env.js(env的初始化以及服务的加载)
路径:addons\web\static\src\env.js
这个文件的作用就是初始化env,主要是加载所有的服务。如orm, title, dialog等。
1、env.js 的加载时机
前文我们讲过前端的启动函数,start.js,其中有这么两句,这里有两个函数makeEnv和startServices,都在同级目录的env.js里
const env = makeEnv();await startServices(env);
2、 makeEnv()
export function makeEnv() {return {bus: new EventBus(),services: {},debug: odoo.debug,get isSmall() {throw new Error("UI service not initialized!");},};
}
从代码可以看出,env有4个属性:
- bus: 全局数据总线
- services:全局服务对象
- debug: 是否debug模式
- isSmall:判断手机端还是移动端
这里抛出一个异常是为了在后面会覆盖这个方法。
从中可以看出,env最重要的其实就两个对象,一个是全局数据总线,负责组件之间通信,另一个就是service。
3、startServices
启动所有在注册表中注册的服务,并且保证所有的依赖都得到满足。
首先获取所有在注册表中注册的服务serviceRegistry
初始化元数据SERVICES_METADATA, 主要是保存service中sync的内容,有什么作用还不清楚
主角开始上场: startServices
启动所有在注册表中注册的服务,并且保证每个服务的依赖都得到满足。
await Promise.resolve(); // 等待之前的异步操作都完成const toStart = new Set(); // 初始化要启动的服务,因为每个服务都不同,所以用了setserviceRegistry.addEventListener // 这段没看懂,这里添加了一个事件监听,动态增加注册服务的await _startServices(env, toStart); // 将env和toStart对象传入,干正事了
4._startServices(env, toStart)
4.1 填充 toStart 集合
const services = env.services; //获取了env中的service对象,这时候还是空的,啥也没有// 根据注册表中的服务信息,初始化了toStart集合,里面都是创建好的实例对象,并且有一个name属性。for (const [name, service] of serviceRegistry.getEntries()) {if (!(name in services)) {const namedService = Object.assign(Object.create(service), { name });toStart.add(namedService);}}
4.2、findNext()
关键的地方来了, 这里有一个关键的函数findNext(),先看看它的定义:
// 从toStart集合中遍历,有过集合中的服务有依赖并且依赖都已经满足了,则返回这个service,如果没有依赖,那么直接返回,找到第一个就返回,不叨叨,直到找不到,返回null
function {for (const s of toStart) {if (s.dependencies) {if (s.dependencies.every((d) => d in services)) {return s;}} else {return s;}}return null;}
4.3 、启动服务,并填充到env的services中
在start函数中,findNext函数返回的服务,第一步要最的就是从toStart 删除,这样遍历的次数会越来越少,我看过,odoo17一共有69个服务,while一共还要遍历69次,每次加载一个服务。 通过这种方式,很好的处理了服务之间的依赖关系,并且最大限度的实现了并行。
// start as many services in parallel as possible 并行启动尽可能多的服务async function start() {let service = null;const proms = [];while ((service = findNext())) {const name = service.name;toStart.delete(service); // 删除要加载的服务const entries = (service.dependencies || []).map((dep) => [dep, services[dep]]);const dependencies = Object.fromEntries(entries);let value;try {value = service.start(env, dependencies); // 调用start函数,并将返回值付给value} catch (e) {value = e;console.error(e);}if ("async" in service) {SERVICES_METADATA[name] = service.async; // 保存服务的元数据,后面可能会有用}if (value instanceof Promise) { // 如果value是一个Promiseproms.push(new Promise((resolve) => {value.then((val) => {services[name] = val || null; // 将promise的返回值保存到services中}).catch((error) => {services[name] = error;console.error("Can't load service '" + name + "' because:", error);}).finally(resolve);}));} else {services[service.name] = value || null; // 如果不是promise,直接将value保存到services中}}await Promise.all(proms); // 等待所有的proms完成if (proms.length) {return start(); }}
到这里,前端js就完成了所有service的加载,要注意的是, env.services中保存的不是 services对象本身,而是service对象的start函数返回的对象。
这点很重要,每个service都要有start函数,而且要有返回值。
4.4、后面还有一段是异常处理
if (toStart.size) {const names = [...toStart].map((s) => s.name);const missingDeps = new Set();[...toStart].forEach((s) =>s.dependencies.forEach((dep) => {if (!(dep in services) && !names.includes(dep)) {missingDeps.add(dep);}}));const depNames = [...missingDeps].join(", ");throw new Error(`Some services could not be started: ${names}. Missing dependencies: ${depNames}`);}
如果toStart.size >0 ,说明这里面的服务的依赖想没有得到满足,所以无法加载,会抛出一个Error
5、附录:odoo17 env.js
/** @odoo-module **/import { registry } from "./core/registry";import { EventBus } from "@odoo/owl";// -----------------------------------------------------------------------------
// Types
// -----------------------------------------------------------------------------/*** @typedef {Object} OdooEnv* @property {import("services").Services} services* @property {EventBus} bus* @property {string} debug* @property {(str: string) => string} _t* @property {boolean} [isSmall]*/// -----------------------------------------------------------------------------
