--- /dev/null
+/*
+ *
+ * Copyright 2017 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.
+ *
+ */
+
+#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RETRY_THROTTLE_H
+#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RETRY_THROTTLE_H
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/lib/gprpp/memory.h"
+#include "src/core/lib/gprpp/ref_counted.h"
+
+namespace grpc_core {
+namespace internal {
+
+/// Tracks retry throttling data for an individual server name.
+class ServerRetryThrottleData : public RefCounted<ServerRetryThrottleData> {
+ public:
+ ServerRetryThrottleData(intptr_t max_milli_tokens, intptr_t milli_token_ratio,
+ ServerRetryThrottleData* old_throttle_data);
+
+ /// Records a failure. Returns true if it's okay to send a retry.
+ bool RecordFailure();
+
+ /// Records a success.
+ void RecordSuccess();
+
+ intptr_t max_milli_tokens() const { return max_milli_tokens_; }
+ intptr_t milli_token_ratio() const { return milli_token_ratio_; }
+
+ private:
+ GRPC_ALLOW_CLASS_TO_USE_NON_PUBLIC_DELETE
+
+ ~ServerRetryThrottleData();
+
+ void GetReplacementThrottleDataIfNeeded(
+ ServerRetryThrottleData** throttle_data);
+
+ const intptr_t max_milli_tokens_;
+ const intptr_t milli_token_ratio_;
+ gpr_atm milli_tokens_;
+ // A pointer to the replacement for this ServerRetryThrottleData entry.
+ // If non-nullptr, then this entry is stale and must not be used.
+ // We hold a reference to the replacement.
+ gpr_atm replacement_ = 0;
+};
+
+/// Global map of server name to retry throttle data.
+class ServerRetryThrottleMap {
+ public:
+ /// Initializes global map of failure data for each server name.
+ static void Init();
+ /// Shuts down global map of failure data for each server name.
+ static void Shutdown();
+
+ /// Returns the failure data for \a server_name, creating a new entry if
+ /// needed.
+ static RefCountedPtr<ServerRetryThrottleData> GetDataForServer(
+ const char* server_name, intptr_t max_milli_tokens,
+ intptr_t milli_token_ratio);
+};
+
+} // namespace internal
+} // namespace grpc_core
+
+#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RETRY_THROTTLE_H */