emergency hardening of process_perf_results

Bug: 936602, 936500
Change-Id: I9265a2950c185c90da7ee07210ab7ff63f4eb5f6
Reviewed-on: https://chromium-review.googlesource.com/c/1493081
Commit-Queue: Caleb Rouleau <crouleau@chromium.org>
Reviewed-by: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636201}

tools/perf/process_perf_results.py

@@ -188,6 +188,7 @@ def _handle_perf_json_test_results(
       # Obtain the test name we are running
       is_ref = '.reference' in benchmark_name
       enabled = True
+      try:
         with open(join(directory, 'test_results.json')) as json_data:
           json_results = json.load(json_data)
           if not json_results:
@@ -206,6 +207,11 @@ def _handle_perf_json_test_results(
             # We don't need to upload reference build data to the
             # flakiness dashboard since we don't monitor the ref build
             test_results_list.append(json_results)
+      except IOError as e:
+        # TODO(crbug.com/936602): Figure out how to surface these errors. Should
+        # we have a non-zero exit code if we error out?
+        logging.error('Failed to obtain test results for %s: %s',
+                      benchmark_name, e)
       if not enabled:
         # We don't upload disabled benchmarks or tests that are run
         # as a smoke test
@@ -375,8 +381,18 @@ def _merge_perf_results(benchmark_name, results_filename, directories):
   collected_results = []
   for directory in directories:
     filename = join(directory, 'perf_results.json')
+    try:
       with open(filename) as pf:
         collected_results.append(json.load(pf))
+    except IOError as e:
+      # TODO(crbug.com/936602): Figure out how to surface these errors. Should
+      # we have a non-zero exit code if we error out?
+      logging.error('Failed to obtain perf results from %s: %s',
+                    directory, e)
+  if not collected_results:
+    logging.error('Failed to obtain any perf results from %s.',
+                  benchmark_name)
+    return
 
   # Assuming that multiple shards will only be chartjson or histogram set
   # Non-telemetry benchmarks only ever run on one shard

tools/perf/process_perf_results_unittest.py

@@ -160,5 +160,21 @@ class ProcessPerfResultsIntegrationTest(unittest.TestCase):
           "speedometer.reference": True
         })
 
+
+class ProcessPerfResults_HardenedUnittest(unittest.TestCase):
+  def test_handle_perf_json_test_results_IOError(self):
+    directory_map = {
+        'benchmark.example': ['directory_that_does_not_exist']}
+    test_results_list = []
+    ppr_module._handle_perf_json_test_results(directory_map, test_results_list)
+    self.assertEqual(test_results_list, [])
+
+  def test_merge_perf_results_IOError(self):
+    results_filename = None
+    directories = ['directory_that_does_not_exist']
+    ppr_module._merge_perf_results('benchmark.example', results_filename,
+                                   directories)
+
+
 if __name__ == '__main__':
   unittest.main()