1// SPDX-License-Identifier: AGPL-3.0-or-later
2
3package usecase
4
5import (
6 "context"
7 "encoding/base64"
8 "errors"
9 "fmt"
10 "math"
11 "runtime/debug"
12 "slices"
13 "strconv"
14 "strings"
15 "sync"
16
17 "github.com/bnema/zerowrap"
18
19 "bnema.dev/ermite/internal/domain"
20 "bnema.dev/ermite/internal/ports"
21)
22
23// MaxMergeRequestCommits is the most commits GetMergeRequest returns.
24const MaxMergeRequestCommits = 100
25
26// maxWriteRetries bounds the retries of a write that loses a race with another
27// write of the same merge request. Each lost race means another writer won, so
28// a writer loses at most as many times as there are other writers at once; the
29// retry is a read and a write of ermite-kv, cheap enough for a bound this high.
30const maxWriteRetries = 32
31
32// MaxCommentsPerMergeRequest is the most comments a merge request holds. Past
33// it AddComment fails with domain.ErrResourceExhausted (resource_exhausted in
34// the API). Comments are never deleted, so the limit counts the ones ever added.
35const MaxCommentsPerMergeRequest = 1000
36
37const mrTokenPrefix = "mp1:"
38
39// MergeRequests are the merge request use cases (ADR 0017): review, comment,
40// close and merge a branch. Reading needs the access of reading the
41// repository: a repository the principal may not read, a missing one and an
42// unknown number all answer domain.ErrNotFound. Writing needs mr:write, and
43// merging mr:merge, on the repository (see scopeAccess), and that scope also
44// makes a private repository visible for the action (see writable).
45type MergeRequests struct {
46 meta ports.RepoMetaStore
47 store ports.MergeRequestStore
48 repos ports.GitRepos
49 git ports.MergeGit
50 signer ports.CommitSigner
51 committer domain.Identity
52 bus ports.EventBus
53 clock ports.Clock
54 maint ports.MaintenanceScheduler
55 ci ports.WorkflowTrigger // nil: no CI
56 checks ports.CIChecksReader // nil: no CI, so no check blocks a merge
57 pulls ports.PullRequestTrigger // nil: no pull_request workflows
58 tips ports.CIRefTipStore // nil: who merges is not recorded
59 verifier ports.CommitVerifier // nil: commits are not checked (ADR 0030)
60 mergeab MergeabilityHook // nil: no mergeability
61
62 mu sync.Mutex
63 locks map[domain.RepoName]chan struct{}
64
65 // after tracks the post-merge side effects running off the request path.
66 after sync.WaitGroup
67 // afterGate, when set by a test, runs first in the post-merge goroutine.
68 afterGate func()
69}
70
71var (
72 _ ports.MergeRequestService = (*MergeRequests)(nil)
73 _ ports.PullGate = (*MergeRequests)(nil)
74)
75
76// MergeRequestsConfig holds what the merge request use cases need. Every field
77// is required.
78type MergeRequestsConfig struct {
79 Meta ports.RepoMetaStore
80 Store ports.MergeRequestStore
81 // Repos gives the default branch of a repository.
82 Repos ports.GitRepos
83 Git ports.MergeGit
84 // Signer signs the squash commits.
85 Signer ports.CommitSigner
86 // Committer is recorded as the committer of the squash commits.
87 Committer domain.Identity
88 Bus ports.EventBus
89 Clock ports.Clock
90 // Maint queues the maintenance that follows a merge, as it does a push.
91 Maint ports.MaintenanceScheduler
92 // CI starts the workflows a merge triggers (GitHub runs "push" workflows
93 // on a merge) and Checks gives the checks the merge rule reads. Both are
94 // optional: without them there is no CI.
95 CI ports.WorkflowTrigger
96 Checks ports.CIChecksReader
97 // PullRequests starts the pull_request workflows when a request is opened,
98 // closed or merged (the push of its source branch reaches CI instead).
99 // Optional.
100 PullRequests ports.PullRequestTrigger
101 // RefTips records who moves the target branch (and deletes the record of a
102 // deleted source branch) before the merge does, as a push does
103 // (domain.CIRefTip). Optional.
104 RefTips ports.CIRefTipStore
105 // Mergeability is queued when a request is opened, closed or merged and
106 // read by Get and List. Optional: without it Mergeability stays zero.
107 Mergeability MergeabilityHook
108}
109
110// NewMergeRequests builds the merge request use cases.
111func NewMergeRequests(cfg MergeRequestsConfig) *MergeRequests {
112 return &MergeRequests{
113 meta: cfg.Meta, store: cfg.Store, repos: cfg.Repos, git: cfg.Git, signer: cfg.Signer,
114 committer: cfg.Committer, bus: cfg.Bus, clock: cfg.Clock, maint: cfg.Maint, ci: cfg.CI, checks: cfg.Checks, pulls: cfg.PullRequests, tips: cfg.RefTips, mergeab: cfg.Mergeability,
115 locks: make(map[domain.RepoName]chan struct{}),
116 }
117}
118
119// WithVerifier makes GetMergeRequest fill the signature state of the commits
120// it lists (ADR 0030).
121func (m *MergeRequests) WithVerifier(v ports.CommitVerifier) *MergeRequests {
122 m.verifier = v
123 return m
124}
125
126// Wait waits for the post-merge side effects still running (source branch
127// deletion, events, CI and mergeability hooks), or for ctx to end. Call it
128// before closing what they use.
129func (m *MergeRequests) Wait(ctx context.Context) {
130 done := make(chan struct{})
131 go func() {
132 m.after.Wait()
133 close(done)
134 }()
135 select {
136 case <-done:
137 case <-ctx.Done():
138 }
139}
140
141// lockRepo takes the merge lock of a repository, waiting until ctx ends. The
142// merges of one repository, and the creation of its merge requests, run one at
143// a time. The returned function releases the lock.
144func (m *MergeRequests) lockRepo(ctx context.Context, name domain.RepoName) (unlock func(), err error) {
145 m.mu.Lock()
146 ch, ok := m.locks[name]
147 if !ok {
148 ch = make(chan struct{}, 1)
149 m.locks[name] = ch
150 }
151 m.mu.Unlock()
152 select {
153 case ch <- struct{}{}:
154 return func() { <-ch }, nil
155 case <-ctx.Done():
156 return nil, ctx.Err()
157 }
158}
159
160// readable looks the repository up and applies the read rule: reading merge
161// requests needs the access of reading the repository (canRead). repo:write
162// alone does not read them, as it does not fetch a private repository either.
163func (m *MergeRequests) readable(ctx context.Context, p domain.Principal, name domain.RepoName) (domain.Repo, error) {
164 repo, err := lookupRepo(ctx, m.meta, name)
165 if err != nil {
166 return domain.Repo{}, err
167 }
168 if !canRead(p, repo) {
169 return domain.Repo{}, domain.ErrNotFound
170 }
171 return repo, nil
172}
173
174// writable looks the repository up for an action that needs a merge request
175// scope. A principal whose token holds that scope on the repository sees the
176// repository for this action even without repo:read, so that the agent preset
177// (repo:write, mr:write) can open a request on the private repository it just
178// pushed. A principal with neither repo:read nor the scope, and an unknown
179// repository, still get domain.ErrNotFound; one that can read the repository
180// but lacks the scope gets the error of scopeAccess.
181func (m *MergeRequests) writable(ctx context.Context, p domain.Principal, name domain.RepoName, scope domain.Scope) (domain.Repo, error) {
182 repo, err := lookupRepo(ctx, m.meta, name)
183 if err != nil {
184 return domain.Repo{}, err
185 }
186 if !canRead(p, repo) && !p.Allows(scope, name) {
187 return domain.Repo{}, domain.ErrNotFound
188 }
189 if err := scopeAccess(p, repo, scope); err != nil {
190 return domain.Repo{}, err
191 }
192 return repo, nil
193}
194
195// withHead fills HeadID of an open request from its source branch: zero when
196// the branch is gone. Merged and closed requests keep the head they stored.
197func (m *MergeRequests) withHead(ctx context.Context, mr domain.MergeRequest) (domain.MergeRequest, error) {
198 if !mr.IsOpen() {
199 return mr, nil
200 }
201 head, err := m.git.BranchHead(ctx, mr.Repo, mr.Source)
202 switch {
203 case errors.Is(err, domain.ErrNotFound):
204 mr.HeadID = domain.ObjectID{}
205 case err != nil:
206 return domain.MergeRequest{}, err
207 default:
208 mr.HeadID = head
209 }
210 return mr, nil
211}
212
213// branchOrZero returns the head of a branch, the zero id when it is gone.
