Fix bugs in impl/memory queries.

impl/memory/gkvlite_iter.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 memory
 
 import (
         "bytes"
         "sync"
 
@@ skipping 47 matching lines @@
         for {
                 stop := false
                 restart := false
 
                 for idx, it := range ts {
                         if skip >= 0 && skip == idx {
                                 continue
                         }
                         def := defs[idx]
 
-                        it.next(serialize.Join(def.prefix, suffix), func(itm *gkvlite.Item) {
+                        pfxLen := prefixLens[idx]
+                        it.next(serialize.Join(def.prefix[:pfxLen], suffix), func(itm *gkvlite.Item) {
                                 if itm == nil {
                                         // we hit the end of an iterator, we're now done with the whole
                                         // query.
                                         stop = true
                                         return
                                 }
 
-                                sfxRO := itm.Key[prefixLens[idx]:]
+                                sfxRO := itm.Key[pfxLen:]
 
                                 if bytes.Compare(sfxRO, suffix) > 0 {
                                         // this row has a higher suffix than anything we've seen before. Set
                                         // ourself to be the skip, and resart this loop from the top.
                                         suffix = append(suffix[:0], sfxRO...)
                                         skip = idx
                                         if idx != 0 {
                                                 // no point to restarting on the 0th index
                                                 restart = true
                                         }
@@ skipping 119 matching lines @@
         t.ch <- &cmd{targ, func(i *gkvlite.Item) {
                 defer close(waiter)
 
                 if i == nil {
                         t.stop()
                 }
                 cb(i)
         }}
         <-waiter
 }