express-cache-file/dist/cache.js

Express middleware to cache static files in server memory

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
const interval_1 = __importDefault(require("./interval"));
function getCacheFile(getFile, cache, options) {
    const expire = (0, interval_1.default)(options.expire);
    const mode = options.mode || 'cache_first';
    return (file, cb) => {
        const item = cache.files[file];
        if (item) {
            if (!item.expire || item.expire > Date.now()) {
                cb(null, item);
                return;
            }
            if (mode === 'cache_first') {
                cb(null, item);
            }
            removeFromCache(cache, file, item);
        }
        getFile(file, (err, content) => {
            if (!err) {
                if (expire >= 0) {
                    content.expire = Date.now() + expire;
                }
                saveToCache(cache, file, content);
                // TODO auto remove other files when cache is too large
            }
            if (!item || mode !== 'cache_first') {
                cb(err, content);
            }
        });
    };
}
function removeFromCache(cache, file, item = cache.files[file]) {
    delete cache.files[file];
    if (item) {
        cache.usedSize -= item.buffer.byteLength;
    }
}
function saveToCache(cache, file, content) {
    removeFromCache(cache, file);
    if (checkCacheSize(cache, content.buffer.byteLength)) {
        cache.files[file] = content;
        cache.usedSize += content.buffer.byteLength;
    }
}
function checkCacheSize(cache, sizeNeeded) {
    if (!cache.capacity)
        return true;
    if (cache.capacity >= cache.usedSize + sizeNeeded) {
        return true;
    }
    const entries = Object.entries(cache.files);
    for (let i = 0; i < entries.length; i++) {
        if (cache.capacity >= cache.usedSize + sizeNeeded) {
            return true;
        }
        let entry = entries[i];
        removeFromCache(cache, entry[0], entry[1]);
    }
    return cache.capacity >= cache.usedSize + sizeNeeded;
}
exports.default = getCacheFile;