pw_log_rpc: Add RPC command for logs
Adds Logs.Get RPC to acquire the logs from log queue.
Change-Id: I5a3d93604906f4dd0471e50964fe36a61c66797c
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/21960
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
Pigweed-Auto-Submit: Prashanth Swaminathan <prashanthsw@google.com>
Reviewed-by: Keir Mierle <keir@google.com>
diff --git a/pw_log_rpc/logs_rpc.cc b/pw_log_rpc/logs_rpc.cc
new file mode 100644
index 0000000..ada5470
--- /dev/null
+++ b/pw_log_rpc/logs_rpc.cc
@@ -0,0 +1,75 @@
+// Copyright 2020 The Pigweed 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
+//
+// https://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 "pw_log_rpc/logs_rpc.h"
+
+#include "pw_log/log.h"
+#include "pw_log_proto/log.pwpb.h"
+#include "pw_status/try.h"
+
+namespace pw::log_rpc {
+namespace {
+
+Result<ConstByteSpan> GenerateDroppedEntryMessage(ByteSpan encode_buffer,
+ size_t dropped_entries) {
+ pw::protobuf::NestedEncoder nested_encoder(encode_buffer);
+ pw::log::LogEntry::Encoder encoder(&nested_encoder);
+ encoder.WriteDropped(dropped_entries);
+ return nested_encoder.Encode();
+}
+
+} // namespace
+
+void Logs::Get(ServerContext&, ConstByteSpan, rpc::RawServerWriter& writer) {
+ response_writer_ = std::move(writer);
+}
+
+Status Logs::Flush() {
+ // If the response writer was not initialized or has since been closed,
+ // ignore the flush operation.
+ if (!response_writer_.open()) {
+ return Status::Ok();
+ }
+
+ // If previous calls to flush resulted in dropped entries, generate a
+ // dropped entry message and write it before further log messages.
+ if (dropped_entries_ > 0) {
+ ByteSpan payload = response_writer_.PayloadBuffer();
+ Result dropped_log = GenerateDroppedEntryMessage(payload, dropped_entries_);
+ PW_TRY(dropped_log.status());
+ PW_TRY(response_writer_.Write(dropped_log.value()));
+ dropped_entries_ = 0;
+ }
+
+ // Write logs to the response writer. An important limitation of this
+ // implementation is that if this RPC call fails, the logs are lost -
+ // a subsequent call to the RPC will produce a drop count message.
+ ByteSpan payload = response_writer_.PayloadBuffer();
+ Result possible_logs = log_queue_.PopMultiple(payload);
+ PW_TRY(possible_logs.status());
+ if (possible_logs.value().entry_count == 0) {
+ return Status::Ok();
+ }
+
+ Status status = response_writer_.Write(possible_logs.value().entries);
+ if (!status.ok()) {
+ // On a failure to send logs, track the dropped entries.
+ dropped_entries_ = possible_logs.value().entry_count;
+ return status;
+ }
+
+ return Status::Ok();
+}
+
+} // namespace pw::log_rpc