get heap statistics from deno (#558)

This adds a planner event to request V8 heap statistics.

This data is gathered from the JS side because the related methods from
the rust side require a `&mut` access to the runtime, which is
impossible since it already runs in an infinite loop.
Since we elected to not run the prelude parts of deno which register
functions like `Deno.memory_usage`, we intern the
[op_runtime_memory_usage
function](https://github.com/denoland/deno/blob/897159dc6e1b2319cf2f5f09d8d6cecc0d3175fa/runtime/ops/os/mod.rs#L329)
and import it directly as a host function, as we've done already with
`op_crypto_get_random_values`. To avoid hosting too much code, the `rss`
field is not filled (it needs platform specific functions), since that
info can generally be obtained by other means.

router-bridge/js-src/plan_worker.ts

@@ -15,6 +15,10 @@ declare namespace Deno {
   }
 }
 
+function memoryUsage(): MemoryUsage {
+  return Deno.core.ops.op_runtime_memory_usage();
+}
+
 let logFunction: (message: string) => void;
 declare let logger: {
   trace: typeof logFunction;
@@ -24,6 +28,16 @@ declare let logger: {
   error: typeof logFunction;
 };
 
+export interface MemoryUsage {
+  /** The total size of the heap for V8, in bytes. */
+  heapTotal: number;
+  /** The amount of the heap used for V8, in bytes. */
+  heapUsed: number;
+  /** Memory, in bytes, associated with JavaScript objects outside of the
+   * JavaScript isolate. */
+  external: number;
+}
+
 enum PlannerEventKind {
   UpdateSchema = "UpdateSchema",
   Plan = "Plan",
@@ -32,6 +46,7 @@ enum PlannerEventKind {
   Introspect = "Introspect",
   Signature = "Signature",
   Subgraphs = "Subgraphs",
+  GetHeapStatistics = "GetHeapStatistics",
 }
 
 interface UpdateSchemaEvent {
@@ -75,13 +90,19 @@ interface Exit {
   kind: PlannerEventKind.Exit;
   schemaId: number;
 }
+
+interface GetHeapStatisticsEvent {
+  kind: PlannerEventKind.GetHeapStatistics;
+}
+
 type PlannerEvent =
   | UpdateSchemaEvent
   | PlanEvent
   | ApiSchemaEvent
   | IntrospectEvent
   | SignatureEvent
   | SubgraphsEvent
+  | GetHeapStatisticsEvent
   | Exit;
 type PlannerEventWithId = {
   id: string;
@@ -92,19 +113,26 @@ type WorkerResultWithId = {
   id?: string;
   payload: WorkerResult;
 };
+
 type WorkerResult =
   | PlanResult
   | ApiSchemaResult
   | ExecutionResult
   | Map<string, string>
-  | String;
+  | String
+  | MemoryUsageResult;
 // Plan result
 type PlanResult =
   | ExecutionResultWithUsageReporting<QueryPlanResult>
   | FatalError;
 type ApiSchemaResult = {
   schema: string;
 };
+type MemoryUsageResult = {
+  heapTotal: number;
+  heapUsed: number;
+  external: number;
+};
 
 type FatalError = {
   errors: (JsError | WorkerGraphQLError)[];
@@ -252,6 +280,7 @@ async function run() {
     try {
       const { id, payload: event } = await receive();
       messageId = id;
+
       try {
         switch (event?.kind) {
           case PlannerEventKind.UpdateSchema:
@@ -290,6 +319,17 @@ async function run() {
 
             await send({ id, payload: subgraphs });
             break;
+          case PlannerEventKind.GetHeapStatistics:
+            const mem = memoryUsage();
+
+            const result: MemoryUsageResult = {
+              heapTotal: mem.heapTotal,
+              heapUsed: mem.heapUsed,
+              external: mem.external,
+            };
+
+            await send({ id, payload: result });
+            break;
           case PlannerEventKind.Exit:
             planners.delete(event.schemaId);
             if (planners.size == 0) {

router-bridge/src/planner.rs

@@ -398,6 +398,18 @@ where
     }
 }
 
+#[derive(Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+/// deno's heap statistics
+pub struct HeapStatistics {
+    /// total size of the heap for V8, in bytes
+    pub heap_total: u64,
+    /// amount of the heap used for V8, in bytes
+    pub heap_used: u64,
+    /// emory, in bytes, associated with JavaScript objects outside of the JavaScript isolate
+    pub external: u64,
+}
+
 /// A Deno worker backed query Planner.
 
