Auto merge of #141 - kennytm:master, r=jdm

Support relabeling when some event happens

Let Homu automatically relabel the issue when some predefined events happened. The labels can be configured through `cfg.toml` via the `[repo.NAME.labels.EVENT]` key, e.g.

```toml
# when a merge conflict is detected...
[repo.rust.labels.conflict]
# remove the `S-waiting-on-bors` and `S-waiting-on-review` labels...
remove = ['S-waiting-on-bors', 'S-waiting-on-review']
# add the `S-waiting-on-author` label...
add = ['S-waiting-on-author']
# but don't do anything if the PR is already labeled with `S-blocked`,
# `S-waiting-on-crater` or `S-waiting-on-team`.
except = ['S-blocked', 'S-waiting-on-crater', 'S-waiting-on-team']
```

See `cfg.sample.toml` for a list of supported events.

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Author: bors-servo

cfg.sample.toml

@@ -96,6 +96,28 @@ try_users = []
 # Arbitrary secret. You can generate one with: openssl rand -hex 20
 secret = ""
 
+# Remove and add GitHub labels when some event happened.
+# See servo/homu#141 for detail.
+#
+#[repo.NAME.labels.approved]    # after homu received `r+`
+#[repo.NAME.labels.rejected]    # after homu received `r-`
+#[repo.NAME.labels.conflict]    # a merge conflict is detected
+#[repo.NAME.labels.succeed]     # test successful
+#[repo.NAME.labels.failed]      # test failed
+#[repo.NAME.labels.exempted]    # test exempted
+#[repo.NAME.labels.timed_out]   # test timed out (after 10 hours)
+#[repo.NAME.labels.interrupted] # test interrupted (buildbot only)
+#[repo.NAME.labels.try]         # after homu received `try`
+#[repo.NAME.labels.try_succeed] # try-build successful
+#[repo.NAME.labels.try_failed]  # try-build failed
+#[repo.NAME.labels.pushed]      # user pushed a commit after `r+`/`try`
+#remove = ['list', 'of', 'labels', 'to', 'remove']
+#add = ['list', 'of', 'labels', 'to', 'add']
+#unless = [
+#   'avoid', 'relabeling', 'if',
+#   'any', 'of', 'these', 'labels', 'are', 'present',
+#]
+
 # Travis integration. Don't forget to allow Travis to test the `auto` branch!
 [repo.NAME.status.travis]
 # String label set by status updates. Don't touch this unless you really know

homu/main.py

@@ -17,7 +17,7 @@
 from queue import Queue
 import os
 import sys
-from enum import IntEnum
+from enum import IntEnum, Enum
 import subprocess
 from .git_helper import SSH_KEY_FILE
 import shlex
@@ -115,7 +115,7 @@ class PullReqState:
     delegate = ''
 
     def __init__(self, num, head_sha, status, db, repo_label, mergeable_que,
-                 gh, owner, name, repos):
+                 gh, owner, name, label_events, repos):
         self.head_advanced('', use_db=False)
 
         self.num = num
@@ -130,6 +130,7 @@ def __init__(self, num, head_sha, status, db, repo_label, mergeable_que,
         self.repos = repos
         self.timeout_timer = None
         self.test_started = time.time()
+        self.label_events = label_events
 
     def head_advanced(self, head_sha, *, use_db=True):
         self.head_sha = head_sha
@@ -178,6 +179,21 @@ def get_issue(self):
     def add_comment(self, text):
         self.get_issue().create_comment(text)
 
+    def change_labels(self, event):
+        event = self.label_events.get(event.value, {})
+        removes = event.get('remove', [])
+        adds = event.get('add', [])
+        unless = event.get('unless', [])
+        if not removes and not adds:
+            return
+
+        issue = self.get_issue()
+        labels = {label.name for label in issue.iter_labels()}
+        if labels.isdisjoint(unless):
+            labels.difference_update(removes)
+            labels.update(adds)
+            issue.replace_labels(list(labels))
+
     def set_status(self, status):
         self.status = status
         if self.timeout_timer:
@@ -347,6 +363,7 @@ def timed_out(self):
             desc,
             context='homu')
         self.add_comment(':boom: {}'.format(desc))
+        self.change_labels(LabelEvent.TIMED_OUT)
 
 
 def sha_cmp(short, full):
@@ -364,6 +381,21 @@ class AuthState(IntEnum):
     NONE = 1
 
