Backups: a revision chain belongs to a PC, not just a machine

tests/test_plugins/test_backups.py

@@ -757,3 +757,93 @@ def test_a_marker_export_shows_the_mark_tab():
     assert any('MARK' in label for label in labels)
     mark = next(s for s in card['sections'] if 'MARK' in s['label'])
     assert any(f['label'] == 'Port Id' and f['value'] == 'COM4' for f in mark['fields'])
+
+
+# =============================================================================
+# Several PCs sharing one machine number
+# =============================================================================
+
+def _markerreg(comport):
+    """A marker config that differs from its sibling only by COM port.
+
+    Which is what the real ones do: the part markers sharing 0613, 0615 and
+    WJPRT are separate devices on separate ports, filed under one machine
+    number.
+    """
+    return CONFIGUREDREG.replace('"MachineNo"="3204"',
+                                 '"MachineNo"="3204"\r\n'
+                                 '"Port Id"="{}"'.format(comport))
+
+
+def test_two_pcs_on_one_machine_number_do_not_thrash(bk_app, bk_plugin):
+    """The bug that filled the table: dedup was against the LATEST revision for
+    the asset, so with two PCs on one machine number each post differed from
+    whichever PC posted last. Nothing ever deduped and the chain grew by a row
+    per PC per collection cycle, forever."""
+    from plugins.backups.models import BackupRevision
+    with bk_app.app_context():
+        for _ in range(5):
+            bk_plugin.apply_collector_payload(
+                _payload(reg=_markerreg('COM3'), sourcehostname='MARKERA'))
+            bk_plugin.apply_collector_payload(
+                _payload(reg=_markerreg('COM4'), sourcehostname='MARKERB'))
+
+        # One revision each, not ten.
+        assert _db.session.query(BackupRevision).count() == 2
+
+
+def test_each_pc_keeps_its_own_history_on_a_shared_machine(bk_app, bk_plugin):
+    """Both markers' configs matter, so both chains are kept in full."""
+    from plugins.backups.models import BackupRevision
+    with bk_app.app_context():
+        bk_plugin.apply_collector_payload(
+            _payload(reg=_markerreg('COM3'), sourcehostname='MARKERA'))
+        bk_plugin.apply_collector_payload(
+            _payload(reg=_markerreg('COM4'), sourcehostname='MARKERB'))
+        # MARKERA is re-cabled. That is a real change on A, and none on B.
+        bk_plugin.apply_collector_payload(
+            _payload(reg=_markerreg('COM5'), sourcehostname='MARKERA'))
+        result = bk_plugin.apply_collector_payload(
+            _payload(reg=_markerreg('COM4'), sourcehostname='MARKERB'))
+
+        assert result['action'] == 'noop'
+        rows = _db.session.query(BackupRevision).all()
+        bysource = {}
+        for row in rows:
+            bysource.setdefault(row.sourcehostname, []).append(row)
+        assert len(bysource['MARKERA']) == 2
+        assert len(bysource['MARKERB']) == 1
+
+
+def test_a_null_source_still_forms_a_chain(bk_app, bk_plugin):
+    """Rows written before sourcehostname was populated, and hand-loaded ones,
+    carry NULL. `column == None` never matches in SQL, so without an IS NULL
+    those rows would dedupe against nothing and re-post every cycle."""
+    from plugins.backups.models import BackupRevision
+    with bk_app.app_context():
+        first = bk_plugin.apply_collector_payload(_payload(sourcehostname=None))
+        second = bk_plugin.apply_collector_payload(_payload(sourcehostname=None))
+        assert second['action'] == 'noop'
+        assert second['backuprevisionid'] == first['backuprevisionid']
+        assert _db.session.query(BackupRevision).count() == 1
+
+
+def test_retention_prunes_each_pc_separately(bk_app, bk_plugin):
+    """Pruning per asset let a busy marker's revisions evict a quiet marker's
+    only backup, which is the one row that mattered on that PC."""
+    from plugins.backups.models import BackupRevision
+    from plugins.backups.services.retention import prune
+    with bk_app.app_context():
+        bk_plugin.apply_collector_payload(
+            _payload(reg=_markerreg('COM9'), sourcehostname='QUIET'))
+        for port in ('COM3', 'COM4', 'COM5', 'COM6', 'COM7'):
+            bk_plugin.apply_collector_payload(
+                _payload(reg=_markerreg(port), sourcehostname='BUSY'))
+
+        asset = _db.session.query(BackupRevision).first().assetid
+        prune(asset, 'ntlars', retentioncount=2)
+        _db.session.commit()
+
+        rows = _db.session.query(BackupRevision).all()
+        sources = [row.sourcehostname for row in rows]
+        assert 'QUIET' in sources, 'the quiet PC lost its only backup'