chromium/third_party/perfetto/src/tracing/internal/tracing_muxer_impl.h

/*
 * Copyright (C) 2019 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_TRACING_INTERNAL_TRACING_MUXER_IMPL_H_
#define SRC_TRACING_INTERNAL_TRACING_MUXER_IMPL_H_

#include <stddef.h>
#include <stdint.h>

#include <array>
#include <atomic>
#include <bitset>
#include <functional>
#include <list>
#include <map>
#include <memory>
#include <set>
#include <utility>
#include <vector>

#include "perfetto/base/time.h"
#include "perfetto/ext/base/scoped_file.h"
#include "perfetto/ext/base/thread_checker.h"
#include "perfetto/ext/tracing/core/basic_types.h"
#include "perfetto/ext/tracing/core/consumer.h"
#include "perfetto/ext/tracing/core/producer.h"
#include "perfetto/tracing/backend_type.h"
#include "perfetto/tracing/core/data_source_descriptor.h"
#include "perfetto/tracing/core/forward_decls.h"
#include "perfetto/tracing/core/trace_config.h"
#include "perfetto/tracing/internal/basic_types.h"
#include "perfetto/tracing/internal/tracing_muxer.h"
#include "perfetto/tracing/tracing.h"

#include "protos/perfetto/common/interceptor_descriptor.gen.h"

namespace perfetto {

class ConsumerEndpoint;
class DataSourceBase;
class ProducerEndpoint;
class TraceWriterBase;
class TracingBackend;
class TracingSession;
struct TracingInitArgs;

namespace base {
class TaskRunner;
}

namespace shlib {
void ResetForTesting();
}

namespace test {
class TracingMuxerImplInternalsForTest;
}

namespace internal {

struct DataSourceStaticState;

// This class acts as a bridge between the public API and the TracingBackend(s).
// It exposes a simplified view of the world to the API methods handling all the
// bookkeeping to map data source instances and trace writers to the various
// backends. It deals with N data sources, M backends (1 backend == 1 tracing
// service == 1 producer connection) and T concurrent tracing sessions.
//
// Handing data source registration and start/stop flows [producer side]:
// ----------------------------------------------------------------------
// 1. The API client subclasses perfetto::DataSource and calls
//    DataSource::Register<MyDataSource>(). In turn this calls into the
//    TracingMuxer.
// 2. The tracing muxer iterates through all the backends (1 backend == 1
//    service == 1 producer connection) and registers the data source on each
//    backend.
// 3. When any (services behind a) backend starts tracing and requests to start
//    that specific data source, the TracingMuxerImpl constructs a new instance
//    of MyDataSource and calls the OnStart() method.
//
// Controlling trace and retrieving trace data [consumer side]:
// ------------------------------------------------------------
// 1. The API client calls Tracing::NewTrace(), returns a RAII TracingSession
//    object.
// 2. NewTrace() calls into internal::TracingMuxer(Impl). TracingMuxer
//    subclasses the TracingSession object (TracingSessionImpl) and returns it.
// 3. The tracing muxer identifies the backend (according to the args passed to
//    NewTrace), creates a new Consumer and connects to it.
// 4. When the API client calls Start()/Stop()/ReadTrace() methods, the
//    TracingMuxer forwards them to the consumer associated to the
//    TracingSession. Likewise for callbacks coming from the consumer-side of
//    the service.
class TracingMuxerImpl : public TracingMuxer { … };

}  // namespace internal
}  // namespace perfetto

#endif  // SRC_TRACING_INTERNAL_TRACING_MUXER_IMPL_H_