Implemented In-Memory-Caching with default CacheModule

src/application/controller/papers.controller.ts

@@ -1,4 +1,4 @@
-import { Controller, Get, HttpCode, Param, ParseUUIDPipe, Req, UseInterceptors } from "@nestjs/common";
+import { CacheInterceptor, Controller, Get, HttpCode, Inject, Param, ParseUUIDPipe, Req, UseInterceptors } from "@nestjs/common";
 import { SearchService } from "../../core/services/common/search.service";
 import { PageInterceptor } from "../../core/interceptors/page.interceptor";
 import { ApiExtraModels, ApiGatewayTimeoutResponse, ApiOperation, ApiResponse, ApiTags, getSchemaPath } from "@nestjs/swagger";
@@ -13,6 +13,7 @@ import { EsHitDto, EsResponseDto, PageDto, PaperDto } from "../../core/domain";
     path: 'papers',
 })
 @ApiExtraModels(RequestDto, EsHitDto, EsResponseDto)
+// @UseInterceptors(CacheInterceptor)
 export class PapersController {
     constructor(private searchService: SearchService) {}
 

src/core/interceptors/page.interceptor.ts

@@ -1,6 +1,6 @@
 import { HttpService } from "@nestjs/axios";
-import { CallHandler, ExecutionContext, Injectable, NestInterceptor } from "@nestjs/common";
+import { CACHE_MANAGER, CallHandler, ExecutionContext, Inject, Injectable, NestInterceptor } from "@nestjs/common";
-import { Observable, map, take } from "rxjs";
+import { Observable, map, take, switchMap } from "rxjs";
 import { PageDto } from "../domain/dtos";
 import { EsQueryDto } from "../domain/dtos/elastic/es-query.dto";
 import { RequestDto } from "../domain/dtos/request.dto";
@@ -9,62 +9,7 @@ import { EsTime } from "../domain/enums/es-time.enum";
 import { Order } from "../domain/enums/page-order.enum";
 import { PageMeta } from "../domain/interfaces";
 import { EsPit } from "../domain/interfaces/elastic/es-pit.interface";
-
+import { Cache } from 'cache-manager'
-/**
- * Previous search data storage
- */
-class PrevSearch {
-    /**
-     * Constructs an uninitialized object
-     */
-    constructor() {
-        this.pit = undefined;
-        this.tiebreaker = undefined;
-        this.prevPage = -1;
-    }
-
-    /**
-     * PIT object of the previous search
-     */
-    private pit: EsPit;
-    set _pit(pit: EsPit) {
-        this.pit = pit;
-    }
-    get _pit(): EsPit {
-        return this.pit;
-    }
-
-    /**
-     * Tiebreaker and sort parameters
-     */
-    private tiebreaker: unknown[];
-    set _tiebreaker(tiebreaker: unknown[]) {
-        this.tiebreaker = tiebreaker;
-    }
-    get _tiebreaker(): unknown[] {
-        return this.tiebreaker;
-    }
-
-    /**
-     * Number of the previous page
-     */
-    private prevPage: number;
-    set _prevPage(page: number) {
-        this.prevPage = page;
-    }
-    get _prevPage(): number {
-        return this.prevPage;
-    }
-
-    /**
-     * Checks if there was the search before current one
-     * @returns true/false, showing whether or not there was another search before
-     */
-    public isSet(): boolean {
-        if (this.pit && this.tiebreaker && this.prevPage !== -1) return true;
-        return false;
-    }
-}
 
 /**
  * Pagination-implementing interceptor
@@ -76,9 +21,20 @@ export class PageInterceptor implements NestInterceptor {
      * @param httpService
      * @param searchService
      */
-    constructor(private readonly httpService: HttpService) {
+    constructor(
-        this.prevSearch = new PrevSearch;
+        private readonly httpService: HttpService,
-    }
+        @Inject(CACHE_MANAGER) private cacheManager: Cache
+    ) {}
+
+    /**
+     * Elastichsearch server port-number
+     */
+    private readonly ES_PORT = process.env.ES_PORT;
+
+    /**
+     * Elastichsearch IP address
+     */
+     private readonly ES_IP = process.env.ES_CONTAINER_NAME;
 
