Golang datastore.RunInTransaction函数代码示例

// Increment increments the named counter.
func Increment(c appengine.Context, name string) error {
    // Get counter config.
    var cfg counterConfig
    ckey := datastore.NewKey(c, configKind, name, 0, nil)
    err := datastore.RunInTransaction(c, func(c appengine.Context) error {
        err := datastore.Get(c, ckey, &cfg)
        if err == datastore.ErrNoSuchEntity {
            cfg.Shards = defaultShards
            _, err = datastore.Put(c, ckey, &cfg)
        }
        return err
    }, nil)
    if err != nil {
        return err
    }
    err = datastore.RunInTransaction(c, func(c appengine.Context) error {
        shardName := fmt.Sprintf("%v%d", name, rand.Intn(cfg.Shards))
        key := datastore.NewKey(c, shardKind, shardName, 0, nil)
        var s shard
        err := datastore.Get(c, key, &s)
        // A missing entity and a present entity will both work.
        if err != nil && err != datastore.ErrNoSuchEntity {
            return err
        }
        s.Count++
		s.Name = name
        _, err = datastore.Put(c, key, &s)
        return err
    }, nil)
    if err != nil {
        return err
    }
    //memcache.Increment(c, memcacheKey(name), 1, 0)
    return nil
}

// Increment increments the named counter.
func Increment(c appengine.Context, valName string) error {

	// Get counter config.
	wNumShards := dsu.WrapInt{}
	dsu.McacheGet(c, mCKNumShards(valName), &wNumShards)
	if wNumShards.I < 1 {
		ckey := datastore.NewKey(c, dsKindNumShards, mCKNumShards(valName), 0, nil)
		errTx := datastore.RunInTransaction(c,
			func(c appengine.Context) error {
				err := datastore.Get(c, ckey, &wNumShards)
				if err == datastore.ErrNoSuchEntity {
					wNumShards.I = defaultNumShards
					_, err = datastore.Put(c, ckey, &wNumShards)
				}
				return err
			}, nil)
		if errTx != nil {
			return errTx
		}
		dsu.McacheSet(c, mCKNumShards(valName), dsu.WrapInt{wNumShards.I})
	}

	// pick random counter and increment it
	errTx := datastore.RunInTransaction(c,
		func(c appengine.Context) error {
			shardId := rand.Intn(wNumShards.I)
			dsKey := datastore.NewKey(c, dsKindShard, dSKSingleShard(valName, shardId), 0, nil)
			var sd WrapShardData
			err := datastore.Get(c, dsKey, &sd)
			// A missing entity and a present entity will both work.
			if err != nil && err != datastore.ErrNoSuchEntity {
				return err
			}
			sd.Name = valName
			sd.ShardId = shardId
			sd.I++
			_, err = datastore.Put(c, dsKey, &sd)
			c.Infof("ds put %v %v", dsKey, sd)
			return err
		}, nil)
	if errTx != nil {
		return errTx
	}

	memcache.Increment(c, mCKValue(valName), 1, 0)

	// collect number of updates
	//    per valName per instance in memory
	//    for every interval of 10 minutes
	//
	//  a batch job checks if the number of shards should be increased or decreased
	//    and truncates this map
	updateSamplingFrequency[valName+util.TimeMarker()[:len("2006-01-02 15:0")]] += 1

	return nil
}

// commitHandler retrieves commit data or records a new commit.
//
// For GET requests it returns a Commit value for the specified
// packagePath and hash.
//
// For POST requests it reads a JSON-encoded Commit value from the request
// body and creates a new Commit entity. It also updates the "tip" Tag for
// each new commit at tip.
//
// This handler is used by a gobuilder process in -commit mode.
func commitHandler(r *http.Request) (interface{}, error) {
	c := appengine.NewContext(r)
	com := new(Commit)

	if r.Method == "GET" {
		com.PackagePath = r.FormValue("packagePath")
		com.Hash = r.FormValue("hash")
		if err := datastore.Get(c, com.Key(c), com); err != nil {
			return nil, fmt.Errorf("getting Commit: %v", err)
		}
		return com, nil
	}
	if r.Method != "POST" {
		return nil, errBadMethod(r.Method)
	}