214func (m *MergeRequests) branchOrZero(ctx context.Context, repo domain.RepoName, branch string) (domain.ObjectID, error) {
215 id, err := m.git.BranchHead(ctx, repo, branch)
216 if errors.Is(err, domain.ErrNotFound) {
217 return domain.ObjectID{}, nil
218 }
219 return id, err
220}
221
222// Create opens a merge request and publishes MergeRequestOpened. The principal
223// needs mr:write. A request that breaks a rule of ADR 0017 (the texts, a
224// branch that does not exist, source and target the same) is rejected whole
225// with an *domain.InvalidFieldsError naming the fields. An open request with
226// the same source and target gives domain.ErrAlreadyExists.
227func (m *MergeRequests) Create(ctx context.Context, p domain.Principal, name domain.RepoName, params ports.CreateMergeRequestParams) (domain.MergeRequest, error) {
228 repo, err := m.writable(ctx, p, name, domain.ScopeMRWrite)
229 if err != nil {
230 return domain.MergeRequest{}, err
231 }
232 var v domain.Violations
233 title, err := domain.ParseMRTitle(params.Title)
234 if err != nil {
235 v.AddErr("title", err)
236 }
237 desc, err := domain.ParsePlainText(params.Description)
238 if err != nil {
239 v.AddErr("description", err)
240 }
241 // Under the lock, so that two requests for the same pair cannot both pass
242 // the check for an existing one, and a merge that deletes its source
243 // cannot remove a branch between its check here and the creation.
244 unlock, err := m.lockRepo(ctx, name)
245 if err != nil {
246 return domain.MergeRequest{}, err
247 }
248 defer unlock()
249 source, target, err := m.checkBranches(ctx, name, params, &v)
250 if err != nil {
251 return domain.MergeRequest{}, err
252 }
253 if err := v.Err(); err != nil {
254 return domain.MergeRequest{}, err
255 }
256 existing, err := m.store.List(ctx, name)
257 if err != nil {
258 return domain.MergeRequest{}, fmt.Errorf("list merge requests of %q: %w", name, err)
259 }
260 for _, e := range existing {
261 if e.IsOpen() && e.Source == source && e.Target == target {
262 return domain.MergeRequest{}, fmt.Errorf("%w: !%d already merges %s into %s", domain.ErrAlreadyExists, e.Number, source, target)
263 }
264 }
265
266 now := m.clock.Now().UTC()
267 mr, err := m.store.Create(ctx, domain.MergeRequest{
268 Repo: name, Title: title, Description: desc, Source: source, Target: target,
269 State: domain.MRStateOpen, Author: domain.AuthorName(p), CreatedAt: now, UpdatedAt: now,
270 })
271 if err != nil {
272 return domain.MergeRequest{}, fmt.Errorf("create merge request of %q: %w", name, err)
273 }
274 log := zerowrap.FromCtx(ctx)
275 log.Info().Str("repo", name.String()).Int64("number", mr.Number).
276 Str("source", source).Str("target", target).
277 Str("principal", p.Label()).Str("token_id", p.TokenID()).Msg("merge request opened")
278 mr, err = m.withHead(ctx, mr)
279 if err != nil {
280 return domain.MergeRequest{}, err
281 }
282 m.bus.Publish(ctx, domain.MergeRequestOpened{MergeRequest: mr, At: now, Visibility: repo.Visibility, CreatedAt: repo.CreatedAt})
283 if m.mergeab != nil {
284 m.mergeab.OnOpened(ctx, mr)
285 }
286 if m.pulls != nil {
287 // The commits the opening is for are the ones of now.
288 base, _ := m.branchOrZero(ctx, name, target)
289 m.pulls.OnPullRequest(ctx, name, ports.PullRequestEvent{Number: mr.Number, Action: domain.PullOpened, Head: mr.HeadID, Base: base}, p)
290 }
291 return mr, nil
292}
293
294// checkBranches validates the branches of a new request and returns them, with
295// the default branch filled in for the target.
296//
297// Only a branch that does not exist is a violation. Any other failure to read
298// Git is returned as an error, so that it is logged and masked, not shown in
299// the field violations.
300func (m *MergeRequests) checkBranches(ctx context.Context, name domain.RepoName, params ports.CreateMergeRequestParams, v *domain.Violations) (source, target string, err error) {
301 source, target = params.Source, params.Target
302 if source == "" {
303 v.Add("source_branch", "is required")
304 } else if _, err := domain.ParseBranchName(source); err != nil {
305 v.Add("source_branch", "is not a valid branch name")
306 source = ""
307 }
308 if target == "" {
309 def, exists, err := m.repos.DefaultBranch(ctx, name)
310 switch {
311 case err != nil: // includes domain.ErrNotFound: the repository is gone
312 return "", "", fmt.Errorf("read the default branch of %q: %w", name, err)
313 case !exists:
314 v.Add("target_branch", fmt.Sprintf("is empty and the default branch %q does not exist", def))
315 default:
316 target = def
317 }
318 } else if _, err := domain.ParseBranchName(target); err != nil {
319 v.Add("target_branch", "is not a valid branch name")
320 target = ""
321 }
322 if source != "" && source == target {
323 v.Add("target_branch", "must differ from source_branch")
324 return source, target, nil
325 }
326 for _, b := range []struct{ field, name string }{{"source_branch", source}, {"target_branch", target}} {
327 if b.name == "" {
328 continue
329 }
330 _, err := m.git.BranchHead(ctx, name, b.name)
331 if errors.Is(err, domain.ErrNotFound) {
332 v.Add(b.field, fmt.Sprintf("branch %q does not exist", b.name))
333 } else if err != nil {
334 return "", "", fmt.Errorf("read branch %q of %q: %w", b.name, name, err)
335 }
336 }
337 return source, target, nil
338}
339
340// List returns a page of the merge requests of a repository, highest number
341// first. The open ones carry the head of their source branch. The page token
342// names the last number of the previous page, so requests created between two
343// pages never shift the others.
344func (m *MergeRequests) List(ctx context.Context, p domain.Principal, name domain.RepoName, params ports.ListMergeRequestsParams) (ports.MergeRequestPage, error) {
345 size, err := pageSize(params.PageSize)
346 if err != nil {
347 return ports.MergeRequestPage{}, err
348 }
349 after, err := decodeMRToken(params.PageToken)
350 if err != nil {
351 return ports.MergeRequestPage{}, err
352 }
353 if _, err := m.readable(ctx, p, name); err != nil {
354 return ports.MergeRequestPage{}, err
355 }
356 all, err := m.store.List(ctx, name)
357 if err != nil {
358 return ports.MergeRequestPage{}, fmt.Errorf("list merge requests of %q: %w", name, err)
359 }
360 var page ports.MergeRequestPage
361 page.MergeRequests, page.NextPageToken = pageAfter(all, size,
362 func(mr domain.MergeRequest) bool {
363 return (params.State == "" || mr.State == params.State) && (after == 0 || mr.Number < after)
364 },
365 encodeMRToken)
366 tips := map[string]domain.ObjectID{} // one BranchHead per distinct target
367 for i, mr := range page.MergeRequests {
368 if page.MergeRequests[i], err = m.withHead(ctx, mr); err != nil {
369 return ports.MergeRequestPage{}, err
370 }
371 if m.mergeab == nil || !mr.IsOpen() {
372 continue
373 }
374 tip, ok := tips[mr.Target]
375 if !ok {
376 if tip, err = m.branchOrZero(ctx, name, mr.Target); err != nil {
377 return ports.MergeRequestPage{}, err
378 }
379 tips[mr.Target] = tip
380 }
381 if page.Mergeability == nil {
382 page.Mergeability = map[int64]domain.Mergeability{}
383 }
384 page.Mergeability[mr.Number] = m.mergeab.Read(ctx, page.MergeRequests[i], tip)
385 }
386 return page, nil
387}
388
389// MarkReady implements ports.MergeRequestService: the title of an open draft
390// loses its draft prefix, so the request can be merged. The principal needs
391// mr:write. A request that is not open, or not a draft, gives
392// domain.ErrPreconditionFailed.