// makeEnv
// -----------------------------------------------------------------------------/*** Return a value Odoo Env object** @returns {OdooEnv}*/
export function makeEnv() {return {bus: new EventBus(),services: {},debug: odoo.debug,get isSmall() {throw new Error("UI service not initialized!");},};
}// -----------------------------------------------------------------------------
// Service Launcher
// -----------------------------------------------------------------------------const serviceRegistry = registry.category("services");export const SERVICES_METADATA = {};
let startServicesPromise = null;/*** Start all services registered in the service registry, while making sure* each service dependencies are properly fulfilled.** @param {OdooEnv} env* @returns {Promise<void>}*/
export async function startServices(env) {// Wait for all synchronous code so that if new services that depend on// one another are added to the registry, they're all present before we// start them regardless of the order they're added to the registry.debuggerawait Promise.resolve();const toStart = new Set();serviceRegistry.addEventListener("UPDATE", async (ev) => {// Wait for all synchronous code so that if new services that depend on// one another are added to the registry, they're all present before we// start them regardless of the order they're added to the registry.await Promise.resolve();const { operation, key: name, value: service } = ev.detail;if (operation === "delete") {// We hardly see why it would be usefull to remove a service.// Furthermore we could encounter problems with dependencies.// Keep it simple!return;}if (toStart.size) {const namedService = Object.assign(Object.create(service), { name });toStart.add(namedService);} else {await _startServices(env, toStart);}});await _startServices(env, toStart);
}async function _startServices(env, toStart) {if (startServicesPromise) {return startServicesPromise.then(() => _startServices(env, toStart));}const services = env.services;for (const [name, service] of serviceRegistry.getEntries()) {if (!(name in services)) {const namedService = Object.assign(Object.create(service), { name });toStart.add(namedService);}}// start as many services in parallel as possibleasync function start() {let service = null;const proms = [];while ((service = findNext())) {const name = service.name;toStart.delete(service);const entries = (service.dependencies || []).map((dep) => [dep, services[dep]]);const dependencies = Object.fromEntries(entries);let value;try {value = service.start(env, dependencies);} catch (e) {value = e;console.error(e);}if ("async" in service) {SERVICES_METADATA[name] = service.async;}if (value instanceof Promise) {proms.push(new Promise((resolve) => {value.then((val) => {services[name] = val || null;}).catch((error) => {services[name] = error;console.error("Can't load service '" + name + "' because:", error);}).finally(resolve);}));} else {services[service.name] = value || null;}}await Promise.all(proms);if (proms.length) {return start();}}startServicesPromise = start();await startServicesPromise;startServicesPromise = null;if (toStart.size) {const names = [...toStart].map((s) => s.name);const missingDeps = new Set();[...toStart].forEach((s) =>s.dependencies.forEach((dep) => {if (!(dep in services) && !names.includes(dep)) {missingDeps.add(dep);}}));const depNames = [...missingDeps].join(", ");throw new Error(`Some services could not be started: ${names}. Missing dependencies: ${depNames}`);}function findNext() {for (const s of toStart) {if (s.dependencies) {if (s.dependencies.every((d) => d in services)) {return s;}} else {return s;}}return null;}
}