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multiprovider.go
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/
multiprovider.go
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package contentutil
import (
"context"
"sync"
"github.com/containerd/containerd/content"
"github.com/containerd/containerd/errdefs"
"github.com/moby/buildkit/session"
digest "github.com/opencontainers/go-digest"
ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
"github.com/pkg/errors"
)
// NewMultiProvider creates a new mutable provider with a base provider
func NewMultiProvider(base content.Provider) *MultiProvider {
return &MultiProvider{
base: base,
sub: map[digest.Digest]content.Provider{},
}
}
// MultiProvider is a provider backed by a mutable map of providers
type MultiProvider struct {
mu sync.RWMutex
base content.Provider
sub map[digest.Digest]content.Provider
}
func (mp *MultiProvider) SnapshotLabels(descs []ocispecs.Descriptor, index int) map[string]string {
if len(descs) < index {
return nil
}
desc := descs[index]
type snapshotLabels interface {
SnapshotLabels([]ocispecs.Descriptor, int) map[string]string
}
mp.mu.RLock()
if p, ok := mp.sub[desc.Digest]; ok {
mp.mu.RUnlock()
if cd, ok := p.(snapshotLabels); ok {
return cd.SnapshotLabels(descs, index)
}
} else {
mp.mu.RUnlock()
}
if cd, ok := mp.base.(snapshotLabels); ok {
return cd.SnapshotLabels(descs, index)
}
return nil
}
func (mp *MultiProvider) CheckDescriptor(ctx context.Context, desc ocispecs.Descriptor) error {
type checkDescriptor interface {
CheckDescriptor(context.Context, ocispecs.Descriptor) error
}
mp.mu.RLock()
if p, ok := mp.sub[desc.Digest]; ok {
mp.mu.RUnlock()
if cd, ok := p.(checkDescriptor); ok {
return cd.CheckDescriptor(ctx, desc)
}
} else {
mp.mu.RUnlock()
}
if cd, ok := mp.base.(checkDescriptor); ok {
return cd.CheckDescriptor(ctx, desc)
}
return nil
}
// ReaderAt returns a content.ReaderAt
func (mp *MultiProvider) ReaderAt(ctx context.Context, desc ocispecs.Descriptor) (content.ReaderAt, error) {
mp.mu.RLock()
if p, ok := mp.sub[desc.Digest]; ok {
mp.mu.RUnlock()
return p.ReaderAt(ctx, desc)
}
mp.mu.RUnlock()
if mp.base == nil {
return nil, errors.Wrapf(errdefs.ErrNotFound, "content %v", desc.Digest)
}
return mp.base.ReaderAt(ctx, desc)
}
// Add adds a new child provider for a specific digest
func (mp *MultiProvider) Add(dgst digest.Digest, p content.Provider) {
mp.mu.Lock()
defer mp.mu.Unlock()
mp.sub[dgst] = p
}
func (mp *MultiProvider) UnlazySession(desc ocispecs.Descriptor) session.Group {
type unlazySession interface {
UnlazySession(ocispecs.Descriptor) session.Group
}
mp.mu.RLock()
if p, ok := mp.sub[desc.Digest]; ok {
mp.mu.RUnlock()
if cd, ok := p.(unlazySession); ok {
return cd.UnlazySession(desc)
}
} else {
mp.mu.RUnlock()
}
if cd, ok := mp.base.(unlazySession); ok {
return cd.UnlazySession(desc)
}
return nil
}