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cacheUtils.js
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cacheUtils.js
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"use strict";
const LRU = require("lru-cache");
function createMemoryLruCache(cacheObj, onCacheEvent) {
return {
get: (key) => {
return new Promise((resolve, reject) => {
onCacheEvent("memory", "try", key);
var val = cacheObj.get(key);
if (val != null) {
onCacheEvent("memory", "hit", key);
} else {
onCacheEvent("memory", "miss", key);
}
resolve(cacheObj.get(key));
});
},
set: (key, obj, maxAge) => {
cacheObj.set(key, obj, maxAge);
onCacheEvent("memory", "set", key);
},
del: (key) => {
cacheObj.del(key);
onCacheEvent("memory", "del", key);
}
}
}
function tryCache(cacheKey, cacheObjs, index, resolve, reject) {
if (index == cacheObjs.length) {
resolve(null);
return;
}
cacheObjs[index].get(cacheKey).then((result) => {
if (result != null) {
resolve(result);
} else {
tryCache(cacheKey, cacheObjs, index + 1, resolve, reject);
}
});
}
function createTieredCache(cacheObjs) {
return {
get:(key) => {
return new Promise((resolve, reject) => {
tryCache(key, cacheObjs, 0, resolve, reject);
});
},
set:(key, obj, maxAge) => {
for (var i = 0; i < cacheObjs.length; i++) {
cacheObjs[i].set(key, obj, maxAge);
}
}
}
}
function lruCache(size) {
return new LRU(size);
}
module.exports = {
lruCache: lruCache,
createMemoryLruCache: createMemoryLruCache,
createTieredCache: createTieredCache
}