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92 lines
2.5 KiB
C++
92 lines
2.5 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* vim: set ts=8 sts=4 et sw=4 tw=99:
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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 <stdint.h>
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namespace js {
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struct JS_PUBLIC_API(TimeBudget)
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{
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int64_t budget;
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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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{
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int64_t budget;
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explicit WorkBudget(int64_t work) { budget = work; }
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};
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/*
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* This class records how much work has been done in a given collection slice,
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* so that we can return before pausing for too long. Some slices are allowed
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* to run for unlimited time, and others are bounded. To reduce the number of
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* gettimeofday calls, we only check the time every 1000 operations.
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*/
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class JS_PUBLIC_API(SliceBudget)
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{
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static const int64_t unlimitedDeadline = INT64_MAX;
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static const intptr_t unlimitedStartCounter = INTPTR_MAX;
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bool checkOverBudget();
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SliceBudget();
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public:
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// Memory of the originally requested budget. If isUnlimited, neither of
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// these are in use. If deadline==0, then workBudget is valid. Otherwise
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// timeBudget is valid.
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TimeBudget timeBudget;
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WorkBudget workBudget;
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int64_t deadline; /* in microseconds */
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intptr_t counter;
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static const intptr_t CounterReset = 1000;
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static const int64_t UnlimitedTimeBudget = -1;
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static const int64_t UnlimitedWorkBudget = -1;
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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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void makeUnlimited() {
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deadline = unlimitedDeadline;
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counter = unlimitedStartCounter;
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}
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void step(intptr_t amt = 1) {
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counter -= amt;
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}
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bool isOverBudget() {
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if (counter > 0)
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return false;
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return checkOverBudget();
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}
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bool isWorkBudget() const { return deadline == 0; }
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bool isTimeBudget() const { return deadline > 0 && !isUnlimited(); }
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bool isUnlimited() const { return deadline == unlimitedDeadline; }
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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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