rds: extracting base classes as reusable generic routing DS implementation.

envoy/rds/BUILD

@@ -0,0 +1,19 @@
+load(
+    "//bazel:envoy_build_system.bzl",
+    "envoy_cc_library",
+    "envoy_package",
+)
+
+licenses(["notice"])  # Apache 2
+
+envoy_package()
+
+envoy_cc_library(
+    name = "rds_interface",
+    hdrs = [
+        "config.h",
+        "config_traits.h",
+        "route_config_provider.h",
+        "route_config_update_receiver.h",
+    ],
+)

envoy/rds/config.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <memory>
+
+namespace Envoy {
+namespace Rds {
+
+/**
+ * Base class for router configuration classes used with Rds.
+ */
+class Config {
+public:
+  virtual ~Config() = default;
+};
+
+using ConfigConstSharedPtr = std::shared_ptr<const Config>;
+
+} // namespace Rds
+} // namespace Envoy

envoy/rds/config_traits.h

@@ -0,0 +1,61 @@
+#pragma once
+
+#include <memory>
+
+#include "envoy/common/pure.h"
+#include "envoy/rds/config.h"
+
+#include "source/common/protobuf/protobuf.h"
+
+namespace Envoy {
+namespace Rds {
+
+/**
+ * Traits of the protocol specific route configuration and proto.
+ * The generic rds classes will call the methods of this interface
+ * to get information which are not visible for them directly.
+ */
+class ProtoTraits {
+public:
+  virtual ~ProtoTraits() = default;
+
+  /**
+   * Give the full name of the route configuration proto description.
+   * For example 'envoy.config.route.v3.RouteConfiguration'
+   */
+  virtual std::string resourceType() const PURE;
+
+  /**
+   * Gives back the name field tag number of the route configuration proto.
+   */
+  virtual int resourceNameFieldNumber() const PURE;
+
+  /**
+   * Create an empty route configuration proto object.
+   */
+  virtual ProtobufTypes::MessagePtr createEmptyProto() const PURE;
+};
+
+class ConfigTraits {
+public:
+  virtual ~ConfigTraits() = default;
+
+  /**
+   * Create a dummy config object without actual route configuration.
+   * This object will be used before the first valid route configuration is fetched.
+   */
+  virtual ConfigConstSharedPtr createNullConfig() const PURE;
+
+  /**
+   * Create a config object based on a route configuration.
+   * The full name of the type of the parameter message is
+   * guaranteed to match with the return value of ProtoTraits::resourceType.
+   * Both dynamic or static cast can be applied to downcast the message
+   * to the corresponding route configuration class.
+   * @throw EnvoyException if the new config can't be applied of.
+   */
+  virtual ConfigConstSharedPtr createConfig(const Protobuf::Message& rc) const PURE;
+};
+
+} // namespace Rds
+} // namespace Envoy

envoy/rds/route_config_provider.h

@@ -0,0 +1,61 @@
+#pragma once
+
+#include <memory>
+
+#include "envoy/common/time.h"
+#include "envoy/rds/config.h"
+
+#include "source/common/protobuf/protobuf.h"
+
+#include "absl/types/optional.h"
+
+namespace Envoy {
+namespace Rds {
+
+/**
+ * A provider for constant route configurations.
+ */
+class RouteConfigProvider {
+public:
+  struct ConfigInfo {
+    // A reference to the currently loaded route configuration. Do not hold this reference beyond
+    // the caller of configInfo()'s scope.
+    const Protobuf::Message& config_;
+
+    // The discovery version that supplied this route. This will be set to "" in the case of
+    // static clusters.
+    const std::string version_;
+  };
+
+  virtual ~RouteConfigProvider() = default;
+
+  /**
+   * @return ConfigConstSharedPtr a route configuration for use during a single request. The
+   * returned config may be different on a subsequent call, so a new config should be acquired for
+   * each request flow.
+   */
+  virtual ConfigConstSharedPtr config() PURE;
+
+  /**
+   * @return the configuration information for the currently loaded route configuration. Note that
+   * if the provider has not yet performed an initial configuration load, no information will be
+   * returned.
+   */
+  virtual absl::optional<ConfigInfo> configInfo() const PURE;
+
+  /**
+   * @return the last time this RouteConfigProvider was updated. Used for config dumps.
+   */
+  virtual SystemTime lastUpdated() const PURE;
+
+  /**
+   * Callback used to notify RouteConfigProvider about configuration changes.
+   */
+  virtual void onConfigUpdate() PURE;
+};
+
+using RouteConfigProviderPtr = std::unique_ptr<RouteConfigProvider>;
+using RouteConfigProviderSharedPtr = std::shared_ptr<RouteConfigProvider>;
+
+} // namespace Rds
+} // namespace Envoy

