Leak reports collect information about the last uptrend

components/metrics/leak_detector/call_stack_table_unittest.cc

Index: components/metrics/leak_detector/call_stack_table_unittest.cc
diff --git a/components/metrics/leak_detector/call_stack_table_unittest.cc b/components/metrics/leak_detector/call_stack_table_unittest.cc
index f56f628499e34915851a5344a11c89fedf269287..3b7918a9725ae1fd91a016db7f273b5af9abffde 100644
--- a/components/metrics/leak_detector/call_stack_table_unittest.cc
+++ b/components/metrics/leak_detector/call_stack_table_unittest.cc
@@ -360,5 +360,95 @@ TEST_F(CallStackTableTest, GetTopCallStacks) {
   EXPECT_EQ(stack2_, iter->value.call_stack());
 }
 
+TEST_F(CallStackTableTest, GetLastUptrendInfo) {
+  CallStackTable table(kDefaultLeakThreshold);
+  size_t timestamp_delta;

[Simon Que, 2016/10/11 01:11:06]

Declare these right before they are used.

[mwlodar, 2016/10/11 07:13:24]

Done.

+  uint32_t count_delta;
+
+  // Add some stack0_ and stack1_.
+  for (int i = 0; i < 60; ++i)
+    table.Add(stack0_);
+  for (int i = 0; i < 60; ++i)
+    table.Add(stack1_);
+  table.UpdateLastDropInfo(100);
+
+  table.GetLastUptrendInfo(stack0_, 100, &timestamp_delta, &count_delta);
+  EXPECT_EQ(0U, timestamp_delta);
+  EXPECT_EQ(0U, count_delta);
+
+  // Remove stack0_ and add stack1_.

[Simon Que, 2016/10/11 01:11:06]

Nit: refer to variables as |stack_*|.

[mwlodar, 2016/10/11 07:13:24]

Done.

+  for (int i = 0; i < 30; ++i)
+        table.Remove(stack0_);

[Simon Que, 2016/10/11 01:11:06]

Nit: fix indendation.

[mwlodar, 2016/10/11 07:13:24]

Done.

+  for (int i = 0; i < 30; ++i)
+        table.Add(stack1_);
+  table.UpdateLastDropInfo(200);
+
+  table.GetLastUptrendInfo(stack0_, 200, &timestamp_delta, &count_delta);
+  EXPECT_EQ(0U, timestamp_delta);
+  EXPECT_EQ(0U, count_delta);
+
+  table.GetLastUptrendInfo(stack1_, 200, &timestamp_delta, &count_delta);
+  EXPECT_EQ(100U, timestamp_delta);
+  EXPECT_EQ(30U, count_delta);
+
+  // Check if previous drop of stack0_ was recorded and introduce stack2_.
+  for (int i = 0; i < 30; ++i)
+        table.Add(stack0_);
+  for (int i = 0; i < 60; ++i)
+        table.Add(stack2_);
+  table.UpdateLastDropInfo(300);
+
+  table.GetLastUptrendInfo(stack0_, 300, &timestamp_delta, &count_delta);
+  EXPECT_EQ(100U, timestamp_delta);
+  EXPECT_EQ(30U, count_delta);
+
+  table.GetLastUptrendInfo(stack2_, 300, &timestamp_delta, &count_delta);
+  EXPECT_EQ(0U, timestamp_delta);
+  EXPECT_EQ(0U, count_delta);
+
+  // Introduce more variation between updates. Decrease stack2_ to 0.
+  // All the history for stack2_ should be forgotten.

[Simon Que, 2016/10/11 01:11:06]

Can you test that |stack2_| has been forgotten?

[mwlodar, 2016/10/11 07:13:24]

If it was not forgotten and the rest of the algorithm worked correctly then
|timestamp_delta| would be 100 in line 449.

[Simon Que, 2016/10/11 08:14:03]

That's true, but what happens when you call GetLastUptrendInfo() for stack2_ at
line 432? This is a way to test the robustness of your function.

[mwlodar, 2016/10/11 20:24:03]

This is an invalid call and just (timestamp, 0) is returned. I have added this
check though.

+  for (int i = 0; i < 30; ++i)
+        table.Add(stack0_);
+  for (int i = 0; i < 40; ++i)
+        table.Remove(stack0_);
+  for (int i = 0; i < 40; ++i)
+        table.Add(stack1_);
+  for (int i = 0; i < 30; ++i)
+        table.Remove(stack1_);
+  for (int i = 0; i < 30; ++i)
+        table.Remove(stack2_);
+  for (int i = 0; i < 30; ++i)
+        table.Remove(stack2_);
+  table.UpdateLastDropInfo(400);
+
+  table.GetLastUptrendInfo(stack0_, 400, &timestamp_delta, &count_delta);
+  EXPECT_EQ(0U, timestamp_delta);
+  EXPECT_EQ(0U, count_delta);
+
+  table.GetLastUptrendInfo(stack1_, 400, &timestamp_delta, &count_delta);
+  EXPECT_EQ(300U, timestamp_delta);
+  EXPECT_EQ(40U, count_delta);
+
+  // Make a 0-sum sequence for stack0_. Introduce stack2_ again.
+  for (int i = 0; i < 30; ++i)
+        table.Add(stack0_);
+  for (int i = 0; i < 30; ++i)
+        table.Remove(stack0_);
+  for (int i = 0; i < 40; ++i)
+        table.Add(stack2_);
+  for (int i = 0; i < 30; ++i)
+        table.Remove(stack2_);
+  table.UpdateLastDropInfo(500);
+
+  table.GetLastUptrendInfo(stack0_, 500, &timestamp_delta, &count_delta);
+  EXPECT_EQ(100U, timestamp_delta);
+  EXPECT_EQ(0U, count_delta);
+
+  table.GetLastUptrendInfo(stack2_, 500, &timestamp_delta, &count_delta);
+  EXPECT_EQ(0U, timestamp_delta);
+  EXPECT_EQ(0U, count_delta);
+}
+
 }  // namespace leak_detector
 }  // namespace metrics