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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 (
"net/http"
"time"
"github.com/philippta/flyscrape"
)
func init() {
flyscrape.RegisterModule(Module{})
}
type Module struct {
Rate float64 `json:"rate"`
ticker *time.Ticker
semaphore 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.disabled() {
return
}
rate := time.Duration(float64(time.Second) / m.Rate)
m.ticker = time.NewTicker(rate)
m.semaphore = make(chan struct{}, 1)
go func() {
for range m.ticker.C {
m.semaphore <- struct{}{}
}
}()
}
func (m *Module) AdaptTransport(t http.RoundTripper) http.RoundTripper {
if m.disabled() {
return t
}
return flyscrape.RoundTripFunc(func(r *http.Request) (*http.Response, error) {
<-m.semaphore
return t.RoundTrip(r)
})
}
func (m *Module) Finalize() {
if m.disabled() {
return
}
m.ticker.Stop()
}
func (m *Module) disabled() bool {
return m.Rate == 0
}
var (
_ flyscrape.TransportAdapter = (*Module)(nil)
_ flyscrape.Provisioner = (*Module)(nil)
_ flyscrape.Finalizer = (*Module)(nil)
)
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