| // 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)) |
| } |