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broker.ts
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broker.ts
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import { ReceiveType, reflect, ReflectionKind, resolveReceiveType, Type } from '@deepkit/type';
import { EventToken } from '@deepkit/event';
export interface BrokerLockOptions {
/**
* Time to live in seconds. Default 2 minutes.
*
* The lock is automatically released after this time.
* This is to prevent deadlocks.
*/
ttl: number;
/**
* Timeout when acquiring the lock in seconds. Default 30 seconds.
* Ween a lock is not acquired after this time, an error is thrown.
*/
timeout: number;
}
export type Release = () => Promise<void>;
export interface BrokerAdapter {
lock(id: string, options: BrokerLockOptions): Promise<undefined | Release>;
isLocked(id: string): Promise<boolean>;
tryLock(id: string, options: BrokerLockOptions): Promise<undefined | Release>;
getCache(key: string, type: Type): Promise<any>;
setCache(key: string, value: any, options: BrokerCacheOptions, type: Type): Promise<void>;
increment(key: string, value: any): Promise<number>;
publish(name: string, message: any, type: Type): Promise<void>;
subscribe(name: string, callback: (message: any) => void, type: Type): Promise<Release>;
consume(name: string, callback: (message: any) => Promise<void>, options: { maxParallel: number }, type: Type): Promise<Release>;
produce(name: string, message: any, type: Type, options?: { delay?: number, priority?: number }): Promise<void>;
disconnect(): Promise<void>;
}
export const onBrokerLock = new EventToken('broker.lock');
export interface BrokerCacheOptions {
ttl: number;
tags: string[];
}
export class CacheError extends Error {
}
export type BrokerBusChannel<Type, Name extends string> = [Name, Type];
export type BrokerCacheKey<Type, Key extends string, Parameters extends object = {}> = [Key, Parameters, Type];
export type BrokerQueueChannel<Type, Name extends string> = [Name, Type];
export type CacheBuilder<T extends BrokerCacheKey<any, any, any>> = (parameters: T[1], options: BrokerCacheOptions) => T[2] | Promise<T[2]>;
export class BrokerQueueMessage<T> {
public state: 'pending' | 'done' | 'failed' = 'pending';
public error?: Error;
public tries: number = 0;
public delayed: number = 0;
constructor(
public channel: string,
public data: T,
) {
}
public failed(error: Error) {
this.state = 'failed';
this.error = error;
}
public delay(seconds: number) {
this.delayed = seconds;
}
}
export class BrokerQueue<T> {
constructor(
public name: string,
private adapter: BrokerAdapter,
private type: Type,
) {
}
async produce<T>(message: T, options?: { delay?: number, priority?: number }): Promise<void> {
await this.adapter.produce(this.name, message, this.type, options);
}
async consume(callback: (message: BrokerQueueMessage<T>) => Promise<void> | void, options: { maxParallel?: number } = {}): Promise<Release> {
return await this.adapter.consume(this.name, async (message) => {
try {
await callback(message);
} catch (error: any) {
message.state = 'failed';
message.error = error;
}
}, Object.assign({ maxParallel: 1 }, options), this.type);
}
}
export class BrokerBus<T> {
constructor(
public name: string,
private adapter: BrokerAdapter,
private type: Type,
) {
}
async publish<T>(message: T) {
return this.adapter.publish(this.name, message, this.type);
}
async subscribe(callback: (message: T) => void): Promise<Release> {
return this.adapter.subscribe(this.name, callback, this.type);
}
}
export class BrokerCache<T extends BrokerCacheKey<any, any, any>> {
constructor(
private key: string,
private builder: CacheBuilder<T>,
private options: BrokerCacheOptions,
private adapter: BrokerAdapter,
private type: Type,
) {
}
protected getCacheKey(parameters: T[1]): string {
//this.key contains parameters e.g. user/:id, id comes from parameters.id. let's replace all of it.
//note: we could create JIT function for this, but it's probably not worth it.
return this.key.replace(/:([a-zA-Z0-9_]+)/g, (v, name) => {
if (!(name in parameters)) throw new CacheError(`Parameter ${name} not given`);
return String(parameters[name]);
});
}
async set(parameters: T[1], value: T[2], options: Partial<BrokerCacheOptions> = {}) {
const cacheKey = this.getCacheKey(parameters);
await this.adapter.setCache(cacheKey, value, { ...this.options, ...options }, this.type);
}
async increment(parameters: T[1], value: number) {
const cacheKey = this.getCacheKey(parameters);
await this.adapter.increment(cacheKey, value);
}
async get(parameters: T[1]): Promise<T[2]> {
const cacheKey = this.getCacheKey(parameters);
let entry = await this.adapter.getCache(cacheKey, this.type);
if (entry !== undefined) return entry;
const options: BrokerCacheOptions = { ...this.options };
entry = await this.builder(parameters, options);
await this.adapter.setCache(cacheKey, entry, options, this.type);
return entry;
}
}
export class BrokerLockError extends Error {
}
export class BrokerLock {
protected releaser?: Release;
constructor(
private id: string,
private adapter: BrokerAdapter,
private options: BrokerLockOptions,
) {
}
/**
* Returns true if the current lock object is the holder of the lock.
