src/traced/probes/ftrace/ftrace_data_source.h

/*
 * Copyright (C) 2018 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_TRACED_PROBES_FTRACE_FTRACE_DATA_SOURCE_H_
#define SRC_TRACED_PROBES_FTRACE_FTRACE_DATA_SOURCE_H_

#include <functional>
#include <map>
#include <memory>
#include <set>
#include <string>
#include <utility>

#include "perfetto/ext/base/scoped_file.h"
#include "perfetto/ext/base/weak_ptr.h"
#include "perfetto/ext/tracing/core/basic_types.h"
#include "perfetto/ext/tracing/core/trace_writer.h"
#include "perfetto/protozero/message_handle.h"
#include "src/traced/probes/ftrace/ftrace_config_utils.h"
#include "src/traced/probes/ftrace/ftrace_metadata.h"
#include "src/traced/probes/ftrace/ftrace_stats.h"
#include "src/traced/probes/probes_data_source.h"

namespace perfetto {

class EventFilter;
class FtraceController;
class ProcessStatsDataSource;
class InodeFileDataSource;

namespace protos {
namespace pbzero {
class FtraceEventBundle;
}  // namespace pbzero
}  // namespace protos

// This class handles the state for one particular tracing session involving
// ftrace. There can be several concurrent tracing sessions involving ftrace
// and this class is essentially the building block used to multiplex them.
// This class is instantiated by ProbesProducer. ProbesProducer also owns the
// FtraceController.
class FtraceDataSource : public ProbesDataSource {
 public:
  static constexpr int kTypeId = 1;
  FtraceDataSource(base::WeakPtr<FtraceController>,
                   TracingSessionID,
                   const FtraceConfig&,
                   std::unique_ptr<TraceWriter>);
  ~FtraceDataSource() override;

  // Called by FtraceController soon after ProbesProducer creates the data
  // source, to inject ftrace dependencies.
  void Initialize(FtraceConfigId, const EventFilter* event_filter);

  // ProbesDataSource implementation.
  void Start() override;

  // Flushes the ftrace buffers into the userspace trace buffers and writes
  // also ftrace stats.
  void Flush(FlushRequestID, std::function<void()> callback) override;
  void OnFtraceFlushComplete(FlushRequestID);

  FtraceConfigId config_id() const { return config_id_; }
  const FtraceConfig& config() const { return config_; }
  const EventFilter* event_filter() { return event_filter_; }
  FtraceMetadata* mutable_metadata() { return &metadata_; }
  TraceWriter* trace_writer() { return writer_.get(); }

 private:
  FtraceDataSource(const FtraceDataSource&) = delete;
  FtraceDataSource& operator=(const FtraceDataSource&) = delete;

  void WriteStats();
  void DumpFtraceStats(FtraceStats*);

  const FtraceConfig config_;
  FtraceMetadata metadata_;
  FtraceStats stats_before_ = {};
  std::map<FlushRequestID, std::function<void()>> pending_flushes_;

  // Initialized by the Initialize() call.
  FtraceConfigId config_id_ = 0;
  std::unique_ptr<TraceWriter> writer_;
  base::WeakPtr<FtraceController> controller_weak_;
  const EventFilter* event_filter_;
};

}  // namespace perfetto

#endif  // SRC_TRACED_PROBES_FTRACE_FTRACE_DATA_SOURCE_H_