git-bug/bug/bug.go

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package bug
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import (
"crypto/sha256"
"errors"
"fmt"
"github.com/MichaelMure/git-bug/repository"
"github.com/MichaelMure/git-bug/util"
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"github.com/kevinburke/go.uuid"
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"strings"
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)
const BugsRefPattern = "refs/bugs/"
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const BugsRemoteRefPattern = "refs/remote/%s/bugs/"
const OpsEntryName = "ops"
const RootEntryName = "root"
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// Bug hold the data of a bug thread, organized in a way close to
// how it will be persisted inside Git. This is the datastructure
// used for merge of two different version.
type Bug struct {
// Id used as unique identifier
id string
lastCommit util.Hash
root util.Hash
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// TODO: need a way to order bugs, probably a Lamport clock
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packs []OperationPack
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staging OperationPack
}
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// Create a new Bug
func NewBug() (*Bug, error) {
// TODO: replace with commit hash of (first commit + some random)
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// Creating UUID Version 4
unique, err := uuid.ID4()
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if err != nil {
return nil, err
}
// Use it as source of uniqueness
hash := sha256.New().Sum(unique.Bytes())
// format in hex and truncate to 40 char
id := fmt.Sprintf("%.40s", fmt.Sprintf("%x", hash))
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return &Bug{
id: id,
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}, nil
}
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// Find an existing Bug matching a prefix
func FindBug(repo repository.Repo, prefix string) (*Bug, error) {
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ids, err := repo.ListRefs(BugsRefPattern)
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if err != nil {
return nil, err
}
// preallocate but empty
matching := make([]string, 0, 5)
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for _, id := range ids {
if strings.HasPrefix(id, prefix) {
matching = append(matching, id)
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}
}
if len(matching) == 0 {
return nil, errors.New("No matching bug found.")
}
if len(matching) > 1 {
return nil, fmt.Errorf("Multiple matching bug found:\n%s", strings.Join(matching, "\n"))
}
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return ReadBug(repo, BugsRefPattern+matching[0])
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}
// Read and parse a Bug from git
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func ReadBug(repo repository.Repo, ref string) (*Bug, error) {
hashes, err := repo.ListCommits(ref)
if err != nil {
return nil, err
}
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refSplitted := strings.Split(ref, "/")
id := refSplitted[len(refSplitted)-1]
bug := Bug{
id: id,
}
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// Load each OperationPack
for _, hash := range hashes {
entries, err := repo.ListEntries(hash)
bug.lastCommit = hash
if err != nil {
return nil, err
}
var opsEntry repository.TreeEntry
opsFound := false
var rootEntry repository.TreeEntry
rootFound := false
for _, entry := range entries {
if entry.Name == OpsEntryName {
opsEntry = entry
opsFound = true
continue
}
if entry.Name == RootEntryName {
rootEntry = entry
rootFound = true
}
}
if !opsFound {
return nil, errors.New("Invalid tree, missing the ops entry")
}
if !rootFound {
return nil, errors.New("Invalid tree, missing the root entry")
}
if bug.root == "" {
bug.root = rootEntry.Hash
}
data, err := repo.ReadData(opsEntry.Hash)
if err != nil {
return nil, err
}
op, err := ParseOperationPack(data)
if err != nil {
return nil, err
}
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// tag the pack with the commit hash
op.commitHash = hash
if err != nil {
return nil, err
}
bug.packs = append(bug.packs, *op)
}
return &bug, nil
}
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// IsValid check if the Bug data is valid
func (bug *Bug) IsValid() bool {
// non-empty
if len(bug.packs) == 0 && bug.staging.IsEmpty() {
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return false
}
// check if each pack is valid
for _, pack := range bug.packs {
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if !pack.IsValid() {
return false
}
}
// check if staging is valid if needed
if !bug.staging.IsEmpty() {
if !bug.staging.IsValid() {
