return 0
}
func (m *CacheStats) GetGets() int64 {
if m != nil && m.Gets != nil {
return *m.Gets
}
return 0
}
func (m *CacheStats) GetHits() int64 {
if m != nil && m.Hits != nil {
return *m.Hits
}
return 0
}
func (m *CacheStats) GetEvicts() int64 {
if m != nil && m.Evicts != nil {
return *m.Evicts
}
return 0
}
type StatsResponse struct {
Gets *int64 `protobuf:"varint,1,opt,name=gets" json:"gets,omitempty"`
CacheHits *int64 `protobuf:"varint,12,opt,name=cache_hits" json:"cache_hits,omitempty"`
Fills *int64 `protobuf:"varint,2,opt,name=fills" json:"fills,omitempty"`
TotalAlloc *uint64 `protobuf:"varint,3,opt,name=total_alloc" json:"total_alloc,omitempty"`
MainCache *CacheStats `protobuf:"bytes,4,opt,name=main_cache" json:"main_cache,omitempty"`
HotCache *CacheStats `protobuf:"bytes,5,opt,name=hot_cache" json:"hot_cache,omitempty"`
ServerIn *int64 `protobuf:"varint,6,opt,name=server_in" json:"server_in,omitempty"`
Loads *int64 `protobuf:"varint,8,opt,name=loads" json:"loads,omitempty"`
PeerLoads *int64 `protobuf:"varint,9,opt,name=peer_loads" json:"peer_loads,omitempty"`
PeerErrors *int64 `protobuf:"varint,10,opt,name=peer_errors" json:"peer_errors,omitempty"`
LocalLoads *int64 `protobuf:"varint,11,opt,name=local_loads" json:"local_loads,omitempty"`
XXX_unrecognized []byte `json:"-"`
}
func (m *StatsResponse) Reset() { *m = StatsResponse{} }
func (m *StatsResponse) String() string { return proto.CompactTextString(m) }
func (*StatsResponse) ProtoMessage() {}
func (m *StatsResponse) GetGets() int64 {
if m != nil && m.Gets != nil {
return *m.Gets
}
return 0
}
func (m *StatsResponse) GetCacheHits() int64 {
if m != nil && m.CacheHits != nil {
return *m.CacheHits
}
return 0
}
func (m *StatsResponse) GetFills() int64 {
if m != nil && m.Fills != nil {
return *m.Fills
}
return 0
}
func (m *StatsResponse) GetTotalAlloc() uint64 {
if m != nil && m.TotalAlloc != nil {
return *m.TotalAlloc
}
return 0
}
func (m *StatsResponse) GetMainCache() *CacheStats {
if m != nil {
return m.MainCache
}
return nil
}
func (m *StatsResponse) GetHotCache() *CacheStats {
if m != nil {
return m.HotCache
}
return nil
}
func (m *StatsResponse) GetServerIn() int64 {
if m != nil && m.ServerIn != nil {
return *m.ServerIn
}
return 0
}
func (m *StatsResponse) GetLoads() int64 {
if m != nil && m.Loads != nil {
return *m.Loads
}
return 0
}
func (m *StatsResponse) GetPeerLoads() int64 {
if m != nil && m.PeerLoads != nil {
return *m.PeerLoads
}
return 0
}
func (m *StatsResponse) GetPeerErrors() int64 {
if m != nil && m.PeerErrors != nil {
return *m.PeerErrors
}
return 0
}
func (m *StatsResponse) GetLocalLoads() int64 {
if m != nil && m.LocalLoads != nil {
return *m.LocalLoads
}
return 0
}
type Empty struct {
XXX_unrecognized []byte `json:"-"`
}
func (m *Empty) Reset() { *m = Empty{} }
func (m *Empty) String() string { return proto.CompactTextString(m) }
func (*Empty) ProtoMessage() {}
func init() {
}

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/*
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 testpb;
message TestMessage {
optional string name = 1;
optional string city = 2;
}
message TestRequest {
required string lower = 1; // to be returned upper case
optional int32 repeat_count = 2 [default = 1]; // .. this many times
}
message TestResponse {
optional string value = 1;
}
message CacheStats {
optional int64 items = 1;
optional int64 bytes = 2;
optional int64 gets = 3;
optional int64 hits = 4;
optional int64 evicts = 5;
}
message StatsResponse {
optional int64 gets = 1;
optional int64 cache_hits = 12;
optional int64 fills = 2;
optional uint64 total_alloc = 3;
optional CacheStats main_cache = 4;
optional CacheStats hot_cache = 5;
optional int64 server_in = 6;
optional int64 loads = 8;
optional int64 peer_loads = 9;
optional int64 peer_errors = 10;
optional int64 local_loads = 11;
}
message Empty {}
service GroupCacheTest {
rpc InitPeers(Empty) returns (Empty) {};
rpc Get(TestRequest) returns (TestResponse) {};
rpc GetStats(Empty) returns (StatsResponse) {};
}