393func (m *MergeRequests) MarkReady(ctx context.Context, p domain.Principal, name domain.RepoName, number int64) (domain.MergeRequest, error) {
394 repo, err := m.writable(ctx, p, name, domain.ScopeMRWrite)
395 if err != nil {
396 return domain.MergeRequest{}, err
397 }
398 unlock, err := m.lockRepo(ctx, name) // a merge sees the request as it is after
399 if err != nil {
400 return domain.MergeRequest{}, err
401 }
402 defer unlock()
403 for range maxWriteRetries {
404 mr, err := m.store.Get(ctx, name, number)
405 if err != nil {
406 return domain.MergeRequest{}, err
407 }
408 if !mr.IsOpen() {
409 return domain.MergeRequest{}, fmt.Errorf("%w: !%d is %s", domain.ErrPreconditionFailed, number, mr.State)
410 }
411 title, ok := domain.ReadyTitle(mr.Title)
412 if !ok {
413 return domain.MergeRequest{}, fmt.Errorf("%w: !%d is not a draft", domain.ErrPreconditionFailed, number)
414 }
415 mr.Title, mr.UpdatedAt = title, m.clock.Now().UTC()
416 err = m.store.Update(ctx, mr)
417 if errors.Is(err, domain.ErrConflict) {
418 continue
419 }
420 if err != nil {
421 return domain.MergeRequest{}, fmt.Errorf("mark !%d of %q ready: %w", number, name, err)
422 }
423 m.bus.Publish(ctx, domain.MergeRequestReady{MergeRequest: mr, At: mr.UpdatedAt, Visibility: repo.Visibility, CreatedAt: repo.CreatedAt})
424 return m.withHead(ctx, mr)
425 }
426 return domain.MergeRequest{}, fmt.Errorf("mark !%d of %q ready: %w", number, name, domain.ErrConflict)
427}
428
429// CountOpen implements ports.MergeRequestService.
430func (m *MergeRequests) CountOpen(ctx context.Context, p domain.Principal, name domain.RepoName) (int, error) {
431 if _, err := m.readable(ctx, p, name); err != nil {
432 return 0, err
433 }
434 n, err := m.store.CountOpen(ctx, name)
435 if err != nil {
436 return 0, fmt.Errorf("count open merge requests of %q: %w", name, err)
437 }
438 return n, nil
439}
440
441// Mergeability implements ports.MergeRequestService: the mergeability of an
442// open merge request for the current tips, queued when there is no up-to-date
443// result. It is the zero value for a request that is not open, or without a
444// mergeability service.
445func (m *MergeRequests) Mergeability(ctx context.Context, p domain.Principal, name domain.RepoName, number int64) (domain.Mergeability, error) {
446 _, mr, err := m.get(ctx, p, name, number)
447 if err != nil {
448 return domain.Mergeability{}, err
449 }
450 if m.mergeab == nil || !mr.IsOpen() {
451 return domain.Mergeability{}, nil
452 }
453 if mr, err = m.withHead(ctx, mr); err != nil {
454 return domain.Mergeability{}, err
455 }
456 tip, err := m.branchOrZero(ctx, name, mr.Target)
457 if err != nil {
458 return domain.Mergeability{}, err
459 }
460 return m.mergeab.Read(ctx, mr, tip), nil
461}
462
463func encodeMRToken(last domain.MergeRequest) string {
464 return base64.RawURLEncoding.EncodeToString([]byte(mrTokenPrefix + strconv.FormatInt(last.Number, 10)))
465}
466
467// decodeMRToken returns 0 for the empty token.
468func decodeMRToken(tok string) (int64, error) {
469 if tok == "" {
470 return 0, nil
471 }
472 raw, ok := decodeToken(tok, mrTokenPrefix)
473 if ok {
474 if n, err := strconv.ParseInt(raw, 10, 64); err == nil && n > 0 {
475 return n, nil
476 }
477 }
478 return 0, fmt.Errorf("%w: merge requests", domain.ErrInvalidPageToken)
479}
480
481// get reads a merge request of a repository the principal can read.
482func (m *MergeRequests) get(ctx context.Context, p domain.Principal, name domain.RepoName, number int64) (domain.Repo, domain.MergeRequest, error) {
483 repo, err := m.readable(ctx, p, name)
484 if err != nil {
485 return domain.Repo{}, domain.MergeRequest{}, err
486 }
487 mr, err := m.store.Get(ctx, name, number)
488 if err != nil {
489 return domain.Repo{}, domain.MergeRequest{}, err
490 }
491 return repo, mr, nil
492}
493
494// Get returns a merge request with its commits, its diff, its comments and the
495// read position. The diff compares the merge base of the target and the head
496// with the head ("target...head"), within domain.DefaultDiffLimits. With
497// opts.SinceLastRead it compares the head recorded by MarkRead with the
498// current head instead, which works after a force-push as long as the recorded
499// commit still exists; when none was recorded the diff is the default one, and
500// when the recorded commit is gone too, with LastReadLost set. A merged or
501// closed request keeps the head and the base it had.
502//
503// opts.Files lists every changed file and reads the hunks of a window of them
504// only; opts.Base and opts.Head make Get fail with domain.ErrConflict when the
505// diff is no longer the one the caller shows (before any diff is read);
506// opts.DiffOnly skips the commits. An invalid window gives domain.ErrInvalid.
507func (m *MergeRequests) Get(ctx context.Context, p domain.Principal, name domain.RepoName, number int64, opts ports.GetMergeRequestOptions) (ports.MergeRequestDetail, error) {
508 limits := domain.DefaultDiffLimits()
509 if w := opts.Files; w != nil {
510 if w.From < 0 || w.To < 0 || (w.To != 0 && w.To < w.From) {
511 return ports.MergeRequestDetail{}, fmt.Errorf("%w: file window [%d, %d)", domain.ErrInvalid, w.From, w.To)
512 }
513 limits.MaxFiles, limits.From, limits.To = 0, w.From, w.To
514 }
515 _, mr, err := m.get(ctx, p, name, number)
516 if err != nil {
517 return ports.MergeRequestDetail{}, err
518 }
519 if mr, err = m.withHead(ctx, mr); err != nil {
520 return ports.MergeRequestDetail{}, err
521 }
522 if !opts.Head.IsZero() && opts.Head != mr.HeadID {
523 return ports.MergeRequestDetail{}, fmt.Errorf("%w: the head of !%d moved to %s", domain.ErrConflict, number, mr.HeadID)
524 }
525 // checkBase fails when the caller shows another diff base than base.
526 checkBase := func(base domain.ObjectID) error {
527 if !opts.Base.IsZero() && opts.Base != base {
528 return fmt.Errorf("%w: the diff base of !%d is now %s", domain.ErrConflict, number, base)
529 }
530 return nil
531 }
532 d := ports.MergeRequestDetail{MergeRequest: mr}
533 if m.mergeab != nil && mr.IsOpen() {
534 tip, err := m.branchOrZero(ctx, name, mr.Target)
535 if err != nil {
536 return ports.MergeRequestDetail{}, err
537 }
538 d.Mergeability = m.mergeab.Read(ctx, mr, tip)
539 }
540 if d.Comments, err = m.store.ListComments(ctx, name, number); err != nil {
541 return ports.MergeRequestDetail{}, fmt.Errorf("list comments of !%d in %q: %w", number, name, err)
542 }
543 d.Verdicts = domain.CurrentVerdicts(d.Comments, mr.HeadID)
544 if d.LastReadID, err = m.store.GetRead(ctx, name, number); err != nil {
545 return ports.MergeRequestDetail{}, err
546 }
547
548 exclude, base, err := m.rangeOf(ctx, mr)
549 if err != nil {
550 return ports.MergeRequestDetail{}, err
551 }
552 head := mr.HeadID
553 if head.IsZero() {
554 return d, checkBase(domain.ObjectID{}) // the source branch is gone: no commits, no diff
555 }
556 if !mr.IsOpen() {
557 // After a squash the reviewed commits are only reachable from the
558 // source branch; once it is deleted, gc may prune them.
559 switch ok, err := m.git.HasCommit(ctx, name, head); {
560 case err != nil:
561 return ports.MergeRequestDetail{}, err
562 case !ok:
563 // The reviewed commits are gone: no commits, no diff.
564 if err := checkBase(domain.ObjectID{}); err != nil {
565 return ports.MergeRequestDetail{}, err
566 }
567 return d, nil
568 }
569 }
570 if !opts.DiffOnly {
571 if d.Commits, d.CommitsTruncated, err = m.git.ListRange(ctx, name, exclude, head, MaxMergeRequestCommits); err != nil {
572 return ports.MergeRequestDetail{}, err
573 }
574 verifyCommits(ctx, m.verifier, name, d.Commits)
575 }
576 if opts.SinceLastRead && !d.LastReadID.IsZero() {
577 switch ok, err := m.git.HasCommit(ctx, name, d.LastReadID); {
578 case err != nil:
579 return ports.MergeRequestDetail{}, err
580 case ok:
581 base = d.LastReadID
582 default:
583 d.LastReadLost = true
584 }
585 }
586 if err := checkBase(base); err != nil {
587 return ports.MergeRequestDetail{}, err
588 }
589 if base.IsZero() {
590 return d, nil
591 }
592 d.DiffBaseID = base
593 if d.Stats, d.Diff, err = m.git.DiffCommits(ctx, name, base, head, limits); err != nil {
594 return ports.MergeRequestDetail{}, err
595 }
596 return d, nil
597}
598
599// rangeOf returns what the review of a request compares: the commit whose
600// history the request's commits exclude, and the base of its diff. For an open
601// request they are the tip of the target and the merge base of the target and
602// the head; both are zero when the target is gone or shares no history with
603// the head. A merged or closed request keeps the base it stored for both.