return false
}
}
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// The very first Op should be a CreateOp
firstOp := bug.firstOp()
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if firstOp == nil || firstOp.OpType() != CreateOp {
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return false
}
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// Check that there is no more CreateOp op
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it := NewOperationIterator(bug)
createCount := 0
for it.Next() {
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if it.Value().OpType() == CreateOp {
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createCount++
}
}
if createCount != 1 {
return false
}
return true
}
func (bug *Bug) Append(op Operation) {
bug.staging.Append(op)
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}
// Write the staging area in Git and move the operations to the packs
func (bug *Bug) Commit(repo repository.Repo) error {
if bug.staging.IsEmpty() {
return nil
}
// Write the Ops as a Git blob containing the serialized array
hash, err := bug.staging.Write(repo)
if err != nil {
return err
}
root := bug.root
if root == "" {
root = hash
bug.root = hash
}
// Write a Git tree referencing this blob
hash, err = repo.StoreTree([]repository.TreeEntry{
{repository.Blob, hash, OpsEntryName}, // the last pack of ops
{repository.Blob, root, RootEntryName}, // always the first pack of ops (might be the same)
})
if err != nil {
return err
}
// Write a Git commit referencing the tree, with the previous commit as parent
if bug.lastCommit != "" {
hash, err = repo.StoreCommitWithParent(hash, bug.lastCommit)
} else {
hash, err = repo.StoreCommit(hash)
}
if err != nil {
return err
}
bug.lastCommit = hash
// Create or update the Git reference for this bug
ref := fmt.Sprintf("%s%s", BugsRefPattern, bug.id)
err = repo.UpdateRef(ref, hash)
if err != nil {
return err
}
bug.packs = append(bug.packs, bug.staging)
bug.staging = OperationPack{}
return nil
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}
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// Merge a different version of the same bug by rebasing operations of this bug
// that are not present in the other on top of the chain of operations of the
// other version.
func (bug *Bug) Merge(repo repository.Repo, other *Bug) (bool, error) {
if bug.id != other.id {
return false, errors.New("merging unrelated bugs is not supported")
}
if len(other.staging.Operations) > 0 {
return false, errors.New("merging a bug with a non-empty staging is not supported")
}
if bug.lastCommit == "" || other.lastCommit == "" {
return false, errors.New("can't merge a bug that has never been stored")
}
ancestor, err := repo.FindCommonAncestor(bug.lastCommit, other.lastCommit)
if err != nil {
return false, err
}
rebaseStarted := false
updated := false
for i, pack := range bug.packs {
if pack.commitHash == ancestor {
rebaseStarted = true
// get other bug's extra pack
for j := i + 1; j < len(other.packs); j++ {
// clone is probably not necessary
newPack := other.packs[j].Clone()
bug.packs = append(bug.packs, newPack)
bug.lastCommit = newPack.commitHash
updated = true
}
continue
}
if !rebaseStarted {
continue
}
updated = true
// get the referenced git tree
treeHash, err := repo.GetTreeHash(pack.commitHash)
if err != nil {
return false, err
}
// create a new commit with the correct ancestor
hash, err := repo.StoreCommitWithParent(treeHash, bug.lastCommit)
// replace the pack
bug.packs[i] = pack.Clone()
bug.packs[i].commitHash = hash
// update the bug
bug.lastCommit = hash
}
// Update the git ref
if updated {
err := repo.UpdateRef(BugsRefPattern+bug.id, bug.lastCommit)
if err != nil {
return false, err
}
}
return updated, nil
}
// Return the Bug identifier
func (bug *Bug) Id() string {
return bug.id
}
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// Return the Bug identifier truncated for human consumption
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func (bug *Bug) HumanId() string {
return fmt.Sprintf("%.8s", bug.id)
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}
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// Lookup for the very first operation of the bug.
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// For a valid Bug, this operation should be a CreateOp
func (bug *Bug) firstOp() Operation {
for _, pack := range bug.packs {
for _, op := range pack.Operations {
return op
}
}
if !bug.staging.IsEmpty() {
return bug.staging.Operations[0]
}
return nil
}
// Compile a bug in a easily usable snapshot
func (bug *Bug) Compile() Snapshot {
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snap := Snapshot{
id: bug.id,
Status: OpenStatus,
}
it := NewOperationIterator(bug)
for it.Next() {
snap = it.Value().Apply(snap)
}
return snap
}