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|
package limited
import (
"context"
"io"
"runtime"
"strings"
"sync"
"github.com/containerd/containerd/content"
"github.com/containerd/containerd/images"
"github.com/containerd/containerd/remotes"
"github.com/distribution/reference"
"github.com/moby/buildkit/util/bklog"
ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
"golang.org/x/sync/semaphore"
)
type contextKeyT string
var contextKey = contextKeyT("buildkit/util/resolver/limited")
var Default = New(4)
type Group struct {
mu sync.Mutex
size int
sem map[string][2]*semaphore.Weighted
}
type req struct {
g *Group
ref string
}
func (r *req) acquire(ctx context.Context, desc ocispecs.Descriptor) (context.Context, func(), error) {
if v := ctx.Value(contextKey); v != nil {
return ctx, func() {}, nil
}
ctx = context.WithValue(ctx, contextKey, struct{}{})
// json request get one additional connection
highPriority := strings.HasSuffix(desc.MediaType, "+json")
r.g.mu.Lock()
s, ok := r.g.sem[r.ref]
if !ok {
s = [2]*semaphore.Weighted{
semaphore.NewWeighted(int64(r.g.size)),
semaphore.NewWeighted(int64(r.g.size + 1)),
}
r.g.sem[r.ref] = s
}
r.g.mu.Unlock()
if !highPriority {
if err := s[0].Acquire(ctx, 1); err != nil {
return ctx, nil, err
}
}
if err := s[1].Acquire(ctx, 1); err != nil {
if !highPriority {
s[0].Release(1)
}
return ctx, nil, err
}
return ctx, func() {
s[1].Release(1)
if !highPriority {
s[0].Release(1)
}
}, nil
}
func New(size int) *Group {
return &Group{
size: size,
sem: make(map[string][2]*semaphore.Weighted),
}
}
func (g *Group) req(ref string) *req {
return &req{g: g, ref: domain(ref)}
}
func (g *Group) WrapFetcher(f remotes.Fetcher, ref string) remotes.Fetcher {
return &fetcher{Fetcher: f, req: g.req(ref)}
}
func (g *Group) PushHandler(pusher remotes.Pusher, provider content.Provider, ref string) images.HandlerFunc {
ph := remotes.PushHandler(pusher, provider)
req := g.req(ref)
return func(ctx context.Context, desc ocispecs.Descriptor) ([]ocispecs.Descriptor, error) {
ctx, release, err := req.acquire(ctx, desc)
if err != nil {
return nil, err
}
defer release()
return ph(ctx, desc)
}
}
type fetcher struct {
remotes.Fetcher
req *req
}
func (f *fetcher) Fetch(ctx context.Context, desc ocispecs.Descriptor) (io.ReadCloser, error) {
ctx, release, err := f.req.acquire(ctx, desc)
if err != nil {
return nil, err
}
rc, err := f.Fetcher.Fetch(ctx, desc)
if err != nil {
release()
return nil, err
}
rcw := &readCloser{ReadCloser: rc}
closer := func() {
if !rcw.closed {
bklog.G(ctx).Warnf("fetcher not closed cleanly: %s", desc.Digest)
}
release()
}
rcw.release = closer
runtime.SetFinalizer(rcw, func(rc *readCloser) {
rc.close()
})
if s, ok := rc.(io.Seeker); ok {
return &readCloserSeeker{rcw, s}, nil
}
return rcw, nil
}
type readCloserSeeker struct {
*readCloser
io.Seeker
}
type readCloser struct {
io.ReadCloser
once sync.Once
closed bool
release func()
}
func (r *readCloser) Close() error {
r.closed = true
r.close()
return r.ReadCloser.Close()
}
func (r *readCloser) close() {
r.once.Do(r.release)
}
func FetchHandler(ingester content.Ingester, fetcher remotes.Fetcher, ref string) images.HandlerFunc {
return remotes.FetchHandler(ingester, Default.WrapFetcher(fetcher, ref))
}
func PushHandler(pusher remotes.Pusher, provider content.Provider, ref string) images.HandlerFunc {
return Default.PushHandler(pusher, provider, ref)
}
func domain(ref string) string {
if ref != "" {
if named, err := reference.ParseNormalizedNamed(ref); err == nil {
return reference.Domain(named)
}
}
return ref
}
|