envoy/rds/route_config_update_receiver.h

@@ -0,0 +1,67 @@
+#pragma once
+
+#include <memory>
+
+#include "envoy/common/pure.h"
+#include "envoy/common/time.h"
+#include "envoy/rds/route_config_provider.h"
+
+#include "absl/types/optional.h"
+
+namespace Envoy {
+namespace Rds {
+
+/**
+ * A primitive that keeps track of updates to a RouteConfiguration.
+ */
+class RouteConfigUpdateReceiver {
+public:
+  virtual ~RouteConfigUpdateReceiver() = default;
+
+  /**
+   * Called on updates via RDS.
+   * @param rc supplies the RouteConfiguration.
+   * @param version_info supplies RouteConfiguration version.
+   * @return bool whether RouteConfiguration has been updated.
+   * @throw EnvoyException if the new config can't be applied.
+   */
+  virtual bool onRdsUpdate(const Protobuf::Message& rc, const std::string& version_info) PURE;
+
+  /**
+   * @return std::string& the version of RouteConfiguration.
+   */
+  virtual const std::string& configVersion() const PURE;
+
+  /**
+   * @return uint64_t the hash value of RouteConfiguration.
+   */
+  virtual uint64_t configHash() const PURE;
+
+  /**
+   * @return absl::optional<RouteConfigProvider::ConfigInfo> containing an instance of
+   * RouteConfigProvider::ConfigInfo if RouteConfiguration has been updated at least once. Otherwise
+   * returns an empty absl::optional<RouteConfigProvider::ConfigInfo>.
+   */
+  virtual absl::optional<RouteConfigProvider::ConfigInfo> configInfo() const PURE;
+
+  /**
+   * @return envoy::config::route::v3::RouteConfiguration& current RouteConfiguration.
+   */
+  virtual const Protobuf::Message& protobufConfiguration() PURE;
+
+  /**
+   * @return ConfigConstSharedPtr a parsed and validated copy of current RouteConfiguration.
+   * @see protobufConfiguration()
+   */
+  virtual ConfigConstSharedPtr parsedConfiguration() const PURE;
+
+  /**
+   * @return SystemTime the time of the last update.
+   */
+  virtual SystemTime lastUpdated() const PURE;
+};
+
+using RouteConfigUpdatePtr = std::unique_ptr<RouteConfigUpdateReceiver>;
+
+} // namespace Rds
+} // namespace Envoy

envoy/router/BUILD

@@ -19,6 +19,7 @@ envoy_cc_library(
     deps = [
         ":router_interface",
         "//envoy/http:filter_interface",
+        "//envoy/rds:rds_interface",
         "@envoy_api//envoy/config/route/v3:pkg_cc_proto",
     ],
 )
@@ -70,6 +71,7 @@ envoy_cc_library(
         "//envoy/http:conn_pool_interface",
         "//envoy/http:hash_policy_interface",
         "//envoy/http:header_map_interface",
+        "//envoy/rds:rds_interface",
         "//envoy/tcp:conn_pool_interface",
         "//envoy/tracing:http_tracer_interface",
         "//envoy/upstream:resource_manager_interface",

envoy/router/rds.h

@@ -4,6 +4,7 @@
 
 #include "envoy/config/route/v3/route.pb.h"
 #include "envoy/http/filter.h"
+#include "envoy/rds/route_config_provider.h"
 #include "envoy/router/router.h"
 
 namespace Envoy {
@@ -12,43 +13,14 @@ namespace Router {
 /**
  * A provider for constant route configurations.
  */
-class RouteConfigProvider {
+class RouteConfigProvider : public Rds::RouteConfigProvider {
 public:
-  struct ConfigInfo {
-    // A reference to the currently loaded route configuration. Do not hold this reference beyond
-    // the caller of configInfo()'s scope.
-    const envoy::config::route::v3::RouteConfiguration& config_;
-
-    // The discovery version that supplied this route. This will be set to "" in the case of
-    // static clusters.
-    std::string version_;
-  };
-
-  virtual ~RouteConfigProvider() = default;
-
-  /**
-   * @return Router::ConfigConstSharedPtr a route configuration for use during a single request. The
-   * returned config may be different on a subsequent call, so a new config should be acquired for
-   * each request flow.
-   */
-  virtual Router::ConfigConstSharedPtr config() PURE;
-
-  /**
-   * @return the configuration information for the currently loaded route configuration. Note that
-   * if the provider has not yet performed an initial configuration load, no information will be
-   * returned.
-   */
-  virtual absl::optional<ConfigInfo> configInfo() const PURE;
-
-  /**
-   * @return the last time this RouteConfigProvider was updated. Used for config dumps.
-   */
-  virtual SystemTime lastUpdated() const PURE;
-
   /**
-   * Callback used to notify RouteConfigProvider about configuration changes.
+   * Same purpose as Rds::RouteConfigProvider::config()
+   * but the return is downcasted to proper type.
+   * @return downcasted ConfigConstSharedPtr from Rds::ConfigConstSharedPtr
    */
-  virtual void onConfigUpdate() PURE;
+  virtual ConfigConstSharedPtr configCast() PURE;
 