604func (m *MergeRequests) rangeOf(ctx context.Context, mr domain.MergeRequest) (exclude, base domain.ObjectID, err error) {
605 if !mr.IsOpen() {
606 return mr.BaseID, mr.BaseID, nil
607 }
608 if mr.HeadID.IsZero() {
609 return domain.ObjectID{}, domain.ObjectID{}, nil
610 }
611 tip, err := m.branchOrZero(ctx, mr.Repo, mr.Target)
612 if err != nil || tip.IsZero() {
613 return domain.ObjectID{}, domain.ObjectID{}, err
614 }
615 base, err = m.git.MergeBase(ctx, mr.Repo, tip, mr.HeadID)
616 if errors.Is(err, domain.ErrNotFound) {
617 return tip, domain.ObjectID{}, nil
618 }
619 return tip, base, err
620}
621
622// AddComment adds a comment and publishes CommentAdded. The principal needs
623// mr:write. The text must follow the rules of ADR 0032 and not be blank unless carrying a verdict; a
624// comment on a line must name a line of the current diff of the request (see
625// domain.Diff.HasLine), else the call fails with domain.ErrInvalid. A request
626// that is not open gives domain.ErrPreconditionFailed, and one that already
627// holds MaxCommentsPerMergeRequest comments domain.ErrResourceExhausted.
628func (m *MergeRequests) AddComment(ctx context.Context, p domain.Principal, name domain.RepoName, number int64, params ports.AddCommentParams) (domain.Comment, error) {
629 repo, err := m.writable(ctx, p, name, domain.ScopeMRWrite)
630 if err != nil {
631 return domain.Comment{}, err
632 }
633 mr, err := m.store.Get(ctx, name, number)
634 if err != nil {
635 return domain.Comment{}, err
636 }
637 var v domain.Violations
638 text, err := domain.ParsePlainText(params.Text)
639 switch {
640 case err != nil:
641 v.AddErr("text", err)
642 case text.IsBlank() && params.Verdict == domain.VerdictNone:
643 v.Add("text", "is required")
644 }
645 general := params.Path == ""
646 switch {
647 case general && (params.Line != 0 || params.Side != domain.SideNone || params.StartLine != 0):
648 v.Add("path", "is required with line and side")
649 case !general && params.Line < 1:
650 v.Add("line", "must be 1 or more with a path")
651 case !general && params.Side != domain.SideOld && params.Side != domain.SideNew:
652 v.Add("side", "is required with a path")
653 }
654 if params.StartLine != 0 && (params.StartLine < 1 || params.StartLine >= params.Line) {
655 v.Add("start_line", "must be 1 or more and less than line")
656 }
657 if params.Verdict > domain.VerdictChangesRequested {
658 v.Add("verdict", "is unknown")
659 }
660 if params.ReplyTo != 0 {
661 if params.Path != "" || params.Line != 0 || params.StartLine != 0 || params.Side != domain.SideNone || params.Verdict != domain.VerdictNone {
662 v.Add("reply_to", "a reply cannot specify an anchor or verdict")
663 }
664 }
665 if err := v.Err(); err != nil {
666 return domain.Comment{}, err
667 }
668 if params.ReplyTo != 0 {
669 root, err := m.replyRoot(ctx, name, number, params.ReplyTo)
670 if err != nil {
671 return domain.Comment{}, err
672 }
673 params.Path, params.Line, params.StartLine, params.Side = root.Path, root.Line, root.StartLine, root.Side
674 }
675 if params.Verdict != domain.VerdictNone {
676 if err := scopeAccess(p, repo, domain.ScopeMRReview); err != nil {
677 return domain.Comment{}, err
678 }
679 }
680 if !mr.IsOpen() {
681 return domain.Comment{}, fmt.Errorf("%w: !%d is %s", domain.ErrPreconditionFailed, number, mr.State)
682 }
683
684 if mr, err = m.withHead(ctx, mr); err != nil {
685 return domain.Comment{}, err
686 }
687 if !general && params.ReplyTo == 0 {
688 if err := m.checkLine(ctx, mr, params); err != nil {
689 return domain.Comment{}, err
690 }
691 }
692
693 var c domain.Comment
694 for range maxWriteRetries {
695 if mr.CommentSeq >= MaxCommentsPerMergeRequest {
696 return domain.Comment{}, fmt.Errorf("%w: !%d already has %d comments", domain.ErrResourceExhausted, number, MaxCommentsPerMergeRequest)
697 }
698 c = domain.Comment{
699 ID: mr.CommentSeq + 1, Author: domain.AuthorName(p), Path: params.Path, Line: params.Line, Side: params.Side,
700 ReplyTo: params.ReplyTo, StartLine: params.StartLine, Verdict: params.Verdict, Resolved: params.Verdict == domain.VerdictApprove,
701 CommitID: mr.HeadID, Text: text, CreatedAt: m.clock.Now().UTC(),
702 }
703 mr.CommentSeq, mr.UpdatedAt = c.ID, c.CreatedAt
704 err = m.store.SaveComment(ctx, mr, c)
705 if !errors.Is(err, domain.ErrConflict) {
706 break
707 }
708 // Another write got in between: read the request again.
709 fresh, gerr := m.store.Get(ctx, name, number)
710 if gerr != nil {
711 return domain.Comment{}, gerr
712 }
713 if !fresh.IsOpen() {
714 return domain.Comment{}, fmt.Errorf("%w: !%d is %s", domain.ErrPreconditionFailed, number, fresh.State)
715 }
716 if params.ReplyTo != 0 {
717 // The root may have been deleted by the write that got in between.
718 if _, rerr := m.replyRoot(ctx, name, number, params.ReplyTo); rerr != nil {
719 return domain.Comment{}, rerr
720 }
721 }
722 fresh.HeadID = mr.HeadID
723 mr = fresh
724 }
725 if err != nil {
726 return domain.Comment{}, fmt.Errorf("save comment on !%d of %q: %w", number, name, err)
727 }
728 log := zerowrap.FromCtx(ctx)
729 log.Info().Str("repo", name.String()).Int64("number", number).Int64("comment", c.ID).
730 Int64("reply_to", c.ReplyTo).Str("verdict", c.Verdict.String()).Bool("on_line", !general).Str("principal", p.Label()).Str("token_id", p.TokenID()).Msg("comment added")
731 m.bus.Publish(ctx, domain.CommentAdded{
732 Repo: name, Number: number, Comment: c, At: c.CreatedAt, Visibility: repo.Visibility, CreatedAt: repo.CreatedAt,
733 })
734 return c, nil
735}
736
737// checkLine verifies that a comment designates a line of the current diff of
738// the request.
739func (m *MergeRequests) checkLine(ctx context.Context, mr domain.MergeRequest, params ports.AddCommentParams) error {
740 var v domain.Violations
741 _, base, err := m.rangeOf(ctx, mr)
742 if err != nil {
743 return err
744 }
745 if mr.HeadID.IsZero() || base.IsZero() {
746 v.Add("path", "the merge request has no diff to comment on")
747 return v.Err()
748 }
749 // A comment may be on a file past the 300th that the web view lists, so
750 // the file is looked up among all the files (MaxFiles 0). Reading every
751 // file's hunks within the default total limits would reject a comment on a
752 // file the earlier ones left no budget for. So a first read lists the files
753 // with no hunks (From past the end: cheap, git is stopped at once), and a
754 // second reads the hunks of the one file within the default per-file limit
755 // and total limits, as the web view does for a window holding it.
