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// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef PLATFORM_BASE_TRACE_LOGGING_ACTIVATION_H_
#define PLATFORM_BASE_TRACE_LOGGING_ACTIVATION_H_
namespace openscreen {
class TraceLoggingPlatform;
// Start or Stop trace logging. It is illegal to call StartTracing() a second
// time without having called StopTracing() to stop the prior tracing session.
//
// Note that StopTracing() may block until all threads have returned from any
// in-progress calls into the TraceLoggingPlatform's methods.
void StartTracing(TraceLoggingPlatform* destination);
void StopTracing();
// An immutable, non-copyable and non-movable smart pointer that references the
// current trace logging destination. If tracing was active when this class was
// intantiated, the pointer is valid for the life of the instance, and can be
// used to directly invoke the methods of the TraceLoggingPlatform API. If
// tracing was not active when this class was intantiated, the pointer is null
// for the life of the instance and must not be dereferenced.
//
// An instance should be short-lived, as a platform's call to StopTracing() will
// be blocked until there are no instances remaining.
//
// NOTE: This is generally not used directly, but instead via the
// util/trace_logging macros.
class CurrentTracingDestination {
public:
CurrentTracingDestination();
~CurrentTracingDestination();
explicit operator bool() const noexcept { return !!destination_; }
TraceLoggingPlatform* operator->() const noexcept { return destination_; }
private:
CurrentTracingDestination(const CurrentTracingDestination&) = delete;
CurrentTracingDestination(CurrentTracingDestination&&) = delete;
CurrentTracingDestination& operator=(const CurrentTracingDestination&) =
delete;
CurrentTracingDestination& operator=(CurrentTracingDestination&&) = delete;
// The destination at the time this class was constructed, and is valid for
// the lifetime of this class. This is nullptr if tracing was inactive.
TraceLoggingPlatform* const destination_;
};
} // namespace openscreen
#endif // PLATFORM_BASE_TRACE_LOGGING_ACTIVATION_H_
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