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local.go
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local.go
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// Copyright (c) 2018 Ashley Jeffs
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package ratelimit
import (
"errors"
"fmt"
"sync"
"time"
"github.com/Jeffail/benthos/lib/log"
"github.com/Jeffail/benthos/lib/metrics"
"github.com/Jeffail/benthos/lib/types"
)
//------------------------------------------------------------------------------
func init() {
Constructors[TypeLocal] = TypeSpec{
constructor: NewLocal,
description: `
The local rate limit is a simple X every Y type rate limit that can be shared
across any number of components within the pipeline.`,
}
}
//------------------------------------------------------------------------------
// LocalConfig is a config struct containing rate limit fields for a local rate
// limit.
type LocalConfig struct {
Count int `json:"count" yaml:"count"`
Interval string `json:"interval" yaml:"interval"`
}
// NewLocalConfig returns a local rate limit configuration struct with default
// values.
func NewLocalConfig() LocalConfig {
return LocalConfig{
Count: 1000,
Interval: "1s",
}
}
//------------------------------------------------------------------------------
// Local is a structure that tracks a rate limit, it can be shared across
// parallel processes in order to maintain a maximum rate of a protected
// resource.
type Local struct {
mut sync.Mutex
bucket int
lastRefresh time.Time
size int
period time.Duration
}
// NewLocal creates a local rate limit from a configuration struct. This type is
// safe to share and call from parallel goroutines.
func NewLocal(
conf Config,
mgr types.Manager,
logger log.Modular,
stats metrics.Type,
) (types.RateLimit, error) {
if conf.Local.Count <= 0 {
return nil, errors.New("count must be larger than zero")
}
period, err := time.ParseDuration(conf.Local.Interval)
if err != nil {
return nil, fmt.Errorf("failed to parse interval: %v", err)
}
return &Local{
bucket: conf.Local.Count,
lastRefresh: time.Now(),
size: conf.Local.Count,
period: period,
}, nil
}
//------------------------------------------------------------------------------
// Access the rate limited resource. Returns a duration or an error if the rate
// limit check fails. The returned duration is either zero (meaning the resource
// can be accessed) or a reasonable length of time to wait before requesting
// again.
func (r *Local) Access() (time.Duration, error) {
r.mut.Lock()
r.bucket--
if r.bucket < 0 {
r.bucket = 0
remaining := r.period - time.Since(r.lastRefresh)
if remaining > 0 {
r.mut.Unlock()
return remaining, nil
}
r.bucket = r.size - 1
r.lastRefresh = time.Now()
}
r.mut.Unlock()
return 0, nil
}
//------------------------------------------------------------------------------