michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
michael@0:  * vim: set ts=8 sts=4 et sw=4 tw=99:
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef js_SliceBudget_h
michael@0: #define js_SliceBudget_h
michael@0: 
michael@0: #include <stdint.h>
michael@0: 
michael@0: namespace js {
michael@0: 
michael@0: /*
michael@0:  * This class records how much work has been done in a given collection slice, so that
michael@0:  * we can return before pausing for too long. Some slices are allowed to run for
michael@0:  * unlimited time, and others are bounded. To reduce the number of gettimeofday
michael@0:  * calls, we only check the time every 1000 operations.
michael@0:  */
michael@0: struct JS_PUBLIC_API(SliceBudget)
michael@0: {
michael@0:     int64_t deadline; /* in microseconds */
michael@0:     intptr_t counter;
michael@0: 
michael@0:     static const intptr_t CounterReset = 1000;
michael@0: 
michael@0:     static const int64_t Unlimited = 0;
michael@0:     static int64_t TimeBudget(int64_t millis);
michael@0:     static int64_t WorkBudget(int64_t work);
michael@0: 
michael@0:     /* Equivalent to SliceBudget(UnlimitedBudget). */
michael@0:     SliceBudget();
michael@0: 
michael@0:     /* Instantiate as SliceBudget(Time/WorkBudget(n)). */
michael@0:     SliceBudget(int64_t budget);
michael@0: 
michael@0:     void reset() {
michael@0:         deadline = INT64_MAX;
michael@0:         counter = INTPTR_MAX;
michael@0:     }
michael@0: 
michael@0:     void step(intptr_t amt = 1) {
michael@0:         counter -= amt;
michael@0:     }
michael@0: 
michael@0:     bool checkOverBudget();
michael@0: 
michael@0:     bool isOverBudget() {
michael@0:         if (counter >= 0)
michael@0:             return false;
michael@0:         return checkOverBudget();
michael@0:     }
michael@0: };
michael@0: 
michael@0: } // namespace js
michael@0: 
michael@0: #endif /* js_SliceBudget_h */