51 lines
1.4 KiB
JavaScript
51 lines
1.4 KiB
JavaScript
/*
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* Copyright 2020 The NATS Authors
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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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*/
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/** Creates a lock that resolves when it's lock count reaches 0.
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* If a timeout is provided, the lock rejects if it has not unlocked
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* by the specified number of milliseconds (default 1000).
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*/
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module.exports.Lock = function lock(count = 1, ms = 5000) {
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let methods;
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const promise = new Promise((resolve, reject) => {
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let timer;
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let cancel = () => {
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if (timer) {
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clearTimeout(timer);
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}
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};
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let lock = () => {
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count++;
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};
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let unlock = () => {
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count--;
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if (count === 0) {
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cancel();
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resolve();
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}
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};
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methods = { resolve, reject, lock, unlock, cancel };
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if (ms) {
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timer = setTimeout(() => {
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reject(new Error("timeout"));
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}, ms);
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}
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});
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return Object.assign(promise, methods);
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};
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