feat etcd: Init etcd client

CMakeLists.txt

@@ -143,6 +143,7 @@ option(USERVER_FEATURE_MYSQL "Provide asynchronous driver for MariaDB/MySQL" "${
 option(USERVER_FEATURE_ROCKS "Provide asynchronous driver for Rocks" "${USERVER_LIB_ENABLED_DEFAULT}")
 option(USERVER_FEATURE_YDB "Provide asynchronous driver for YDB" "${USERVER_YDB_DEFAULT}")
 option(USERVER_FEATURE_OTLP "Provide asynchronous OTLP exporters" "${USERVER_LIB_ENABLED_DEFAULT}")
+option(USERVER_FEATURE_ETCD "Provide asynchronous driver for etcd" "${USERVER_LIB_ENABLED_DEFAULT}")
 
 set(CMAKE_DEBUG_POSTFIX d)
 
@@ -277,6 +278,11 @@ if (USERVER_FEATURE_YDB)
   list(APPEND USERVER_AVAILABLE_COMPONENTS ydb)
 endif()
 
+if (USERVER_FEATURE_ETCD)
+  _require_userver_core("USERVER_FEATURE_ETCD")
+  add_subdirectory(etcd)
+endif()
+
 add_subdirectory(libraries)
 
 if (USERVER_BUILD_TESTS)

cmake/install/userver-etcd-config.cmake

@@ -0,0 +1,11 @@
+include_guard(GLOBAL)
+
+if(userver_etcd_FOUND)
+  return()
+endif()
+
+find_package(userver REQUIRED COMPONENTS
+  core
+)
+
+set(userver_etcd_FOUND TRUE)

etcd/CMakeLists.txt

@@ -0,0 +1,6 @@
+project(userver-etcd CXX)
+
+userver_module(etcd
+    SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}"
+    UTEST_SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/src/*_test.cpp"
+)

etcd/include/userver/etcd/client.hpp

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <chrono>
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <userver/clients/http/component.hpp>
+#include <userver/concurrent/queue.hpp>
+#include <userver/engine/task/task_with_result.hpp>
+#include <userver/etcd/settings.hpp>
+#include <userver/etcd/watch_listener.hpp>
+#include <userver/yaml_config/fwd.hpp>
+
+USERVER_NAMESPACE_BEGIN
+
+namespace etcd {
+
+class Client {
+public:
+    virtual ~Client() = default;
+
+    virtual void Put(const std::string& key, const std::string& value) = 0;
+
+    [[nodiscard]] virtual std::optional<std::string> Get(const std::string& key) = 0;
+
+    [[nodiscard]] virtual std::vector<std::string> Range(const std::string& key) = 0;
+
+    virtual void Delete(const std::string& key) = 0;
+
+    virtual WatchListener StartWatch(const std::string& key) = 0;
+};
+
+using ClientPtr = std::shared_ptr<Client>;
+
+}  // namespace etcd
+
+USERVER_NAMESPACE_END

etcd/include/userver/etcd/component.hpp

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <userver/components/component_base.hpp>
+#include <userver/components/component_config.hpp>
+#include <userver/components/component_context.hpp>
+#include <userver/etcd/client.hpp>
+
+USERVER_NAMESPACE_BEGIN
+
+namespace etcd {
+
+class Component final : public components::ComponentBase {
+public:
+    static constexpr std::string_view kName = "etcd-сlient";
+
+    Component(const components::ComponentConfig&, const components::ComponentContext&);
+
+    static yaml_config::Schema GetStaticConfigSchema();
+
+    ClientPtr GetClient();
+
+private:
+    const ClientPtr etcd_client_ptr_;
+};
+
+}  // namespace etcd
+
+USERVER_NAMESPACE_END

etcd/include/userver/etcd/exceptions.hpp

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <string>
+
+#include <stdexcept>
+
+USERVER_NAMESPACE_BEGIN
+
+namespace etcd {
+
+/// @brief Base class for all etcd client exceptions
+class EtcdError : public std::runtime_error {
+public:
+    using std::runtime_error::runtime_error;
+};
+
+}  // namespace etcd
+
+USERVER_NAMESPACE_END

etcd/include/userver/etcd/settings.hpp

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <chrono>
+#include <string>
+#include <vector>
+
+#include <userver/yaml_config/yaml_config.hpp>
+
+USERVER_NAMESPACE_BEGIN
+
+namespace etcd {
+
+struct ClientSettings final {
+    const std::vector<std::string> endpoints;
+    const std::uint32_t attempts;
+    const std::chrono::microseconds request_timeout_ms;
+};
+
+}  // namespace etcd
+
+namespace formats::parse {
+
+etcd::ClientSettings Parse(const yaml_config::YamlConfig& value, To<etcd::ClientSettings>);
+
+}
+
+USERVER_NAMESPACE_END

etcd/include/userver/etcd/watch_listener.hpp

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <string>
+
+#include <userver/concurrent/queue.hpp>
+#include <userver/formats/json/value.hpp>
+
+USERVER_NAMESPACE_BEGIN
+
+namespace etcd {
+
+struct KeyValueEvent final {
+    std::string key;
+    std::string value;
+    std::int32_t version;
+};
+
+struct WatchListener final {
+    concurrent::SpscQueue<KeyValueEvent>::Consumer consumer;
+
+    KeyValueEvent GetEvent();
+};
+
+}  // namespace etcd
+
+namespace formats::parse {
+
+etcd::KeyValueEvent Parse(const formats::json::Value& value, To<etcd::KeyValueEvent>);
+
+}
+
+USERVER_NAMESPACE_END

etcd/library.yaml

@@ -0,0 +1,9 @@
+project-name: userver-etcd
+project-alt-names:
+  - yandex-userver-etcd
+maintainers:
+  - Common components
+description: Etcd driver
+
+libraries:
+  - userver-core