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