You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: worker.go
    path of file: ./repos/juju/worker/modelcache
    
    the code of the file until where you have to start completion: // Copyright 2018 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.

package modelcache

import (
	"sync"
	"time"

	"github.com/juju/clock"
	"github.com/juju/errors"
	"github.com/juju/worker/v3"
	"github.com/juju/worker/v3/catacomb"
	"github.com/kr/pretty"
	"github.com/prometheus/client_golang/prometheus"

	"github.com/juju/juju/core/cache"
	"github.com/juju/juju/core/lxdprofile"
	"github.com/juju/juju/core/multiwatcher"
	"github
    
func (c *cacheWorker) handleWatcherErr(err error) {
	// If the backing watcher has stopped and the watcher's tomb
	// error is nil, this means a legitimate clean stop. If we have
	// been told to die, then we exit cleanly. Otherwise die with an
	// error and let the dependency engine handle starting us up
	// again.
	if multiwatcher.IsErrStopped(err) {
		select {
		case <-c.catacomb.Dying():
			return
		default:
			c.catacomb.Kill(err)
			return
		}
	}

	// For any other errors close the watcher, which will cause us
	// to create a new one after the restart delay.
	select {
	case <-c.catacomb.Dying():
		return
	case <-c.config.Clock.After(c.watcherRestartDelay):
		// The restart delay increases exponentially until we hit the max.
		c.watcherRestartDelay = c.watcherRestartDelay * 2
		if c.watcherRestartDelay > c.config.WatcherRestartDelayMax {
			c.watcherRestartDelay = c.config.WatcherRestartDelayMax
		}

		c.config.Logger.Errorf("watcher error: %v, getting new watcher", err)
		_ = c.watcher.Stop()
	}
}