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|
package identity
import (
"fmt"
"strings"
"github.com/MichaelMure/git-bug/repository"
"github.com/pkg/errors"
)
// Fetch retrieve updates from a remote
// This does not change the local identities state
func Fetch(repo repository.Repo, remote string) (string, error) {
remoteRefSpec := fmt.Sprintf(identityRemoteRefPattern, remote)
fetchRefSpec := fmt.Sprintf("%s:%s*", identityRefPattern, remoteRefSpec)
return repo.FetchRefs(remote, fetchRefSpec)
}
// Push update a remote with the local changes
func Push(repo repository.Repo, remote string) (string, error) {
return repo.PushRefs(remote, identityRefPattern+"*")
}
// Pull will do a Fetch + MergeAll
// This function won't give details on the underlying process. If you need more,
// use Fetch and MergeAll separately.
func Pull(repo repository.ClockedRepo, remote string) error {
_, err := Fetch(repo, remote)
if err != nil {
return err
}
for merge := range MergeAll(repo, remote) {
if merge.Err != nil {
return merge.Err
}
if merge.Status == MergeStatusInvalid {
// Not awesome: simply output the merge failure here as this function
// is only used in tests for now.
fmt.Println(merge)
}
}
return nil
}
// MergeAll will merge all the available remote identity
// To make sure that an Identity history can't be altered, a strict fast-forward
// only policy is applied here. As an Identity should be tied to a single user, this
// should work in practice but it does leave a possibility that a user would edit his
// Identity from two different repo concurrently and push the changes in a non-centralized
// network of repositories. In this case, it would result some of the repo accepting one
// version, some other accepting another, preventing the network in general to converge
// to the same result. This would create a sort of partition of the network, and manual
// cleaning would be required.
//
// An alternative approach would be to have a determinist rebase:
// - any commits present in both local and remote version would be kept, never changed.
// - newer commits would be merged in a linear chain of commits, ordered based on the
// Lamport time
//
// However, this approach leave the possibility, in the case of a compromised crypto keys,
// of forging a new version with a bogus Lamport time to be inserted before a legit version,
// invalidating the correct version and hijacking the Identity. There would only be a short
// period of time where this would be possible (before the network converge) but I'm not
// confident enough to implement that. I choose the strict fast-forward only approach,
// despite it's potential problem with two different version as mentioned above.
func MergeAll(repo repository.ClockedRepo, remote string) <-chan MergeResult {
out := make(chan MergeResult)
go func() {
defer close(out)
remoteRefSpec := fmt.Sprintf(identityRemoteRefPattern, remote)
remoteRefs, err := repo.ListRefs(remoteRefSpec)
if err != nil {
out <- MergeResult{Err: err}
return
}
for _, remoteRef := range remoteRefs {
refSplitted := strings.Split(remoteRef, "/")
id := refSplitted[len(refSplitted)-1]
remoteIdentity, err := ReadLocal(repo, remoteRef)
remoteBug, err := readBug(repo, remoteRef)
if err != nil {
out <- newMergeInvalidStatus(id, errors.Wrap(err, "remote bug is not readable").Error())
continue
}
// Check for error in remote data
if err := remoteBug.Validate(); err != nil {
out <- newMergeInvalidStatus(id, errors.Wrap(err, "remote bug is invalid").Error())
continue
}
localRef := bugsRefPattern + remoteBug.Id()
localExist, err := repo.RefExist(localRef)
if err != nil {
out <- newMergeError(err, id)
continue
}
// the bug is not local yet, simply create the reference
if !localExist {
err := repo.CopyRef(remoteRef, localRef)
if err != nil {
out <- newMergeError(err, id)
return
}
out <- newMergeStatus(MergeStatusNew, id, remoteBug)
continue
}
localBug, err := readBug(repo, localRef)
if err != nil {
out <- newMergeError(errors.Wrap(err, "local bug is not readable"), id)
return
}
updated, err := localBug.Merge(repo, remoteBug)
if err != nil {
out <- newMergeInvalidStatus(id, errors.Wrap(err, "merge failed").Error())
return
}
if updated {
out <- newMergeStatus(MergeStatusUpdated, id, localBug)
} else {
out <- newMergeStatus(MergeStatusNothing, id, localBug)
}
}
}()
return out
}
// MergeStatus represent the result of a merge operation of a bug
type MergeStatus int
const (
_ MergeStatus = iota
MergeStatusNew
MergeStatusInvalid
MergeStatusUpdated
MergeStatusNothing
)
// Todo: share a generalized MergeResult with the bug package ?
type MergeResult struct {
// Err is set when a terminal error occur in the process
Err error
Id string
Status MergeStatus
// Only set for invalid status
Reason string
// Not set for invalid status
Identity *Identity
}
func (mr MergeResult) String() string {
switch mr.Status {
case MergeStatusNew:
return "new"
case MergeStatusInvalid:
return fmt.Sprintf("invalid data: %s", mr.Reason)
case MergeStatusUpdated:
return "updated"
case MergeStatusNothing:
return "nothing to do"
default:
panic("unknown merge status")
}
}
func newMergeError(err error, id string) MergeResult {
return MergeResult{
Err: err,
Id: id,
}
}
func newMergeStatus(status MergeStatus, id string, identity *Identity) MergeResult {
return MergeResult{
Id: id,
Status: status,
// Identity is not set for an invalid merge result
Identity: identity,
}
}
func newMergeInvalidStatus(id string, reason string) MergeResult {
return MergeResult{
Id: id,
Status: MergeStatusInvalid,
Reason: reason,
}
}
|
