Convert retry throttle code to C++ and add tests.

2 files changed, 157 insertions, 0 deletions

diff --git a/test/core/client_channel/BUILD b/test/core/client_channel/BUILD
index 5148dc5f74..db98ffab77 100644
--- a/test/core/client_channel/BUILD
+++ b/test/core/client_channel/BUILD
@@ -53,3 +53,18 @@ grpc_cc_test(
         "//test/core/util:grpc_test_util",
     ],
 )
+
+grpc_cc_test(
+    name = "retry_throttle_test",
+    srcs = ["retry_throttle_test.cc"],
+    external_deps = [
+        "gtest",
+    ],
+    language = "C++",
+    deps = [
+        "//:gpr",
+        "//:grpc",
+        "//test/core/util:gpr_test_util",
+        "//test/core/util:grpc_test_util",
+    ],
+)
diff --git a/test/core/client_channel/retry_throttle_test.cc b/test/core/client_channel/retry_throttle_test.cc
new file mode 100644
index 0000000000..c6d5d3ebbb
--- /dev/null
+++ b/test/core/client_channel/retry_throttle_test.cc
@@ -0,0 +1,142 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include "src/core/ext/filters/client_channel/retry_throttle.h"
+
+#include <gtest/gtest.h>
+
+#include "test/core/util/test_config.h"
+
+namespace grpc_core {
+namespace internal {
+namespace {
+
+TEST(ServerRetryThrottleData, Basic) {
+  // Max token count is 4, so threshold for retrying is 2.
+  // Token count starts at 4.
+  // Each failure decrements by 1.  Each success increments by 1.6.
+  auto throttle_data =
+      MakeRefCounted<ServerRetryThrottleData>(4000, 1600, nullptr);
+  // Failure: token_count=3.  Above threshold.
+  EXPECT_TRUE(throttle_data->RecordFailure());
+  // Success: token_count=4.  Not incremented beyond max.
+  throttle_data->RecordSuccess();
+  // Failure: token_count=3.  Above threshold.
+  EXPECT_TRUE(throttle_data->RecordFailure());
+  // Failure: token_count=2.  At threshold, so no retries.
+  EXPECT_FALSE(throttle_data->RecordFailure());
+  // Failure: token_count=1.  Below threshold, so no retries.
+  EXPECT_FALSE(throttle_data->RecordFailure());
+  // Failure: token_count=0.  Below threshold, so no retries.
+  EXPECT_FALSE(throttle_data->RecordFailure());
+  // Failure: token_count=0.  Below threshold, so no retries.  Not
+  // decremented below min.
+  EXPECT_FALSE(throttle_data->RecordFailure());
+  // Success: token_count=1.6.
+  throttle_data->RecordSuccess();
+  // Success: token_count=3.2.
+  throttle_data->RecordSuccess();
+  // Failure: token_count=2.2.  Above threshold.
+  EXPECT_TRUE(throttle_data->RecordFailure());
+  // Failure: token_count=1.2.  Below threshold, so no retries.
+  EXPECT_FALSE(throttle_data->RecordFailure());
+  // Success: token_count=2.8.
+  throttle_data->RecordSuccess();
+  // Failure: token_count=1.8.  Below threshold, so no retries.
+  EXPECT_FALSE(throttle_data->RecordFailure());
+  // Success: token_count=3.4.
+  throttle_data->RecordSuccess();
+  // Failure: token_count=2.4.  Above threshold.
+  EXPECT_TRUE(throttle_data->RecordFailure());
+}
+
+TEST(ServerRetryThrottleData, Replacement) {
+  // Create old throttle data.
+  // Max token count is 4, so threshold for retrying is 2.
+  // Token count starts at 4.
+  // Each failure decrements by 1.  Each success increments by 1.
+  auto old_throttle_data =
+      MakeRefCounted<ServerRetryThrottleData>(4000, 1000, nullptr);
+  // Failure: token_count=3.  Above threshold.
+  EXPECT_TRUE(old_throttle_data->RecordFailure());
+  // Create new throttle data.
+  // Max token count is 10, so threshold for retrying is 5.
+  // Token count starts at 7.5 (ratio inherited from old_throttle_data).
+  // Each failure decrements by 1.  Each success increments by 3.
+  auto throttle_data = MakeRefCounted<ServerRetryThrottleData>(
+      10000, 3000, old_throttle_data.get());
+  // Failure via old_throttle_data: token_count=6.5.
+  EXPECT_TRUE(old_throttle_data->RecordFailure());
+  // Failure: token_count=5.5.
+  EXPECT_TRUE(old_throttle_data->RecordFailure());
+  // Failure via old_throttle_data: token_count=4.5.  Below threshold.
+  EXPECT_FALSE(old_throttle_data->RecordFailure());
+  // Failure: token_count=3.5.  Below threshold.
+  EXPECT_FALSE(throttle_data->RecordFailure());
+  // Success: token_count=6.5.
+  throttle_data->RecordSuccess();
+  // Failure via old_throttle_data: token_count=5.5.  Above threshold.
+  EXPECT_TRUE(old_throttle_data->RecordFailure());
+  // Failure: token_count=4.5.  Below threshold.
+  EXPECT_FALSE(throttle_data->RecordFailure());
+}
+
+TEST(ServerRetryThrottleMap, Replacement) {
+  ServerRetryThrottleMap::Init();
+  const char kServerName[] = "server_name";
+  // Create old throttle data.
+  // Max token count is 4, so threshold for retrying is 2.
+  // Token count starts at 4.
+  // Each failure decrements by 1.  Each success increments by 1.
+  auto old_throttle_data =
+      ServerRetryThrottleMap::GetDataForServer(kServerName, 4000, 1000);
+  // Failure: token_count=3.  Above threshold.
+  EXPECT_TRUE(old_throttle_data->RecordFailure());
+  // Create new throttle data.
+  // Max token count is 10, so threshold for retrying is 5.
+  // Token count starts at 7.5 (ratio inherited from old_throttle_data).
+  // Each failure decrements by 1.  Each success increments by 3.
+  auto throttle_data =
+      ServerRetryThrottleMap::GetDataForServer(kServerName, 10000, 3000);
+  // Failure via old_throttle_data: token_count=6.5.
+  EXPECT_TRUE(old_throttle_data->RecordFailure());
+  // Failure: token_count=5.5.
+  EXPECT_TRUE(old_throttle_data->RecordFailure());
+  // Failure via old_throttle_data: token_count=4.5.  Below threshold.
+  EXPECT_FALSE(old_throttle_data->RecordFailure());
+  // Failure: token_count=3.5.  Below threshold.
+  EXPECT_FALSE(throttle_data->RecordFailure());
+  // Success: token_count=6.5.
+  throttle_data->RecordSuccess();
+  // Failure via old_throttle_data: token_count=5.5.  Above threshold.
+  EXPECT_TRUE(old_throttle_data->RecordFailure());
+  // Failure: token_count=4.5.  Below threshold.
+  EXPECT_FALSE(throttle_data->RecordFailure());
+  // Clean up.
+  ServerRetryThrottleMap::Shutdown();
+}
+
+}  // namespace
+}  // namespace internal
+}  // namespace grpc_core
+
+int main(int argc, char** argv) {
+  grpc_test_init(argc, argv);
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}