77 lines
3.1 KiB
C++
77 lines
3.1 KiB
C++
// Copyright 2014 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 BASE_PROFILER_SCOPED_TRACKER_H_
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#define BASE_PROFILER_SCOPED_TRACKER_H_
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//------------------------------------------------------------------------------
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// Utilities for temporarily instrumenting code to dig into issues that were
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// found using profiler data.
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#include "base/base_export.h"
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#include "base/bind.h"
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#include "base/callback_forward.h"
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#include "base/location.h"
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#include "base/macros.h"
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#include "base/profiler/scoped_profile.h"
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namespace tracked_objects {
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// ScopedTracker instruments a region within the code if the instrumentation is
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// enabled. It can be used, for example, to find out if a source of jankiness is
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// inside the instrumented code region.
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// Details:
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// 1. This class creates a task (like ones created by PostTask calls or IPC
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// message handlers). This task can be seen in chrome://profiler and is sent as
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// a part of profiler data to the UMA server. See profiler_event.proto.
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// 2. That task's lifetime is same as the lifetime of the ScopedTracker
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// instance.
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// 3. The execution time associated with the task is the wallclock time between
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// its constructor and destructor, minus wallclock times of directly nested
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// tasks.
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// 4. Task creation that this class utilizes is highly optimized.
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// 5. The class doesn't create a task unless this was enabled for the current
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// process. Search for ScopedTracker::Enable for the current list of processes
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// and channels where it's activated.
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// 6. The class is designed for temporarily instrumenting code to find
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// performance problems, after which the instrumentation must be removed.
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class BASE_EXPORT ScopedTracker {
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public:
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ScopedTracker(const Location& location);
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// Enables instrumentation for the remainder of the current process' life. If
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// this function is not called, all profiler instrumentations are no-ops.
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static void Enable();
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// Augments a |callback| with provided |location|. This is useful for
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// instrumenting cases when we know that a jank is in a callback and there are
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// many possible callbacks, but they come from a relatively small number of
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// places. We can instrument these few places and at least know which one
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// passes the janky callback.
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template <typename P1>
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static base::Callback<void(P1)> TrackCallback(
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const Location& location,
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const base::Callback<void(P1)>& callback) {
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return base::Bind(&ScopedTracker::ExecuteAndTrackCallback<P1>, location,
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callback);
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}
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private:
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// Executes |callback|, augmenting it with provided |location|.
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template <typename P1>
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static void ExecuteAndTrackCallback(const Location& location,
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const base::Callback<void(P1)>& callback,
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P1 p1) {
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ScopedTracker tracking_profile(location);
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callback.Run(p1);
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}
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const ScopedProfile scoped_profile_;
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DISALLOW_COPY_AND_ASSIGN(ScopedTracker);
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};
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} // namespace tracked_objects
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#endif // BASE_PROFILER_SCOPED_TRACKER_H_
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