/
config.go
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/
config.go
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// Copyright (c) Facebook, Inc. and its affiliates.
//
// 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 client
import (
"flag"
"fmt"
"regexp"
"time"
)
var userAgentRe = regexp.MustCompile("^[[:ascii:]]+$")
// Config is used to configure a client
type Config struct {
UserAgent string
numRetries int
retryDelay time.Duration
retryPolicy RetryPolicy
requestsPerPeriod int
period time.Duration
}
// AddFlags adds flags used to configure a client
func (conf *Config) AddFlags() {
flag.StringVar(&conf.UserAgent, "user-agent", conf.UserAgent, "which user agent to use when making requests")
flag.IntVar(&conf.numRetries, "num-retries", 0, "how many times will specified statuses get retried. 0 means no retries")
// TODO implement exponential backoff (for some statuses?)
flag.DurationVar(&conf.retryDelay, "retry-delay", time.Second, "delay between each retry")
flag.Var(&conf.retryPolicy, "retry", "which http statuses to retry. empty string means no retries, all means retry all, or provide a comma separated list of status codes")
flag.IntVar(&conf.requestsPerPeriod, "requests-per-period", 0, "how many requests per period to make. 0 means no throttling")
flag.DurationVar(&conf.period, "period", time.Second, "period in which requests are capped by the requests-per-period flag")
}
func (conf *Config) Validate() error {
if conf.UserAgent == "" {
return fmt.Errorf("need to specify user agent")
}
if !userAgentRe.MatchString(conf.UserAgent) {
return fmt.Errorf("User-Agent contains non ascii characters")
}
return nil
}
// Configure configures the given client (add throttling, retries, ...)
func (conf *Config) Configure(c Client) Client {
if conf.numRetries > 0 {
c = WithRetries(c, conf.numRetries, conf.retryDelay, conf.retryPolicy)
}
if conf.requestsPerPeriod > 0 {
c = WithThrottling(c, conf.period, conf.requestsPerPeriod)
}
if conf.UserAgent != "" {
c = WithUserAgent(c, conf.UserAgent)
}
return c
}