feat(db): Implement db cache (Closes #72)

For most frequent db request we want to implement cache
which will decrease db usage

src/env.ts

@@ -27,6 +27,8 @@ export const ngRokToken: string = process.env.NGROK_TOKEN || "";
 export const authorTelegramAccount: string =
   process.env.AUTHOR_TELEGRAM_ACCOUNT || "";
 
+export const cacheSize: number = Number(process.env.CACHE_SIZE) || 50;
+
 export const googleApi = {
   projectId: process.env.GOOGLE_PROJECT_ID || "",
   clientEmail: process.env.GOOGLE_CLIENT_EMAIL || "",

src/scripts/chart.ts

@@ -5,10 +5,11 @@ import { resolve as resolvePath } from "path";
 import { Logger } from "../logger";
 import { appPort, enableSSL } from "../env";
 import { httpsCert, httpsKey } from "../../certs";
+import { sSuffix } from "../text";
 
-export function run(): void {
-  const logger = new Logger("chart");
+const logger = new Logger("chart-script");
 
+export function run(): void {
   const chartHtml = resolvePath(__dirname, "../chart/index.html");
 
   const app = express();
@@ -18,7 +19,7 @@ export function run(): void {
     res.status(200).sendFile(chartHtml);
   });
 
-  logger.info(`Starting ${logger.y(`http${enableSSL ? "s" : ""}`)} server`);
+  logger.info(`Starting ${logger.y(sSuffix("http", enableSSL))} server`);
 
   const httpsOptions = {
     cert: httpsCert,

src/scripts/dev.ts

@@ -9,6 +9,7 @@ import {
   ngRokToken,
   authorTelegramAccount,
   appVersion,
+  cacheSize,
 } from "../env";
 import { Logger } from "../logger";
 import { VoiceConverterOptions } from "../recognition/types";
@@ -21,7 +22,7 @@ import { StatisticApi } from "../statistic";
 import { TelegramBotModel } from "../telegram/bot";
 import { ExpressServer } from "../server/express";
 
-const logger = new Logger("run handler");
+const logger = new Logger("dev-script");
 
 export function run(): void {
   const server = new ExpressServer(appPort, enableSSL, appVersion);
@@ -39,7 +40,8 @@ export function run(): void {
     dbStat.statUrl,
     dbStat.appId,
     dbStat.appKey,
-    dbStat.masterKey
+    dbStat.masterKey,
+    cacheSize
   );
   const bot = new TelegramBotModel(telegramBotApi, converter, stat).setAuthor(
     authorTelegramAccount

src/scripts/start.ts

@@ -11,6 +11,7 @@ import {
   authorTelegramAccount,
   appVersion,
   ngRokToken,
+  cacheSize,
 } from "../env";
 import {
   getVoiceConverterInstance,
@@ -23,7 +24,7 @@ import { TelegramBotModel } from "../telegram/bot";
 import { ExpressServer } from "../server/express";
 import { getHostName } from "../server/tunnel";
 
-const logger = new Logger("run handler");
+const logger = new Logger("start-script");
 
 export function run(): void {
   const server = new ExpressServer(appPort, enableSSL, appVersion);
@@ -42,7 +43,8 @@ export function run(): void {
     dbStat.statUrl,
     dbStat.appId,
     dbStat.appKey,
-    dbStat.masterKey
+    dbStat.masterKey,
+    cacheSize
   );
   const bot = new TelegramBotModel(telegramBotApi, converter, stat).setAuthor(
     authorTelegramAccount

src/server/express.ts

@@ -8,6 +8,7 @@ import { HealthDto, HealthSsl, HealthStatus } from "./types";
 import { runGetDto } from "./request";
 import { StatisticApi } from "../statistic";
 import { sleepForRandom } from "../common/timer";
+import { sSuffix } from "../text";
 
 const logger = new Logger("server");
 
