Improve existing InputDispatcher traces
Previously, we traced using ATRACE_NAME inside an
if condition after checking if atrace was enabled. This was so that we
could avoid the addtional overhead of formatting the trace string when
there's no ongoing trace.
Since ATRACE_NAME is expected to be scoped trace of the call, doing it
inside an if condition means the scope of the trace ends immediately
once we leave the inner scope of the conditional. This essentially makes
all of our scoped traces point traces.
We get around this by adding a new helper macro ATRACE_NAME_IF that
takes a lambda that formats the message. This way, we can avoid the
formatting overhead and ensure the entire scope of the method is traced.
Bug: 210460522
Test: manual: take a trace with Perfetto
Change-Id: Ibee1e7dc5021296bdb5871dec59d8d4978fcf0c9
diff --git a/include/input/TraceTools.h b/include/input/TraceTools.h
new file mode 100644
index 0000000..70b23c5
--- /dev/null
+++ b/include/input/TraceTools.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include <utils/Trace.h>
+#include <optional>
+
+#define ATRACE_NAME_IF(condition, messageProvider) \
+ const auto _trace_token = condition \
+ ? std::make_optional<android::ScopedTrace>(ATRACE_TAG, messageProvider().c_str()) \
+ : std::nullopt