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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sts=4 et sw=4 tw=99:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef js_SliceBudget_h
#define js_SliceBudget_h
#include <stdint.h>
namespace js {
struct JS_PUBLIC_API(TimeBudget)
{
int64_t budget;
explicit TimeBudget(int64_t milliseconds) { budget = milliseconds; }
};
struct JS_PUBLIC_API(WorkBudget)
{
int64_t budget;
explicit WorkBudget(int64_t work) { budget = work; }
};
/*
* This class records how much work has been done in a given collection slice,
* so that we can return before pausing for too long. Some slices are allowed
* to run for unlimited time, and others are bounded. To reduce the number of
* gettimeofday calls, we only check the time every 1000 operations.
*/
class JS_PUBLIC_API(SliceBudget)
{
static const int64_t unlimitedDeadline = INT64_MAX;
static const intptr_t unlimitedStartCounter = INTPTR_MAX;
bool checkOverBudget();
SliceBudget();
public:
// Memory of the originally requested budget. If isUnlimited, neither of
// these are in use. If deadline==0, then workBudget is valid. Otherwise
// timeBudget is valid.
TimeBudget timeBudget;
WorkBudget workBudget;
int64_t deadline; /* in microseconds */
intptr_t counter;
static const intptr_t CounterReset = 1000;
static const int64_t UnlimitedTimeBudget = -1;
static const int64_t UnlimitedWorkBudget = -1;
/* Use to create an unlimited budget. */
static SliceBudget unlimited() { return SliceBudget(); }
/* Instantiate as SliceBudget(TimeBudget(n)). */
explicit SliceBudget(TimeBudget time);
/* Instantiate as SliceBudget(WorkBudget(n)). */
explicit SliceBudget(WorkBudget work);
void makeUnlimited() {
deadline = unlimitedDeadline;
counter = unlimitedStartCounter;
}
void step(intptr_t amt = 1) {
counter -= amt;
}
bool isOverBudget() {
if (counter > 0)
return false;
return checkOverBudget();
}
bool isWorkBudget() const { return deadline == 0; }
bool isTimeBudget() const { return deadline > 0 && !isUnlimited(); }
bool isUnlimited() const { return deadline == unlimitedDeadline; }
int describe(char* buffer, size_t maxlen) const;
};
} // namespace js
#endif /* js_SliceBudget_h */
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