*
* This does not check whether the lock is acquired by someone else.
*/
get acquired(): boolean {
return this.releaser !== undefined;
}
/**
* Acquires the lock. If the lock is already acquired by someone else, this method waits until the lock is released.
*
* @throws BrokerLockError when lock is already acquired by this object.
*/
async acquire(): Promise<this> {
if (this.releaser) throw new BrokerLockError(`Lock already acquired. Call release first.`);
this.releaser = await this.adapter.lock(this.id, this.options);
return this;
}
/**
* Checks if the lock is acquired by someone else.
*/
async isReserved(): Promise<boolean> {
return await this.adapter.isLocked(this.id);
}
/**
* Tries to acquire the lock.
* If the lock is already acquired, nothing happens.
*
* @throws BrokerLockError when lock is already acquired by this object.
*/
async try(): Promise<this | undefined> {
if (this.releaser) throw new BrokerLockError(`Lock already acquired. Call release first.`);
this.releaser = await this.adapter.tryLock(this.id, this.options);
return this.releaser ? this : undefined;
}
/**
* Releases the lock.
*/
async release(): Promise<void> {
if (!this.releaser) return;
await this.releaser();
this.releaser = undefined;
}
}
export class Broker {
constructor(
private readonly adapter: BrokerAdapter
) {
}
/**
* Creates a new BrokerLock for the given id and options.
*
* The object returned can be used to acquire and release the lock.
*/
public lock(id: string, options: Partial<BrokerLockOptions> = {}): BrokerLock {
return new BrokerLock(id, this.adapter, Object.assign({ ttl: 60 * 2, timeout: 30 }, options));
}
public disconnect(): Promise<void> {
return this.adapter.disconnect();
}
protected cacheProvider: { [path: string]: (...args: any[]) => any } = {};
public provideCache<T extends BrokerCacheKey<any, any, any>>(provider: (options: T[1]) => T[2] | Promise<T[2]>, type?: ReceiveType<T>) {
type = resolveReceiveType(type);
if (type.kind !== ReflectionKind.tuple) throw new CacheError(`Invalid type given`);
if (type.types[0].type.kind !== ReflectionKind.literal) throw new CacheError(`Invalid type given`);
const path = String(type.types[0].type.literal);
this.cacheProvider[path] = provider;
}
public cache<T extends BrokerCacheKey<any, any, any>>(type?: ReceiveType<T>): BrokerCache<T> {
type = resolveReceiveType(type);
if (type.kind !== ReflectionKind.tuple) throw new CacheError(`Invalid type given`);
if (type.types[0].type.kind !== ReflectionKind.literal) throw new CacheError(`Invalid type given`);
const path = String(type.types[0].type.literal);
const provider = this.cacheProvider[path];
if (!provider) throw new CacheError(`No cache provider for cache ${type.typeName} (${path}) registered`);
return new BrokerCache<T>(path, provider, { ttl: 30, tags: [] }, this.adapter, type.types[2].type);
}
public async get<T>(key: string, builder: (options: BrokerCacheOptions) => Promise<T>, type?: ReceiveType<T>): Promise<T> {
if (!type) {
//type not manually provided via Broker.get<Type>, so we try to extract it from the builder.
const fn = reflect(builder);
if (fn.kind !== ReflectionKind.function) throw new CacheError(`Can not detect type of builder function`);
type = fn.return;
while (type.kind === ReflectionKind.promise) type = type.type;
} else {
type = resolveReceiveType(type);
}
const cache = await this.adapter.getCache(key, type);
if (cache !== undefined) return cache;
const options: BrokerCacheOptions = { ttl: 30, tags: [] };
const value = await builder(options);
await this.adapter.setCache(key, value, options, type);
return value;
}
public bus<T>(path: string, type?: ReceiveType<T>): BrokerBus<T> {
type = resolveReceiveType(type);
return new BrokerBus(path, this.adapter, type);
}
public busChannel<T extends BrokerBusChannel<any, any>>(type?: ReceiveType<T>): BrokerBus<T[1]> {
type = resolveReceiveType(type);
if (type.kind !== ReflectionKind.tuple) throw new CacheError(`Invalid type given`);
if (type.types[0].type.kind !== ReflectionKind.literal) throw new CacheError(`Invalid type given`);
const path = String(type.types[0].type.literal);
return new BrokerBus(path, this.adapter, type.types[1].type);
}
public queue<T extends BrokerQueueChannel<any, any>>(type?: ReceiveType<T>): BrokerQueue<T[1]> {
type = resolveReceiveType(type);
if (type.kind !== ReflectionKind.tuple) throw new CacheError(`Invalid type given`);
if (type.types[0].type.kind !== ReflectionKind.literal) throw new CacheError(`Invalid type given`);
const name = String(type.types[0].type.literal);
return new BrokerQueue(name, this.adapter, type.types[1].type);
}
}