756 list := domain.DefaultDiffLimits()
757 list.MaxFiles, list.From = 0, math.MaxInt
758 _, diff, err := m.git.DiffCommits(ctx, mr.Repo, base, mr.HeadID, list)
759 if err != nil {
760 return err
761 }
762 idx := slices.IndexFunc(diff.Files, func(f domain.FileDiff) bool { return diffFileName(f) == params.Path })
763 if idx >= 0 {
764 one := domain.DefaultDiffLimits()
765 one.MaxFiles, one.From, one.To = 0, idx, idx+1
766 if _, diff, err = m.git.DiffCommits(ctx, mr.Repo, base, mr.HeadID, one); err != nil {
767 return err
768 }
769 }
770 if idx < 0 || !diff.HasLine(params.Path, params.Side, params.Line) {
771 v.Add("path", fmt.Sprintf("%s:%d on the %s side is not a line of the diff", params.Path, params.Line, params.Side))
772 }
773 if params.StartLine != 0 && !diff.HasLine(params.Path, params.Side, params.StartLine) {
774 v.Add("start_line", "is not a line of the diff")
775 }
776 return v.Err()
777}
778
779// diffFileName is the path a comment designates for f, as Diff.HasLine reads it.
780func diffFileName(f domain.FileDiff) string {
781 if f.Status == domain.FileDeleted {
782 return f.OldPath
783 }
784 return f.NewPath
785}
786
787// ResolveComment marks a comment resolved or unresolved. The principal needs
788// mr:write. An unknown comment gives domain.ErrNotFound and a request that is
789// not open domain.ErrPreconditionFailed. Setting the state the comment already
790// has succeeds and writes nothing.
791func (m *MergeRequests) ResolveComment(ctx context.Context, p domain.Principal, name domain.RepoName, number, commentID int64, resolved bool) (domain.Comment, error) {
792 repo, err := m.writable(ctx, p, name, domain.ScopeMRWrite)
793 if err != nil {
794 return domain.Comment{}, err
795 }
796 for range maxWriteRetries {
797 mr, err := m.store.Get(ctx, name, number)
798 if err != nil {
799 return domain.Comment{}, err
800 }
801 c, err := m.store.GetComment(ctx, name, number, commentID)
802 if err != nil {
803 return domain.Comment{}, err
804 }
805 if !mr.IsOpen() {
806 return domain.Comment{}, fmt.Errorf("%w: !%d is %s", domain.ErrPreconditionFailed, number, mr.State)
807 }
808 if c.IsReply() {
809 var v domain.Violations
810 v.Add("comment_id", fmt.Sprintf("resolve the thread on its root ^%d", c.ReplyTo))
811 return domain.Comment{}, v.Err()
812 }
813 if c.Resolved == resolved {
814 return c, nil
815 }
816 c.Resolved = resolved
817 mr.UpdatedAt = m.clock.Now().UTC()
818 err = m.store.SaveComment(ctx, mr, c)
819 if errors.Is(err, domain.ErrConflict) {
820 continue
821 }
822 if err != nil {
823 return domain.Comment{}, fmt.Errorf("resolve comment %d of !%d in %q: %w", commentID, number, name, err)
824 }
825 m.bus.Publish(ctx, domain.CommentResolved{Repo: name, Number: number, Comment: c, At: mr.UpdatedAt, Visibility: repo.Visibility, CreatedAt: repo.CreatedAt})
826 return c, nil
827 }
828 return domain.Comment{}, fmt.Errorf("resolve comment %d of !%d in %q: %w", commentID, number, name, domain.ErrConflict)
829}
830
831// Close closes an open merge request without merging it and publishes
832// MergeRequestClosed. The principal needs mr:write. A request that is not open
833// gives domain.ErrPreconditionFailed. The request keeps the head it had and
834// its merge base, so that its diff stays readable.
835func (m *MergeRequests) Close(ctx context.Context, p domain.Principal, name domain.RepoName, number int64) (domain.MergeRequest, error) {
836 repo, err := m.writable(ctx, p, name, domain.ScopeMRWrite)
837 if err != nil {
838 return domain.MergeRequest{}, err
839 }
840 unlock, err := m.lockRepo(ctx, name) // a merge and a close of one request exclude each other
841 if err != nil {
842 return domain.MergeRequest{}, err
843 }
844 defer unlock()
845 for range maxWriteRetries {
846 mr, err := m.store.Get(ctx, name, number)
847 if err != nil {
848 return domain.MergeRequest{}, err
849 }
850 if !mr.IsOpen() {
851 return domain.MergeRequest{}, fmt.Errorf("%w: !%d is %s", domain.ErrPreconditionFailed, number, mr.State)
852 }
853 if mr, err = m.withHead(ctx, mr); err != nil {
854 return domain.MergeRequest{}, err
855 }
856 _, base, err := m.rangeOf(ctx, mr)
857 if err != nil {
858 return domain.MergeRequest{}, err
859 }
860 mr.State, mr.BaseID, mr.UpdatedAt = domain.MRStateClosed, base, m.clock.Now().UTC()
861 err = m.store.Update(ctx, mr)
862 if errors.Is(err, domain.ErrConflict) {
863 continue
864 }
865 if err != nil {
866 return domain.MergeRequest{}, fmt.Errorf("close !%d of %q: %w", number, name, err)
867 }
868 log := zerowrap.FromCtx(ctx)
869 log.Info().Str("repo", name.String()).Int64("number", number).
870 Str("principal", p.Label()).Str("token_id", p.TokenID()).Msg("merge request closed")
871 m.bus.Publish(ctx, domain.MergeRequestClosed{MergeRequest: mr, At: mr.UpdatedAt, Visibility: repo.Visibility, CreatedAt: repo.CreatedAt})
872 if m.pulls != nil {
873 m.pulls.OnPullRequest(ctx, name, ports.PullRequestEvent{Number: number, Action: domain.PullClosed, Head: mr.HeadID, Base: mr.BaseID}, p)
874 }
875 return mr, nil
876 }
877 return domain.MergeRequest{}, fmt.Errorf("close !%d of %q: %w", number, name, domain.ErrConflict)
878}
879
880// MarkRead records the head the reviewer has read, for the since-last-read diff
881// of Get. The principal needs mr:write. A zero head means the current head of
882// the source branch (the stored one for a merged or closed request); one that
883// is not a commit of the repository gives domain.ErrInvalid. It returns the
884// head recorded.
885func (m *MergeRequests) MarkRead(ctx context.Context, p domain.Principal, name domain.RepoName, number int64, head domain.ObjectID) (domain.ObjectID, error) {
886 if _, err := m.writable(ctx, p, name, domain.ScopeMRWrite); err != nil {
887 return domain.ObjectID{}, err
888 }
889 mr, err := m.store.Get(ctx, name, number)
890 if err != nil {
891 return domain.ObjectID{}, err
892 }
893 if head.IsZero() {
894 if mr, err = m.withHead(ctx, mr); err != nil {
895 return domain.ObjectID{}, err
896 }
897 if head = mr.HeadID; head.IsZero() {
898 return domain.ObjectID{}, fmt.Errorf("%w: the source branch %q no longer exists, give a head", domain.ErrPreconditionFailed, mr.Source)
899 }
900 } else {
901 var v domain.Violations
902 switch ok, err := m.git.HasCommit(ctx, name, head); {
903 case err != nil:
904 return domain.ObjectID{}, err
905 case !ok:
906 v.Add("head_id", fmt.Sprintf("%s is not a commit of the repository", head))
907 return domain.ObjectID{}, v.Err()
908 }
909 }
910 if err := m.store.SetRead(ctx, name, number, head); err != nil {
911 return domain.ObjectID{}, err
912 }
913 return head, nil
914}
915
916// Merge merges an open merge request, publishes MergeRequestMerged then a
917// PushEvent for the target branch, and returns the merged request. The
918// principal needs mr:merge. Merges of one repository run one at a time.
919//
920// It fails with domain.ErrInvalid for a zero head, and with
921// domain.ErrPreconditionFailed when the request is not open, the mode is not
922// allowed by the settings of the repository, the source branch no longer
923// points to the head ("branch moved, read again") or is gone, the target is
924// gone, the mode's own condition does not hold (see below), or the branch
925// brings nothing. Checks come with CI (CI-1): there are none yet, so the
926// setting that lets failing checks block the merge has nothing to act on.
927//
928// The conditions are always checked with Git, under the lock, never from the
929// stored mergeability. A fast-forward needs the target to be an ancestor of
930// the head (the author rebases and pushes again) and moves the target to the
931// head, with the old value as a precondition. A squash and a merge commit need
932// the head to merge cleanly into the target (a behind branch is fine). A squash
933// writes one commit with the merged tree, the target as parent and the author
934// and message of domain.NewSquashCommit; a merge commit has two parents (the
935// target, then the head) and the message of domain.NewMergeCommit. Both are
936// signed by the instance key and move the target the same way.
937//
938// With DeleteSource the merge is also refused, before anything changes, when
939// the source is the default branch or the source or target of another open
940// request.
