1 files changed, 140 insertions, 0 deletions
diff --git a/src/core/ext/filters/client_channel/lb_policy/xds/client_load_reporting_filter.cc b/src/core/ext/filters/client_channel/lb_policy/xds/client_load_reporting_filter.cc
new file mode 100644
index 0000000000..d79453d008
--- /dev/null
+++ b/src/core/ext/filters/client_channel/lb_policy/xds/client_load_reporting_filter.cc
@@ -0,0 +1,140 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/ext/filters/client_channel/lb_policy/xds/client_load_reporting_filter.h"
+
+#include <grpc/support/atm.h>
+#include <grpc/support/log.h>
+
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h"
+#include "src/core/lib/iomgr/error.h"
+#include "src/core/lib/profiling/timers.h"
+
+static grpc_error* init_channel_elem(grpc_channel_element* elem,
+                                     grpc_channel_element_args* args) {
+  return GRPC_ERROR_NONE;
+}
+
+static void destroy_channel_elem(grpc_channel_element* elem) {}
+
+namespace {
+
+struct call_data {
+  // Stats object to update.
+  grpc_core::RefCountedPtr<grpc_core::XdsLbClientStats> client_stats;
+  // State for intercepting send_initial_metadata.
+  grpc_closure on_complete_for_send;
+  grpc_closure* original_on_complete_for_send;
+  bool send_initial_metadata_succeeded;
+  // State for intercepting recv_initial_metadata.
+  grpc_closure recv_initial_metadata_ready;
+  grpc_closure* original_recv_initial_metadata_ready;
+  bool recv_initial_metadata_succeeded;
+};
+
+}  // namespace
+
+static void on_complete_for_send(void* arg, grpc_error* error) {
+  call_data* calld = static_cast<call_data*>(arg);
+  if (error == GRPC_ERROR_NONE) {
+    calld->send_initial_metadata_succeeded = true;
+  }
+  GRPC_CLOSURE_RUN(calld->original_on_complete_for_send, GRPC_ERROR_REF(error));
+}
+
+static void recv_initial_metadata_ready(void* arg, grpc_error* error) {
+  call_data* calld = static_cast<call_data*>(arg);
+  if (error == GRPC_ERROR_NONE) {
+    calld->recv_initial_metadata_succeeded = true;
+  }
+  GRPC_CLOSURE_RUN(calld->original_recv_initial_metadata_ready,
+                   GRPC_ERROR_REF(error));
+}
+
+static grpc_error* init_call_elem(grpc_call_element* elem,
+                                  const grpc_call_element_args* args) {
+  call_data* calld = static_cast<call_data*>(elem->call_data);
+  // Get stats object from context and take a ref.
+  GPR_ASSERT(args->context != nullptr);
+  if (args->context[GRPC_GRPCLB_CLIENT_STATS].value != nullptr) {
+    calld->client_stats = static_cast<grpc_core::XdsLbClientStats*>(
+                              args->context[GRPC_GRPCLB_CLIENT_STATS].value)
+                              ->Ref();
+    // Record call started.
+    calld->client_stats->AddCallStarted();
+  }
+  return GRPC_ERROR_NONE;
+}
+
+static void destroy_call_elem(grpc_call_element* elem,
+                              const grpc_call_final_info* final_info,
+                              grpc_closure* ignored) {
+  call_data* calld = static_cast<call_data*>(elem->call_data);
+  if (calld->client_stats != nullptr) {
+    // Record call finished, optionally setting client_failed_to_send and
+    // received.
+    calld->client_stats->AddCallFinished(
+        !calld->send_initial_metadata_succeeded /* client_failed_to_send */,
+        calld->recv_initial_metadata_succeeded /* known_received */);
+    // All done, so unref the stats object.
+    // TODO(roth): Eliminate this once filter stack is converted to C++.
+    calld->client_stats.reset();
+  }
+}
+
+static void start_transport_stream_op_batch(
+    grpc_call_element* elem, grpc_transport_stream_op_batch* batch) {
+  call_data* calld = static_cast<call_data*>(elem->call_data);
+  GPR_TIMER_SCOPE("clr_start_transport_stream_op_batch", 0);
+  if (calld->client_stats != nullptr) {
+    // Intercept send_initial_metadata.
+    if (batch->send_initial_metadata) {
+      calld->original_on_complete_for_send = batch->on_complete;
+      GRPC_CLOSURE_INIT(&calld->on_complete_for_send, on_complete_for_send,
+                        calld, grpc_schedule_on_exec_ctx);
+      batch->on_complete = &calld->on_complete_for_send;
+    }
+    // Intercept recv_initial_metadata.
+    if (batch->recv_initial_metadata) {
+      calld->original_recv_initial_metadata_ready =
+          batch->payload->recv_initial_metadata.recv_initial_metadata_ready;
+      GRPC_CLOSURE_INIT(&calld->recv_initial_metadata_ready,
+                        recv_initial_metadata_ready, calld,
+                        grpc_schedule_on_exec_ctx);
+      batch->payload->recv_initial_metadata.recv_initial_metadata_ready =
+          &calld->recv_initial_metadata_ready;
+    }
+  }
+  // Chain to next filter.
+  grpc_call_next_op(elem, batch);
+}
+
+const grpc_channel_filter xds_client_load_reporting_filter = {
+    start_transport_stream_op_batch,
+    grpc_channel_next_op,
+    sizeof(call_data),
+    init_call_elem,
+    grpc_call_stack_ignore_set_pollset_or_pollset_set,
+    destroy_call_elem,
+    0,  // sizeof(channel_data)
+    init_channel_elem,
+    destroy_channel_elem,
+    grpc_channel_next_get_info,
+    "client_load_reporting"};