1 files changed, 127 insertions, 0 deletions
diff --git a/src/buildtool/common/remote/retry_parameters.hpp b/src/buildtool/common/remote/retry_parameters.hpp
new file mode 100644
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+++ b/src/buildtool/common/remote/retry_parameters.hpp
@@ -0,0 +1,127 @@
+// Copyright 2023 Huawei Cloud Computing Technology Co., Ltd.
+//
+// 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 <mutex>
+#include <random>
+
+#include "src/buildtool/logging/logger.hpp"
+
+constexpr unsigned int kDefaultInitialBackoffSeconds{1};
+constexpr unsigned int kDefaultMaxBackoffSeconds{60};
+constexpr unsigned int kDefaultAttempts{1};
+constexpr auto kRetryLogLevel = LogLevel::Progress;
+class Retry {
+    using dist_type = std::uniform_int_distribution<std::mt19937::result_type>;
+
+  public:
+    Retry() = default;
+    [[nodiscard]] static auto Instance() -> Retry& {
+        static Retry instance{};
+        return instance;
+    }
+
+    [[nodiscard]] static auto SetInitialBackoffSeconds(unsigned int x) noexcept
+        -> bool {
+        if (x < 1) {
+            Logger::Log(
+                LogLevel::Error,
+                "Invalid initial amount of seconds provided: {}. Value must "
+                "be strictly greater than 0.",
+                x);
+            return false;
+        }
+        Instance().initial_backoff_seconds_ = x;
+        return true;
+    }
+
+    [[nodiscard]] static auto SetMaxBackoffSeconds(unsigned int x) noexcept
+        -> bool {
+        if (x < 1) {
+            Logger::Log(LogLevel::Error,
+                        "Invalid max backoff provided: {}. Value must be "
+                        "strictly greater than 0.",
+                        x);
+            return false;
+        }
+        Instance().max_backoff_seconds_ = x;
+        return true;
+    }
+
+    [[nodiscard]] static auto GetMaxBackoffSeconds() noexcept -> unsigned int {
+        return Instance().max_backoff_seconds_;
+    }
+
+    [[nodiscard]] static auto SetMaxAttempts(unsigned int x) noexcept -> bool {
+        if (x < 1) {
+            Logger::Log(LogLevel::Error,
+                        "Invalid number of max number of attempts provided: "
+                        "{}. Value must be strictly greater than 0",
+                        x);
+            return false;
+        }
+        Instance().attempts_ = x;
+        return true;
+    }
+
+    [[nodiscard]] static auto GetInitialBackoffSeconds() noexcept
+        -> unsigned int {
+        return Instance().initial_backoff_seconds_;
+    }
+
+    [[nodiscard]] static auto GetMaxAttempts() noexcept -> unsigned int {
+        return Instance().attempts_;
+    }
+
+    [[nodiscard]] static auto Jitter(unsigned int backoff) noexcept ->
+        typename dist_type::result_type {
+        auto& inst = Instance();
+        try {
+            dist_type dist{0, backoff * 3};
+            std::unique_lock lock(inst.mutex_);
+            return dist(inst.rng_);
+        } catch (...) {
+            return 0;
+        }
+    }
+
+    /// \brief The waiting time is exponentially increased at each \p attempt
+    /// until it exceeds max_backoff_seconds.
+    ///
+    /// To avoid overloading of the reachable resources, a jitter (aka, random
+    /// value) is added to distributed the workload.
+    [[nodiscard]] static auto GetSleepTimeSeconds(unsigned int attempt) noexcept
+        -> unsigned int {
+        auto backoff = Retry::GetInitialBackoffSeconds();
+        auto const& max_backoff = Retry::GetMaxBackoffSeconds();
+        // on the first attempt, we don't double the backoff time
+        // also we do it in a for loop to avoid overflow
+        for (auto x = 1U; x < attempt; ++x) {
+            backoff <<= 1U;
+            if (backoff >= max_backoff) {
+                backoff = max_backoff;
+                break;
+            }
+        }
+        return backoff + Retry::Jitter(backoff);
+    }
+
+  private:
+    unsigned int initial_backoff_seconds_{kDefaultInitialBackoffSeconds};
+    unsigned int max_backoff_seconds_{kDefaultMaxBackoffSeconds};
+    unsigned int attempts_{kDefaultAttempts};
+    LogLevel retry_log_level_{kRetryLogLevel};
+    std::mutex mutex_;
+    std::random_device dev_;
+    std::mt19937 rng_{dev_()};
+};