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package git
import (
"fmt"
"time"
"gopkg.in/src-d/go-git.v4/plumbing"
"gopkg.in/src-d/go-git.v4/plumbing/filemode"
"gopkg.in/src-d/go-git.v4/plumbing/object"
"gopkg.in/src-d/go-git.v4/storage"
)
type PruneHandler func(unreferencedObjectHash plumbing.Hash) error
type PruneOptions struct {
// OnlyObjectsOlderThan if set to non-zero value
// selects only objects older than the time provided.
OnlyObjectsOlderThan time.Time
// Handler is called on matching objects
Handler PruneHandler
}
// DeleteObject deletes an object from a repository.
// The type conveniently matches PruneHandler.
func (r *Repository) DeleteObject(hash plumbing.Hash) error {
return r.Storer.DeleteLooseObject(hash)
}
func (r *Repository) Prune(opt PruneOptions) error {
pw := &pruneWalker{
Storer: r.Storer,
seen: map[plumbing.Hash]struct{}{},
}
// Walk over all the references in the repo.
it, err := r.Storer.IterReferences()
if err != nil {
return nil
}
defer it.Close()
err = it.ForEach(func(ref *plumbing.Reference) error {
// Exit this iteration early for non-hash references.
if ref.Type() != plumbing.HashReference {
return nil
}
return pw.walkObjectTree(ref.Hash())
})
if err != nil {
return err
}
// Now walk all (loose) objects in storage.
err = r.Storer.ForEachObjectHash(func(hash plumbing.Hash) error {
// Get out if we have seen this object.
if pw.isSeen(hash) {
return nil
}
// Otherwise it is a candidate for pruning.
// Check out for too new objects next.
if opt.OnlyObjectsOlderThan != (time.Time{}) {
// Errors here are non-fatal. The object may be e.g. packed.
// Or concurrently deleted. Skip such objects.
t, err := r.Storer.LooseObjectTime(hash)
if err != nil {
return nil
}
// Skip too new objects.
if !t.Before(opt.OnlyObjectsOlderThan) {
return nil
}
}
return opt.Handler(hash)
})
if err != nil {
return err
}
return nil
}
type pruneWalker struct {
Storer storage.Storer
// seen is the set of objects seen in the repo.
// seen map can become huge if walking over large
// repos. Thus using struct{} as the value type.
seen map[plumbing.Hash]struct{}
}
func (p *pruneWalker) isSeen(hash plumbing.Hash) bool {
_, seen := p.seen[hash]
return seen
}
func (p *pruneWalker) add(hash plumbing.Hash) {
p.seen[hash] = struct{}{}
}
// walkObjectTree walks over all objects and remembers references
// to them in the pruneWalker. This is used instead of the revlist
// walks because memory usage is tight with huge repos.
func (p *pruneWalker) walkObjectTree(hash plumbing.Hash) error {
// Check if we have already seen, and mark this object
if p.isSeen(hash) {
return nil
}
p.add(hash)
// Fetch the object.
obj, err := object.GetObject(p.Storer, hash)
if err != nil {
return fmt.Errorf("Getting object %s failed: %v", hash, err)
}
// Walk all children depending on object type.
switch obj := obj.(type) {
case *object.Commit:
err = p.walkObjectTree(obj.TreeHash)
if err != nil {
return err
}
for _, h := range obj.ParentHashes {
err = p.walkObjectTree(h)
if err != nil {
return err
}
}
case *object.Tree:
for i := range obj.Entries {
// Shortcut for blob objects:
// 'or' the lower bits of a mode and check that it
// it matches a filemode.Executable. The type information
// is in the higher bits, but this is the cleanest way
// to handle plain files with different modes.
// Other non-tree objects are somewhat rare, so they
// are not special-cased.
if obj.Entries[i].Mode|0755 == filemode.Executable {
p.add(obj.Entries[i].Hash)
continue
}
// Normal walk for sub-trees (and symlinks etc).
err = p.walkObjectTree(obj.Entries[i].Hash)
if err != nil {
return err
}
}
default:
// Error out on unhandled object types.
return fmt.Errorf("Unknown object %X %s %T\n", obj.ID(), obj.Type(), obj)
}
return nil
}
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