Implement heap snapshot memorytracker for http types

src/workerd/api/http.h

@@ -163,6 +163,12 @@ class Headers: public jsg::Object {
     });
   }
 
+  void visitForMemoryInfo(jsg::MemoryTracker& tracker) const {
+    for (const auto& entry : headers) {
+      tracker.trackField(entry.first, entry.second);
+    }
+  }
+
 private:
   struct Header {
     jsg::ByteString key;   // lower-cased name
@@ -187,6 +193,14 @@ class Headers: public jsg::Object {
         : key(kj::mv(key)), name(kj::mv(name)), values(1) {
       values.add(kj::mv(value));
     }
+
+    JSG_MEMORY_INFO(Header) {
+      tracker.trackField("key", key);
+      tracker.trackField("name", name);
+      for (const auto& value : values) {
+        tracker.trackField(nullptr, value);
+      }
+    }
   };
 
   Guard guard;
@@ -238,6 +252,9 @@ class Body: public jsg::Object {
   struct RefcountedBytes final: public kj::Refcounted {
     kj::Array<kj::byte> bytes;
     RefcountedBytes(kj::Array<kj::byte>&& bytes): bytes(kj::mv(bytes)) {}
+    JSG_MEMORY_INFO(RefcountedBytes) {
+      tracker.trackFieldWithSize("bytes", bytes.size());
+    }
   };
 
   // The Fetch spec calls this type the body's "source", even though it really is a buffer. I end
@@ -278,11 +295,26 @@ class Body: public jsg::Object {
           view(ownBytes.get<jsg::Ref<Blob>>()->getData()) {}
 
     Buffer clone(jsg::Lock& js);
+
+    JSG_MEMORY_INFO(Buffer) {
+      KJ_SWITCH_ONEOF(ownBytes) {
+        KJ_CASE_ONEOF(bytes, kj::Own<RefcountedBytes>) {
+          tracker.trackField("bytes", bytes);
+        }
+        KJ_CASE_ONEOF(blob, jsg::Ref<Blob>) {
+          tracker.trackField("blob", blob);
+        }
+      }
+    }
   };
 
   struct Impl {
     jsg::Ref<ReadableStream> stream;
     kj::Maybe<Buffer> buffer;
+    JSG_MEMORY_INFO(Impl) {
+      tracker.trackField("stream", stream);
+      tracker.trackField("buffer", buffer);
+    }
   };
 
   struct ExtractedBody {
@@ -346,6 +378,10 @@ class Body: public jsg::Object {
     // Allow JSON body type to be specified
   }
 
+  void visitForMemoryInfo(jsg::MemoryTracker& tracker) const {
+    tracker.trackField("impl", impl);
+  }
+
 protected:
   // Helper to implement Request/Response::clone().
   kj::Maybe<ExtractedBody> clone(jsg::Lock& js);
@@ -843,6 +879,15 @@ class Request: public Body {
     }
   }
 
+  void visitForMemoryInfo(jsg::MemoryTracker& tracker) const {
+    tracker.trackField("url", url);
+    tracker.trackField("headers", headers);
+    tracker.trackField("fetcher", fetcher);
+    tracker.trackField("signal", signal);
+    tracker.trackField("thisSignal", thisSignal);
+    tracker.trackField("cf", cf);
+  }
+
 private:
   kj::HttpMethod method;
   kj::String url;
@@ -1020,6 +1065,17 @@ class Response: public Body {
     // Use `BodyInit` and `ResponseInit` type aliases in constructor instead of inlining
   }
 
+  void visitForMemoryInfo(jsg::MemoryTracker& tracker) const {
+    tracker.trackField("statusText", statusText);
+    tracker.trackField("headers", headers);
+    tracker.trackField("webSocket", webSocket);
+    tracker.trackField("cf", cf);
+    for (const auto& url : urlList) {
+      tracker.trackField("urlList", url);
+    }
+    tracker.trackField("asyncContext", asyncContext);
+  }
+
 private:
   int statusCode;
   kj::String statusText;
@@ -1083,6 +1139,13 @@ class FetchEvent: public ExtendableEvent {
     JSG_METHOD(passThroughOnException);
   }
 
+  void visitForMemoryInfo(jsg::MemoryTracker& tracker) const {
+    tracker.trackField("request", request);
+    KJ_IF_SOME(respondWithCalled, state.tryGet<RespondWithCalled>()) {
+      tracker.trackField("promise", respondWithCalled.promise);
+    }
+  }
+
 private:
   jsg::Ref<Request> request;
 
@@ -1096,6 +1159,9 @@ class FetchEvent: public ExtendableEvent {
 
   void visitForGc(jsg::GcVisitor& visitor) {
     visitor.visit(request);
+    KJ_IF_SOME(respondWithCalled, state.tryGet<RespondWithCalled>()) {
+      visitor.visit(respondWithCalled.promise);
+    }
   }
 };