54 lines
1.5 KiB
JavaScript
54 lines
1.5 KiB
JavaScript
var queue = require('queue-async');
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/**
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* @param {Array|Object} cacheBackends each backend backend should respond to `invalidate(cacheObject, callback)` method
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* @constructor
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*/
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function SurrogateKeysCache(cacheBackends) {
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this.cacheBackends = Array.isArray(cacheBackends) ? cacheBackends : [cacheBackends];
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}
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module.exports = SurrogateKeysCache;
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/**
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* @param response should respond to `header(key, value)` method
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* @param cacheObject should respond to `key() -> String` method
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*/
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SurrogateKeysCache.prototype.tag = function(response, cacheObject) {
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var newKey = cacheObject.key();
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response.set('Surrogate-Key', appendSurrogateKey(
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response.get('Surrogate-Key'),
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Array.isArray(newKey) ? cacheObject.key().join(' ') : newKey
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));
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};
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function appendSurrogateKey(currentKey, newKey) {
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if (!!currentKey) {
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newKey = currentKey + ' ' + newKey;
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}
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return newKey;
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}
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/**
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* @param cacheObject should respond to `key() -> String` method
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* @param {Function} callback
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*/
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SurrogateKeysCache.prototype.invalidate = function(cacheObject, callback) {
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var invalidationQueue = queue(this.cacheBackends.length);
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this.cacheBackends.forEach(function(cacheBackend) {
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invalidationQueue.defer(function(cacheBackend, done) {
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cacheBackend.invalidate(cacheObject, done);
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}, cacheBackend);
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});
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invalidationQueue.awaitAll(function(err, result) {
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if (err) {
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return callback(err);
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}
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callback(null, result);
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});
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};
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