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watchtower/container/sort.go

107 lines
2.5 KiB
Go

package container
import (
"fmt"
"time"
)
// ByCreated allows a list of Container structs to be sorted by the container's
// created date.
type ByCreated []Container
func (c ByCreated) Len() int { return len(c) }
func (c ByCreated) Swap(i, j int) { c[i], c[j] = c[j], c[i] }
// Less will compare two elements (identified by index) in the Container
// list by created-date.
func (c ByCreated) Less(i, j int) bool {
t1, err := time.Parse(time.RFC3339Nano, c[i].containerInfo.Created)
if err != nil {
t1 = time.Now()
}
t2, _ := time.Parse(time.RFC3339Nano, c[j].containerInfo.Created)
if err != nil {
t1 = time.Now()
}
return t1.Before(t2)
}
// SortByDependencies will sort the list of containers taking into account any
// links between containers. Container with no outgoing links will be sorted to
// the front of the list while containers with links will be sorted after all
// of their dependencies. This sort order ensures that linked containers can
// be started in the correct order.
func SortByDependencies(containers []Container) ([]Container, error) {
sorter := dependencySorter{}
return sorter.Sort(containers)
}
type dependencySorter struct {
unvisited []Container
marked map[string]bool
sorted []Container
}
func (ds *dependencySorter) Sort(containers []Container) ([]Container, error) {
ds.unvisited = containers
ds.marked = map[string]bool{}
for len(ds.unvisited) > 0 {
if err := ds.visit(ds.unvisited[0]); err != nil {
return nil, err
}
}
return ds.sorted, nil
}
func (ds *dependencySorter) visit(c Container) error {
if _, ok := ds.marked[c.Name()]; ok {
return fmt.Errorf("Circular reference to %s", c.Name())
}
// Mark any visited node so that circular references can be detected
ds.marked[c.Name()] = true
defer delete(ds.marked, c.Name())
// Recursively visit links
for _, linkName := range c.Links() {
if linkedContainer := ds.findUnvisited(linkName); linkedContainer != nil {
if err := ds.visit(*linkedContainer); err != nil {
return err
}
}
}
// Move container from unvisited to sorted
ds.removeUnvisited(c)
ds.sorted = append(ds.sorted, c)
return nil
}
func (ds *dependencySorter) findUnvisited(name string) *Container {
for _, c := range ds.unvisited {
if c.Name() == name {
return &c
}
}
return nil
}
func (ds *dependencySorter) removeUnvisited(c Container) {
var idx int
for i := range ds.unvisited {
if ds.unvisited[i].Name() == c.Name() {
idx = i
break
}
}
ds.unvisited = append(ds.unvisited[0:idx], ds.unvisited[idx+1:]...)
}