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setup/e2/RIC-E2-TERMINATION/openTracing.h

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+/*
+ * Copyright 2019 AT&T Intellectual Property
+ * Copyright 2019 Nokia
+ *
+ * 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.
+ */
+
+/*
+ * This source code is part of the near-RT RIC (RAN Intelligent Controller)
+ * platform project (RICP).
+ */
+
+
+//
+// Created by adi ENZEL on 8/21/19.
+//
+
+#ifndef E2_OPENTRACING_H
+#define E2_OPENTRACING_H
+
+#include <iostream>
+#include <string>
+#include <tracelibcpp/tracelibcpp.hpp>
+#include <opentracing/tracer.h>
+#include <opentracing/propagation.h>
+#include <nlohmann/json.hpp>  // use nlohmann json library as an example
+
+struct RICCarrierWriter : opentracing::TextMapWriter {
+    explicit RICCarrierWriter(
+            std::unordered_map<std::string, std::string>& data_)
+            : data{data_} {}
+
+    opentracing::expected<void> Set(
+            opentracing::string_view key,
+            opentracing::string_view value) const override {
+        // OpenTracing uses opentracing::expected for error handling. This closely
+        // follows the expected proposal for the C++ Standard Library. See
+        //    http://open-std.org/JTC1/SC22/WG21/docs/papers/2017/p0323r3.pdf
+        // for more background.
+        opentracing::expected<void> result;
+
+        auto was_successful = data.emplace(key, value);
+        if (was_successful.second) {
+            // Use a default constructed opentracing::expected<void> to indicate
+            // success.
+            return result;
+        } else {
+            // `key` clashes with existing data, so the span context can't be encoded
+            // successfully; set opentracing::expected<void> to an std::error_code.
+            return opentracing::make_unexpected(
+                    std::make_error_code(std::errc::not_supported));
+        }
+    }
+
+    std::unordered_map<std::string, std::string>& data;
+};
+
+struct RICCarrierReader : opentracing::TextMapReader {
+    explicit RICCarrierReader(
+            const std::unordered_map<std::string, std::string>& data_)
+            : data{data_} {}
+
+    using F = std::function<opentracing::expected<void>(
+            opentracing::string_view, opentracing::string_view)>;
+
+    opentracing::expected<void> ForeachKey(F f) const override {
+        // Iterate through all key-value pairs, the tracer will use the relevant keys
+        // to extract a span context.
+        for (auto& key_value : data) {
+            auto was_successful = f(key_value.first, key_value.second);
+            if (!was_successful) {
+                // If the callback returns and unexpected value, bail out of the loop.
+                return was_successful;
+            }
+        }
+
+        // Indicate successful iteration.
+        return {};
+    }
+
+    // Optional, define TextMapReader::LookupKey to allow for faster extraction.
+    opentracing::expected<opentracing::string_view> LookupKey(
+            opentracing::string_view key) const override {
+        auto iter = data.find(key);
+        if (iter != data.end()) {
+            return opentracing::make_unexpected(opentracing::key_not_found_error);
+        }
+        return opentracing::string_view{iter->second};
+    }
+
+    const std::unordered_map<std::string, std::string>& data;
+};
+
+
+
+#endif //E2_OPENTRACING_H