[pinpoint] Gerrit patch support.

dashboard/dashboard/pinpoint/models/change/patch.py

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import collections
+import urlparse
+
+from dashboard.services import gerrit_service
 
 
-class Patch(collections.namedtuple('Patch', ('server', 'issue', 'patchset'))):
-  """A patch in Rietveld."""
-  # TODO: Support Gerrit.
-  # https://github.com/catapult-project/catapult/issues/3599
+def FromDict(data):
+  # If we have more Patch types in the future, we can loop
+  # through them all and try each one's FromDict() in turn.
+  return GerritPatch.FromDict(data)
+
+
+class GerritPatch(collections.namedtuple(
+    'GerritPatch', ('server', 'change', 'revision'))):
+  """A patch in Gerrit.
+
+  change is a change ID of the format '<project>~<branch>~<Change-Id>' and
+  revision is a commit ID. Both are described in the Gerrit API documentation.
+  https://gerrit-review.googlesource.com/Documentation/rest-api-changes.html#ids
+
+  They must be in a canonical format so we can look up builds precisely.
+  """
 
   def __str__(self):
     return self.id_string
 
   @property
   def id_string(self):
-    return '%s/%d/%d' % (self.server, self.issue, self.patchset)
+    return '%s/%s/%s' % (self.server, self.change, self.revision)
+
+  def BuildParameters(self):
+    patch_info = gerrit_service.GetChange(
+        self.server, self.change, fields=('ALL_REVISIONS',))
+    revision_info = patch_info['revisions'][self.revision]
+    return {
+        'patch_gerrit_url': self.server,
+        'patch_issue': patch_info['_number'],
+        'patch_project': patch_info['project'],
+        'patch_ref': revision_info['fetch']['http']['ref'],
+        'patch_repository_url': revision_info['fetch']['http']['url'],
+        'patch_set': revision_info['_number'],
+        'patch_storage': 'gerrit',
+    }
 
   def AsDict(self):
     return self._asdict()
 
   @classmethod
   def FromDict(cls, data):
-    # TODO: Validate to ensure the patch exists on the server.
-    return cls(data['server'], data['issue'], data['patchset'])
+    """Creates a new GerritPatch from the given data.
+
+    Args:
+      data: A patch URL string, for example:
+        https://chromium-review.googlesource.com/c/chromium/tools/build/+/679595
+        Or a dict containing {server, change, revision [optional]}.
+        change is a {change-id} as described in the Gerrit API documentation.
+        revision is a commit ID hash or numeric patch number.
+        If revision is omitted, it is the change's current revision.
+
+    Returns:
+      A GerritPatch.
+
+    Raises:
+      KeyError: The patch doesn't have the given revision.
+    """
+    if isinstance(data, basestring):
+      url_parts = urlparse.urlparse(data)
+      server = urlparse.urlunsplit(
+          (url_parts.scheme, url_parts.netloc, '', '', ''))
+      change = url_parts.path.rsplit('/', 1)[-1]
+      revision = None

[perezju, 2017/09/26 09:15:47]

how do we know to which repository should the patch be applied (i.e. the
"tools/build" part)?

[dtu, 2017/09/26 20:00:23]

As far as I can tell from the Gerrit doc, the numeric Change-Id is unique across
all repos.
On line 84, we convert the Change-Id to a canonical {change-id}.
In BuildParameters() on line 44, we look up the repository from the {change-id}
using the Gerrit API.

[perezju, 2017/09/27 08:21:47]

Wow, had no idea. Ok, thanks for the explanation!

+    else:
+      server = data['server']
+      change = data['change']
+      revision = data.get('revision')
+
+    # Look up the patch and convert everything to a canonical format.
+    patch_info = gerrit_service.GetChange(
+        server, change, fields=('ALL_REVISIONS',))
+    change = patch_info['id']
+
+    # Revision can be a revision ID or numeric patch number.
+    if not revision:
+      revision = patch_info['current_revision']
+    for revision_id, revision_info in patch_info['revisions'].iteritems():
+      if revision == revision_id or revision == revision_info['_number']:
+        revision = revision_id
+        break
+    else:
+      raise KeyError('Patch revision not found: %s/%s revision %s' %
+                     (server, change, revision))
+
+    return cls(server, change, revision)