forked from vmware-archive/atc
/
fetcher.go
150 lines (127 loc) · 3.18 KB
/
fetcher.go
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package resource
import (
"errors"
"io"
"os"
"time"
"code.cloudfoundry.org/clock"
"code.cloudfoundry.org/lager"
"github.com/concourse/atc"
"github.com/concourse/atc/creds"
"github.com/concourse/atc/db/lock"
"github.com/concourse/atc/worker"
)
const GetResourceLockInterval = 5 * time.Second
var ErrFailedToGetLock = errors.New("failed-to-get-lock")
var ErrInterrupted = errors.New("interrupted")
//go:generate counterfeiter . Fetcher
type Fetcher interface {
Fetch(
logger lager.Logger,
session Session,
tags atc.Tags,
teamID int,
resourceTypes creds.VersionedResourceTypes,
resourceInstance ResourceInstance,
metadata Metadata,
imageFetchingDelegate worker.ImageFetchingDelegate,
signals <-chan os.Signal,
ready chan<- struct{},
) (VersionedSource, error)
}
func NewFetcher(
clock clock.Clock,
lockFactory lock.LockFactory,
fetchSourceProviderFactory FetchSourceProviderFactory,
) Fetcher {
return &fetcher{
clock: clock,
lockFactory: lockFactory,
fetchSourceProviderFactory: fetchSourceProviderFactory,
}
}
type fetcher struct {
clock clock.Clock
lockFactory lock.LockFactory
fetchSourceProviderFactory FetchSourceProviderFactory
}
func (f *fetcher) Fetch(
logger lager.Logger,
session Session,
tags atc.Tags,
teamID int,
resourceTypes creds.VersionedResourceTypes,
resourceInstance ResourceInstance,
metadata Metadata,
imageFetchingDelegate worker.ImageFetchingDelegate,
signals <-chan os.Signal,
ready chan<- struct{},
) (VersionedSource, error) {
sourceProvider := f.fetchSourceProviderFactory.NewFetchSourceProvider(
logger,
session,
metadata,
tags,
teamID,
resourceTypes,
resourceInstance,
imageFetchingDelegate,
)
source, err := sourceProvider.Get()
if err != nil {
return nil, err
}
ticker := f.clock.NewTicker(GetResourceLockInterval)
defer ticker.Stop()
versionedSource, err := f.fetchWithLock(logger, source, imageFetchingDelegate.Stdout(), signals, ready)
if err != ErrFailedToGetLock {
return versionedSource, err
}
for {
select {
case <-ticker.C():
versionedSource, err := f.fetchWithLock(logger, source, imageFetchingDelegate.Stdout(), signals, ready)
if err != nil {
if err == ErrFailedToGetLock {
break
}
return nil, err
}
return versionedSource, nil
case <-signals:
return nil, ErrInterrupted
}
}
}
func (f *fetcher) fetchWithLock(
logger lager.Logger,
source FetchSource,
stdout io.Writer,
signals <-chan os.Signal,
ready chan<- struct{},
) (VersionedSource, error) {
versionedSource, found, err := source.Find()
if err != nil {
return nil, err
}
if found {
close(ready)
return versionedSource, nil
}
lockName, err := source.LockName()
if err != nil {
return nil, err
}
lockLogger := logger.Session("lock-task", lager.Data{"lock-name": lockName})
lock, acquired, err := f.lockFactory.Acquire(lockLogger, lock.NewTaskLockID(lockName))
if err != nil {
lockLogger.Error("failed-to-get-lock", err)
return nil, ErrFailedToGetLock
}
if !acquired {
lockLogger.Debug("did-not-get-lock")
return nil, ErrFailedToGetLock
}
defer lock.Release()
return source.Create(signals, ready)
}