RPC Consistency Proposal

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Added
 - [2551](https://github.com/FuelLabs/fuel-core/pull/2551): Enhanced the DA compressed block header to include block id.
+- [2473](https://github.com/FuelLabs/fuel-core/pull/2473): Graphql requests and responses make use of a new `extensions` object to specify request/response metadata. A request `extensions` object can contain an integer-valued `required_fuel_block_height` field. When specified, the request will return an error unless the node's current fuel block height is at least the value specified in the `required_fuel_block_height` field. All graphql responses now contain an integer-valued `current_fuel_block_height` field in the `extensions` object, which contains the block height of the last block processed by the node.
 
 ### Fixed
 - [2599](https://github.com/FuelLabs/fuel-core/pull/2599): Use the proper `url` apis to construct full url path in `BlockCommitterHttpApi` client

crates/client/src/client.rs

@@ -39,7 +39,6 @@ use base64::prelude::{
 #[cfg(feature = "subscriptions")]
 use cynic::StreamingOperation;
 use cynic::{
-    http::ReqwestExt,
     GraphQlResponse,
     Id,
     MutationBuilder,
@@ -78,6 +77,13 @@ use pagination::{
     PaginatedResult,
     PaginationRequest,
 };
+use reqwest::header::{
+    AsHeaderName,
+    HeaderMap,
+    HeaderValue,
+    IntoHeaderName,
+    CONTENT_TYPE,
+};
 use schema::{
     assets::AssetInfoArg,
     balance::BalanceArgs,
@@ -119,6 +125,7 @@ use schema::{
 #[cfg(feature = "subscriptions")]
 use std::future;
 use std::{
+    collections::HashMap,
     convert::TryInto,
     io::{
         self,
@@ -151,12 +158,25 @@ pub mod types;
 
 type RegisterId = u32;
 
+#[derive(Debug, derive_more::Display, derive_more::From)]
+#[non_exhaustive]
+/// Error occurring during interaction with the FuelClient
+// anyhow::Error is wrapped inside a custom Error type,
+// so that we can specific error variants in the future.
+pub enum Error {
+    /// Unknown or not expected(by architecture) error.
+    #[from]
+    Other(anyhow::Error),
+}
+
 #[derive(Debug, Clone)]
 pub struct FuelClient {
     client: reqwest::Client,
     #[cfg(feature = "subscriptions")]
     cookie: std::sync::Arc<reqwest::cookie::Jar>,
     url: reqwest::Url,
+    headers: HeaderMap,
+    extensions: HashMap<&'static str, serde_json::Value>,
 }
 
 impl FromStr for FuelClient {
@@ -184,13 +204,20 @@ impl FromStr for FuelClient {
                 client,
                 cookie,
                 url,
+                headers: HeaderMap::new(),
+                extensions: HashMap::new(),
             })
         }
 
         #[cfg(not(feature = "subscriptions"))]
         {
             let client = reqwest::Client::new();
-            Ok(Self { client, url })
+            Ok(Self {
+                client,
+                url,
+                headers: HeaderMap::new(),
+                extensions: HashMap::new(),
+            })
         }
     }
 }
@@ -223,6 +250,34 @@ impl FuelClient {
         Self::from_str(url.as_ref())
     }
 
+    pub fn set_header(
+        &mut self,
+        key: impl IntoHeaderName,
+        value: impl TryInto<HeaderValue>,
+    ) -> Result<&mut Self, Error> {
+        let header_value: HeaderValue = value
+            .try_into()
+            .map_err(|_err| anyhow::anyhow!("Cannot parse value for header"))?;
+        self.headers.insert(key, header_value);
+        Ok(self)
+    }
+
+    pub fn remove_header(&mut self, key: impl AsHeaderName) -> &mut Self {
+        self.headers.remove(key);
+        self
+    }
+
+    pub fn with_required_fuel_block_height(&mut self, height: u64) -> &mut Self {
+        self.extensions
+            .insert("required_fuel_block_height", height.into());
+        self
+    }
+
+    pub fn without_required_fuel_block_height(&mut self) -> &mut Self {
+        self.extensions.remove("required_fuel_block_height");
+        self
+    }
+
     /// Send the GraphQL query to the client.
     pub async fn query<ResponseData, Vars>(
         &self,
@@ -232,13 +287,33 @@ impl FuelClient {
         Vars: serde::Serialize,
         ResponseData: serde::de::DeserializeOwned + 'static,
     {
-        let response = self
+        let mut operation_json = serde_json::to_value(&q)?;
+        let operation_object = operation_json
+            .as_object_mut()
+            .expect("Graphql operation is a valid json object");
+        operation_object.insert(
+            "extensions".to_owned(),
+            serde_json::to_value(self.extensions.clone())?,
+        );
+
+        println!("{}", serde_json::to_string_pretty(&operation_json).unwrap());
+        let request_builder = self
             .client
             .post(self.url.clone())
-            .run_graphql(q)
+            .headers(self.headers.clone())
+            .header(CONTENT_TYPE, "application/json")
+            .body(serde_json::to_string(&operation_json)?);
+
+        let response = request_builder
+            .send()
+            .await
+            .map_err(|e| io::Error::new(io::ErrorKind::Other, e))?
+            .text()
             .await
             .map_err(|e| io::Error::new(io::ErrorKind::Other, e))?;
 
