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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 */