86 lines
1.9 KiB
C
86 lines
1.9 KiB
C
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// Copyright (c) Facebook, Inc. and its affiliates.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#pragma once
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#include <cassert>
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#include <cstddef>
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#include <limits>
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namespace rsocket {
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class Allowance {
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public:
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using ValueType = size_t;
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Allowance() = default;
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explicit Allowance(ValueType initialValue) : value_(initialValue) {}
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bool tryConsume(ValueType n) {
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if (!canConsume(n)) {
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return false;
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}
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value_ -= n;
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return true;
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}
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ValueType add(ValueType n) {
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auto old_value = value_;
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value_ += n;
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if (old_value > value_) {
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value_ = max();
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}
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return old_value;
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}
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bool canConsume(ValueType n) const {
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return value_ >= n;
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}
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ValueType consumeAll() {
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return consumeUpTo(max());
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}
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ValueType consumeUpTo(ValueType limit) {
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if (limit > value_) {
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limit = value_;
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}
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value_ -= limit;
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return limit;
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}
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explicit operator bool() const {
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return value_;
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}
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ValueType get() const {
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return value_;
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}
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static ValueType max() {
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return std::numeric_limits<ValueType>::max();
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}
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private:
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static_assert(
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!std::numeric_limits<ValueType>::is_signed,
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"Allowance representation must be an unsigned type");
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static_assert(
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std::numeric_limits<ValueType>::is_integer,
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"Allowance representation must be an integer type");
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ValueType value_{0};
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};
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} // namespace rsocket
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