@@ -84,9 +85,10 @@ export class ExpressServer {
   public setBots(bots: TelegramBotModel[] = []): this {
     this.bots = bots;
     logger.info(
-      `Requested ${logger.y(bots.length)} bot${
-        bots.length === 1 ? "" : "s"
-      } to set up`
+      `Requested ${logger.y(bots.length)} ${sSuffix(
+        "bot",
+        bots.length
+      )} to set up`
     );
 
     bots.forEach((bot) => {
@@ -119,9 +121,7 @@ export class ExpressServer {
   }
 
   public start(): Promise<() => Promise<void>> {
-    logger.info(
-      `Starting ${logger.y(`http${this.isHttps ? "s" : ""}`)} server`
-    );
+    logger.info(`Starting ${logger.y(sSuffix("http", this.isHttps))} server`);
 
     const server = this.isHttps
       ? createHttps(this.httpsOptions, this.app)
@@ -172,9 +172,9 @@ export class ExpressServer {
     this.nextReplicaUrl = nextReplicaUrl;
     this.daysRunning = [];
     logger.info(
-      `Lifecycle interval is set to ${logger.y(this.lifecycleInterval)} day${
-        this.lifecycleInterval === 1 ? "" : "s"
-      }`
+      `Lifecycle interval is set to ${logger.y(
+        this.lifecycleInterval
+      )} ${sSuffix("day", this.lifecycleInterval)}`
     );
 
     sleepForRandom()

src/statistic/cache.ts

@@ -0,0 +1,118 @@
+import { Logger } from "../logger";
+import { sSuffix } from "../text";
+
+const logger = new Logger("cache");
+
+export class CacheProvider<Data, UniqId extends keyof Data> {
+  private cache: Data[] = [];
+
+  constructor(
+    private readonly cacheSize: number,
+    private readonly idKey: UniqId
+  ) {
+    if (!this.hasCacheEnabled()) {
+      logger.warn(
+        `Cache size cacheSize=${cacheSize}, so the cache is turned off for ${logger.y(
+          idKey
+        )}`
+      );
+    } else {
+      logger.info(
+        `Cache size is cacheSize=${logger.y(cacheSize)} ${sSuffix(
+          "item",
+          cacheSize
+        )} initialized for ${logger.y(idKey)}`
+      );
+    }
+  }
+
+  public addItem(item: Data): void {
+    if (!this.hasCacheEnabled()) {
+      return;
+    }
+
+    if (!item[this.idKey]) {
+      logger.error(
+        `The item with ${this.idKey}=${
+          item[this.idKey]
+        } can not have empty index value. Caching skipped`,
+        new Error("Cache item can not have empty index value")
+      );
+      return;
+    }
+
+    const existingItem = this.cache.find(
+      (cItem) => cItem[this.idKey] === item[this.idKey]
+    );
+    if (existingItem) {
+      logger.warn(
+        `The item with ${this.idKey}=${
+          item[this.idKey]
+        } is already exists. Removing old data from the cache`
+      );
+
+      this.removeItem(item[this.idKey]);
+    }
+
+    const newCacheData = [...this.cache, item];
+
+    if (newCacheData.length > this.cacheSize) {
+      logger.warn(
+        `Cache storage exceeds the limit of ${this.cacheSize} ${sSuffix(
+          "item",
+          this.cacheSize
+        )} and have a size of ${
+          newCacheData.length
+        }. Old records will be removed to keep storage under the limit`
+      );
+    }
+
+    this.cache = newCacheData.slice(
+      Math.max(newCacheData.length - this.cacheSize, 0)
+    );
+
+    logger.info(
+      `Added cache item with ${this.idKey}=${item[this.idKey]}. Cache size=${
+        this.cache.length
+      }`
+    );
+  }
+
+  public getItem(idValue: Data[UniqId]): Data | null {
+    if (!this.hasCacheEnabled()) {
+      return null;
+    }
+
+    const cachedItem = this.cache.find(
+      (cItem) => cItem[this.idKey] === idValue
+    );
+
+    if (!cachedItem) {
+      logger.info(
+        `Did not find the item with ${this.idKey}=${idValue} in cache`
+      );
+      return null;
+    }
+
+    logger.info(
+      `Found the item with ${this.idKey}=${idValue} in cache. Skipping DB request`
+    );
+    return cachedItem;
+  }
+
+  public removeItem(idValue: Data[UniqId]): void {
+    if (!this.hasCacheEnabled()) {
+      return;
+    }
+
+    this.cache = this.cache.filter((cItem) => cItem[this.idKey] !== idValue);
+
+    logger.info(
+      `Removed cache item for ${this.idKey}=${idValue}. Cache size=${this.cache.length}`
+    );
+  }
+
+  private hasCacheEnabled(): boolean {
+    return this.cacheSize > 0;
+  }
+}

