data_source.h | Explore in Territory

/*
 * 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 INCLUDE_PERFETTO_TRACING_DATA_SOURCE_H_
#define INCLUDE_PERFETTO_TRACING_DATA_SOURCE_H_

// This header contains the key class (DataSource) that a producer app should
// override in order to create a custom data source that gets tracing Start/Stop
// notifications and emits tracing data.

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

#include <array>
#include <atomic>
#include <functional>
#include <memory>
#include <mutex>

#include "perfetto/protozero/message_handle.h"
#include "perfetto/tracing/buffer_exhausted_policy.h"
#include "perfetto/tracing/core/flush_flags.h"
#include "perfetto/tracing/core/forward_decls.h"
#include "perfetto/tracing/internal/basic_types.h"
#include "perfetto/tracing/internal/data_source_internal.h"
#include "perfetto/tracing/internal/data_source_type.h"
#include "perfetto/tracing/internal/tracing_muxer.h"
#include "perfetto/tracing/locked_handle.h"
#include "perfetto/tracing/trace_writer_base.h"

#include "protos/perfetto/trace/trace_packet.pbzero.h"

// DEPRECATED: Instead of using this macro, prefer specifying symbol linkage
// attributes explicitly using the `_WITH_ATTRS` macro variants (e.g.,
// PERFETTO_DECLARE_DATA_SOURCE_STATIC_MEMBERS_WITH_ATTRS). This avoids
// potential macro definition collisions between two libraries using Perfetto.
//
// PERFETTO_COMPONENT_EXPORT is used to mark symbols in Perfetto's headers
// (typically templates) that are defined by the user outside of Perfetto and
// should be made visible outside the current module. (e.g., in Chrome's
// component build).
#if !defined(PERFETTO_COMPONENT_EXPORT)
#if PERFETTO_BUILDFLAG(PERFETTO_COMPILER_MSVC)
// Workaround for C4003: not enough arguments for function-like macro invocation
// 'PERFETTO_INTERNAL_DECLARE_TRACK_EVENT_DATA_SOURCE'
#define PERFETTO_COMPONENT_EXPORT …
#else
#define PERFETTO_COMPONENT_EXPORT
#endif
#endif

namespace perfetto {
namespace internal {
class TracingMuxerImpl;
class TrackEventCategoryRegistry;
template <typename, const internal::TrackEventCategoryRegistry*>
class TrackEventDataSource;
}  // namespace internal

namespace shlib {
class TrackEvent;
}  // namespace shlib

namespace test {
class DataSourceInternalForTest;
}  // namespace test

// Base class with the virtual methods to get start/stop notifications.
// Embedders are supposed to derive the templated version below, not this one.
class PERFETTO_EXPORT_COMPONENT DataSourceBase { … };

struct DefaultDataSourceTraits { … };

// Holds the type for a DataSource. Accessed by the static Trace() method
// fastpaths. This allows redefinitions under a component where a component
// specific export macro is used.
// Due to C2086 (redefinition) error on MSVC/clang-cl, internal::DataSourceType
// can't be a static data member. To avoid explicit specialization after
// instantiation error, type() needs to be in a template helper class that's
// instantiated independently from DataSource. See b/280777748.
template <typename DerivedDataSource,
          typename DataSourceTraits = DefaultDataSourceTraits>
struct DataSourceHelper { … };

// Templated base class meant to be derived by embedders to create a custom data
// source. DerivedDataSource must be the type of the derived class itself, e.g.:
// class MyDataSource : public DataSource<MyDataSource> {...}.
//
// |DataSourceTraits| allows customizing the behavior of the data source. See
// |DefaultDataSourceTraits|.
template <typename DerivedDataSource,
          typename DataSourceTraits = DefaultDataSourceTraits>
class DataSource : public DataSourceBase { … };

// static
template <typename T, typename D>
thread_local internal::DataSourceThreadLocalState* DataSource<T, D>::tls_state_;

}  // namespace perfetto

// If placed at the end of a macro declaration, eats the semicolon at the end of
// the macro invocation (e.g., "MACRO(...);") to avoid warnings about extra
// semicolons.
#define PERFETTO_INTERNAL_SWALLOW_SEMICOLON() …

// This macro must be used once for each data source next to the data source's
// declaration.
#define PERFETTO_DECLARE_DATA_SOURCE_STATIC_MEMBERS(...) …

// Similar to `PERFETTO_DECLARE_DATA_SOURCE_STATIC_MEMBERS` but it also takes
// custom attributes, which are useful when DataSource is defined in a component
// where a component specific export macro is used.
#define PERFETTO_DECLARE_DATA_SOURCE_STATIC_MEMBERS_WITH_ATTRS(attrs, ...) …

// This macro must be used once for each data source in one source file to
// allocate static storage for the data source's static state.
#define PERFETTO_DEFINE_DATA_SOURCE_STATIC_MEMBERS(...) …

// Similar to `PERFETTO_DEFINE_DATA_SOURCE_STATIC_MEMBERS` but it also takes
// custom attributes, which are useful when DataSource is defined in a component
// where a component specific export macro is used.
#define PERFETTO_DEFINE_DATA_SOURCE_STATIC_MEMBERS_WITH_ATTRS(attrs, ...) …

#endif  // INCLUDE_PERFETTO_TRACING_DATA_SOURCE_H_
chromium/third_party/perfetto/include/perfetto/tracing/data_source.h
