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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
package ratelimit
import (
"math"
"net/http"
"time"
"github.com/philippta/flyscrape"
)
func init() {
flyscrape.RegisterModule(Module{})
}
type Module struct {
Rate int `json:"rate"`
Concurrency int `json:"concurrency"`
ticker *time.Ticker
ratelimit chan struct{}
concurrency chan struct{}
}
func (Module) ModuleInfo() flyscrape.ModuleInfo {
return flyscrape.ModuleInfo{
ID: "ratelimit",
New: func() flyscrape.Module { return new(Module) },
}
}
func (m *Module) Provision(v flyscrape.Context) {
if m.rateLimitEnabled() {
rate := time.Duration(float64(time.Minute) / float64(m.Rate))
m.ticker = time.NewTicker(rate)
m.ratelimit = make(chan struct{}, int(math.Max(float64(m.Rate)/10, 1)))
go func() {
m.ratelimit <- struct{}{}
for range m.ticker.C {
m.ratelimit <- struct{}{}
}
}()
}
if m.concurrencyEnabled() {
m.concurrency = make(chan struct{}, m.Concurrency)
for i := 0; i < m.Concurrency; i++ {
m.concurrency <- struct{}{}
}
}
}
func (m *Module) AdaptTransport(t http.RoundTripper) http.RoundTripper {
return flyscrape.RoundTripFunc(func(r *http.Request) (*http.Response, error) {
if m.rateLimitEnabled() {
<-m.ratelimit
}
if m.concurrencyEnabled() {
<-m.concurrency
defer func() { m.concurrency <- struct{}{} }()
}
return t.RoundTrip(r)
})
}
func (m *Module) Finalize() {
if m.rateLimitEnabled() {
m.ticker.Stop()
}
}
func (m *Module) rateLimitEnabled() bool {
return m.Rate != 0
}
func (m *Module) concurrencyEnabled() bool {
return m.Concurrency > 0
}
var (
_ flyscrape.TransportAdapter = (*Module)(nil)
_ flyscrape.Provisioner = (*Module)(nil)
_ flyscrape.Finalizer = (*Module)(nil)
)
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