 
+class LabelEvent(Enum):
+    APPROVED = 'approved'
+    REJECTED = 'rejected'
+    CONFLICT = 'conflict'
+    SUCCEED = 'succeed'
+    FAILED = 'failed'
+    TRY = 'try'
+    TRY_SUCCEED = 'try_succeed'
+    TRY_FAILED = 'try_failed'
+    EXEMPTED = 'exempted'
+    TIMED_OUT = 'timed_out'
+    INTERRUPTED = 'interrupted'
+    PUSHED = 'pushed'
+
+
 def verify_auth(username, repo_cfg, state, auth, realtime, my_username):
     # In some cases (e.g. non-fully-qualified r+) we recursively talk to
     # ourself via a hidden markdown comment in the message. This is so that
@@ -534,15 +566,17 @@ def parse_commands(body, username, repo_cfg, state, my_username, db, states,
                             ':evergreen_tree: The tree is currently closed for pull requests below priority {}, this pull request will be tested once the tree is reopened'  # noqa
                             .format(treeclosed)
                         )
+                    state.change_labels(LabelEvent.APPROVED)
 
         elif word == 'r-':
             if not verify_auth(username, repo_cfg, state, AuthState.REVIEWER,
                                realtime, my_username):
                 continue
 
             state.approved_by = ''
-
             state.save()
+            if realtime:
+                state.change_labels(LabelEvent.REJECTED)
 
         elif word.startswith('p='):
             if not verify_auth(username, repo_cfg, state, AuthState.TRY,
@@ -601,6 +635,9 @@ def parse_commands(body, username, repo_cfg, state, my_username, db, states,
             if not _try_auth_verified():
                 continue
             state.set_status('')
+            if realtime:
+                event = LabelEvent.TRY if state.try_ else LabelEvent.APPROVED
+                state.change_labels(event)
 
         elif word in ['try', 'try-'] and realtime:
             if not _try_auth_verified():
@@ -611,6 +648,10 @@ def parse_commands(body, username, repo_cfg, state, my_username, db, states,
             state.init_build_res([])
 
             state.save()
+            if realtime and state.try_:
+                # `try-` just resets the `try` bit and doesn't correspond to
+                # any meaningful labeling events.
+                state.change_labels(LabelEvent.TRY)
 
         elif word in ['rollup', 'rollup-']:
             if not _try_auth_verified():
@@ -924,6 +965,7 @@ def create_merge(state, repo_cfg, branch, logger, git_cfg,
         context='homu')
 
     state.add_comment(':lock: ' + desc)
+    state.change_labels(LabelEvent.CONFLICT)
 
     return ''
 
@@ -979,6 +1021,7 @@ def do_exemption_merge(state, logger, repo_cfg, git_cfg, url, check_merge,
     utils.github_create_status(state.get_repo(), state.head_sha, 'success',
                                url, desc, context='homu')
     state.add_comment(':zap: {}: {}.'.format(desc, reason))
+    state.change_labels(LabelEvent.EXEMPTED)
 
     state.merge_sha = merge_sha
     state.save()
@@ -1343,6 +1386,7 @@ def fetch_mergeability(mergeable_que):
                 state.add_comment(':umbrella: The latest upstream changes{} made this pull request unmergeable. Please resolve the merge conflicts.'.format(  # noqa
                     _blame
                 ))
+                state.change_labels(LabelEvent.CONFLICT)
 
             state.set_mergeable(mergeable, que=False)
 
@@ -1388,7 +1432,7 @@ def synchronize(repo_label, repo_cfg, logger, gh, states, repos, db, mergeable_q
                     status = info.state
                     break
 
