@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, described 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.

Using @cacheBy

Since v2.0.0 @cacheBy decorator introduced and helps simplify caching invalidation definition for those service methods which rely on a root sequelize model output. In combination of passing the fields map to such service methods it will also provide more efficient caching for the method calls.

Take a look at such example:

import { IMQService, expose } from '@imqueue/rpc';
import { PgCache, cacheBy } from '@imqueue/pg-cache';
import {
    FieldsInput,
    FindOptions,
    OrderByInput,
    PaginationInput,
    query,
} from '@imqueue/sequelize';
import { cacheConfig } from '../config';
import { MyDbEntity } from './orm/models';
import { MyDbEntityFilter } from './types';
import withRangeFilters = query.withRangeFilters;
import autoCountQuery = query.autoCountQuery;
import autoQuery = query.autoQuery;
import toWhereOptions = query.toWhereOptions;
import toLimitOptions = query.toLimitOptions;
import toOrderOptions = query.toOrderOptions;

@PgCache(cacheConfig)
class MyCoolService extends IMQService {
    @expose()
    @cacheBy(MyDbEntity, { fieldsArg: 1 })
    public async listEntities(
        filter?: MyDbEntityFilter,
        fields?: FieldsInput,
        pageOptions?: PaginationInput,
        orderBy?: OrderByInput,
    ): Promise<{ total: number, data: MyDbEntity[] }> {
        const where = toWhereOptions<MyDbEntityFilter>(
            withRangeFilters(filter),
            MyDbEntityFilter,
        );
        const countQuery = autoCountQuery(MyDbEntity, fields, where);
        const findQuery = autoQuery<FindOptions>(
            MyDbEntity, fields, where,
            toLimitOptions<MyDbEntity>(pageOptions),
            toOrderOptions(orderBy),
        );
        const [total, data] = await Promise.all([
            MyDbEntity.count(countQuery),
            MyDbEntity.findAll(findQuery),
        ]);

        return { total, data } as { total: number, data: MyDbEntity[] };
    }
}

By doing so, @cacheBy will take care of invalidating only those queries which has selection of fields matching db changes events, so if the actual query was not selecting some joined data, but there was a change only on that joined data - cache won't invalidate, as far as real selection was not influenced by a data change. And yes, it will automatically monitor all related to the root model entities for changes and match them with runtime selections. This makes caching more efficient and more obvious for developer.

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
    ) => payload.operation === ChannelOperation.DELETE,
}})

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!