forked from mirrors/gecko-dev
9c0f970552
- Fixes a data race where the member variable is being written to by EnsurePerformanceCounter on the worker thread while being read on a separate thread (via Worker.postMessage). - Apply some pointer guildelines to the member variable getters. - Constify some things that should be const. Differential Revision: https://phabricator.services.mozilla.com/D82475
139 lines
4.3 KiB
C++
139 lines
4.3 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_PerformanceCounter_h
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#define mozilla_PerformanceCounter_h
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#include "mozilla/Array.h"
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#include "mozilla/Atomics.h"
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#include "mozilla/TaskCategory.h"
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#include "nsISupportsImpl.h"
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#include "nsString.h"
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namespace mozilla {
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/*
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* The DispatchCategory class is used to fake the inheritance
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* of the TaskCategory enum so we can extend it to hold
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* one more value corresponding to the category
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* we use when a worker dispatches a call.
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*
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*/
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class DispatchCategory final {
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public:
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explicit DispatchCategory(uint32_t aValue) : mValue(aValue) {
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// Since DispatchCategory is adding one single value to the
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// TaskCategory enum, we can check here that the value is
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// the next index e.g. TaskCategory::Count
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MOZ_ASSERT(aValue == (uint32_t)TaskCategory::Count);
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}
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constexpr explicit DispatchCategory(TaskCategory aValue)
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: mValue((uint32_t)aValue) {}
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uint32_t GetValue() const { return mValue; }
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static const DispatchCategory Worker;
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private:
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uint32_t mValue;
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};
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typedef Array<Atomic<uint32_t>, (uint32_t)TaskCategory::Count + 1>
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DispatchCounter;
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// PerformanceCounter is a class that can be used to keep track of
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// runnable execution times and dispatch counts.
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//
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// - runnable execution time: time spent in a runnable when called
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// in nsThread::ProcessNextEvent (not counting recursive calls)
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// - dispatch counts: number of times a tracked runnable is dispatched
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// in nsThread. Useful to measure the activity of a tab or worker.
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//
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// The PerformanceCounter class is currently instantiated in DocGroup
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// and WorkerPrivate in order to count how many scheduler dispatches
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// are done through them, and how long the execution lasts.
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//
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// The execution time is calculated by the nsThread class (and its
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// inherited WorkerThread class) in its ProcessNextEvent method.
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//
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// For each processed runnable, nsThread will reach out the
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// PerformanceCounter attached to the runnable via its DocGroup
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// or WorkerPrivate and call IncrementExecutionDuration()
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//
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// Notice that the execution duration counting takes into account
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// recursivity. If an event triggers a recursive call to
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// nsThread::ProcessNextEVent, the counter will discard the time
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// spent in sub events.
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class PerformanceCounter final {
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public:
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NS_INLINE_DECL_THREADSAFE_REFCOUNTING(PerformanceCounter)
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explicit PerformanceCounter(const nsACString& aName);
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/**
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* This is called everytime a runnable is dispatched.
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*
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* aCategory can be used to distinguish counts per TaskCategory
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*
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* Note that an overflow will simply reset the counter.
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*/
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void IncrementDispatchCounter(DispatchCategory aCategory);
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/**
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* This is called via nsThread::ProcessNextEvent to measure runnable
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* execution duration.
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*
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* Note that an overflow will simply reset the counter.
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*/
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void IncrementExecutionDuration(uint32_t aMicroseconds);
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/**
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* Returns a category/counter array of all dispatches.
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*/
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const DispatchCounter& GetDispatchCounter() const;
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/**
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* Returns the total execution duration.
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*/
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uint64_t GetExecutionDuration() const;
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/**
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* Returns the number of dispatches per TaskCategory.
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*/
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uint32_t GetDispatchCount(DispatchCategory aCategory) const;
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/**
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* Returns the total number of dispatches.
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*/
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uint64_t GetTotalDispatchCount() const;
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/**
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* Returns the unique id for the instance.
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*
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* Used to distinguish instances since the lifespan of
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* a PerformanceCounter can be shorter than the
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* host it's tracking. That leads to edge cases
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* where a counter appears to have values that go
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* backwards. Having this id let the consumers
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* detect that they are dealing with a new counter
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* when it happens.
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*/
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uint64_t GetID() const;
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private:
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~PerformanceCounter() = default;
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Atomic<uint64_t> mExecutionDuration;
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Atomic<uint64_t> mTotalDispatchCount;
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DispatchCounter mDispatchCounter;
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nsCString mName;
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const uint64_t mID;
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};
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} // namespace mozilla
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#endif // mozilla_PerformanceCounter_h
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