add graph-indexed header (#5710)

This adds a `graph-indexed` header to query responses. The header value contains the block hash, number, and timestamp for the most recently processed block in the subgraph. This avoids the need to rewrite all queries to include `_meta { block { hash number timestamp } }` in either the indexer-service or gateway.

Related: edgeandnode/gateway#900, graphprotocol/indexer-rs#494

graph/src/data/query/mod.rs

@@ -7,5 +7,5 @@ mod trace;
 pub use self::cache_status::CacheStatus;
 pub use self::error::{QueryError, QueryExecutionError};
 pub use self::query::{Query, QueryTarget, QueryVariables};
-pub use self::result::{QueryResult, QueryResults};
+pub use self::result::{LatestBlockInfo, QueryResult, QueryResults};
 pub use self::trace::Trace;

graph/src/data/query/result.rs

@@ -4,7 +4,7 @@ use crate::cheap_clone::CheapClone;
 use crate::components::server::query::ServerResponse;
 use crate::data::value::Object;
 use crate::derive::CacheWeight;
-use crate::prelude::{r, CacheWeight, DeploymentHash};
+use crate::prelude::{r, BlockHash, BlockNumber, CacheWeight, DeploymentHash};
 use http_body_util::Full;
 use hyper::header::{
     ACCESS_CONTROL_ALLOW_HEADERS, ACCESS_CONTROL_ALLOW_METHODS, ACCESS_CONTROL_ALLOW_ORIGIN,
@@ -48,20 +48,37 @@ where
     ser.end()
 }
 
+fn serialize_block_hash<S>(data: &BlockHash, serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+{
+    serializer.serialize_str(&data.to_string())
+}
+
 pub type Data = Object;
 
 #[derive(Debug)]
 /// A collection of query results that is serialized as a single result.
 pub struct QueryResults {
     results: Vec<Arc<QueryResult>>,
     pub trace: Trace,
+    pub indexed_block: Option<LatestBlockInfo>,
+}
+
+#[derive(Debug, Serialize)]
+pub struct LatestBlockInfo {
+    #[serde(serialize_with = "serialize_block_hash")]
+    pub hash: BlockHash,
+    pub number: BlockNumber,
+    pub timestamp: Option<u64>,
 }
 
 impl QueryResults {
-    pub fn empty(trace: Trace) -> Self {
+    pub fn empty(trace: Trace, indexed_block: Option<LatestBlockInfo>) -> Self {
         QueryResults {
             results: Vec::new(),
             trace,
+            indexed_block,
         }
     }
 
@@ -155,6 +172,7 @@ impl From<Data> for QueryResults {
         QueryResults {
             results: vec![Arc::new(x.into())],
             trace: Trace::None,
+            indexed_block: None,
         }
     }
 }
@@ -164,6 +182,7 @@ impl From<QueryResult> for QueryResults {
         QueryResults {
             results: vec![Arc::new(x)],
             trace: Trace::None,
+            indexed_block: None,
         }
     }
 }
@@ -173,6 +192,7 @@ impl From<Arc<QueryResult>> for QueryResults {
         QueryResults {
             results: vec![x],
             trace: Trace::None,
+            indexed_block: None,
         }
     }
 }
@@ -182,6 +202,7 @@ impl From<QueryExecutionError> for QueryResults {
         QueryResults {
             results: vec![Arc::new(x.into())],
             trace: Trace::None,
+            indexed_block: None,
         }
     }
 }
@@ -191,6 +212,7 @@ impl From<Vec<QueryExecutionError>> for QueryResults {
         QueryResults {
             results: vec![Arc::new(x.into())],
             trace: Trace::None,
+            indexed_block: None,
         }
     }
 }
@@ -205,14 +227,16 @@ impl QueryResults {
     pub fn as_http_response(&self) -> ServerResponse {
         let json = serde_json::to_string(&self).unwrap();
         let attestable = self.results.iter().all(|r| r.is_attestable());
+        let indexed_block = serde_json::to_string(&self.indexed_block).unwrap();
         Response::builder()
             .status(200)
             .header(ACCESS_CONTROL_ALLOW_ORIGIN, "*")
             .header(CONTENT_TYPE, "application/json")
             .header(ACCESS_CONTROL_ALLOW_HEADERS, "Content-Type, User-Agent")
             .header(ACCESS_CONTROL_ALLOW_METHODS, "GET, OPTIONS, POST")
             .header(CONTENT_TYPE, "application/json")
-            .header("Graph-Attestable", attestable.to_string())
+            .header("graph-attestable", attestable.to_string())
+            .header("graph-indexed", indexed_block)
             .body(Full::from(json))
             .unwrap()
     }
@@ -386,8 +410,7 @@ fn multiple_data_items() {
     let obj1 = make_obj("key1", "value1");
     let obj2 = make_obj("key2", "value2");
 
-    let trace = Trace::None;
-    let mut res = QueryResults::empty(trace);
+    let mut res = QueryResults::empty(Trace::None, None);
     res.append(obj1, CacheStatus::default());
     res.append(obj2, CacheStatus::default());
 

graphql/src/runner.rs

@@ -17,7 +17,7 @@ use graph::{
 };
 use graph::{data::graphql::load_manager::LoadManager, prelude::QueryStoreManager};
 use graph::{
-    data::query::{QueryResults, QueryTarget},
+    data::query::{LatestBlockInfo, QueryResults, QueryTarget},
     prelude::QueryStore,
 };
 
@@ -117,6 +117,20 @@ where
         let network = Some(store.network_name().to_string());
         let schema = store.api_schema()?;
 
+        let latest_block = match store.block_ptr().await.ok().flatten() {
+            Some(block) => Some(LatestBlockInfo {
+                timestamp: store
+                    .block_number_with_timestamp_and_parent_hash(&block.hash)
+                    .await
+                    .ok()
+                    .flatten()
+                    .and_then(|(_, t, _)| t),
+                hash: block.hash,
+                number: block.number,
+            }),
+            None => None,
+        };
+
         // Test only, see c435c25decbc4ad7bbbadf8e0ced0ff2
         #[cfg(debug_assertions)]
         let state = INITIAL_DEPLOYMENT_STATE_FOR_TESTS
@@ -148,7 +162,8 @@ where
         let by_block_constraint =
             StoreResolver::locate_blocks(store.as_ref(), &state, &query).await?;
         let mut max_block = 0;
-        let mut result: QueryResults = QueryResults::empty(query.root_trace(do_trace));
+        let mut result: QueryResults =
+            QueryResults::empty(query.root_trace(do_trace), latest_block);
         let mut query_res_futures: Vec<_> = vec![];
         let setup_elapsed = execute_start.elapsed();
 

store/test-store/src/store.rs

@@ -526,7 +526,7 @@ async fn execute_subgraph_query_internal(
         100,
         graphql_metrics(),
     ));
-    let mut result = QueryResults::empty(query.root_trace(trace));
+    let mut result = QueryResults::empty(query.root_trace(trace), None);
     let deployment = query.schema.id().clone();
     let store = STORE
         .clone()