+        println!("Response: {}", response);
+        let response = serde_json::from_str(&response)?;
         Self::decode_response(response)
     }
 

crates/fuel-core/src/graphql_api.rs

@@ -14,6 +14,7 @@ pub mod database;
 pub(crate) mod indexation;
 pub(crate) mod metrics_extension;
 pub mod ports;
+pub(crate) mod required_fuel_block_height_extension;
 pub mod storage;
 pub(crate) mod validation_extension;
 pub(crate) mod view_extension;

crates/fuel-core/src/graphql_api/api_service.rs

@@ -15,7 +15,10 @@ use crate::{
         view_extension::ViewExtension,
         Config,
     },
-    graphql_api,
+    graphql_api::{
+        self,
+        required_fuel_block_height_extension::RequiredFuelBlockHeightExtension,
+    },
     schema::{
         CoreSchema,
         CoreSchemaBuilder,
@@ -85,6 +88,9 @@ use tower_http::{
     trace::TraceLayer,
 };
 
+pub(crate) const REQUIRED_FUEL_BLOCK_HEIGHT: &str = "required_fuel_block_height";
+pub(crate) const CURRENT_FUEL_BLOCK_HEIGHT: &str = "current_fuel_block_height";
+
 pub type Service = fuel_core_services::ServiceRunner<GraphqlService>;
 
 pub use super::database::ReadDatabase;
@@ -282,6 +288,9 @@ where
         ))
         .extension(async_graphql::extensions::Tracing)
         .extension(ViewExtension::new())
+        // `RequiredFuelBlockHeightExtension` uses the view set by the ViewExtension.
+        // Do not reorder this line before adding the `ViewExtension`.
+        .extension(RequiredFuelBlockHeightExtension::new())
         .finish();
 
     let graphql_endpoint = "/v1/graphql";
@@ -358,15 +367,18 @@ async fn graphql_handler(
     schema: Extension<CoreSchema>,
     req: Json<Request>,
 ) -> Json<Response> {
-    schema.execute(req.0).await.into()
+    let response = schema.execute(req.0).await;
+
+    response.into()
 }
 
 async fn graphql_subscription_handler(
     schema: Extension<CoreSchema>,
     req: Json<Request>,
 ) -> Sse<impl Stream<Item = anyhow::Result<Event, serde_json::Error>>> {
+    let request = req.0;
     let stream = schema
-        .execute_stream(req.0)
+        .execute_stream(request)
         .map(|r| Event::default().json_data(r));
     Sse::new(stream)
         .keep_alive(axum::response::sse::KeepAlive::new().text("keep-alive-text"))