941//
942// Only the merge itself runs before Merge returns, under the lock. Afterwards,
943// off the request path and without the lock: the deletion of the source branch
944// (if it still points to the head; a failure is logged and leaves the branch),
945// MergeRequestMerged then a PushEvent (which carries the deletion too), and
946// the CI and mergeability hooks. Wait waits for them. SourceDeleted therefore
947// only says that the deletion was requested.
948func (m *MergeRequests) Merge(ctx context.Context, p domain.Principal, name domain.RepoName, number int64, params ports.MergeParams) (ports.MergeResult, error) {
949 mr, err := m.merge(ctx, p, name, number, params)
950 return ports.MergeResult{MergeRequest: mr, SourceDeleted: err == nil && params.DeleteSource}, err
951}
952
953// maxConflictPathsShown is how many conflicting paths a refusal lists.
954const maxConflictPathsShown = 5
955
956// checkMode is the authoritative per-mode check of a merge, done with Git. It
957// returns the tree a squash or merge commit gets (zero for a fast-forward).
958func (m *MergeRequests) checkMode(ctx context.Context, mr domain.MergeRequest, mode domain.MergeMode, tip, head domain.ObjectID) (domain.ObjectID, error) {
959 if mode == domain.MergeModeFastForward {
960 ok, err := m.git.IsAncestor(ctx, mr.Repo, tip, head)
961 if err != nil {
962 return domain.ObjectID{}, err
963 }
964 if !ok {
965 return domain.ObjectID{}, fmt.Errorf("%w: the target has moved: rebase and push again, or merge with squash or a merge commit", domain.ErrPreconditionFailed)
966 }
967 return domain.ObjectID{}, nil
968 }
969 res, err := m.git.MergeTree(ctx, mr.Repo, tip, head)
970 if err != nil {
971 return domain.ObjectID{}, err
972 }
973 res = res.Bounded()
974 if !res.Clean {
975 what := "no common history"
976 if len(res.ConflictPaths) > 0 {
977 shown := res.ConflictPaths
978 if len(shown) > maxConflictPathsShown {
979 shown = shown[:maxConflictPathsShown]
980 }
981 what = strings.Join(shown, ", ")
982 if len(shown) < len(res.ConflictPaths) || res.Truncated {
983 what += ", ..."
984 }
985 }
986 return domain.ObjectID{}, fmt.Errorf("%w: conflicts with %s: %s: rebase and push again", domain.ErrPreconditionFailed, mr.Target, what)
987 }
988 return res.Tree, nil
989}
990
991func (m *MergeRequests) merge(ctx context.Context, p domain.Principal, name domain.RepoName, number int64, params ports.MergeParams) (domain.MergeRequest, error) {
992 repo, err := m.writable(ctx, p, name, domain.ScopeMRMerge)
993 if err != nil {
994 return domain.MergeRequest{}, err
995 }
996 mode := params.Mode
997 if mode == "" {
998 mode = domain.MergeModeFastForward
999 }
1000 var v domain.Violations
1001 if _, err := domain.ParseMergeMode(mode.String()); err != nil {
1002 v.Add("mode", "is not a merge mode")
1003 }
1004 if params.HeadID.IsZero() {
1005 v.Add("head_id", "is required")
1006 }
1007 if err := v.Err(); err != nil {
1008 return domain.MergeRequest{}, err
1009 }
1010
1011 unlock, err := m.lockRepo(ctx, name)
1012 if err != nil {
1013 return domain.MergeRequest{}, err
1014 }
1015 var once sync.Once
1016 release := func() { once.Do(unlock) }
1017 defer release()
1018
1019 mr, err := m.store.Get(ctx, name, number)
1020 if err != nil {
1021 return domain.MergeRequest{}, err
1022 }
1023 // A merge moves the target and may delete the source: a token limited to
1024 // branch prefixes may do so only within them.
1025 if !p.AllowsRef("refs/heads/" + mr.Target) {
1026 return domain.MergeRequest{}, fmt.Errorf("%w: this token may not write %s", domain.ErrForbidden, mr.Target)
1027 }
1028 if params.DeleteSource && !p.AllowsRef("refs/heads/"+mr.Source) {
1029 return domain.MergeRequest{}, fmt.Errorf("%w: this token may not write %s", domain.ErrForbidden, mr.Source)
1030 }
1031 if !mr.IsOpen() {
1032 return domain.MergeRequest{}, fmt.Errorf("%w: !%d is %s", domain.ErrPreconditionFailed, number, mr.State)
1033 }
1034 if mr.IsDraft() {
1035 return domain.MergeRequest{}, fmt.Errorf("%w: !%d is a draft: mark it ready for review first", domain.ErrPreconditionFailed, number)
1036 }
1037 // The settings are read again under the lock: a change applies at once.
1038 repo, err = m.meta.Get(ctx, name)
1039 if err != nil {
1040 if errors.Is(err, domain.ErrNotFound) {
1041 return domain.MergeRequest{}, err // deleted meanwhile
1042 }
1043 return domain.MergeRequest{}, fmt.Errorf("get repository %q: %w", name, err)
1044 }
1045 settings := repo.Settings
1046 if settings.IsZero() {
1047 settings = domain.DefaultRepoSettings()
1048 }
1049 if !settings.Allows(mode) {
1050 return domain.MergeRequest{}, fmt.Errorf("%w: the %s merge mode is not allowed in %s", domain.ErrPreconditionFailed, mode, name)
1051 }
1052
1053 head, err := m.branchOrZero(ctx, name, mr.Source)
1054 switch {
1055 case err != nil:
1056 return domain.MergeRequest{}, err
1057 case head.IsZero():
1058 return domain.MergeRequest{}, fmt.Errorf("%w: the source branch %q no longer exists", domain.ErrPreconditionFailed, mr.Source)
1059 case head != params.HeadID:
1060 return domain.MergeRequest{}, fmt.Errorf("%w: branch moved, read again: %q is at %s, not %s", domain.ErrPreconditionFailed, mr.Source, head, params.HeadID)
1061 }
1062 tip, err := m.branchOrZero(ctx, name, mr.Target)
1063 switch {
1064 case err != nil:
1065 return domain.MergeRequest{}, err
1066 case tip.IsZero():
1067 return domain.MergeRequest{}, fmt.Errorf("%w: the target branch %q no longer exists", domain.ErrPreconditionFailed, mr.Target)
1068 case tip == head:
1069 return domain.MergeRequest{}, fmt.Errorf("%w: nothing to merge, %q already is at %s", domain.ErrPreconditionFailed, mr.Target, head)
1070 }
1071 // A head behind the target (or at it) has nothing to merge, in any mode.
1072 if behind, err := m.git.IsAncestor(ctx, name, head, tip); err != nil {
1073 return domain.MergeRequest{}, err
1074 } else if behind {
1075 return domain.MergeRequest{}, fmt.Errorf("%w: nothing to merge, %q already contains %s", domain.ErrPreconditionFailed, mr.Target, head)
1076 }
1077 tree, err := m.checkMode(ctx, mr, mode, tip, head)
1078 if err != nil {
1079 return domain.MergeRequest{}, err
1080 }
1081 if settings.FailingChecksBlock {
1082 if err := m.checksAllow(ctx, name, head); err != nil {
1083 return domain.MergeRequest{}, err
1084 }
1085 }
1086 if params.DeleteSource {
1087 if err := m.checkDeletable(ctx, name, mr); err != nil {
1088 return domain.MergeRequest{}, err
1089 }
1090 }
1091
1092 merged, err := m.moveTarget(ctx, mr, mode, tip, head, tree, p)
1093 if err != nil {
1094 return domain.MergeRequest{}, err
1095 }
1096 m.recordPush(ctx, name) // the target moved, whatever happens next
1097 mr, err = m.markMerged(ctx, name, number, mode, tip, head, merged)
1098 if err != nil {
1099 return domain.MergeRequest{}, err
1100 }
1101 log := zerowrap.FromCtx(ctx)
1102 log.Info().Str("repo", name.String()).Int64("number", number).Str("mode", mode.String()).
1103 Str("target", mr.Target).Str("commit", merged.String()).
1104 Str("principal", p.Label()).Str("token_id", p.TokenID()).Msg("merge request merged")
1105
1106 // The merge is done and recorded. The rest runs without the lock and after
1107 // the caller got its answer.
1108 release()
1109 bg := context.WithoutCancel(ctx)
1110 m.after.Add(1)
1111 go func() {
1112 defer m.after.Done()
1113 defer func() {
1114 if r := recover(); r != nil {
1115 log := zerowrap.FromCtx(bg)
1116 log.Error().Str("repo", name.String()).Int64("number", number).
