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：

1. bus： 全局数据总线
2. services：全局服务对象
3. debug： 是否debug模式
4. 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 =newSet();// 初始化要启动的服务，因为每个服务都不同，所以用了set 	serviceRegistry.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;}}returnnull;}

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asyncfunctionstart(){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 instanceofPromise){// 如果value是一个Promise proms.push(newPromise((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){returnstart();}}

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 =newSet();[...toStart].forEach((s)=> s.dependencies.forEach((dep)=>{if(!(dep in services)&&!names.includes(dep)){ missingDeps.add(dep);}}));const depNames =[...missingDeps].join(", ");thrownewError(`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} */exportfunctionmakeEnv(){return{bus:newEventBus(),services:{},debug: odoo.debug,getisSmall(){thrownewError("UI service not initialized!");},};}// -----------------------------------------------------------------------------// Service Launcher// -----------------------------------------------------------------------------const serviceRegistry = registry.category("services");exportconstSERVICES_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>} */exportasyncfunctionstartServices(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 =newSet(); 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);}asyncfunction_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 possibleasyncfunctionstart(){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 instanceofPromise){ proms.push(newPromise((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){returnstart();}} startServicesPromise =start();await startServicesPromise; startServicesPromise =null;if(toStart.size){const names =[...toStart].map((s)=> s.name);const missingDeps =newSet();[...toStart].forEach((s)=> s.dependencies.forEach((dep)=>{if(!(dep in services)&&!names.includes(dep)){ missingDeps.add(dep);}}));const depNames =[...missingDeps].join(", ");thrownewError(`Some services could not be started: ${names}. Missing dependencies: ${depNames}`);}functionfindNext(){for(const s of toStart){if(s.dependencies){if(s.dependencies.every((d)=> d in services)){return s;}}else{return s;}}returnnull;}}