crates/fuel-core/src/graphql_api/required_fuel_block_height_extension.rs

@@ -0,0 +1,148 @@
+use super::database::ReadView;
+use crate::fuel_core_graphql_api::api_service::{
+    CURRENT_FUEL_BLOCK_HEIGHT,
+    REQUIRED_FUEL_BLOCK_HEIGHT,
+};
+use async_graphql::{
+    extensions::{
+        Extension,
+        ExtensionContext,
+        ExtensionFactory,
+        NextExecute,
+        NextPrepareRequest,
+    },
+    Pos,
+    Request,
+    Response,
+    ServerError,
+    ServerResult,
+    Value,
+};
+use async_graphql_value::ConstValue;
+use fuel_core_types::fuel_types::BlockHeight;
+use std::sync::{
+    Arc,
+    OnceLock,
+};
+
+/// The extension that implements the logic for checking whether
+/// the precondition that REQUIRED_FUEL_BLOCK_HEADER must
+/// be higher than the current block height is met.
+/// The value of the REQUIRED_FUEL_BLOCK_HEADER is set in
+/// the request data by the graphql handler as a value of type
+/// `RequiredHeight`.
+#[derive(Debug, derive_more::Display, derive_more::From)]
+pub(crate) struct RequiredFuelBlockHeightExtension;
+
+impl RequiredFuelBlockHeightExtension {
+    pub fn new() -> Self {
+        Self
+    }
+}
+
+pub(crate) struct RequiredFuelBlockHeightInner {
+    required_height: OnceLock<BlockHeight>,
+}
+
+impl RequiredFuelBlockHeightInner {
+    pub fn new() -> Self {
+        Self {
+            required_height: OnceLock::new(),
+        }
+    }
+}
+
+impl ExtensionFactory for RequiredFuelBlockHeightExtension {
+    fn create(&self) -> Arc<dyn Extension> {
+        Arc::new(RequiredFuelBlockHeightInner::new())
+    }
+}
+
+#[async_trait::async_trait]
+impl Extension for RequiredFuelBlockHeightInner {
+    async fn prepare_request(
+        &self,
+        ctx: &ExtensionContext<'_>,
+        request: Request,
+        next: NextPrepareRequest<'_>,
+    ) -> ServerResult<Request> {
+        let required_fuel_block_height =
+            request.extensions.get(REQUIRED_FUEL_BLOCK_HEIGHT);
+
+        if let Some(ConstValue::Number(required_fuel_block_height)) =
+            required_fuel_block_height
+        {
+            if let Some(required_fuel_block_height) = required_fuel_block_height.as_u64()
+            {
+                let required_fuel_block_height: u32 =
+                    required_fuel_block_height.try_into().unwrap_or(u32::MAX);
+                let required_block_height: BlockHeight =
+                    required_fuel_block_height.into();
+                self.required_height
+                    .set(required_block_height)
+                    .expect("`prepare_request` called only once; qed");
+            }
+        }
+
+        next.run(ctx, request).await
+    }
+
+    async fn execute(
+        &self,
+        ctx: &ExtensionContext<'_>,
+        operation_name: Option<&str>,
+        next: NextExecute<'_>,
+    ) -> Response {
+        let view: &ReadView = ctx.data_unchecked();
+
+        let current_block_height = view.latest_block_height();
+
+        if let Some(required_block_height) = self.required_height.get() {
+            if let Ok(current_block_height) = current_block_height {
+                if *required_block_height > current_block_height {
+                    let (line, column) = (line!(), column!());
+                    let mut response = Response::from_errors(vec![ServerError::new(
+                        format!(
+                            "The required fuel block height is higher than the current block height. \
+                            Required: {}, Current: {}",
+                            // required_block_height: &BlockHeight, dereference twice to get the 
+                            // corresponding value as u32. This is necessary because the Display 
+                            // implementation for BlockHeight displays values in hexadecimal format.
+                            **required_block_height,
+                            // current_fuel_block_height: BlockHeight, dereference once to get the 
+                            // corresponding value as u32.
+                            *current_block_height
+                        ),
+                        Some(Pos {
+                            line: line as usize,
+                            column: column as usize,
+                        }),
+                    )]);
+
+                    response.extensions.insert(
+                        CURRENT_FUEL_BLOCK_HEIGHT.to_string(),
+                        Value::Number((*current_block_height).into()),
+                    );
+
+                    return response
+                }
+            }
+        }
+
+        let mut response = next.run(ctx, operation_name).await;
+
+        let current_block_height = view.latest_block_height();
+
+        if let Ok(current_block_height) = current_block_height {
+            let current_block_height: u32 = *current_block_height;
+            response.extensions.insert(
+                CURRENT_FUEL_BLOCK_HEIGHT.to_string(),
+                Value::Number(current_block_height.into()),
+            );
+        } else {
+            tracing::error!("Failed to get the current block height");
+        }
+
+        response
+    }
+}

tests/tests/lib.rs

@@ -50,6 +50,8 @@ mod regenesis;
 #[cfg(not(feature = "only-p2p"))]
 mod relayer;
 #[cfg(not(feature = "only-p2p"))]
+mod required_fuel_block_height_extension;
+#[cfg(not(feature = "only-p2p"))]
 mod snapshot;
 #[cfg(not(feature = "only-p2p"))]
 mod state_rewind;