 pub struct Planner<T>
@@ -586,6 +598,11 @@ where
             })
             .await
     }
+
+    /// Get deno's heap statistics
+    pub async fn get_heap_statistics(&self) -> Result<HeapStatistics, crate::error::Error> {
+        self.worker.request(PlanCmd::GetHeapStatistics).await
+    }
 }
 
 impl<T> Drop for Planner<T>
@@ -647,7 +664,10 @@ enum PlanCmd {
     Subgraphs { schema_id: u64 },
     #[serde(rename_all = "camelCase")]
     Exit { schema_id: u64 },
+    #[serde(rename_all = "camelCase")]
+    GetHeapStatistics,
 }
+
 #[derive(Serialize, Debug, Clone, PartialEq, Eq, Hash)]
 #[serde(rename_all = "camelCase")]
 /// Query planner configuration
@@ -767,8 +787,8 @@ pub struct QueryPlannerDebugConfig {
 }
 #[cfg(test)]
 mod tests {
+    use futures::stream;
     use futures::stream::StreamExt;
-    use futures::stream::{self};
 
     use std::collections::BTreeMap;
 
@@ -1871,6 +1891,19 @@ ofType {
             insta::assert_snapshot!(schema);
         }
     }
+
+    #[tokio::test]
+    async fn heap_statistics() {
+        let planner =
+            Planner::<serde_json::Value>::new(SCHEMA.to_string(), QueryPlannerConfig::default())
+                .await
+                .unwrap();
+
+        let _subgraphs = planner.subgraphs().await.unwrap();
+        let statistics = planner.get_heap_statistics().await.unwrap();
+
+        println!("statistics: {statistics:?}");
+    }
 }
 
 #[cfg(test)]

router-bridge/src/worker.rs

@@ -1,7 +1,7 @@
 use crate::error::Error;
 use async_channel::{bounded, Receiver, Sender};
-use deno_core::Op;
 use deno_core::{op, Extension, OpState};
+use deno_core::{v8, Op};
 use rand::rngs::StdRng;
 use rand::{thread_rng, Rng};
 use serde::de::DeserializeOwned;
@@ -79,6 +79,7 @@ impl JsWorker {
                     log_warn::DECL,
                     log_error::DECL,
                     op_crypto_get_random_values::DECL,
+                    op_runtime_memory_usage::DECL,
                 ]),
                 op_state_fn: Some(Box::new(move |state| {
                     state.put(response_sender.clone());
@@ -302,6 +303,30 @@ fn op_crypto_get_random_values(state: &mut OpState, out: &mut [u8]) -> Result<()
     Ok(())
 }
 
+// HeapStats stores values from a isolate.get_heap_statistics() call
+#[derive(Serialize)]
+#[serde(rename_all = "camelCase")]
+struct MemoryUsage {
+    //rss: usize,
+    heap_total: usize,
+    heap_used: usize,
+    external: usize,
+}
+
+// from https://github.com/denoland/deno/blob/897159dc6e1b2319cf2f5f09d8d6cecc0d3175fa/runtime/ops/os/mod.rs#L329
+// tested in planner.rs
+#[op(v8)]
+fn op_runtime_memory_usage(scope: &mut v8::HandleScope<'_>) -> MemoryUsage {
+    let mut s = v8::HeapStatistics::default();
+    scope.get_heap_statistics(&mut s);
+    MemoryUsage {
+        //rss: rss(),
+        heap_total: s.total_heap_size(),
+        heap_used: s.used_heap_size(),
+        external: s.external_memory(),
+    }
+}
+
 #[cfg(test)]
 mod worker_tests {
     use super::JsWorker;