From 0ddb5ea6faf15b3da2732f8fff57e2eaa4429735 Mon Sep 17 00:00:00 2001
From: Giulia Naponiello <gnaponie@redhat.com>
Date: Jan 16 2019 13:44:41 +0000
Subject: Limit results returned when verbose=true


When asked for a decision with verbose flag = true, Greenwave returns
the list of matching results for that decision. But when those
results are too many, the request returns with a timeout. Let's just
return the first 20 results and log that the reply is truncated for
debugging reasons.

---

diff --git a/functional-tests/test_api_v1.py b/functional-tests/test_api_v1.py
index de7c080..53232bc 100644
--- a/functional-tests/test_api_v1.py
+++ b/functional-tests/test_api_v1.py
@@ -279,6 +279,32 @@ def test_make_a_decision_with_verbose_flag(requests_session, greenwave_server, t
     assert res_data['satisfied_requirements'] == expected_satisfied_requirements
 
 
+def test_make_a_decision_with_verbose_flag_too_many_results(requests_session, greenwave_server,
+                                                            testdatabuilder):
+    nvr = testdatabuilder.unique_nvr()
+    results = []
+    for i in range(0, 21):
+        results.append(testdatabuilder.create_result(item=nvr,
+                                                     testcase_name='rhproduct.default.sanity',
+                                                     outcome='PASSED'))
+    data = {
+        'decision_context': 'bodhi_update_push_stable',
+        'product_version': 'fedora-26',
+        'subject_type': 'koji_build',
+        'subject_identifier': nvr,
+        'verbose': True,
+    }
+
+    r = requests_session.post(greenwave_server + 'api/v1.0/decision',
+                              headers={'Content-Type': 'application/json'},
+                              data=json.dumps(data))
+    assert r.status_code == 200
+    res_data = r.json()
+
+    assert len(res_data['results']) == 20
+    assert res_data['results'] == list(reversed(results))[:-1]
+
+
 def test_make_a_decision_with_verbose_flag_and_multiple_nvrs_with_results(
         requests_session, greenwave_server, testdatabuilder):
     build_nvrs = [testdatabuilder.unique_nvr(), testdatabuilder.unique_nvr()]
diff --git a/greenwave/api_v1.py b/greenwave/api_v1.py
index 9b17676..23e62d2 100644
--- a/greenwave/api_v1.py
+++ b/greenwave/api_v1.py
@@ -360,7 +360,7 @@ def make_decision():
 
         if verbose:
             # Retrieve test results for all items when verbose output is requested.
-            verbose_results.extend(results_retriever.retrieve(subject_type, subject_identifier))
+            verbose_results.extend(results_retriever.retrieve(subject_type, subject_identifier, limit=20))
             verbose_waivers.extend(waivers)
 
     response = {
diff --git a/greenwave/resources.py b/greenwave/resources.py
index 48cebf5..00abe7b 100644
--- a/greenwave/resources.py
+++ b/greenwave/resources.py
@@ -54,15 +54,15 @@ class ResultsRetriever(object):
         self.verify = verify
         self.url = url
 
-    def retrieve(self, subject_type, subject_identifier, testcase=None):
+    def retrieve(self, subject_type, subject_identifier, testcase=None, limit=None):
         """
         Return generator over results.
         """
-        for result in self._retrieve_helper(subject_type, subject_identifier, testcase):
+        for result in self._retrieve_helper(subject_type, subject_identifier, testcase, limit):
             if result['id'] not in self.ignore_results:
                 yield result
 
-    def _retrieve_helper(self, subject_type, subject_identifier, testcase):
+    def _retrieve_helper(self, subject_type, subject_identifier, testcase, limit=None):
         cache_key = results_cache_key(
             subject_type, subject_identifier, testcase)
 
@@ -75,14 +75,18 @@ class ResultsRetriever(object):
 
         while cached_results.can_fetch_more:
             cached_results.last_page += 1
-            results = self._retrieve_page(
-                cached_results.last_page, subject_type, subject_identifier,
-                testcase)
-            cached_results.results.extend(results)
-            cached_results.can_fetch_more = bool(results)
-            self.cache.set(cache_key, cached_results)
-            for result in results:
-                yield result
+            if limit is None or (limit is not None and cached_results.last_page < limit):
+                results = self._retrieve_page(
+                    cached_results.last_page, subject_type, subject_identifier,
+                    testcase)
+                cached_results.results.extend(results)
+                cached_results.can_fetch_more = bool(results)
+                self.cache.set(cache_key, cached_results)
+                for result in results:
+                    yield result
+            else:
+                log.warning("The list of results was truncated. Too many items.")
+                break
 
     def _make_request(self, params):
         response = requests_session.get(