diff --git a/swh/provenance/origin.py b/swh/provenance/origin.py
index 07f07eb..e14e94e 100644
--- a/swh/provenance/origin.py
+++ b/swh/provenance/origin.py
@@ -1,100 +1,107 @@
 # Copyright (C) 2021  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 from itertools import islice
 from typing import Generator, Iterable, Iterator, List, Optional, Tuple
 
 from swh.core.statsd import statsd
 from swh.model.model import Sha1Git
 
 from .archive import ArchiveInterface
 from .graph import HistoryGraph
 from .interface import ProvenanceInterface
 from .model import OriginEntry, RevisionEntry
 
 ORIGIN_DURATION_METRIC = "swh_provenance_origin_revision_layer_duration_seconds"
 
 
 class CSVOriginIterator:
     """Iterator over origin visit statuses typically present in the given CSV
     file.
 
     The input is an iterator that produces 2 elements per row:
 
       (url, snap)
 
     where:
     - url: is the origin url of the visit
     - snap: sha1_git of the snapshot pointed by the visit status
     """
 
     def __init__(
         self,
         statuses: Iterable[Tuple[str, Sha1Git]],
         limit: Optional[int] = None,
     ) -> None:
         self.statuses: Iterator[Tuple[str, Sha1Git]]
         if limit is not None:
             self.statuses = islice(statuses, limit)
         else:
             self.statuses = iter(statuses)
 
     def __iter__(self) -> Generator[OriginEntry, None, None]:
         return (OriginEntry(url, snapshot) for url, snapshot in self.statuses)
 
 
 @statsd.timed(metric=ORIGIN_DURATION_METRIC, tags={"method": "main"})
 def origin_add(
     provenance: ProvenanceInterface,
     archive: ArchiveInterface,
     origins: List[OriginEntry],
     commit: bool = True,
 ) -> None:
     for origin in origins:
-        provenance.origin_add(origin)
-        origin.retrieve_revisions(archive)
-        for revision in origin.revisions:
-            if not provenance.revision_is_head(revision):
-                graph = HistoryGraph(archive, revision)
-                origin_add_revision(provenance, origin, graph)
-            # head is treated separately
-            check_preferred_origin(provenance, origin, revision)
-            provenance.revision_add_to_origin(origin, revision)
+        proceed_origin(provenance, archive, origin)
     if commit:
         provenance.flush()
 
+@statsd.timed(metric=ORIGIN_DURATION_METRIC, tags={"method": "proceed_origin"})
+def proceed_origin(
+        provenance: ProvenanceInterface,
+        archive: ArchiveInterface,
+        origin: OriginEntry) -> None:
+    provenance.origin_add(origin)
+    origin.retrieve_revisions(archive)
+    for revision in origin.revisions:
+        if not provenance.revision_is_head(revision):
+            graph = HistoryGraph(archive, revision)
+            origin_add_revision(provenance, origin, graph)
+        # head is treated separately
+        check_preferred_origin(provenance, origin, revision)
+        provenance.revision_add_to_origin(origin, revision)
+
 
 @statsd.timed(metric=ORIGIN_DURATION_METRIC, tags={"method": "process_revision"})
 def origin_add_revision(
     provenance: ProvenanceInterface,
     origin: OriginEntry,
     graph: HistoryGraph,
 ) -> None:
     visited = {graph.head}
     # head's history should be recursively iterated starting from its parents
     stack = list(graph.parents[graph.head])
     while stack:
         current = stack.pop()
         check_preferred_origin(provenance, origin, current)
 
         # create a link between it and the head, and recursively walk its history
         provenance.revision_add_before_revision(graph.head, current)
         visited.add(current)
         for parent in graph.parents[current]:
             if parent not in visited:
                 stack.append(parent)
 
 
 @statsd.timed(metric=ORIGIN_DURATION_METRIC, tags={"method": "check_preferred_origin"})
 def check_preferred_origin(
     provenance: ProvenanceInterface,
     origin: OriginEntry,
     revision: RevisionEntry,
 ) -> None:
     # if the revision has no preferred origin just set the given origin as the
     # preferred one. TODO: this should be improved in the future!
     preferred = provenance.revision_get_preferred_origin(revision)
     if preferred is None:
         provenance.revision_set_preferred_origin(origin, revision)