Caching (#2935)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **New Features**
- Introduced caching capabilities to the FlowControlService with new
RPCs for cache management.
- Added cache key and value fields to request and response messages for
enhanced service functionality.
- Implemented a new cache package with upsert and delete operations for
distributed caching.
- Expanded SDKs with new cache-related types and methods for managing
cached values.

- **Enhancements**
  - Updated SDKs to include new cache-related RPCs and message types.
- Improved error handling and added new utility functions in SDKs for
better integration with caching features.
- Refactored existing code to accommodate caching logic and improve
readability.

- **Documentation**
- Updated example usage in SDKs to demonstrate new caching features and
API changes.

- **Refactor**
- Renamed packages and updated import paths to align with new caching
functionality.
  - Replaced logging packages for consistency across the codebase.

- **Style**
- Made minor adjustments to code formatting for better consistency and
readability.

- **Chores**
- Updated Makefile to copy new generated SDK stubs for flow control to
respective SDK directories.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: Hasit Mistry <hasit@fluxninja.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

api/Makefile

@@ -26,6 +26,11 @@ buf-generate:
 
 	@#generate sdk flowcontrol stubs and copy them over
 
+	@#golang
+	@rm -rf ../sdks/aperture-go/gen/proto/flowcontrol/*
+	@cp -R gen/proto/go/aperture/flowcontrol/check ../sdks/aperture-go/gen/proto/flowcontrol/
+	@cp -R gen/proto/go/aperture/flowcontrol/checkhttp ../sdks/aperture-go/gen/proto/flowcontrol/
+
 	@#csharp
 	@rm -rf ../sdks/aperture-csharp/Generated/Aperture/Flowcontrol/
 	@cp -R gen/proto/csharp/Aperture/Flowcontrol/Check ../sdks/aperture-csharp/Generated/Aperture/Flowcontrol/

api/aperture/flowcontrol/check/v1/check.proto

@@ -9,13 +9,17 @@ import "google/protobuf/timestamp.proto";
 service FlowControlService {
   // Check wraps the given arbitrary resource and matches the given labels against Flow Control Limiters to makes a decision whether to allow/deny.
   rpc Check(CheckRequest) returns (CheckResponse) {}
+  rpc CacheUpsert(CacheUpsertRequest) returns (CacheUpsertResponse) {}
+  rpc CacheDelete(CacheDeleteRequest) returns (CacheDeleteResponse) {}
 }
 
 // CheckRequest contains fields required to perform Check call.
 message CheckRequest {
   string control_point = 1;
   map<string, string> labels = 2;
   bool ramp_mode = 3;
+  // Cache item to fetch.
+  string cache_key = 4;
 }
 
 // CheckResponse contains fields that represent decision made by Check call.
@@ -63,6 +67,47 @@ message CheckResponse {
   // http_status contains the http status code to be returned to the client, if
   // decision_type is REJECTED. Optional.
   StatusCode denied_response_status_code = 14;
+  // Matching cached value.
+  CachedValue cached_value = 15;
+}
+
+enum CacheLookupStatus {
+  HIT = 0;
+  MISS = 1;
+}
+
+enum CacheOperationStatus {
+  SUCCESS = 0;
+  ERROR = 1;
+}
+
+message CachedValue {
+  bytes value = 1;
+  CacheLookupStatus lookup_status = 2;
+  CacheOperationStatus operation_status = 3;
+  string error = 4;
+}
+
+message CacheUpsertRequest {
+  string control_point = 1;
+  string key = 2;
+  bytes value = 3;
+  google.protobuf.Duration ttl = 4;
+}
+
+message CacheUpsertResponse {
+  CacheOperationStatus operation_status = 1;
+  string error = 2;
+}
+
+message CacheDeleteRequest {
+  string control_point = 1;
+  string key = 2;
+}
+
+message CacheDeleteResponse {
+  CacheOperationStatus operation_status = 1;
+  string error = 2;
 }
 
 // ClassifierInfo describes details for each ClassifierInfo.