1117 Str("panic", fmt.Sprint(r)).Bytes("stack", debug.Stack()).Msg("post-merge side effects panicked")
1118 }
1119 }()
1120 if m.afterGate != nil {
1121 m.afterGate()
1122 }
1123 m.afterMerge(bg, p, repo, mr, head, tip, merged, params.DeleteSource)
1124 }()
1125 return mr, nil
1126}
1127
1128// afterMerge is what follows a merge off the request path: errors are logged,
1129// never returned. mr is the merged request, tip the old target and merged the
1130// new one.
1131func (m *MergeRequests) afterMerge(ctx context.Context, p domain.Principal, repo domain.Repo, mr domain.MergeRequest, head, tip, merged domain.ObjectID, deleteSource bool) {
1132 name := repo.Name
1133 updates := []domain.RefUpdate{{Old: tip.String(), New: merged.String(), Ref: "refs/heads/" + mr.Target}}
1134 if deleteSource && m.deleteSource(ctx, p, name, mr, head) {
1135 updates = append(updates, domain.RefUpdate{Old: head.String(), New: domain.ZeroOID, Ref: "refs/heads/" + mr.Source})
1136 }
1137 at := mr.UpdatedAt
1138 m.bus.Publish(ctx, domain.MergeRequestMerged{MergeRequest: mr, At: at, Visibility: repo.Visibility, CreatedAt: repo.CreatedAt})
1139 m.bus.Publish(ctx, domain.PushEvent{
1140 Repo: name, At: at, Visibility: repo.Visibility, CreatedAt: repo.CreatedAt, Updates: updates,
1141 })
1142 if m.pulls != nil {
1143 m.pulls.OnPullRequest(ctx, name, ports.PullRequestEvent{Number: mr.Number, Action: domain.PullClosed, Head: mr.HeadID, Base: mr.BaseID, Merged: true}, p)
1144 }
1145 if m.ci != nil {
1146 // GitHub runs the "push" workflows of a merge, with the owner as actor;
1147 // the run is trusted with what the merging principal may read.
1148 m.ci.OnMerge(ctx, name, updates, p)
1149 }
1150 if m.mergeab != nil {
1151 m.mergeab.OnBranchesMoved(ctx, name, updates) // the other requests of the moved target
1152 }
1153}
1154
1155// deleteSource deletes the source branch of a merged request if it is still
1156// head and still unused, and reports whether it did. The eligibility is checked
1157// again and the branch deleted in one critical section of the merge lock: a
1158// request opened on the branch since the merge, or a push to it, keeps it. The
1159// record of who pushed the branch goes only after a deletion, and only if it
1160// still names head.
1161func (m *MergeRequests) deleteSource(ctx context.Context, p domain.Principal, name domain.RepoName, mr domain.MergeRequest, head domain.ObjectID) bool {
1162 log := zerowrap.FromCtx(ctx).With().Str("repo", name.String()).Int64("number", mr.Number).Str("branch", mr.Source).Logger()
1163 unlock, err := m.lockRepo(ctx, name)
1164 if err != nil {
1165 log.Warn().Err(err).Msg("source branch kept after the merge")
1166 return false
1167 }
1168 defer unlock()
1169 if err := m.checkDeletable(ctx, name, mr); err != nil {
1170 log.Warn().Err(err).Msg("source branch kept after the merge")
1171 return false
1172 }
1173 if err := m.git.DeleteBranch(ctx, name, mr.Source, head); err != nil {
1174 log.Warn().Err(err).Msg("source branch kept after the merge")
1175 return false
1176 }
1177 if m.tips != nil {
1178 if err := m.tips.DeleteRefTipIf(ctx, name, "refs/heads/"+mr.Source, head.String()); err != nil && !errors.Is(err, domain.ErrNotFound) {
1179 log.Warn().Err(err).Msg("the record of the source branch was kept")
1180 }
1181 }
1182 log.Info().Str("principal", p.Label()).Str("token_id", p.TokenID()).Msg("source branch deleted after the merge")
1183 return true
1184}
1185
1186// WhileOpen implements ports.PullGate: fn runs under the merge lock, so a
1187// close or a merge of the request cannot complete in the middle of it, and not
1188// at all when the request is no longer open.
1189func (m *MergeRequests) WhileOpen(ctx context.Context, name domain.RepoName, number int64, fn func() error) error {
1190 unlock, err := m.lockRepo(ctx, name)
1191 if err != nil {
1192 return err
1193 }
1194 defer unlock()
1195 mr, err := m.store.Get(ctx, name, number)
1196 if err != nil {
1197 return err
1198 }
1199 if !mr.IsOpen() {
1200 return fmt.Errorf("%w: !%d is %s", domain.ErrPreconditionFailed, number, mr.State)
1201 }
1202 return fn()
1203}
1204
1205// checksAllow is the merge rule of FailingChecksBlock: every check of the
1206// head must have ended as success, skipped or neutral. A check still queued or
1207// running blocks too (the merge could land code that then fails), and a head
1208// without any check merges.
1209func (m *MergeRequests) checksAllow(ctx context.Context, name domain.RepoName, head domain.ObjectID) error {
1210 if m.checks == nil {
1211 return nil
1212 }
1213 checks, err := m.checks.CommitChecks(ctx, name, head.String())
1214 if errors.Is(err, domain.ErrResourceExhausted) {
1215 return fmt.Errorf("%w: too many checks to tell whether they passed: %v", domain.ErrPreconditionFailed, err)
1216 }
1217 if err != nil {
1218 return fmt.Errorf("read the checks of %s: %w", head, err)
1219 }
1220 var failing, pending []string
1221 for _, c := range checks {
1222 switch {
1223 case c.Status != domain.CICompleted:
1224 pending = append(pending, c.Name)
1225 case !c.Conclusion.PassesMerge():
1226 failing = append(failing, c.Name)
1227 }
1228 }
1229 switch {
1230 case len(failing) > 0:
1231 return fmt.Errorf("%w: failing checks block the merge: %s (turn off failing_checks_block to merge anyway)", domain.ErrPreconditionFailed, strings.Join(failing, ", "))
1232 case len(pending) > 0:
1233 return fmt.Errorf("%w: checks have not finished: %s", domain.ErrPreconditionFailed, strings.Join(pending, ", "))
1234 }
1235 return nil
1236}
1237
1238// checkDeletable refuses to delete the source branch of mr when it is the
1239// default branch or the source or target of another open request. It runs
1240// under the merge lock, which Create also holds while it checks its branches
1241// and stores the request.
1242func (m *MergeRequests) checkDeletable(ctx context.Context, name domain.RepoName, mr domain.MergeRequest) error {
1243 def, _, err := m.repos.DefaultBranch(ctx, name)
1244 if err != nil {
1245 return fmt.Errorf("default branch of %q: %w", name, err)
1246 }
1247 if mr.Source == def {
1248 return fmt.Errorf("%w: %q is the default branch of %s: it cannot be deleted", domain.ErrPreconditionFailed, mr.Source, name)
1249 }
1250 all, err := m.store.List(ctx, name)
1251 if err != nil {
1252 return fmt.Errorf("list merge requests of %q: %w", name, err)
1253 }
1254 for _, o := range all {
1255 if o.Number != mr.Number && o.IsOpen() && (o.Source == mr.Source || o.Target == mr.Source) {
1256 return fmt.Errorf("%w: !%d still uses %q: it cannot be deleted", domain.ErrPreconditionFailed, o.Number, mr.Source)
1257 }
1258 }
1259 return nil
1260}
1261
1262// recordPush does for a merge what Pushes.Record does for a push, as the merge
1263// moved a branch: it sets pushed_at and queues the maintenance of the
1264// repository. The target already moved, so a failure is logged, not returned,
1265// and the caller giving up does not stop it.
1266func (m *MergeRequests) recordPush(ctx context.Context, name domain.RepoName) {
1267 ctx = context.WithoutCancel(ctx)
1268 if _, err := touchPushedAt(ctx, m.meta, name, m.clock.Now().UTC()); err != nil {
1269 log := zerowrap.FromCtx(ctx)
1270 log.Error().Err(err).Str("repo", name.String()).Msg("record pushed_at after a merge")
1271 }
1272 m.maint.Schedule(ctx, name)
1273}
1274
1275// moveTarget moves the target branch from tip to the head (fast-forward) or to
1276// a new signed squash or merge commit with the given tree, and returns the new tip.
