Post commit execution: part 2 (#4296)

Add get_user_data and set_user_data functions to the RpcContext to enable passing data to the post local-commit handler without going through serialization and deserialization.

CHANGELOG.md

@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Added
 
 - New "attestation" section in node JSON configuration to specify remote endpoint required to retrieve the endorsement certificates for SEV-SNP attestation report (#4277, #4302).
+- The `ccf::RpcContext` now contains functionality for storing user data with `set_user_data` and retrieving it with `get_user_data` (#4291).
+- There are now `make_endpoint_with_local_commit_handler` and `make_read_only_endpoint_with_local_commit_handler` functions to install endpoints with post local-commit logic (#4296).
 
 ### Fixed
 

include/ccf/endpoint_registry.h

@@ -260,4 +260,4 @@ namespace ccf::endpoints
     virtual void increment_metrics_failures(const ccf::RpcContext& rpc_ctx);
     virtual void increment_metrics_retries(const ccf::RpcContext& rpc_ctx);
   };
-}
+}

include/ccf/rpc_context.h

@@ -60,6 +60,12 @@ namespace ccf
     /// the same long-lived session.
     virtual std::shared_ptr<SessionContext> get_session_context() const = 0;
 
+    // Set user data that will be available in the post-local-commit handler.
+    // This is useful to avoid the serialisation/deserialisation cost.
+    virtual void set_user_data(std::shared_ptr<void> data) = 0;
+    // Get the user data that was previously set.
+    virtual void* get_user_data() const = 0;
+
     virtual const std::vector<uint8_t>& get_request_body() const = 0;
     virtual const std::string& get_request_query() const = 0;
     virtual const ccf::RESTVerb& get_request_verb() const = 0;

samples/apps/logging/logging.cpp

@@ -317,20 +317,18 @@ namespace loggingapp
       auto add_txid_in_body_put = [](auto& ctx, const auto& tx_id) {
         static constexpr auto CCF_TX_ID = "x-ms-ccf-transaction-id";
         ctx.rpc_ctx->set_response_header(CCF_TX_ID, tx_id.to_str());
+        ctx.rpc_ctx->set_response_status(HTTP_STATUS_OK);
 
-        const nlohmann::json body_j =
-          nlohmann::json::parse(ctx.rpc_ctx->get_response_body());
-
-        auto interm = body_j.get<LoggingPut::Intermediate>();
+        auto out = static_cast<LoggingPut::Out*>(ctx.rpc_ctx->get_user_data());
 
-        if (interm.fail)
+        if (out == nullptr)
         {
-          throw std::runtime_error("oops, might have failed serialization");
+          throw std::runtime_error("didn't set user_data!");
         }
 
-        interm.out.tx_id = tx_id.to_str();
+        out->tx_id = tx_id.to_str();
 
-        ctx.rpc_ctx->set_response_body(nlohmann::json(interm.out).dump());
+        ctx.rpc_ctx->set_response_body(nlohmann::json(*out).dump());
       };
 
       auto record_v2 = [this](auto& ctx, nlohmann::json&& params) {
@@ -354,27 +352,19 @@ namespace loggingapp
 
         std::string error_reason;
         std::string fail;
-        if (!http::get_query_value(parsed_query, "fail", fail, error_reason))
-        {
-          return ccf::make_error(
-            HTTP_STATUS_BAD_REQUEST,
-            ccf::errors::InvalidQueryParameterValue,
-            std::move(error_reason));
-        }
+        http::get_query_value(parsed_query, "fail", fail, error_reason);
 
-        LoggingPut::Out resp;
-        resp.success = true;
-        LoggingPut::Intermediate interm;
-        interm.out = resp;
-        if (fail == "true")
-        {
-          interm.fail = true;
-        }
-        else
+        auto out = std::make_shared<LoggingPut::Out>();
+        out->success = true;
+
+        if (fail != "true")
         {
-          interm.fail = false;
+          ctx.rpc_ctx->set_user_data(out);
         }
-        return ccf::make_success(interm);
+
+        // return a default value as we'll set the response in the post-commit
+        // handler
+        return ccf::make_success(nullptr);
       };
 
       make_endpoint_with_local_commit_handler(

samples/apps/logging/logging_schema.h

@@ -39,11 +39,6 @@ namespace loggingapp
       bool success;
       std::string tx_id;
     };
-    struct Intermediate
-    {
-      Out out;
-      bool fail;
-    };
   };
 
   struct LoggingGetReceipt
@@ -69,8 +64,6 @@ namespace loggingapp
 
   DECLARE_JSON_TYPE(LoggingPut::Out);
   DECLARE_JSON_REQUIRED_FIELDS(LoggingPut::Out, success, tx_id);
-  DECLARE_JSON_TYPE(LoggingPut::Intermediate);
-  DECLARE_JSON_REQUIRED_FIELDS(LoggingPut::Intermediate, out, fail);
 
   DECLARE_JSON_TYPE(LoggingGetReceipt::In);
   DECLARE_JSON_REQUIRED_FIELDS(LoggingGetReceipt::In, id);

src/endpoints/endpoint_registry.cpp

@@ -163,7 +163,7 @@ namespace ccf::endpoints
 
     endpoint.dispatch.verb = verb;
     endpoint.func = f;
-    endpoint.locally_committed_func = &default_locally_committed_func;
+    endpoint.locally_committed_func = default_locally_committed_func;
 
     endpoint.authn_policies = ap;
     // By default, all write transactions are forwarded
@@ -554,4 +554,4 @@ namespace ccf::endpoints
       rpc_ctx.get_method(), rpc_ctx.get_request_verb().c_str())
       .retries++;
   }
-}
+}

src/node/rpc/rpc_context_impl.h

@@ -16,6 +16,8 @@ namespace ccf
   protected:
     std::shared_ptr<SessionContext> session;
 
+    std::shared_ptr<void> user_data;
+
   public:
     RpcContextImpl(const std::shared_ptr<SessionContext>& s) : session(s) {}
 
@@ -24,6 +26,16 @@ namespace ccf
       return session;
     }
 
+    virtual void set_user_data(std::shared_ptr<void> data) override
+    {
+      user_data = data;
+    }
+
+    virtual void* get_user_data() const override
+    {
+      return user_data.get();
+    }
+
     ccf::ClaimsDigest claims = ccf::empty_claims();
     void set_claims_digest(ccf::ClaimsDigest::Digest&& digest) override
     {

tests/e2e_logging.py

@@ -1527,7 +1527,7 @@ def test_post_local_commit_failure(network, args):
         assert r.body.json() == {
             "error": {
                 "code": "InternalError",
-                "message": "Failed to execute local commit handler func: oops, might have failed serialization",
+                "message": "Failed to execute local commit handler func: didn't set user_data!",
             }
         }, r.body.json()