	// POST request
	defer r.Body.Close()
	if err := json.NewDecoder(r.Body).Decode(com); err != nil {
		return nil, fmt.Errorf("decoding Body: %v", err)
	}
	if len(com.Desc) > maxDatastoreStringLen {
		com.Desc = com.Desc[:maxDatastoreStringLen]
	}
	if err := com.Valid(); err != nil {
		return nil, fmt.Errorf("validating Commit: %v", err)
	}
	defer cache.Tick(c)
	tx := func(c appengine.Context) error {
		return addCommit(c, com)
	}
	return nil, datastore.RunInTransaction(c, tx, nil)
}

// method to import from JSON read with the file reader
func importFile(c *context, file io.Reader) {
	// run in a transaction so that each datastore write doesn't redo the index,
	//  rather all the indecies get updated at once when we're done
	datastore.RunInTransaction(c.c, func(tc appengine.Context) error {
		// decode the data
		decoder := json.NewDecoder(file)
		data := backup{}
		err := decoder.Decode(&data)
		check(err)
		// setup a worker to do the work
		worker := &importer{
			context:           *c,
			jsonData:          data,
			fixUpKeys:         make(map[string]*datastore.Key),
			allTags:           make(map[string]map[string]bool),
			newTags:           make([]interface{}, 0, 100),
			newTagKeys:        make([]*datastore.Key, 0, 100),
			dirtyCacheEntries: make([]string, 0, 1000),
		}
		worker.c = tc
		// kick off the import
		worker.doImport()
		return nil
	}, nil)
}

func SetPlayerName(w http.ResponseWriter, r *http.Request) {
	c := appengine.NewContext(r)
	seasonName := r.FormValue("SeasonName")
	seasonYear := r.FormValue("SeasonYear")
	playerId := r.FormValue("PlayerId")
	newPlayerName := r.FormValue("NewPlayerName")
	c.Infof("Replaceing '%v' with '%v' for season '%v' '%v'", playerId, newPlayerName, seasonName, seasonYear)
	var season *model.Season
	if seasonName == "" || seasonYear == "" {
		c.Infof("Lookup season")
		tmpSeason := api.GetActiveSeasonWithContext(c)
		season = &tmpSeason
	} else {
		season = api.LoadSeasonByNameYear(c, seasonName, seasonYear)
	}
	players := season.GetPlayers(c)
	targetIndex := playerIndex(players, playerId)
	replacePlayer := players[targetIndex]
	replacePlayer.Name = newPlayerName
	season.Schedule = []byte(strings.Replace(string(season.Schedule), playerId, newPlayerName, -1))
	season.Conferences = []byte(strings.Replace(string(season.Conferences), playerId, newPlayerName, -1))
	pkey := model.PlayerKey(c, season.Name, season.Year, newPlayerName)
	season.Players[targetIndex] = pkey
	err := datastore.RunInTransaction(c, func(c appengine.Context) error {
		model.SavePlayer(c, season, replacePlayer)
		err := model.SaveSeason(c, *season)
		return err
	}, nil)
	if err != nil {
		panic(err)
	}
}

// Transactions in phase FINISHED will cause the price to be credited on the seller's
// account, and the fee to be deducted.
// All other phases will lead to price and fee being reimbursed to the buyer.
// Returns ErrTransactionTooYoung if the transaction has not passed its timout at the
// time of the call.
// Returns ErrTransactionAlreadyRetired if the transaction has already been retired at
// the time of the call.
func RetireTransaction(c appengine.Context, key *datastore.Key) error {
	f := func(c appengine.Context) error {
		now := time.Now()
		dao := NewGaeAccountingDao(c, true)
		var tx Transaction
		if err := datastore.Get(c, key, txCodec{&tx}); err != nil {
			return err
		}

		if err := tx.Retire(dao, key.Encode(), now); err == ErrTooYoung {
			return ErrTransactionTooYoung
		} else if err == ErrAlreadyRetired {
			return ErrTransactionAlreadyRetired
		} else if err != nil {
			return err
		}

		if _, err := datastore.Put(c, key, txCodec{&tx}); err != nil {
			return err
		}

		return dao.Flush()
	}

	return datastore.RunInTransaction(c, f, &datastore.TransactionOptions{XG: true})
}

