зеркало из https://github.com/mozilla/gecko-dev.git
89 строки
2.5 KiB
C++
89 строки
2.5 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 js_SliceBudget_h
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#define js_SliceBudget_h
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#include "mozilla/Assertions.h"
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#include "mozilla/TimeStamp.h"
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#include "mozilla/Variant.h"
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#include <stdint.h>
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#include "jstypes.h"
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namespace js {
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struct JS_PUBLIC_API TimeBudget {
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const int64_t budget;
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mozilla::TimeStamp deadline; // Calculated when SliceBudget is constructed.
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explicit TimeBudget(int64_t milliseconds) : budget(milliseconds) {}
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};
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struct JS_PUBLIC_API WorkBudget {
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const int64_t budget;
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explicit WorkBudget(int64_t work) : budget(work) {}
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};
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struct UnlimitedBudget {};
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/*
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* This class describes a limit to the amount of work to be performed in a GC
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* slice, so that we can return to the mutator without pausing for too long. The
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* budget may be based on a deadline time or an amount of work to be performed,
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* or may be unlimited.
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*
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* To reduce the number of gettimeofday calls, we only check the time every 1000
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* operations.
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*/
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class JS_PUBLIC_API SliceBudget {
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static const intptr_t UnlimitedCounter = INTPTR_MAX;
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mozilla::Variant<TimeBudget, WorkBudget, UnlimitedBudget> budget;
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int64_t counter;
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SliceBudget() : budget(UnlimitedBudget()), counter(UnlimitedCounter) {}
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bool checkOverBudget();
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public:
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static const intptr_t StepsPerTimeCheck = 1000;
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// Use to create an unlimited budget.
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static SliceBudget unlimited() { return SliceBudget(); }
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// Instantiate as SliceBudget(TimeBudget(n)).
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explicit SliceBudget(TimeBudget time);
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// Instantiate as SliceBudget(WorkBudget(n)).
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explicit SliceBudget(WorkBudget work);
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explicit SliceBudget(mozilla::TimeDuration time)
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: SliceBudget(TimeBudget(time.ToMilliseconds())) {}
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void step(uint64_t steps = 1) {
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MOZ_ASSERT(steps > 0);
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counter -= steps;
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}
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bool isOverBudget() { return counter <= 0 && checkOverBudget(); }
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bool isWorkBudget() const { return budget.is<WorkBudget>(); }
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bool isTimeBudget() const { return budget.is<TimeBudget>(); }
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bool isUnlimited() const { return budget.is<UnlimitedBudget>(); }
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int64_t timeBudget() const { return budget.as<TimeBudget>().budget; }
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int64_t workBudget() const { return budget.as<WorkBudget>().budget; }
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int describe(char* buffer, size_t maxlen) const;
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};
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} // namespace js
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#endif /* js_SliceBudget_h */
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