[LNT] Fixed fieldchanges grouping to a regression

Note active_indicators is not a list of regression indicators. It is a list of fieldchanges actually.
After that fix all new fieldchanges will be grouped mostly in the same regression as expected.
It prevents creating of thousand new regressions and ageing them out immediately to keep regressions count under 50.

Reviewed By: thopre

Differential Revision: https://reviews.llvm.org/D109216

Author: Pavel Kosov

lnt/server/db/fieldchange.py

@@ -125,7 +125,7 @@ def regenerate_fieldchanges_for_run(session, ts, run_id):
                               .filter(ts.FieldChange.field_id.in_(field_ids))
                               .all())
 
-    active_indicators = session.query(ts.FieldChange) \
+    active_changes = session.query(ts.FieldChange) \
         .join(ts.RegressionIndicator) \
         .join(ts.Regression) \
         .filter(or_(ts.Regression.state == RegressionState.DETECTED,
@@ -175,12 +175,12 @@ def regenerate_fieldchanges_for_run(session, ts, run_id):
                 session.flush()
                 try:
                     found, new_reg = identify_related_changes(session, ts,
-                                                              f, active_indicators)
+                                                              f, active_changes)
                 except ObjectDeletedError:
                     # This can happen from time to time.
                     # So, lets retry once.
                     found, new_reg = identify_related_changes(session, ts,
-                                                              f, active_indicators)
+                                                              f, active_changes)
 
                 if found:
                     logger.info("Found field change: {}".format(
@@ -225,7 +225,7 @@ def percent_similar(a, b):
 
 
 @timed
-def identify_related_changes(session, ts, fc, active_indicators):
+def identify_related_changes(session, ts, fc, active_changes):
     # type: (Session, TestSuiteDB, TestSuiteDB.FieldChange, List) -> Tuple[bool, List]
     """Can we find a home for this change in some existing regression? If a
     match is found add a regression indicator adding this change to that
@@ -236,7 +236,7 @@ def identify_related_changes(session, ts, fc, active_indicators):
 
     """
 
-    for change in active_indicators:
+    for change in active_changes:
         if is_overlaping(change, fc):
             confidence = 0.0
 
@@ -260,13 +260,13 @@ def identify_related_changes(session, ts, fc, active_indicators):
                 ri = ts.RegressionIndicator(regression, fc)
                 session.add(ri)
                 session.flush()
-                active_indicators.append(ri)
+                active_changes.append(fc)
                 # Update the default title if needed.
                 rebuild_title(session, ts, regression)
                 logger.info("Updated title of Regression({}) to \"{}\"".format(regression.id, regression.title))
                 return True, regression
 
-    new_reg, new_indicators = new_regression(session, ts, [fc.id])
+    new_reg, new_indicators = new_regression(session, ts, [fc])
     logger.info("Could not find a partner, creating new Regression for change: {}".format(new_reg.title))
-    active_indicators.extend(new_indicators)
+    active_changes.append(fc)
     return False, new_reg