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group.go
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group.go
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// Copyright (C) 2020 Storj Labs, Inc.
// See LICENSE for copying information.
// Package lifecycle allows controlling group of items.
package lifecycle
import (
"context"
"github.com/spacemonkeygo/monkit/v3"
"github.com/zeebo/errs"
"go.uber.org/zap"
"golang.org/x/sync/errgroup"
"storj.io/common/errs2"
)
var mon = monkit.Package()
// Group implements a collection of items that have a
// concurrent start and are closed in reverse order.
type Group struct {
log *zap.Logger
items []Item
}
// Item is the lifecycle item that group runs and closes.
type Item struct {
Name string
Run func(ctx context.Context) error
Close func() error
}
// NewGroup creates a new group.
func NewGroup(log *zap.Logger) *Group {
return &Group{log: log}
}
// Add adds item to the group.
func (group *Group) Add(item Item) {
group.items = append(group.items, item)
}
// Run starts all items concurrently under group g.
func (group *Group) Run(ctx context.Context, g *errgroup.Group) {
defer mon.Task()(&ctx)(nil)
var started []string
for _, item := range group.items {
item := item
started = append(started, item.Name)
if item.Run == nil {
continue
}
g.Go(func() error {
return errs2.IgnoreCanceled(item.Run(ctx))
})
}
group.log.Debug("started", zap.Strings("items", started))
}
// Close closes all items in reverse order.
func (group *Group) Close() error {
var errlist errs.Group
for i := len(group.items) - 1; i >= 0; i-- {
item := group.items[i]
if item.Close == nil {
continue
}
errlist.Add(item.Close())
}
return errlist.Err()
}