dscache: Only log unusual memcache errors.

filter/dscache/ds_txn_state.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package dscache
 
 import (
         "sync"
 
         "github.com/luci/gae/service/datastore"
         "github.com/luci/gae/service/memcache"
+        "github.com/luci/luci-go/common/errors"
         log "github.com/luci/luci-go/common/logging"
 )
 
 type dsTxnState struct {
         sync.Mutex
 
         toLock   []memcache.Item
         toDelete map[string]struct{}
 }
 
@@ skipping 31 matching lines @@
 // they'll expire soon).
 func (s *dsTxnState) release(sc *supportContext) {
         s.Lock()
         defer s.Unlock()
 
         delKeys := make([]string, 0, len(s.toDelete))
         for k := range s.toDelete {
                 delKeys = append(delKeys, k)
         }
 
-        err := sc.mc.DeleteMulti(delKeys)
-        if err != nil {
+        if err := errors.Filter(sc.mc.DeleteMulti(delKeys), memcache.ErrCacheMiss); err != nil {
                 (log.Fields{log.ErrorKey: err}).Warningf(
                         sc.c, "dscache: txn.release: memcache.DeleteMulti")
         }
 }
 
 func (s *dsTxnState) add(sc *supportContext, keys []*datastore.Key) {
         lockItems, lockKeys := sc.mkAllLockItems(keys)
         if lockItems == nil {
                 return
         }
 
         s.Lock()
         defer s.Unlock()
 
         for i, li := range lockItems {
                 k := lockKeys[i]
                 if _, ok := s.toDelete[k]; !ok {
                         s.toLock = append(s.toLock, li)
                         s.toDelete[k] = struct{}{}
                 }
         }
 }