polling_policy.h

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// Copyright 2019 Google LLC
//
// 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 GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_SPANNER_POLLING_POLICY_H
#define GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_SPANNER_POLLING_POLICY_H

#include "google/cloud/spanner/backoff_policy.h"
#include "google/cloud/spanner/retry_policy.h"
#include "google/cloud/status.h"

namespace google {
namespace cloud {
namespace spanner {
inline namespace SPANNER_CLIENT_NS {

class PollingPolicy {
 public:
  virtual ~PollingPolicy() = default;

  virtual std::unique_ptr<PollingPolicy> clone() const = 0;

  virtual bool OnFailure(google::cloud::Status const& status) = 0;

  virtual std::chrono::milliseconds WaitPeriod() = 0;
};

template <typename Retry = LimitedTimeRetryPolicy,
          typename Backoff = ExponentialBackoffPolicy>
class GenericPollingPolicy : public PollingPolicy {
 public:
  GenericPollingPolicy(Retry retry_policy, Backoff backoff_policy)
      : retry_policy_(std::move(retry_policy)),
        backoff_policy_(std::move(backoff_policy)) {}

  std::unique_ptr<PollingPolicy> clone() const override {
    return std::unique_ptr<PollingPolicy>(new GenericPollingPolicy(*this));
  }

  bool OnFailure(google::cloud::Status const& status) override {
    return retry_policy_.OnFailure(status);
  }

  std::chrono::milliseconds WaitPeriod() override {
    return backoff_policy_.OnCompletion();
  }

 private:
  Retry retry_policy_;
  Backoff backoff_policy_;
};

}  // namespace SPANNER_CLIENT_NS
}  // namespace spanner
}  // namespace cloud
}  // namespace google

#endif  // GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_SPANNER_POLLING_POLICY_H