swh.lister.core: Make gitlab lister a paging lister instance

Related T989

swh/lister/core/paging_lister.py

+# Copyright (C) 2015-2018 the Software Heritage developers
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+import abc
+import logging
+
+from .lister_transports import SWHListerHttpTransport
+from .lister_base import SWHListerBase
+
+
+class SWHPagingLister(SWHListerBase):
+    """Lister* intermediate class for any service that follows the simple
+       pagination page pattern.
+
+    - Client sends a request to list repositories starting from a
+      given page identifier.
+
+    - Client receives structured (json/xml/etc) response with
+      information about a sequential series of repositories (per page)
+      starting from a given index. And, if available, some indication
+      of the next page index for fetching the remaining repository
+      data.
+
+    See :class:`swh.lister.core.lister_base.SWHListerBase` for more
+    details.
+
+    This class cannot be instantiated. To create a new Lister for a
+    source code listing service that follows the model described
+    above, you must subclass this class. Then provide the required
+    overrides in addition to any unmet implementation/override
+    requirements of this class's base (see parent class and member
+    docstrings for details).
+
+    Required Overrides::
+
+        def get_next_target_from_response
+
+    """
+    @abc.abstractmethod
+    def get_next_target_from_response(self, response):
+        """Find the next server endpoint page given the entire response.
+
+        Implementation of this method depends on the server API spec
+        and the shape of the network response object returned by the
+        transport_request method.
+
+        For example, some api can use the headers links to provide the
+        next page.
+
+        Args:
+            response (transport response): response page from the server
+
+        Returns:
+            index of next page, possibly extracted from a next href url
+
+        """
+        pass
+
+    # You probably don't need to override anything below this line.
+
+    def run(self, min_index=None, max_index=None):
+        """Main entry function. Sequentially fetches repository data from the
+           service according to the basic outline in the class
+           docstring. Continually fetching sublists until either there
+           is no next index reference given or the given next index is
+           greater than the desired max_index.
+
+        Args:
+            min_index (indexable type): optional index to start from
+            max_index (indexable type): optional index to stop at
+
+        Returns:
+            nothing
+
+        """
+        index = min_index or ''
+        loop_count = 0
+        self.min_index = min_index
+        self.max_index = max_index
+
+        while self.is_within_bounds(index, self.min_index, self.max_index):
+            logging.info('listing repos starting at %s' % index)
+
+            response, injected_repos = self.ingest_data(index)
+            next_index = self.get_next_target_from_response(response)
+
+            # termination condition
+
+            if (next_index is None) or (next_index == index):
+                logging.info('stopping after index %s, no next link found' %
+                             index)
+                break
+            else:
+                index = next_index
+
+            loop_count += 1
+            if loop_count == 20:
+                logging.info('flushing updates')
+                loop_count = 0
+                self.db_session.commit()
+                self.db_session = self.mk_session()
+
+        self.db_session.commit()
+        self.db_session = self.mk_session()
+
+
+class SWHPagingHttpLister(SWHListerHttpTransport, SWHPagingLister):
+    """Convenience class for ensuring right lookup and init order when
+       combining SWHPagingLister and SWHListerHttpTransport.
+
+    """
+    def __init__(self, lister_name=None, api_baseurl=None,
+                 override_config=None):
+        SWHListerHttpTransport.__init__(self, api_baseurl=api_baseurl)
+        SWHPagingLister.__init__(self, lister_name=lister_name,
+                                 override_config=override_config)

swh/lister/gitlab/lister.py

@@ -6,20 +6,14 @@ import random
 import re
 import time
 
-from ..core.indexing_lister import SWHIndexingHttpLister
+from ..core.paging_lister import SWHPagingHttpLister
 from .models import GitLabModel
 
 
-class GitLabLister(SWHIndexingHttpLister):
-    # Path to give and mentioning the last id for the next page
+class GitLabLister(SWHPagingHttpLister):
+    # Template path expecting an integer that represents the page id
     PATH_TEMPLATE = '/projects?page=%d&order_by=id&sort=asc&simple=true'
-    # gitlab api do not have an indexable identifier so using the page
-    # id
     API_URL_INDEX_RE = re.compile(r'^.*/projects.*\&page=(\d+).*')
-    # The indexable field, the one we are supposed to use in the api
-    # query is not part of the lookup query. So, we cannot filter
-    # (method filter_before_inject), nor detect and disable origins
-    # (method disable_deleted_repo_tasks)
     MODEL = GitLabModel
 
     @property
@@ -79,12 +73,6 @@ class GitLabLister(SWHIndexingHttpLister):
                 params['auth'] = (auth['username'], auth['password'])
         return params
 
-    def filter_before_inject(self, models_list):
-        """We cannot filter so returns the models_list as is.
-
-        """
-        return models_list
-
     def get_model_from_repo(self, repo):
         return {
             'instance': self.lister_name,