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moby--moby/graph/history.go
Aaron Lehmann d4836cd7ec Documentation improvements and code cleanups for graph package
Expand the godoc documentation for the graph package.

Centralize DefaultTag in the graphs/tag package instead of defining it
twice.

Remove some unnecessary "config" structs that are only used to pass
a few parameters to a function.

Simplify the GetParentsSize function - there's no reason for it to take
an accumulator argument.

Unexport some functions that aren't needed outside the package.

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
2015-07-30 14:27:10 -07:00

122 lines
3.2 KiB
Go

package graph
import (
"fmt"
"strings"
"github.com/docker/docker/api/types"
"github.com/docker/docker/image"
"github.com/docker/docker/utils"
)
// WalkHistory calls the handler function for each image in the
// provided images lineage starting from immediate parent.
func (graph *Graph) WalkHistory(img *image.Image, handler func(image.Image) error) (err error) {
currentImg := img
for currentImg != nil {
if handler != nil {
if err := handler(*currentImg); err != nil {
return err
}
}
currentImg, err = graph.GetParent(currentImg)
if err != nil {
return fmt.Errorf("Error while getting parent image: %v", err)
}
}
return nil
}
// depth returns the number of parents for a
// current image
func (graph *Graph) depth(img *image.Image) (int, error) {
var (
count = 0
parent = img
err error
)
for parent != nil {
count++
parent, err = graph.GetParent(parent)
if err != nil {
return -1, err
}
}
return count, nil
}
// Set the max depth to the aufs default that most
// kernels are compiled with
// For more information see: http://sourceforge.net/p/aufs/aufs3-standalone/ci/aufs3.12/tree/config.mk
const MaxImageDepth = 127
// CheckDepth returns an error if the depth of an image, as returned
// by ImageDepth, is too large to support creating a container from it
// on this daemon.
func (graph *Graph) CheckDepth(img *image.Image) error {
// We add 2 layers to the depth because the container's rw and
// init layer add to the restriction
depth, err := graph.depth(img)
if err != nil {
return err
}
if depth+2 >= MaxImageDepth {
return fmt.Errorf("Cannot create container with more than %d parents", MaxImageDepth)
}
return nil
}
// History returns a slice of ImageHistory structures for the specified image
// name by walking the image lineage.
func (s *TagStore) History(name string) ([]*types.ImageHistory, error) {
foundImage, err := s.LookupImage(name)
if err != nil {
return nil, err
}
lookupMap := make(map[string][]string)
for name, repository := range s.Repositories {
for tag, id := range repository {
// If the ID already has a reverse lookup, do not update it unless for "latest"
if _, exists := lookupMap[id]; !exists {
lookupMap[id] = []string{}
}
lookupMap[id] = append(lookupMap[id], utils.ImageReference(name, tag))
}
}
history := []*types.ImageHistory{}
err = s.graph.WalkHistory(foundImage, func(img image.Image) error {
history = append(history, &types.ImageHistory{
ID: img.ID,
Created: img.Created.Unix(),
CreatedBy: strings.Join(img.ContainerConfig.Cmd.Slice(), " "),
Tags: lookupMap[img.ID],
Size: img.Size,
Comment: img.Comment,
})
return nil
})
return history, err
}
// GetParent returns the parent image for the specified image.
func (graph *Graph) GetParent(img *image.Image) (*image.Image, error) {
if img.Parent == "" {
return nil, nil
}
return graph.Get(img.Parent)
}
// GetParentsSize returns the combined size of all parent images. If there is
// no parent image or it's unavailable, it returns 0.
func (graph *Graph) GetParentsSize(img *image.Image) int64 {
parentImage, err := graph.GetParent(img)
if err != nil || parentImage == nil {
return 0
}
return parentImage.Size + graph.GetParentsSize(parentImage)
}