   /**
    * Callback used to request an update to the route configuration from the management server.

envoy/router/route_config_update_receiver.h

@@ -5,7 +5,7 @@
 #include "envoy/common/pure.h"
 #include "envoy/common/time.h"
 #include "envoy/config/route/v3/route.pb.h"
-#include "envoy/router/rds.h"
+#include "envoy/rds/route_config_update_receiver.h"
 #include "envoy/service/discovery/v3/discovery.pb.h"
 
 #include "source/common/protobuf/protobuf.h"
@@ -18,19 +18,14 @@ namespace Router {
 /**
  * A primitive that keeps track of updates to a RouteConfiguration.
  */
-class RouteConfigUpdateReceiver {
+class RouteConfigUpdateReceiver : public Rds::RouteConfigUpdateReceiver {
 public:
-  virtual ~RouteConfigUpdateReceiver() = default;
-
   /**
-   * Called on updates via RDS.
-   * @param rc supplies the RouteConfiguration.
-   * @param version_info supplies RouteConfiguration version.
-   * @return bool whether RouteConfiguration has been updated.
-   * @throw EnvoyException if the new config can't be applied.
+   * Same purpose as Rds::RouteConfigUpdateReceiver::protobufConfigurationCast()
+   * but the return is downcasted to proper type.
+   * @return current RouteConfiguration downcasted from Protobuf::Message&
    */
-  virtual bool onRdsUpdate(const envoy::config::route::v3::RouteConfiguration& rc,
-                           const std::string& version_info) PURE;
+  virtual const envoy::config::route::v3::RouteConfiguration& protobufConfigurationCast() PURE;
 
   using VirtualHostRefVector =
       std::vector<std::reference_wrapper<const envoy::config::route::v3::VirtualHost>>;
@@ -48,16 +43,6 @@ class RouteConfigUpdateReceiver {
                             const Protobuf::RepeatedPtrField<std::string>& removed_resources,
                             const std::string& version_info) PURE;
 
-  /**
-   * @return std::string& the name of RouteConfiguration.
-   */
-  virtual const std::string& routeConfigName() const PURE;
-
-  /**
-   * @return std::string& the version of RouteConfiguration.
-   */
-  virtual const std::string& configVersion() const PURE;
-
   /**
    * @return bool return whether VHDS configuration has been changed in the last RDS update.
    */
@@ -66,34 +51,6 @@ class RouteConfigUpdateReceiver {
   // intent and the lifecycle of the "last update state" less muddled.
   virtual bool vhdsConfigurationChanged() const PURE;
 
-  /**
-   * @return uint64_t the hash value of RouteConfiguration.
-   */
-  virtual uint64_t configHash() const PURE;
-
-  /**
-   * @return absl::optional<RouteConfigProvider::ConfigInfo> containing an instance of
-   * RouteConfigProvider::ConfigInfo if RouteConfiguration has been updated at least once. Otherwise
-   * returns an empty absl::optional<RouteConfigProvider::ConfigInfo>.
-   */
-  virtual absl::optional<RouteConfigProvider::ConfigInfo> configInfo() const PURE;
-
-  /**
-   * @return envoy::config::route::v3::RouteConfiguration& current RouteConfiguration.
-   */
-  virtual const envoy::config::route::v3::RouteConfiguration& protobufConfiguration() PURE;
-
-  /**
-   * @return Router::ConfigConstSharedPtr a parsed and validated copy of current RouteConfiguration.
-   * @see protobufConfiguration()
-   */
-  virtual ConfigConstSharedPtr parsedConfiguration() const PURE;
-
-  /**
-   * @return SystemTime the time of the last update.
-   */
-  virtual SystemTime lastUpdated() const PURE;
-
   /**
    * @return the union of all resource names and aliases (if any) received with the last VHDS
    * update.