Reland: Refactor current GAE abstraction library to be free of the SDK*

go/src/infra/gae/libs/wrapper/memory/gkvlite_utils.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"
-        "runtime"
-        "sync"
-
-        "github.com/luci/gkvlite"
-)
-
-func gkvCollide(o, n *memCollection, f func(k, ov, nv []byte)) {
-        oldItems, newItems := make(chan *gkvlite.Item), make(chan *gkvlite.Item)
-        walker := func(c *memCollection, ch chan<- *gkvlite.Item, wg *sync.WaitGroup) {
-                defer close(ch)
-                defer wg.Done()
-                if c != nil {
-                        c.VisitItemsAscend(nil, true, func(i *gkvlite.Item) bool {
-                                ch <- i
-                                return true
-                        })
-                }
-        }
-
-        wg := &sync.WaitGroup{}
-        wg.Add(2)
-        go walker(o, oldItems, wg)
-        go walker(n, newItems, wg)
-
-        l, r := <-oldItems, <-newItems
-        for {
-                if l == nil && r == nil {
-                        break
-                }
-
-                if l == nil {
-                        f(r.Key, nil, r.Val)
-                        r = <-newItems
-                } else if r == nil {
-                        f(l.Key, l.Val, nil)
-                        l = <-oldItems
-                } else {
-                        switch bytes.Compare(l.Key, r.Key) {
-                        case -1: // l < r
-                                f(l.Key, l.Val, nil)
-                                l = <-oldItems
-                        case 0: // l == r
-                                f(l.Key, l.Val, r.Val)
-                                l, r = <-oldItems, <-newItems
-                        case 1: // l > r
-                                f(r.Key, nil, r.Val)
-                                r = <-newItems
-                        }
-                }
-        }
-        wg.Wait()
-}
-
-// memStore is a gkvlite.Store which will panic for anything which might
-// otherwise return an error.
-//
-// This is reasonable for in-memory Store objects, since the only errors that
-// should occur happen with file IO on the underlying file (which of course
-// doesn't exist).
-type memStore gkvlite.Store
-
-func newMemStore() *memStore {
-        ret, err := gkvlite.NewStore(nil)
-        if err != nil {
-                panic(err)
-        }
-        return (*memStore)(ret)
-}
-
-func (ms *memStore) Snapshot() *memStore {
-        ret := (*memStore)((*gkvlite.Store)(ms).Snapshot())
-        runtime.SetFinalizer((*gkvlite.Store)(ret), func(s *gkvlite.Store) {
-                go s.Close()
-        })
-        return ret
-}
-
-func (ms *memStore) MakePrivateCollection(cmp gkvlite.KeyCompare) *memCollection {
-        return (*memCollection)((*gkvlite.Store)(ms).MakePrivateCollection(cmp))
-}
-
-func (ms *memStore) GetCollection(name string) *memCollection {
-        return (*memCollection)((*gkvlite.Store)(ms).GetCollection(name))
-}
-
-func (ms *memStore) SetCollection(name string, cmp gkvlite.KeyCompare) *memCollection {
-        return (*memCollection)((*gkvlite.Store)(ms).SetCollection(name, cmp))
-}
-
-func (ms *memStore) RemoveCollection(name string) {
-        (*gkvlite.Store)(ms).RemoveCollection(name)
-}
-
-func (ms *memStore) GetCollectionNames() []string {
-        return (*gkvlite.Store)(ms).GetCollectionNames()
-}
-
-// memCollection is a gkvlite.Collection which will panic for anything which
-// might otherwise return an error.
-//
-// This is reasonable for in-memory Store objects, since the only errors that
-// should occur happen with file IO on the underlying file (which of course
-// doesn't exist.
-type memCollection gkvlite.Collection
-
-func (mc *memCollection) Get(k []byte) []byte {
-        ret, err := (*gkvlite.Collection)(mc).Get(k)
-        if err != nil {
-                panic(err)
-        }
-        return ret
-}
-
-func (mc *memCollection) MinItem(withValue bool) *gkvlite.Item {
-        ret, err := (*gkvlite.Collection)(mc).MinItem(withValue)
-        if err != nil {
-                panic(err)
-        }
-        return ret
-}
-
-func (mc *memCollection) Set(k, v []byte) {
-        if err := (*gkvlite.Collection)(mc).Set(k, v); err != nil {
-                panic(err)
-        }
-}
-
-func (mc *memCollection) Delete(k []byte) bool {
-        ret, err := (*gkvlite.Collection)(mc).Delete(k)
-        if err != nil {
-                panic(err)
-        }
-        return ret
-}
-
-func (mc *memCollection) VisitItemsAscend(target []byte, withValue bool, visitor gkvlite.ItemVisitor) {
-        if err := (*gkvlite.Collection)(mc).VisitItemsAscend(target, withValue, visitor); err != nil {
-                panic(err)
-        }
-}
-
-func (mc *memCollection) GetTotals() (numItems, numBytes uint64) {
-        numItems, numBytes, err := (*gkvlite.Collection)(mc).GetTotals()
-        if err != nil {
-                panic(err)
-        }
-        return
-}