GELF infrastructure

2022-11-13 00:16:43 -05:00
parent f4af8e4a89
commit 883913b92d
14 changed files with 1053 additions and 4 deletions
@@ -0,0 +1,176 @@
+#pragma once
+
+#include <rapidjson/document.h>
+#include <unordered_set>
+#include <string>
+#include <chrono>
+
+
+namespace gelfcpp
+{
+
+namespace detail
+{
+struct DocumentAccessor;
+}
+
+/**
+ * \brief A single GELF message, with write-only access to its fields.
+ *
+ * \note This class only supports GELF version 1.1 and treats deprecated standard fields as normal additional fields.
+ *
+ * Currently the following standard fields are handled: <code>version, host, short_message, full_message, timestamp, level</code>.
+ * Standard fields are included "as-is". All other fields are prefixed with "_".
+ */
+class GelfMessage
+{
+    friend struct detail::DocumentAccessor;
+
+    struct FieldSetter
+    {
+        GelfMessage& owner;
+        std::string field;
+
+        template<typename T>
+        void operator=(T&& value)
+        {
+            owner.SetField(field, std::forward<T>(value));
+        }
+    };
+
+public:
+    GelfMessage() :
+            doc_(rapidjson::kObjectType)
+    {
+        SetField("version", "1.1");
+    }
+
+    /**
+     * \brief Quick accessor for <code>short_message</code> field.
+     *
+     * Behaves like \code SetField("short_message", message). \endcode
+     *
+     * \param message message
+     */
+    void SetMessage(const std::string& message)
+    {
+        SetField("short_message", message);
+    }
+
+    /**
+     * \brief Quick accessor for <code>full_message</code> field.
+     *
+     * Behaves like \code SetField("full_message", message). \endcode
+     *
+     * \param message message
+     */
+    void SetFullMessage(const std::string& message)
+    {
+        SetField("full_message", message);
+    }
+
+    /**
+     * \brief Quick accessor for <code>host</code> field.
+     *
+     * Behaves like \code SetField("host", message). \endcode
+     *
+     * \param host hostname
+     */
+    void SetHost(const std::string& host)
+    {
+        SetField("host", host);
+    }
+
+    /**
+     * \brief Quick accessor for <code>timestamp</code> field.
+     *
+     * Behaves like \code SetField("timestamp", message). \endcode
+     *
+     * \param timestamp timestamp
+     */
+    void SetTimestamp(double timestamp)
+    {
+        SetField("timestamp", timestamp);
+    }
+
+#ifndef GELFCPP_DOXYGEN_RUNNING
+
+    template<typename T>
+    auto SetField(const std::string& name, T value) -> std::enable_if_t<std::is_arithmetic<T>::value && !std::is_same<T, bool>::value>
+    {
+        rapidjson::Value json(std::forward<T>(value));
+        SetField(name, std::move(json));
+    }
+
+    void SetField(const std::string& name, bool value)
+    {
+        SetField(name, value ? 1 : 0);
+    }
+
+    void SetField(const std::string& name, const char* value)
+    {
+        rapidjson::Value json(value, doc_.GetAllocator());
+        SetField(name, std::move(json));
+    }
+
+    void SetField(const std::string& name, const std::string& value)
+    {
+        rapidjson::Value json(value, doc_.GetAllocator());
+        SetField(name, std::move(json));
+    }
+
+#else
+    /**
+     * \brief Adds a field to the message.
+     *
+     * \note If a field was already assigned the old value is overwritten.
+     *
+     * \tparam T value type, supported: <code>bool, integral, floating point, strings</code>
+     * \param name field name, the "_" prefix is added automatically
+     * \param value field value of any supported type
+     */
+    template<typename T> void SetField(const std::string& name, T value) {}
+#endif
+
+    /**
+     * \brief Adds a field to the message.
+     *
+     * This behaves like SetField(const std::string&, T) but allows map/array like syntax.
+     *
+     * Example usage:
+     * \code{.cpp}
+     * GelfMessage message;
+     * message["field_name"] = field_value;
+     * \endcode
+     *
+     * \param field field name, the "_" prefix is added automatically
+     * \return wrapper to allow assignment, see the usage example.
+     */
+    FieldSetter operator[](const std::string& field)
+    {
+        return { *this, field };
+    }
+
+private:
+    void SetField(const std::string& field, rapidjson::Value&& value)
+    {
+        static const std::unordered_set<std::string> BUILDIN_FIELDS{ "version", "host", "short_message", "full_message", "timestamp", "level" };
+
+        rapidjson::Value key;
+        if (BUILDIN_FIELDS.find(field) != BUILDIN_FIELDS.end())
+            key.SetString(field.c_str(), static_cast<rapidjson::SizeType>(field.size()), doc_.GetAllocator());
+        else
+            key.SetString(("_" + field).c_str(), static_cast<rapidjson::SizeType>(field.size() + 1), doc_.GetAllocator());
+
+        auto find = doc_.FindMember(key);
+        if (find != doc_.MemberEnd())
+            find->value = std::move(value);
+        else
+            doc_.AddMember(std::move(key), std::move(value), doc_.GetAllocator());
+    }
+
+private:
+    rapidjson::Document doc_;
+};
+
+}