Merge pull request #12276 from ClickHouse/test-pod-array

Added a test for PaddedPODArray just in case

src/Common/tests/gtest_pod_array.cpp

@@ -44,3 +44,25 @@ TEST(Common, PODPushBackRawMany)
     EXPECT_EQ(15, chars.size());
     EXPECT_EQ(std::string("first0123456789"), std::string(chars.data(), chars.size()));
 }
+
+TEST(Common, PODNoOverallocation)
+{
+    /// Check that PaddedPODArray allocates for smaller number of elements than the power of two due to padding.
+    /// NOTE: It's Ok to change these numbers if you will modify initial size or padding.
+
+    PaddedPODArray<char> chars;
+    std::vector<size_t> capacities;
+
+    size_t prev_capacity = 0;
+    for (size_t i = 0; i < 1000000; ++i)
+    {
+        chars.emplace_back();
+        if (chars.capacity() != prev_capacity)
+        {
+            prev_capacity = chars.capacity();
+            capacities.emplace_back(prev_capacity);
+        }
+    }
+
+    EXPECT_EQ(capacities, (std::vector<size_t>{4065, 8161, 16353, 32737, 65505, 131041, 262113, 524257, 1048545}));
+}