chromium/third_party/perfetto/src/trace_processor/tp_metatrace.h

/*
 * Copyright (C) 2020 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.
 */

#ifndef SRC_TRACE_PROCESSOR_TP_METATRACE_H_
#define SRC_TRACE_PROCESSOR_TP_METATRACE_H_

#include <array>
#include <functional>
#include <vector>

#include "perfetto/base/time.h"
#include "perfetto/ext/base/metatrace_events.h"
#include "perfetto/ext/base/string_view.h"
#include "perfetto/ext/base/thread_checker.h"
#include "perfetto/trace_processor/metatrace_config.h"
#include "protos/perfetto/trace_processor/metatrace_categories.pbzero.h"

// Trace processor maintains its own base implementation to avoid the
// threading and task runners which are required by base's metatracing.
// Moreover, this metatrace also adds support for args which is missing
// from base's metatracing.
// On the other hand, this implementation is not (currently) thread-safe
// and is likely less performant than base's implementation.
namespace perfetto {
namespace trace_processor {
namespace metatrace {

Category;

// Stores whether meta-tracing is enabled.
extern Category g_enabled_categories;

inline uint64_t TraceTimeNowNs() { … }

struct Record { … };

// Implementation of fixed-size ring buffer. The implementation of this
// class is modelled on the RingBuffer in metatrace.h of base but is different
// in a couple of ways:
//  1. This class is *not* thread safe.
//  2. The Record type stored in this class has the capability of storing
//     extra, event-specific context. For example, when tracing SQL query
//     execution, we store the query string.
//  3. The buffer is designed to be written continuously while meta-tracing
//     is enabled and read one-shot at the end of execution.
class RingBuffer { … };

class ScopedEvent { … };

// Enables meta-tracing of trace-processor.
void Enable(MetatraceConfig config = {});

// Disables meta-tracing of trace-processor and reads all records.
void DisableAndReadBuffer(std::function<void(Record*)>);

// Boilerplate to derive a unique variable name for the event.
#define PERFETTO_TP_METATRACE_UID2(a, b) …
#define PERFETTO_TP_METATRACE_UID(x) …

#define PERFETTO_TP_TRACE(...) …

}  // namespace metatrace
}  // namespace trace_processor
}  // namespace perfetto

#endif  // SRC_TRACE_PROCESSOR_TP_METATRACE_H_