[Monitoring] Enable job and status granularity in UNTRIAGED_TESTCASE_COUNT (#4500)

### Motivation

The UNTRIAGED_TESTCASE_COUNT metric worked as expected, however it is
hard to figure out which job the testcase belongs to, and why the
testcase is stuck. This PR adds the job label, and a status one, which
can be one of four values:

PENDING_CRITICAL_TASKS = 'pending_critical_tasks'
PENDING_PROGRESSION = 'pending_progression'
PENDING_GROUPING = 'pending_grouping'
PENDING_FILING = 'pending_filing'

Since (job, status) tuples might disappear from one triage run to the
next, the period of time the gauge is valid for should be, at most, the
interval at which the triage cronjob runs, otherwise it might overcount
things.

Part of #4271

Author: vitorguidi

src/clusterfuzz/_internal/cron/triage.py

@@ -309,6 +309,25 @@ def _file_issue(testcase, issue_tracker, throttler):
   return filed
 
 
+untriaged_testcases = {}
+
+
+def _increment_untriaged_testcase_count(job, status):
+  identifier = (job, status)
+  if identifier not in untriaged_testcases:
+    untriaged_testcases[identifier] = 0
+  untriaged_testcases[identifier] += 1
+
+
+def _emit_untriaged_testcase_count_metric():
+  for (job, status) in untriaged_testcases:
+    monitoring_metrics.UNTRIAGED_TESTCASE_COUNT.set(
+        untriaged_testcases, labels={
+            'job': job,
+            'status': status,
+        })
+
+
 def _emit_untriaged_testcase_age_metric(testcase: data_types.Testcase):
   """Emmits a metric to track age of untriaged testcases."""
   if not testcase.timestamp:
@@ -324,6 +343,12 @@ def _emit_untriaged_testcase_age_metric(testcase: data_types.Testcase):
       })
 
 
+PENDING_CRITICAL_TASKS = 'pending_critical_tasks'
+PENDING_PROGRESSION = 'pending_progression'
+PENDING_GROUPING = 'pending_grouping'
+PENDING_FILING = 'pending_filing'
+
+
 def main():
   """Files bugs."""
   try:
@@ -346,8 +371,6 @@ def main():
 
   throttler = Throttler()
 
-  untriaged_testcases = 0
-
   for testcase_id in data_handler.get_open_testcase_id_iterator():
     logs.info(f'Triaging {testcase_id}')
     try:
@@ -376,7 +399,8 @@ def main():
     if testcase.get_metadata('progression_pending'):
       logs.info(f'Skipping testcase {testcase_id}, progression pending')
       _emit_untriaged_testcase_age_metric(testcase)
-      untriaged_testcases += 1
+      _increment_untriaged_testcase_count(testcase.job_type,
+                                          PENDING_PROGRESSION)
       continue
 
     # If the testcase has a bug filed already, no triage is needed.
@@ -396,7 +420,8 @@ def main():
     # finished.
     if not critical_tasks_completed:
       _emit_untriaged_testcase_age_metric(testcase)
-      untriaged_testcases += 1
+      _increment_untriaged_testcase_count(testcase.job_type,
+                                          PENDING_CRITICAL_TASKS)
       logs.info(
           f'Skipping testcase {testcase_id}, critical tasks still pending.')
       continue
@@ -414,14 +439,14 @@ def main():
     if not testcase.group_id and not dates.time_has_expired(
         testcase.timestamp, hours=data_types.MIN_ELAPSED_TIME_SINCE_REPORT):
       _emit_untriaged_testcase_age_metric(testcase)
-      untriaged_testcases += 1
+      _increment_untriaged_testcase_count(testcase.job_type, PENDING_GROUPING)
       logs.info(f'Skipping testcase {testcase_id}, pending grouping.')
       continue
 
     if not testcase.get_metadata('ran_grouper'):
       # Testcase should be considered by the grouper first before filing.
       _emit_untriaged_testcase_age_metric(testcase)
-      untriaged_testcases += 1
+      _increment_untriaged_testcase_count(testcase.job_type, PENDING_GROUPING)
       logs.info(f'Skipping testcase {testcase_id}, pending grouping.')
       continue
 
@@ -450,7 +475,7 @@ def main():
 
     # A testcase is untriaged, until immediately before a bug is opened
     _emit_untriaged_testcase_age_metric(testcase)
-    untriaged_testcases += 1
+    _increment_untriaged_testcase_count(testcase.job_type, PENDING_FILING)
 
     # File the bug first and then create filed bug metadata.
     if not _file_issue(testcase, issue_tracker, throttler):
@@ -463,9 +488,7 @@ def main():
     logs.info('Filed new issue %s for testcase %d.' % (testcase.bug_information,
                                                        testcase_id))
 
-    monitoring_metrics.UNTRIAGED_TESTCASE_COUNT.set(
-        untriaged_testcases, labels={})
-
+  _emit_untriaged_testcase_count_metric()
   logs.info('Triage testcases succeeded.')
   return True
 

src/clusterfuzz/_internal/metrics/monitoring_metrics.py

@@ -370,7 +370,10 @@
     description='Number of testcases that were not yet triaged '
     '(have not yet completed analyze, regression,'
     ' minimization, impact task), in hours.',
-    field_spec=[],
+    field_spec=[
+        monitor.StringField('job'),
+        monitor.StringField('status'),
+    ],
 )
 
 ANALYZE_TASK_REPRODUCIBILITY = monitor.CounterMetric(