117 lines
2.1 KiB
JavaScript
Executable file
117 lines
2.1 KiB
JavaScript
Executable file
/**
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* Module dependencies.
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*/
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var crypto = require('crypto')
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, nodes = require('../nodes');
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var MemoryCache = module.exports = function(options) {
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options = options || {};
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this.limit = options['cache limit'] || 256;
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this._cache = {};
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this.length = 0;
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this.head = this.tail = null;
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};
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/**
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* Set cache item with given `key` to `value`.
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*
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* @param {String} key
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* @param {Object} value
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* @api private
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*/
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MemoryCache.prototype.set = function(key, value) {
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var clone = value.clone()
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, item;
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clone.filename = nodes.filename;
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clone.lineno = nodes.lineno;
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clone.column = nodes.column;
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item = { key: key, value: clone };
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this._cache[key] = item;
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if (this.tail) {
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this.tail.next = item;
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item.prev = this.tail;
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} else {
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this.head = item;
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}
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this.tail = item;
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if (this.length++ == this.limit) this.purge();
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};
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/**
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* Get cache item with given `key`.
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*
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* @param {String} key
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* @return {Object}
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* @api private
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*/
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MemoryCache.prototype.get = function(key) {
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var item = this._cache[key]
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, val = item.value.clone();
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if (item == this.tail) return val;
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if (item.next) {
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if (item == this.head) this.head = item.next;
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item.next.prev = item.prev;
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}
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if (item.prev) item.prev.next = item.next;
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item.next = null;
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item.prev = this.tail;
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if (this.tail) this.tail.next = item;
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this.tail = item;
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return val;
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};
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/**
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* Check if cache has given `key`.
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*
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* @param {String} key
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* @return {Boolean}
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* @api private
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*/
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MemoryCache.prototype.has = function(key) {
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return !!this._cache[key];
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};
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/**
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* Generate key for the source `str` with `options`.
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*
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* @param {String} str
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* @param {Object} options
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* @return {String}
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* @api private
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*/
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MemoryCache.prototype.key = function(str, options) {
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var hash = crypto.createHash('sha1');
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hash.update(str + options.prefix);
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return hash.digest('hex');
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};
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/**
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* Remove the oldest item from the cache.
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*
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* @api private
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*/
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MemoryCache.prototype.purge = function() {
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var item = this.head;
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if (this.head.next) {
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this.head = this.head.next;
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this.head.prev = null;
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}
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this._cache[item.key] = item.prev = item.next = null;
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this.length--;
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};
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