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aememcache.go
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aememcache.go
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package aememcache
import (
"bytes"
"context"
"encoding/gob"
"time"
"go.mercari.io/datastore/v2"
"go.mercari.io/datastore/v2/dsmiddleware/storagecache"
"google.golang.org/appengine/v2"
"google.golang.org/appengine/v2/memcache"
)
var _ storagecache.Storage = &cacheHandler{}
var _ datastore.Middleware = &cacheHandler{}
// New AE Memcache middleware creates & returns.
func New(opts ...CacheOption) interface {
datastore.Middleware
storagecache.Storage
} {
ch := &cacheHandler{
stOpts: &storagecache.Options{},
}
for _, opt := range opts {
opt.Apply(ch)
}
s := storagecache.New(ch, ch.stOpts)
ch.Middleware = s
if ch.logf == nil {
ch.logf = func(ctx context.Context, format string, args ...interface{}) {}
}
if ch.cacheKey == nil {
ch.cacheKey = func(key datastore.Key) string {
return "mercari:aememcache:" + key.Encode()
}
}
return ch
}
type cacheHandler struct {
datastore.Middleware
stOpts *storagecache.Options
raiseMemcacheError bool
expireDuration time.Duration
logf func(ctx context.Context, format string, args ...interface{})
cacheKey func(key datastore.Key) string
}
// A CacheOption is an cache option for a AE Memcache middleware.
type CacheOption interface {
Apply(*cacheHandler)
}
func (ch *cacheHandler) SetMulti(ctx context.Context, cis []*storagecache.CacheItem) error {
ch.logf(ctx, "dsmiddleware/aememcache.SetMulti: incoming len=%d", len(cis))
itemList := make([]*memcache.Item, 0, len(cis))
for _, ci := range cis {
if ci.Key.Incomplete() {
panic("incomplete key incoming")
}
var buf bytes.Buffer
enc := gob.NewEncoder(&buf)
err := enc.Encode(ci.PropertyList)
if err != nil {
ch.logf(ctx, "dsmiddleware/aememcache.SetMulti: gob.Encode error key=%s err=%s", ci.Key.String(), err.Error())
continue
}
itemList = append(itemList, &memcache.Item{
Key: ch.cacheKey(ci.Key),
Value: buf.Bytes(),
Expiration: ch.expireDuration,
})
}
ch.logf(ctx, "dsmiddleware/aememcache.SetMulti: len=%d", len(itemList))
err := memcache.SetMulti(ctx, itemList)
if err != nil {
ch.logf(ctx, "dsmiddleware/aememcache: error on memcache.SetMulti %s", err.Error())
if ch.raiseMemcacheError {
if merr, ok := err.(appengine.MultiError); ok {
for _, err := range merr {
if err == nil || err == memcache.ErrCacheMiss {
continue
}
return merr
}
} else {
return err
}
}
keys := make([]string, 0, len(cis))
for _, ci := range cis {
keys = append(keys, ci.Key.Encode())
}
err = memcache.DeleteMulti(ctx, keys)
if err != nil {
ch.logf(ctx, "dsmiddleware/aememcache: error on memcache.DeleteMulti %s", err.Error())
if ch.raiseMemcacheError {
if merr, ok := err.(appengine.MultiError); ok {
for _, err := range merr {
if err == nil || err == memcache.ErrCacheMiss {
continue
}
return merr
}
} else {
return err
}
}
}
}
return nil
}
func (ch *cacheHandler) GetMulti(ctx context.Context, keys []datastore.Key) ([]*storagecache.CacheItem, error) {
ch.logf(ctx, "dsmiddleware/aememcache.GetMulti: incoming len=%d", len(keys))
resultList := make([]*storagecache.CacheItem, len(keys))
cacheKeys := make([]string, 0, len(keys))
for _, key := range keys {
cacheKeys = append(cacheKeys, ch.cacheKey(key))
}
itemMap, err := memcache.GetMulti(ctx, cacheKeys)
if err != nil {
ch.logf(ctx, "dsmiddleware/aememcache: error on memcache.GetMulti %s", err.Error())
if ch.raiseMemcacheError {
if merr, ok := err.(appengine.MultiError); ok {
for _, err := range merr {
if err == nil || err == memcache.ErrCacheMiss {
continue
}
return nil, datastore.MultiError(merr)
}
} else {
return nil, err
}
}
return resultList, nil
}
hit, miss := 0, 0
for idx, key := range keys {
item, ok := itemMap[ch.cacheKey(key)]
if !ok {
resultList[idx] = nil
miss++
continue
}
buf := bytes.NewBuffer(item.Value)
dec := gob.NewDecoder(buf)
var ps datastore.PropertyList
err = dec.Decode(&ps)
if err != nil {
resultList[idx] = nil
ch.logf(ctx, "dsmiddleware/aememcache.GetMulti: gob.Decode error key=%s err=%s", key.String(), err.Error())
miss++
continue
}
resultList[idx] = &storagecache.CacheItem{
Key: key,
PropertyList: ps,
}
hit++
}
ch.logf(ctx, "dsmiddleware/aememcache.GetMulti: hit=%d miss=%d", hit, miss)
return resultList, nil
}
func (ch *cacheHandler) DeleteMulti(ctx context.Context, keys []datastore.Key) error {
ch.logf(ctx, "dsmiddleware/aememcache.DeleteMulti: incoming len=%d", len(keys))
cacheKeys := make([]string, 0, len(keys))
for _, key := range keys {
cacheKeys = append(cacheKeys, ch.cacheKey(key))
}
err := memcache.DeleteMulti(ctx, cacheKeys)
if err != nil {
ch.logf(ctx, "dsmiddleware/aememcache: error on memcache.DeleteMulti %s", err.Error())
if ch.raiseMemcacheError {
if merr, ok := err.(appengine.MultiError); ok {
for _, err := range merr {
if err == nil || err == memcache.ErrCacheMiss {
continue
}
return merr
}
} else {
return err
}
}
}
return nil
}