rclone/fs/accounting/accounting_unix.go

// Accounting and limiting reader
// Unix specific functions.

//go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
// +build darwin dragonfly freebsd linux netbsd openbsd solaris

package accounting

import (
	"os"
	"os/signal"
	"syscall"

	"github.com/rclone/rclone/fs"
)

// startSignalHandler() sets a signal handler to catch SIGUSR2 and toggle throttling.
func (tb *tokenBucket) startSignalHandler() {
	signals := make(chan os.Signal, 1)
	signal.Notify(signals, syscall.SIGUSR2)

	go func() {
		// This runs forever, but blocks until the signal is received.
		for {
			<-signals
			tb.mu.Lock()
			tb.toggledOff = !tb.toggledOff
			tb.curr, tb.prev = tb.prev, tb.curr
			s := "disabled"
			if !tb.curr._isOff() {
				s = "enabled"
			}
			tb.mu.Unlock()
			fs.Logf(nil, "Bandwidth limit %s by user", s)
		}
	}()
}