ServiceRouter: IEQE Support Fixes.

Summary:
In ordr to support IEQE using client interceptors to direct
traffic to experimental vs control targets:

1. Make RPCOptions non-const to allow the interceptor to modify it.
2. getOperationMask in RpcOptions must return a reference -  else
   operationMask_ref() in RoutingParamsResolver will return a
   reference to a stack value -> memory corruption.

Reviewed By: tlj77, joshbollarmeta

Differential Revision: D77077414

fbshipit-source-id: 3c26d61c1017e24494a73400c940d986f3cda20f

Author: Michal Ostrowski

third-party/thrift/src/thrift/lib/cpp2/async/ClientInterceptorBase.h

@@ -59,7 +59,7 @@ class ClientInterceptorBase {
     /**
      * RpcOptions that were applied to this request
      */
-    const RpcOptions* rpcOptions = nullptr;
+    RpcOptions* rpcOptions = nullptr;
   };
   virtual void internal_onRequest(RequestInfo) = 0;
 

third-party/thrift/src/thrift/lib/cpp2/async/RpcOptions.cpp

@@ -164,7 +164,7 @@ RpcOptions& RpcOptions::setOperationMask(int32_t operationMask) {
   return *this;
 }
 
-int32_t RpcOptions::getOperationMask() const {
+const int32_t& RpcOptions::getOperationMask() const {
   return operationMask_;
 }
 

third-party/thrift/src/thrift/lib/cpp2/async/RpcOptions.h

@@ -133,7 +133,7 @@ class RpcOptions {
   const std::string& getShardId() const;
 
   RpcOptions& setOperationMask(int32_t operationMask);
-  int32_t getOperationMask() const;
+  const int32_t& getOperationMask() const;
 
   void setWriteHeader(std::string_view key, std::string value);
   const transport::THeader::StringToStringMap& getWriteHeaders() const;