// This will reimburse the bid's price and fee to the buyer.
func RetireBid(c appengine.Context, key *datastore.Key) error {
	f := func(c appengine.Context) error {
		now := time.Now()
		dao := NewGaeAccountingDao(c, true)
		var bid Bid
		if err := datastore.Get(c, key, bidCodec{&bid}); err != nil {
			return err
		}

		if bid.State == Matched {
			c.Infof("Not retiring matched bid %v", key)
			return nil
		}

		if err := bid.Retire(dao, key.Encode(), now); err != nil {
			return err
		}

		if _, err := datastore.Put(c, key, bidCodec{&bid}); err != nil {
			return err
		}

		return dao.Flush()
	}

	if err := datastore.RunInTransaction(c, f, &datastore.TransactionOptions{XG: true}); err != nil {
		return err
	}

	return nil
}

// RefreshFeed fetches and updates a feed from the remote source,
// stores it's info and articles in the datastore, and removes old articles
// (those not retrieved on the latest fetch).
func (f *FeedInfo) refresh(c appengine.Context) error {
	fnew, articles, fetchErr := f.readSource(c)

	err := datastore.RunInTransaction(c, func(c appengine.Context) error {
		var stored FeedInfo
		key := datastore.NewKey(c, feedKind, f.Url, 0, nil)
		err := fixMissingFieldError(datastore.Get(c, key, &stored))
		if err != nil && err != datastore.ErrNoSuchEntity {
			return err
		}
		if fetchErr != nil {
			*f = stored
			f.LastFetch = time.Now()
		} else {
			*f = fnew
		}
		f.Refs = stored.Refs
		_, err = datastore.Put(c, key, f)
		return err
	}, nil)
	if fetchErr != nil {
		return fetchErr
	}
	if err != nil {
		return err
	}

	return f.updateArticles(c, articles)
}

func sit(w http.ResponseWriter, r *http.Request) {
	c := appengine.NewContext(r)
	u := user.Current(c)
	id := r.FormValue("id")
	g, err := poker.LoadGame(id, r)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}
	err = datastore.RunInTransaction(c, func(c appengine.Context) error {
		name := r.FormValue("name")
		if name == "" {
			return errors.New("Please choose a name")
		}
		return g.Sit(u.Email, name)
	}, nil)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	if err = g.Save(r); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	err = broadcastState(c, g)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
}

func addAtom(c appengine.Context, url string) error {
	feedRoot := datastore.NewKey(c, "feedRoot", "feedRoot", 0, nil)
	fk := datastore.NewKey(c, "feed", url, 0, feedRoot)
	err := datastore.RunInTransaction(c, func(c appengine.Context) error {
		done, err := exists(c, fk)
		if err != nil {
			return err
		}
		if !done {
			f, err := fetchAtom(c, url)
			if err != nil {
				return err
			}
			_, err = datastore.Put(c, fk, f)
			if err != nil {
				return err
			}
			err = f.update(c, fk)
			if err != nil {
				return err
			}
			return nil
		}
		return nil
	}, nil)
	if err != nil {
		return err
	}
	return subscribe(c, fk, true)
}

// TODO(dlluncor): Merge this with ChangeGame as they are the same except for the key
// and the type of the changeEntityFunc, and the defaultLounge() thing.
// Utility function for reading from and updating a game before then
// doing further processing.
func ChangeLounge(c appengine.Context, loungeId string, clf changeLoungeFunc) *MyLounge {
	// Store all tables as part of the game state and send
	// a "startTimer" response.
	loungeKey := loungeId
	l := defaultLounge()
	err := datastore.RunInTransaction(c, func(c appengine.Context) error {
		k := datastore.NewKey(c, "WrLounge", loungeKey, 0, nil)
		if err := datastore.Get(c, k, l); err != nil {
			return err
		}

