yangxiangyuan
85 lines
2.4 KiB
JavaScript
85 lines
2.4 KiB
JavaScript
// 简单的 localStorage 心跳锁实现（兼容性回退）
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// 若浏览器支持 BroadcastChannel，可替换为更即时的通讯方式
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(function () {
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const LOCK_KEY = 'calendar_instance_lock';
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const HEARTBEAT_INTERVAL = 2000; // ms
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const STALE_THRESHOLD = 5000; // ms
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const instanceId = Date.now() + '-' + Math.random().toString(36).slice(2);
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function now() { return Date.now(); }
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function tryAcquire() {
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const raw = localStorage.getItem(LOCK_KEY);
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if (raw) {
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try {
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const obj = JSON.parse(raw);
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if (now() - obj.heartbeat < STALE_THRESHOLD) {
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// 有活跃实例
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return false;
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}
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} catch (e) {
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// malformed, ignore
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}
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}
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// 申请锁
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localStorage.setItem(LOCK_KEY, JSON.stringify({ id: instanceId, heartbeat: now() }));
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return true;
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}
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function heartbeat() {
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const raw = localStorage.getItem(LOCK_KEY);
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if (!raw) return;
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try {
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const obj = JSON.parse(raw);
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if (obj.id === instanceId) {
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obj.heartbeat = now();
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localStorage.setItem(LOCK_KEY, JSON.stringify(obj));
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} else {
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// 被其他实例抢占，通知并退出
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alert('你好，每次只能运行一个程序。你已经运行了。');
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cleanupAndExit();
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}
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} catch (e) { /* ignore */ }
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}
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function cleanupAndExit() {
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try { // 尝试清理自己持有的锁
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const raw = localStorage.getItem(LOCK_KEY);
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if (raw) {
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const obj = JSON.parse(raw);
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if (obj.id === instanceId) {
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localStorage.removeItem(LOCK_KEY);
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}
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}
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} catch (e) {}
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// 停止应用初始化（这里简单重载或关闭页面）
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window.close && window.close();
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}
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if (!tryAcquire()) {
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alert('你好，每次只能运行一个程序。你已经运行了。');
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// 直接阻止后续初始化
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throw new Error('Single instance active');
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}
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// 定时心跳
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const hbTimer = setInterval(heartbeat, HEARTBEAT_INTERVAL);
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// 在页面卸载时释放锁
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window.addEventListener('beforeunload', function () {
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try {
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const raw = localStorage.getItem(LOCK_KEY);
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if (raw) {
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const obj = JSON.parse(raw);
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if (obj.id === instanceId) {
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localStorage.removeItem(LOCK_KEY);
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}
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}
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} catch (e) {}
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clearInterval(hbTimer);
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});
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// ... 应用其他初始化继续 ...
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})(); |