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// Copyright 2016 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 BASE_TRACE_EVENT_TRACE_EVENT_FILTER_H_
#define BASE_TRACE_EVENT_TRACE_EVENT_FILTER_H_
#include <memory>
#include "base/base_export.h"
#include "base/macros.h"
namespace base {
namespace trace_event {
class TraceEvent;
// TraceEventFilter is like iptables for TRACE_EVENT macros. Filters can be
// enabled on a per-category basis, hence a single filter instance can serve
// more than a TraceCategory. There are two use cases for filters:
// 1. Snooping TRACE_EVENT macros without adding them to the TraceLog. This is
// possible by setting the ENABLED_FOR_FILTERING flag on a category w/o
// ENABLED_FOR_RECORDING (see TraceConfig for user-facing configuration).
// 2. Filtering TRACE_EVENT macros before they are added to the TraceLog. This
// requires both the ENABLED_FOR_FILTERING and ENABLED_FOR_RECORDING flags
// on the category.
// More importantly, filters must be thread-safe. The FilterTraceEvent and
// EndEvent methods can be called concurrently as trace macros are hit on
// different threads.
class BASE_EXPORT TraceEventFilter {
public:
TraceEventFilter();
virtual ~TraceEventFilter();
// If the category is ENABLED_FOR_RECORDING, the event is added iff all the
// filters enabled for the category return true. false causes the event to be
// discarded.
virtual bool FilterTraceEvent(const TraceEvent& trace_event) const = 0;
// Notifies the end of a duration event when the RAII macro goes out of scope.
virtual void EndEvent(const char* category_name,
const char* event_name) const;
private:
DISALLOW_COPY_AND_ASSIGN(TraceEventFilter);
};
} // namespace trace_event
} // namespace base
#endif // BASE_TRACE_EVENT_TRACE_EVENT_FILTER_H_