-        state = PullReqState(pull.number, pull.head.sha, status, db, repo_label, mergeable_que, gh, repo_cfg['owner'], repo_cfg['name'], repos)  # noqa
+        state = PullReqState(pull.number, pull.head.sha, status, db, repo_label, mergeable_que, gh, repo_cfg['owner'], repo_cfg['name'], repo_cfg.get('labels', {}), repos)  # noqa
         state.title = pull.title
         state.body = pull.body
         state.head_ref = pull.head.repo[0] + ':' + pull.head.ref
@@ -1557,7 +1601,7 @@ def main():
             'SELECT num, head_sha, status, title, body, head_ref, base_ref, assignee, approved_by, priority, try_, rollup, delegate, merge_sha FROM pull WHERE repo = ?',   # noqa
             [repo_label])
         for num, head_sha, status, title, body, head_ref, base_ref, assignee, approved_by, priority, try_, rollup, delegate, merge_sha in db.fetchall():  # noqa
-            state = PullReqState(num, head_sha, status, db, repo_label, mergeable_que, gh, repo_cfg['owner'], repo_cfg['name'], repos)  # noqa
+            state = PullReqState(num, head_sha, status, db, repo_label, mergeable_que, gh, repo_cfg['owner'], repo_cfg['name'], repo_cfg.get('labels', {}), repos)  # noqa
             state.title = title
             state.body = body
             state.head_ref = head_ref

homu/server.py

@@ -7,6 +7,7 @@
     db_query,
     INTERRUPTED_BY_HOMU_RE,
     synchronize,
+    LabelEvent,
 )
 from . import utils
 from .utils import lazy_debug
@@ -328,7 +329,9 @@ def github():
             state = PullReqState(pull_num, head_sha, '', g.db, repo_label,
                                  g.mergeable_que, g.gh,
                                  info['repository']['owner']['login'],
-                                 info['repository']['name'], g.repos)
+                                 info['repository']['name'],
+                                 repo_cfg.get('labels', {}),
+                                 g.repos)
             state.title = info['pull_request']['title']
             state.body = info['pull_request']['body']
             state.head_ref = info['pull_request']['head']['repo']['owner']['login'] + ':' + info['pull_request']['head']['ref']  # noqa
@@ -419,6 +422,8 @@ def fail(err):
                 })
 
             if state.head_sha == info['before']:
+                if state.status:
+                    state.change_labels(LabelEvent.PUSHED)
                 state.head_advanced(info['after'])
 
                 state.save()
@@ -499,6 +504,7 @@ def report_build_res(succ, url, builder, state, logger, repo_cfg):
                            ).format(state.approved_by, state.merge_sha,
                                     state.base_ref)
                 state.add_comment(comment)
+                state.change_labels(LabelEvent.SUCCEED)
                 try:
                     try:
                         utils.github_set_ref(state.get_repo(), 'heads/' +
@@ -529,6 +535,7 @@ def report_build_res(succ, url, builder, state, logger, repo_cfg):
                            'State: approved={} try={}'
                            ).format(state.approved_by, state.try_)
                 state.add_comment(comment)
+                state.change_labels(LabelEvent.TRY_SUCCEED)
 
     else:
         if state.status == 'pending':
@@ -540,6 +547,8 @@ def report_build_res(succ, url, builder, state, logger, repo_cfg):
             state.add_comment(':broken_heart: {} - [{}]({})'.format(desc,
                                                                     builder,
                                                                     url))
+            event = LabelEvent.TRY_FAILED if state.try_ else LabelEvent.FAILED
+            state.change_labels(event)
 
     g.queue_handler()
 
@@ -625,6 +634,7 @@ def buildbot():
                                 desc = (':snowman: The build was interrupted '
                                         'to prioritize another pull request.')
                                 state.add_comment(desc)
+                                state.change_labels(LabelEvent.INTERRUPTED)
                                 utils.github_create_status(state.get_repo(),
                                                            state.head_sha,
                                                            'error', url,