src/statistic/index.ts

@@ -9,9 +9,16 @@ export class StatisticApi {
     statUrl: string,
     appId: string,
     appKey: string,
-    masterKey: string
+    masterKey: string,
+    cacheSize: number
   ) {
     this.node = new NodeStatisticApi(statUrl, appId, appKey, masterKey);
-    this.usage = new UsageStatisticApi(statUrl, appId, appKey, masterKey);
+    this.usage = new UsageStatisticApi(
+      statUrl,
+      appId,
+      appKey,
+      masterKey,
+      cacheSize
+    );
   }
 }

src/statistic/nodes.ts

@@ -1,14 +1,9 @@
 import Parse from "parse/node";
 import { Logger } from "../logger";
+import { NodeStatKey } from "./types";
 
 const logger = new Logger("db");
 
-enum StatKey {
-  Active = "active",
-  SelfUrl = "selfUrl",
-  Version = "version",
-}
-
 export class NodeStatisticApi {
   private readonly dbClass = "NodeStat";
 
@@ -40,8 +35,8 @@ export class NodeStatisticApi {
   ): Promise<void> {
     logger.info(`Updating active state for ${logger.y(instance.id)}`);
 
-    instance.set(StatKey.Active, active);
-    instance.set(StatKey.Version, version);
+    instance.set(NodeStatKey.Active, active);
+    instance.set(NodeStatKey.Version, version);
     return instance.save().then(() => {
       // Empty promise result
     });
@@ -56,9 +51,9 @@ export class NodeStatisticApi {
 
     const NodeStatClass = Parse.Object.extend(this.dbClass);
     const instance = new NodeStatClass();
-    instance.set(StatKey.SelfUrl, selfUrl);
-    instance.set(StatKey.Active, active);
-    instance.set(StatKey.Version, version);
+    instance.set(NodeStatKey.SelfUrl, selfUrl);
+    instance.set(NodeStatKey.Active, active);
+    instance.set(NodeStatKey.Version, version);
     return instance.save().then((stat: Parse.Object) => stat.id);
   }
 
@@ -75,7 +70,8 @@ export class NodeStatisticApi {
 
     const NodeStatClass = Parse.Object.extend(this.dbClass);
     const query = new Parse.Query(NodeStatClass);
-    query.equalTo(StatKey.SelfUrl, selfUrl);
+    query.equalTo(NodeStatKey.SelfUrl, selfUrl);
+
     return query.find().then((results) => {
       if (!results.length) {
         return Promise.reject(new Error(`Record ${selfUrl} not found`));

src/statistic/types.ts

@@ -0,0 +1,19 @@
+import { LanguageCode } from "../recognition/types";
+
+export enum NodeStatKey {
+  Active = "active",
+  SelfUrl = "selfUrl",
+  Version = "version",
+}
+
+export enum UsageStatKey {
+  UsageCount = "usageCount",
+  LangId = "langId",
+  ChatId = "chatId",
+  UserName = "user",
+}
+
+export interface UsageStatCache {
+  [UsageStatKey.ChatId]: number;
+  [UsageStatKey.LangId]: LanguageCode;
+}