1277func (m *MergeRequests) moveTarget(ctx context.Context, mr domain.MergeRequest, mode domain.MergeMode, tip, head, tree domain.ObjectID, p domain.Principal) (domain.ObjectID, error) {
1278 newTip := head
1279 switch mode {
1280 case domain.MergeModeMerge:
1281 commit := domain.NewMergeCommit(mr, tree, tip, head, m.committer, m.clock.Now())
1282 armored, err := m.signer.Sign(commit.Payload())
1283 if err != nil {
1284 return domain.ObjectID{}, fmt.Errorf("sign the merge commit of !%d in %q: %w", mr.Number, mr.Repo, err)
1285 }
1286 if newTip, err = m.git.WriteCommit(ctx, mr.Repo, commit.Signed(armored)); err != nil {
1287 return domain.ObjectID{}, err
1288 }
1289 case domain.MergeModeSquash:
1290 commits, more, err := m.git.ListRange(ctx, mr.Repo, tip, head, domain.MaxSquashCommits)
1291 if err != nil {
1292 return domain.ObjectID{}, err
1293 }
1294 if more {
1295 return domain.ObjectID{}, fmt.Errorf("%w: the branch has more than %d commits to squash", domain.ErrPreconditionFailed, domain.MaxSquashCommits)
1296 }
1297 commit := domain.NewSquashCommit(mr, tree, tip, commits, m.committer, m.clock.Now())
1298 armored, err := m.signer.Sign(commit.Payload())
1299 if err != nil {
1300 return domain.ObjectID{}, fmt.Errorf("sign the squash commit of !%d in %q: %w", mr.Number, mr.Repo, err)
1301 }
1302 if newTip, err = m.git.WriteCommit(ctx, mr.Repo, commit.Signed(armored)); err != nil {
1303 return domain.ObjectID{}, err
1304 }
1305 }
1306 // The target is the merger's from the moment it moves: recorded before it
1307 // does, under the merge lock (domain.CIRefTip). The run shows the owner, as a
1308 // merge's push does on GitHub.
1309 if err := recordRefTips(ctx, m.tips, mr.Repo, []domain.RefUpdate{{Old: tip.String(), New: newTip.String(), Ref: "refs/heads/" + mr.Target}},
1310 domain.AuthorName(domain.Owner()), domain.PusherOf(p), domain.TrustedActor(p)); err != nil {
1311 return domain.ObjectID{}, err
1312 }
1313 err := m.git.UpdateBranch(ctx, mr.Repo, mr.Target, tip, newTip)
1314 if errors.Is(err, domain.ErrConflict) {
1315 return domain.ObjectID{}, fmt.Errorf("%w: the target branch %q moved during the merge, try again", domain.ErrPreconditionFailed, mr.Target)
1316 }
1317 if err != nil {
1318 return domain.ObjectID{}, err
1319 }
1320 return newTip, nil
1321}
1322
1323// markMerged records the merge. The target already moved, so a write that
1324// loses a race (a comment added meanwhile) is repeated on the fresh request.
1325func (m *MergeRequests) markMerged(ctx context.Context, name domain.RepoName, number int64, mode domain.MergeMode, base, head, merged domain.ObjectID) (domain.MergeRequest, error) {
1326 // The merge must be recorded even when the caller gives up.
1327 ctx = context.WithoutCancel(ctx)
1328 for range maxWriteRetries {
1329 mr, err := m.store.Get(ctx, name, number)
1330 if err != nil {
1331 return domain.MergeRequest{}, fmt.Errorf("record the merge of !%d in %q: %w", number, name, err)
1332 }
1333 mr.State, mr.HeadID, mr.BaseID, mr.MergedCommitID, mr.MergeMode = domain.MRStateMerged, head, base, merged, mode
1334 mr.UpdatedAt = m.clock.Now().UTC()
1335 err = m.store.Update(ctx, mr)
1336 if errors.Is(err, domain.ErrConflict) {
1337 continue
1338 }
1339 if err != nil {
1340 return domain.MergeRequest{}, fmt.Errorf("record the merge of !%d in %q: %w", number, name, err)
1341 }
1342 return mr, nil
1343 }
1344 log := zerowrap.FromCtx(ctx)
1345 log.Error().Str("repo", name.String()).Int64("number", number).Str("commit", merged.String()).
1346 Msg("the target branch moved but the merge request could not be marked merged")
1347 return domain.MergeRequest{}, fmt.Errorf("record the merge of !%d in %q: %w", number, name, domain.ErrConflict)
1348}
1349
1350// EditComment changes only the author's text, preserving the immutable verdict.
1351func (m *MergeRequests) EditComment(ctx context.Context, p domain.Principal, name domain.RepoName, number, commentID int64, text string) (domain.Comment, error) {
1352 return m.changeComment(ctx, p, name, number, commentID, text, false)
1353}
1354
1355// DeleteComment removes text but retains the anchor, ID and verdict. Repeated deletion is a no-op.
1356func (m *MergeRequests) DeleteComment(ctx context.Context, p domain.Principal, name domain.RepoName, number, commentID int64) (domain.Comment, error) {
1357 return m.changeComment(ctx, p, name, number, commentID, "", true)
1358}
1359
1360func (m *MergeRequests) changeComment(ctx context.Context, p domain.Principal, name domain.RepoName, number, commentID int64, text string, remove bool) (domain.Comment, error) {
1361 repo, err := m.writable(ctx, p, name, domain.ScopeMRWrite)
1362 if err != nil {
1363 return domain.Comment{}, err
1364 }
1365 for range maxWriteRetries {
1366 mr, err := m.store.Get(ctx, name, number)
1367 if err != nil {
1368 return domain.Comment{}, err
1369 }
1370 c, err := m.store.GetComment(ctx, name, number, commentID)
1371 if err != nil {
1372 return domain.Comment{}, err
1373 }
1374 if !mr.IsOpen() {
1375 return domain.Comment{}, fmt.Errorf("%w: !%d is %s", domain.ErrPreconditionFailed, number, mr.State)
1376 }
1377 if domain.AuthorName(p) != c.Author {
1378 return domain.Comment{}, fmt.Errorf("%w: only the author of a note can edit or delete it", domain.ErrForbidden)
1379 }
1380 if c.Deleted {
1381 if remove {
1382 return c, nil
1383 }
1384 return domain.Comment{}, fmt.Errorf("%w: the note was deleted", domain.ErrPreconditionFailed)
1385 }
1386 parsed, err := domain.ParsePlainText(text)
1387 var v domain.Violations
1388 if err != nil {
1389 v.AddErr("text", err)
1390 } else if !remove && parsed.IsBlank() && c.Verdict == domain.VerdictNone {
1391 v.Add("text", "is required")
1392 }
1393 if err := v.Err(); err != nil {
1394 return domain.Comment{}, err
1395 }
1396 if !remove && parsed == c.Text {
1397 return c, nil
1398 }
1399 c.Text, c.Deleted, c.EditedAt = parsed, remove, m.clock.Now().UTC()
1400 mr.UpdatedAt = c.EditedAt
1401 if err := m.store.SaveComment(ctx, mr, c); errors.Is(err, domain.ErrConflict) {
1402 continue
1403 } else if err != nil {
1404 return domain.Comment{}, fmt.Errorf("save note %d of !%d in %q: %w", commentID, number, name, err)
1405 }
1406 log := zerowrap.FromCtx(ctx)
1407 log.Info().Str("repo", name.String()).Int64("number", number).Int64("comment", c.ID).Bool("deleted", remove).Str("principal", p.Label()).Str("token_id", p.TokenID()).Msg("comment changed")
1408 if remove {
1409 m.bus.Publish(ctx, domain.CommentDeleted{Repo: name, Number: number, Comment: c, At: c.EditedAt, Visibility: repo.Visibility, CreatedAt: repo.CreatedAt})
1410 } else {
1411 m.bus.Publish(ctx, domain.CommentEdited{Repo: name, Number: number, Comment: c, At: c.EditedAt, Visibility: repo.Visibility, CreatedAt: repo.CreatedAt})
1412 }
1413 return c, nil
1414 }
1415 return domain.Comment{}, fmt.Errorf("save note %d of !%d in %q: %w", commentID, number, name, domain.ErrConflict)
1416}
1417
1418// replyRoot returns the note a reply targets, or a violation when it is
1419// missing, itself a reply, or deleted.
1420func (m *MergeRequests) replyRoot(ctx context.Context, name domain.RepoName, number, id int64) (domain.Comment, error) {
1421 root, err := m.store.GetComment(ctx, name, number, id)
1422 var v domain.Violations
1423 switch {
1424 case errors.Is(err, domain.ErrNotFound):
1425 v.Add("reply_to", fmt.Sprintf("no note ^%d", id))
1426 case err != nil:
1427 return domain.Comment{}, err
1428 case root.IsReply() || root.Deleted:
1429 v.Add("reply_to", "must name a non-deleted root note")
1430 }
1431 if err := v.Err(); err != nil {
1432 return domain.Comment{}, err
1433 }
1434 return root, nil
1435}