github.com/kunnos/engine@v1.13.1/layer/mounted_layer.go (about)

     1  package layer
     2  
     3  import (
     4  	"io"
     5  
     6  	"github.com/docker/docker/pkg/archive"
     7  )
     8  
     9  type mountedLayer struct {
    10  	name       string
    11  	mountID    string
    12  	initID     string
    13  	parent     *roLayer
    14  	path       string
    15  	layerStore *layerStore
    16  
    17  	references map[RWLayer]*referencedRWLayer
    18  }
    19  
    20  func (ml *mountedLayer) cacheParent() string {
    21  	if ml.initID != "" {
    22  		return ml.initID
    23  	}
    24  	if ml.parent != nil {
    25  		return ml.parent.cacheID
    26  	}
    27  	return ""
    28  }
    29  
    30  func (ml *mountedLayer) TarStream() (io.ReadCloser, error) {
    31  	return ml.layerStore.driver.Diff(ml.mountID, ml.cacheParent())
    32  }
    33  
    34  func (ml *mountedLayer) Name() string {
    35  	return ml.name
    36  }
    37  
    38  func (ml *mountedLayer) Parent() Layer {
    39  	if ml.parent != nil {
    40  		return ml.parent
    41  	}
    42  
    43  	// Return a nil interface instead of an interface wrapping a nil
    44  	// pointer.
    45  	return nil
    46  }
    47  
    48  func (ml *mountedLayer) Size() (int64, error) {
    49  	return ml.layerStore.driver.DiffSize(ml.mountID, ml.cacheParent())
    50  }
    51  
    52  func (ml *mountedLayer) Changes() ([]archive.Change, error) {
    53  	return ml.layerStore.driver.Changes(ml.mountID, ml.cacheParent())
    54  }
    55  
    56  func (ml *mountedLayer) Metadata() (map[string]string, error) {
    57  	return ml.layerStore.driver.GetMetadata(ml.mountID)
    58  }
    59  
    60  func (ml *mountedLayer) getReference() RWLayer {
    61  	ref := &referencedRWLayer{
    62  		mountedLayer: ml,
    63  	}
    64  	ml.references[ref] = ref
    65  
    66  	return ref
    67  }
    68  
    69  func (ml *mountedLayer) hasReferences() bool {
    70  	return len(ml.references) > 0
    71  }
    72  
    73  func (ml *mountedLayer) deleteReference(ref RWLayer) error {
    74  	if _, ok := ml.references[ref]; !ok {
    75  		return ErrLayerNotRetained
    76  	}
    77  	delete(ml.references, ref)
    78  	return nil
    79  }
    80  
    81  func (ml *mountedLayer) retakeReference(r RWLayer) {
    82  	if ref, ok := r.(*referencedRWLayer); ok {
    83  		ml.references[ref] = ref
    84  	}
    85  }
    86  
    87  type referencedRWLayer struct {
    88  	*mountedLayer
    89  }
    90  
    91  func (rl *referencedRWLayer) Mount(mountLabel string) (string, error) {
    92  	return rl.layerStore.driver.Get(rl.mountedLayer.mountID, mountLabel)
    93  }
    94  
    95  // Unmount decrements the activity count and unmounts the underlying layer
    96  // Callers should only call `Unmount` once per call to `Mount`, even on error.
    97  func (rl *referencedRWLayer) Unmount() error {
    98  	return rl.layerStore.driver.Put(rl.mountedLayer.mountID)
    99  }