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|
package resource
import (
"fmt"
"log"
"sort"
"strings"
"sync"
)
var (
repo repository
once sync.Once
)
func getRepository() *repository {
once.Do(func() {
repo = newRepository()
})
return &repo
}
func ResetRepository() {
repo = newRepository()
}
type repository struct {
registered map[string]Resource
mu sync.Mutex
}
func newRepository() repository {
return repository{
registered: make(map[string]Resource),
}
}
func (r *repository) register(res Resource) error {
r.mu.Lock()
defer r.mu.Unlock()
if _, exists := r.registered[res.ID()]; exists {
return fmt.Errorf("resource %v already registered", res)
}
r.registered[res.ID()] = res
log.Printf("Registered resource %v\n", res)
return nil
}
func (r *repository) apply() error {
r.mu.Lock()
defer r.mu.Unlock()
visited := make(map[string]bool)
visiting := make(map[string]bool)
var order []Resource
var visit func(id string) error
visit = func(id string) error {
if visiting[id] {
return fmt.Errorf("circular dependency detected involving %s", id)
}
if visited[id] {
return nil
}
res, ok := r.registered[id]
if !ok {
return fmt.Errorf("resource %s is depended upon but not registered", id)
}
visiting[id] = true
// Visit dependencies in sorted order so the resulting apply order is
// stable and the log output is reproducible.
for _, depID := range res.sortedDependsOn() {
log.Printf("Resolving dependency of %v: needs %s first", res, depID)
if err := visit(depID); err != nil {
return err
}
}
delete(visiting, id)
visited[id] = true
order = append(order, res)
return nil
}
// Seed the traversal from a sorted list of roots so the overall order is
// deterministic regardless of map iteration order.
roots := make([]string, 0, len(r.registered))
for id := range r.registered {
roots = append(roots, id)
}
sort.Strings(roots)
for _, id := range roots {
if err := visit(id); err != nil {
return err
}
}
orderIDs := make([]string, 0, len(order))
for _, res := range order {
orderIDs = append(orderIDs, res.ID())
}
log.Printf("Resolved apply order: %s", strings.Join(orderIDs, " -> "))
for _, res := range order {
if deps := res.sortedDependsOn(); len(deps) > 0 {
log.Printf("Applying resource %v (dependencies already applied: %s)",
res, strings.Join(deps, ", "))
} else {
log.Printf("Applying resource %v (no dependencies)", res)
}
if err := res.Apply(); err != nil {
return fmt.Errorf("failed to apply %v: %w", res, err)
}
}
return nil
}
func Apply() error {
return getRepository().apply()
}
|