     /**
      * Override of intercept() method, specified in NestInterceptor interface
@@ -87,12 +43,11 @@ export class PageInterceptor implements NestInterceptor {
      * @returns Page with content and metadata
      */
     async intercept(context: ExecutionContext, next: CallHandler<any>): Promise<Observable<PageDto>> {
-        let request: RequestDto = context.switchToHttp().getRequest<RequestDto>();
+        const request: RequestDto = context.switchToHttp().getRequest<RequestDto>();
         const query: SearchQueryDto = request.query;
         let reverse: boolean = false;
 
         request.es_query = new EsQueryDto();
-
         request.es_query.query = {
             query_string: {
                 query: query.query,
@@ -104,31 +59,27 @@ export class PageInterceptor implements NestInterceptor {
             { _shard_doc: 'desc' }
         ];
 
-        if (this.prevSearch.isSet()) {
+        const limit = !query?.limit ? 10 : query.limit;
-            request.es_query.pit = this.prevSearch._pit;
-            request.es_query.search_after = this.prevSearch._tiebreaker;
 
-            let limit = !query?.limit ? 10 : query.limit;
+        if (await this.cacheManager.get('prevPage')) {
-            request.es_query.size = limit * Math.abs(query.page - this.prevSearch._prevPage);
+            if (query.page == (await this.cacheManager.get('_pagenum'))) return await this.cacheManager.get('prevPage');
 
-            if (query.page < this.prevSearch._prevPage) {
+            request.es_query.pit = await this.cacheManager.get('_pit');
-                request.es_query.sort = [{ _score: { order: 'asc' } }];
+            request.es_query.search_after = await this.cacheManager.get('_sa');
+            request.es_query.size = limit * Math.abs(query.page - (await this.cacheManager.get('_pagenum')));
+
+            if (query.page < (await this.cacheManager.get('_pagenum'))) {
+                request.es_query.sort = [{ _score: { order: Order.ASC } }];
                 request.es_query.size += limit - 1;
                 reverse = true;
-            } else if (query.page == this.prevSearch._prevPage) {
-                // Caching should be HERE
-                request.es_query.sort = [{ _score: { order: 'asc' } }];
-                reverse = true;
             }
         } else {
-            this.prevSearch._pit = request.es_query.pit = await this.getPIT(1);
+            request.es_query.pit = await this.getPIT(1);
-
-            let limit = !query?.limit ? 10 : query.limit;
             request.es_query.size = limit * query.page;
         }
 
         return next.handle().pipe(
-            map((res) => {
+            switchMap(async (res) => {
                 // Setting the page meta-data
                 let meta: PageMeta = {
                     total: res.hits.total.value,
@@ -142,14 +93,14 @@ export class PageInterceptor implements NestInterceptor {
                 meta.hasPrev = meta.pagenum != 1 ? true : false;
 
                 // Saving the search info
-                this.prevSearch._pit.id = res.pit_id;
+                await this.cacheManager.set('_pit', { id: res.pit_id, keep_alive: `1${EsTime.min}` })
-                this.prevSearch._tiebreaker = res.hits.hits[res.hits.hits.length - 1]?.sort;
+                await this.cacheManager.set('_sa', res.hits.hits[res.hits.hits.length - 1]?.sort);
-                this.prevSearch._prevPage = query.page;
+                await this.cacheManager.set('_pagenum', query.page);
 
                 // Check if the performed search is a backwards search
                 let data = res.hits.hits.slice(-meta.pagesize);
                 if (reverse) {
-                    this.prevSearch._tiebreaker = data[0]?.sort;
+                    this.cacheManager.set('_sa', data[0]?.sort);
                     data.reverse();
                     reverse = false;
                 }
@@ -157,27 +108,14 @@ export class PageInterceptor implements NestInterceptor {
                 // Omitting the redundant info and leaving only the document
                 data = data.map((el) => el._source);
 
-                // Return the page
+                // Cache and return the page
-                return new PageDto(data, meta);
+                const page: PageDto = new PageDto(data, meta);
+                await this.cacheManager.set('prevPage', page);
+                return page;
             })
         );
     }
 
-    /**
-     * Elastichsearch server port-number
-     */
-    private readonly ES_PORT = process.env.ES_PORT;
-
-    /**
-     * Elastichsearch IP address
-     */
-     private readonly ES_IP = process.env.ES_CONTAINER_NAME;
-
-    /**
-     * Info about previously completed search
-     */
-    private prevSearch: PrevSearch;
-
     /**
      * Acquires a PIT ID from Elasticsearch, needed for a request
      * @param alive, amount of time in minutes (defaults to 1). If time unit is not specified - defaults to minutes.

