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// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package bigquery
import (
"math/rand"
"os"
"sync"
"time"
)
// Support for random values (typically job IDs and insert IDs).
const alphanum = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
var (
rngMu sync.Mutex
rng = rand.New(rand.NewSource(time.Now().UnixNano() ^ int64(os.Getpid())))
)
// For testing.
var randomIDFn = randomID
// As of August 2017, the BigQuery service uses 27 alphanumeric characters for
// suffixes.
const randomIDLen = 27
func randomID() string {
// This is used for both job IDs and insert IDs.
var b [randomIDLen]byte
rngMu.Lock()
for i := 0; i < len(b); i++ {
b[i] = alphanum[rng.Intn(len(alphanum))]
}
rngMu.Unlock()
return string(b[:])
}
// Seed seeds this package's random number generator, used for generating job and
// insert IDs. Use Seed to obtain repeatable, deterministic behavior from bigquery
// clients. Seed should be called before any clients are created.
func Seed(s int64) {
rng = rand.New(rand.NewSource(s))
}
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