@imqueue/pg-cache

@imqueue/pg-cache

Links @imqueue/pg-pubsub with @imqueue/tag-cache and provides generic way to implement intellectual cache management based on database changes notifications for @imqueue-based service methods.

Usage

import { IMQService, expose } from '@imqueue/rpc';
import { PgCache, cacheWith } from '@imqueue/pg-cache';
import { MyDbEntity } from './orm/models';

@PgCache({
    postgres: 'postgres://localhost:5432/db-name',
    redis: { host: 'localhost', port: 6379 },
    prefix: 'my-cool-service', // optional, if not passed will use class name as prefix
})
class MyCoolService extends IMQService {
    @expose()
    @cacheWith({ channels: [MyDbEnity.tableName] })
    public async listEntities(): Promise<MyDbEntity> {
        return await MyDbEntity.findAll();
    }
}

With the setup, descibed above first call to MyCoolService.listEntities() will save method return value to cache and each next call will return cached value, stored in redis instead of making database query. Each function call is signed by a call signature, so if your method accepts arguments which influence database query execution caching is made for each unique method call. Cached result will be automatically invalidated each time each table described in channels will trigger INSERT, UPDATE or DELETE. Or when TTL on a cache entity expires. By default TTL is 24 hours. If you want different TTL to be used, do it as:

@cacheWith({ channels: [MyDbEnity.tableName], ttl: 5 * 60 * 1000 })

In this example TTL is set to 5 minutes. TTL should be provided in milliseconds.

Extended channels API

import { cacheWith, ChannelOperation, ChannelPayload } from '@imqueue/pg-cache';

// using simple filtering by operation
@cacheWith({ channels: {
    [MyDbEnity.tableName]: [ChannelOperation.UPDATE, ChannelOperation.INSERT]
}})

// or by using custom filtering function
@cacheWith({ channels: {
    [MyDbEnity.tableName]: (
        payload: ChannelPayload, // payload caught from db event
        args: any[],             // method runtime arguments
    ) => payload.record.id === args.id,
}})

Contributing

Any contributions are greatly appreciated. Feel free to fork, propose PRs, open issues, do whatever you think may be helpful to this project. PRs which passes all tests and do not brake tslint rules are first-class candidates to be accepted!

License

ISC

Happy Coding!