		// Perform special logic here to manipulate game.
		shouldRunUpdate := clf(l)
		if !shouldRunUpdate {
			// Sometimes we don't need to update the database so don't.
			return nil
		}

		if _, err := datastore.Put(c, k, l); err != nil {
			return err
		}
		return nil
	}, nil)

	if err != nil {
		c.Errorf("Err in db transaction %v", err)
	}
	return l
}

func createLounge(w http.ResponseWriter, r *http.Request) {
	c := appengine.NewContext(r)
	queryMap := r.URL.Query()
	loungeName := queryMap.Get("l")
	gamesStr := queryMap.Get("g")
	games := strings.Split(gamesStr, ",")
	l := defaultLounge()
	l.Name = loungeName
	l.Games = games
	addLoungeNameDb(c, loungeName)
	// Create the lounges.
	err := datastore.RunInTransaction(c, func(c appengine.Context) error {
		k := datastore.NewKey(c, "WrLounge", loungeName, 0, nil)
		if _, err := datastore.Put(c, k, l); err != nil {
			return err
		}
		return nil
	}, nil)
	if err != nil {
		fmt.Fprintf(w, "Error creating a lounge: %v", err)
	} else {
		fmt.Fprintf(w, "Success in creating lounge: %v with games: %s", loungeName, games)
	}
	// Create the games as well.
	lang := queryMap.Get("lang")
	for _, tableKey := range games {
		g := defaultGame()
		g.Language = lang
		createGame(c, tableKey, g)
	}
}

func tx(w http.ResponseWriter, r *http.Request) {
	c := appengine.NewContext(r)

	// start tx OMIT
	key := datastore.NewKey(c, "Book", "book1", 0, nil) // HL

	if err := datastore.RunInTransaction(c, func(c appengine.Context) error { // HL
		var book Book
		if err := datastore.Get(c, key, &book); err != nil { // HL
			return err
		}

		book.Price += 200

		if _, err := datastore.Put(c, key, &book); err != nil { // HL
			return err
		}

		return nil
	}, nil); err != nil { // HL
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	// end tx OMIT

	w.Write([]byte("success"))
}

// Claim attempts to uniquely associate the user and email.
func (e *ClaimedEmail) Claim(c appengine.Context) error {
	err := datastore.RunInTransaction(c, func(c appengine.Context) error {
		key := e.key(c)
		old := &ClaimedEmail{}
		lookupErr := datastore.Get(c, key, old)
		switch {
		case lookupErr == nil:
			return ErrEmailAlreadyClaimed
		case lookupErr == datastore.ErrNoSuchEntity:
			// Didn't find old claim: all is well.
			break
		default:
			return lookupErr
		}

		if _, storeErr := datastore.Put(c, key, e); storeErr != nil {
			return storeErr
		}
		return nil
	}, nil)
	if err != nil {
		return err
	}
	return nil
}

// RewriteID transactionally rewrites the Account under the
// correct (i.e., obfuscated) key.
func (a *Account) RewriteID(c appengine.Context, u *user.User) error {
	var err error
	a.ID, err = ID(u)
	if err != nil {
		return fmt.Errorf("couldn't create ID for %v", u)
	}
	var txnErr error
	for i := 0; i < 10; i++ {
		txnErr = datastore.RunInTransaction(c, func(c appengine.Context) error {
			if err := a.Put(c); err != nil {
				return err
			}
			oldKey := datastore.NewKey(c, "UserAccount", u.ID, 0, nil)
			if err := datastore.Delete(c, oldKey); err != nil {
				return err
			}
			return nil
		}, &datastore.TransactionOptions{XG: true})
		if txnErr != datastore.ErrConcurrentTransaction {
			break
		}
	}
	if txnErr != nil {
		return txnErr
	}
	return nil
}