Add an index to thread pipeline iterators for load balancing

src/http_handler.cpp

@@ -51,6 +51,22 @@ void HttpHandler::on_write_progress(std::unique_ptr<Connection> &conn_ptr) {
   }
 }
 
+void HttpHandler::on_post_batch(std::span<std::unique_ptr<Connection>> batch) {
+  int readyCount = 0;
+  for (int i = 0; i < int(batch.size()); ++i) {
+    readyCount += batch[i] && batch[i]->outgoingBytesQueued() > 0;
+  }
+  if (readyCount > 0) {
+    auto guard = pipeline.push(readyCount, /*block=*/true);
+    auto outIter = guard.batch.begin();
+    for (int i = 0; i < int(batch.size()); ++i) {
+      if (batch[i] && batch[i]->outgoingBytesQueued() > 0) {
+        *outIter++ = std::move(batch[i]);
+      }
+    }
+  }
+}
+
 void HttpHandler::on_data_arrived(std::string_view data,
                                   std::unique_ptr<Connection> &conn_ptr) {
   auto *state = static_cast<HttpConnectionState *>(conn_ptr->user_data);
@@ -112,13 +128,6 @@ void HttpHandler::on_data_arrived(std::string_view data,
       handleNotFound(*conn_ptr, *state);
       break;
     }
-
-    {
-      auto guard = ok_pipeline.push(1, true);
-      for (auto &c : guard.batch) {
-        c = std::move(conn_ptr);
-      }
-    }
   }
 }