makit/dist/db/data-base.js

Make in JavaScript done right!

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.DataBase = void 0;
const util_1 = require("util");
const logger_1 = require("../utils/logger");
const number_1 = require("../utils/number");
const l = logger_1.Logger.getOrCreate();
/**
 * 一个简易的 JSON 非关系性数据库。它的构成如下：
 *
 * * 一个 DataBase 对象由若干个 Document 构成
 * * 一个 Document 由若干个 Property 构成
 *
 * Note: sqlite 是各方面比较理想的替代品，但它有 Native Binding，
 * 能否成功安装会受网络、操作系统、Node 版本的影响，移植性不够。
 */
class DataBase {
    constructor(filepath, fs) {
        this.filepath = filepath;
        this.fs = fs;
        this.data = {};
        this.dirty = false;
        this.readFromDisk();
    }
    /**
     * 查询文档属性
     *
     * @param doc 文档名
     * @param prop 属性名
     * @param defaultValue 如果没有，则返回的默认值
     */
    query(doc, prop, defaultValue) {
        if (!this.data[doc]) {
            return defaultValue;
        }
        const value = this.data[doc][prop];
        return value !== undefined ? value : defaultValue;
    }
    /**
     * 写入文档属性
     *
     * @param doc 文档名
     * @param prop 属性名
     * @param newValue 新的属性值
     */
    write(doc, prop, newValue) {
        l.debug('DTBS', () => `setting ${doc}.${prop} to ${util_1.inspect(newValue)}`);
        this.dirty = true;
        this.data[doc] = this.data[doc] || {};
        this.data[doc][prop] = newValue;
        return this.data[doc][prop];
    }
    /**
     * 清空文档的所有属性，或清空数据库
     *
     * @param doc 文档名，如果不传则清空所有文档
     */
    clear(doc) {
        this.dirty = true;
        if (doc)
            this.data[doc] = {};
        else
            this.data = {};
    }
    /**
     * 同步数据库到磁盘
     *
     * @throws 文件写入错误
     */
    syncToDisk() {
        if (!this.dirty) {
            l.debug('DTBS', `documents clean, skip syncing`);
            return false;
        }
        l.verbose('DTBS', () => `syncing to disk ${this.filepath}`);
        const data = Buffer.from(JSON.stringify(this.data), 'utf8');
        try {
            // Note: should be synchronous to handle exit event,
            // after which microtasks will not be scheduled or called.
            this.fs.writeFileSync(this.filepath, data);
        }
        catch (err) {
            err.message = 'Error sync to disk: ' + err.message;
            throw err;
        }
        l.verbose('DTBS', () => `${number_1.humanReadable(data.length)} bytes written to ${this.filepath}`);
        this.dirty = false;
        return true;
    }
    readFromDisk() {
        let str, data;
        try {
            str = this.fs.readFileSync(this.filepath, 'utf8');
        }
        catch (err) {
            if (err.code === 'ENOENT') {
                // ignore if not exists, will be created on first sync
                str = '{}';
            }
            else {
                throw err;
            }
        }
        try {
            data = JSON.parse(str);
        }
        catch (err) {
            // ignore corrupted file, it will be regenerated anyway
        }
        if (typeof data === 'object' && data !== null)
            this.data = data;
    }
}
exports.DataBase = DataBase;