src/infrastructure/modules/search.module.ts

@@ -1,5 +1,5 @@
 import { HttpModule } from "@nestjs/axios";
-import { Module } from "@nestjs/common";
+import { CacheModule, Module } from "@nestjs/common";
 import { PapersController } from "../../application";
 import { SearchService } from "../../core/services/common/search.service";
 
@@ -9,6 +9,7 @@ import { SearchService } from "../../core/services/common/search.service";
 @Module({
     imports: [
         HttpModule,
+        CacheModule.register(),
     ],
     exports: [SearchService],
     providers: [SearchService],

src/test/e2e/papers.controller.e2e.spec.ts

@@ -75,7 +75,7 @@ describe('E2E Testing of /papers', () => {
         let httpGetSpy = jest.spyOn(httpService, 'get').mockReturnValueOnce(axiosRes);
 
         const test = await request(app.getHttpServer())
-            .get('/papers/2d3dc418-7778-abab-b33f-3d63aa25db41') // ??? Fetch a random object from DB
+            .get('/papers/2d3dc418-7778-abab-b33f-3d63aa25db41')
             .expect(200);
 
         // Expect HttpService.get() method to be touched

src/test/page.interceptor.spec.ts

@@ -1,4 +1,5 @@
 import { HttpService } from "@nestjs/axios";
+import { CacheModule, CACHE_MANAGER } from "@nestjs/common";
 import { ConfigModule } from "@nestjs/config";
  import { Test } from "@nestjs/testing";
 import { Observable, of } from "rxjs";
@@ -44,7 +45,8 @@ describe('Unit tests for PageInterceptor', () => {
                     isGlobal: true,
                     cache: true,
                     expandVariables: true,
-                })
+                }),
+                CacheModule.register()
             ],
         }).compile();
 
@@ -159,7 +161,7 @@ describe('Unit tests for PageInterceptor', () => {
             });
         });
 
-        it('Should reverse the search results', () => {
+        it('Should reverse the search results', async () => {
             execCtxMock.getRequest.mockReturnValueOnce({
                 query: {
                     page: 1,
@@ -168,10 +170,8 @@ describe('Unit tests for PageInterceptor', () => {
                 }
             });
 
-            pageInter['prevSearch']._prevPage = 3;
+            await pageInter['cacheManager'].set('_pagenum', 3);
-            pageInter['prevSearch'].isSet = jest.fn().mockImplementationOnce(() => {
+            await pageInter['cacheManager'].set('prevPage', { set: "yes" });
-                return true;
-            })
 
             callHandlerMock.handle.mockReturnValueOnce(
                 of({
@@ -187,8 +187,8 @@ describe('Unit tests for PageInterceptor', () => {
             );
 
             pageInter.intercept(execCtxMock, callHandlerMock).then((res) => {
-                res.subscribe((page) => {
+                res.subscribe(async (page) => {
-                    expect(pageInter['prevSearch']._tiebreaker).toEqual(['1', 'less relevant']);
+                    expect(await pageInter['cacheManager'].get('_sa')).toEqual(['1', 'less relevant']);
                     expect(page.data).toEqual(['3', '2', '1']);
                 });
             });
@@ -315,4 +315,8 @@ describe('Unit tests for PageInterceptor', () => {
             expect(pageInter.deletePIT('')).resolves.toBe(true);
         });
     });
+
+    afterEach(() => {
+        pageInter['cacheManager'].reset();
+    })
 });

src/test/papers.controller.spec.ts

@@ -1,5 +1,5 @@
 import { HttpModule } from "@nestjs/axios";
-import { NotFoundException } from "@nestjs/common";
+import { CacheModule, NotFoundException } from "@nestjs/common";
 import { Test } from "@nestjs/testing";
 import { PapersController } from "src/application";
 import { SearchService } from "src/core/services/common/search.service";
@@ -21,7 +21,10 @@ describe('Unit tests for PapersController', () => {
                     }
                 }
             ],
-            imports: [HttpModule]
+            imports: [
+                HttpModule,
+                CacheModule.register()
+            ]
         }).compile();
 
         papersController = moduleRef.get(PapersController);