ref(replay): Make session a POJO

To trim down bundle size a bit.

Author: mydea

packages/replay/src/session/Session.ts

@@ -5,7 +5,7 @@ import { isSampled } from '../util/isSampled';
 
 type Sampled = false | 'session' | 'error';
 
-export interface SessionObject {
+export interface Session {
   id: string;
 
   /**
@@ -24,52 +24,34 @@ export interface SessionObject {
   segmentId: number;
 
   /**
-   * Is the session sampled? `null` if the sampled, otherwise, `session` or `error`
+   * The ID of the previous session.
+   * If this is empty, there was no previous session.
+   */
+  previousSessionId?: string;
+
+  /**
+   * Is the session sampled? `false` if not sampled, otherwise, `session` or `error`
    */
   sampled: Sampled;
 }
 
 /**
- * A wrapper for the session object that handles sampling.
+ * Get a session with defaults & applied sampling.
  */
-export class Session {
-  /**
-   * Session ID
-   */
-  public readonly id: string;
-
-  /**
-   * Start time of current session
-   */
-  public started: number;
-
-  /**
-   * Last known activity of the session
-   */
-  public lastActivity: number;
-
-  /**
-   * Sequence ID specific to replay updates
-   */
-  public segmentId: number;
-
-  /**
-   * Previous session ID
-   */
-  public previousSessionId: string | undefined;
-
-  /**
-   * Is the Session sampled?
-   */
-  public readonly sampled: Sampled;
-
-  public constructor(session: Partial<SessionObject> = {}, { sessionSampleRate, errorSampleRate }: SampleRates) {
-    const now = new Date().getTime();
-    this.id = session.id || uuid4();
-    this.started = session.started ?? now;
-    this.lastActivity = session.lastActivity ?? now;
-    this.segmentId = session.segmentId ?? 0;
-    this.sampled =
-      session.sampled ?? (isSampled(sessionSampleRate) ? 'session' : isSampled(errorSampleRate) ? 'error' : false);
-  }
+export function makeSession(session: Partial<Session>, { sessionSampleRate, errorSampleRate }: SampleRates): Session {
+  const now = new Date().getTime();
+  const id = session.id || uuid4();
+  const started = session.started ?? now;
+  const lastActivity = session.lastActivity ?? now;
+  const segmentId = session.segmentId ?? 0;
+  const sampled =
+    session.sampled ?? (isSampled(sessionSampleRate) ? 'session' : isSampled(errorSampleRate) ? 'error' : false);
+
+  return {
+    id,
+    started,
+    lastActivity,
+    segmentId,
+    sampled,
+  };
 }

packages/replay/src/session/createSession.ts

@@ -2,18 +2,21 @@ import { logger } from '@sentry/utils';
 
 import { SessionOptions } from '../types';
 import { saveSession } from './saveSession';
-import { Session } from './Session';
+import { makeSession, Session } from './Session';
 
 /**
  * Create a new session, which in its current implementation is a Sentry event
  * that all replays will be saved to as attachments. Currently, we only expect
  * one of these Sentry events per "replay session".
  */
 export function createSession({ sessionSampleRate, errorSampleRate, stickySession = false }: SessionOptions): Session {
-  const session = new Session(undefined, {
-    errorSampleRate,
-    sessionSampleRate,
-  });
+  const session = makeSession(
+    {},
+    {
+      errorSampleRate,
+      sessionSampleRate,
+    },
+  );
 
   __DEBUG_BUILD__ && logger.log(`[Replay] Creating new session: ${session.id}`);
 

packages/replay/src/session/fetchSession.ts

@@ -1,6 +1,6 @@
 import { REPLAY_SESSION_KEY, WINDOW } from '../constants';
 import { SampleRates } from '../types';
-import { Session } from './Session';
+import { makeSession, Session } from './Session';
 
 /**
  * Fetches a session from storage
@@ -22,7 +22,7 @@ export function fetchSession({ sessionSampleRate, errorSampleRate }: SampleRates
 
     const sessionObj = JSON.parse(sessionStringFromStorage);
 
-    return new Session(sessionObj, { sessionSampleRate, errorSampleRate });
+    return makeSession(sessionObj, { sessionSampleRate, errorSampleRate });
   } catch {
     return null;
   }

packages/replay/test/unit/session/Session.test.ts

@@ -26,7 +26,7 @@ jest.mock('@sentry/utils', () => {
 import * as Sentry from '@sentry/browser';
 
 import { WINDOW } from '../../../src/constants';
-import { Session } from '../../../src/session/Session';
+import { makeSession } from '../../../src/session/Session';
 
 type CaptureEventMockType = jest.MockedFunction<typeof Sentry.captureEvent>;
 
@@ -39,34 +39,43 @@ afterEach(() => {
 });
 
 it('does not sample', function () {
-  const newSession = new Session(undefined, {
-    sessionSampleRate: 0.0,
-    errorSampleRate: 0.0,
-  });
+  const newSession = makeSession(
+    {},
+    {
+      sessionSampleRate: 0.0,
+      errorSampleRate: 0.0,
+    },
+  );
 
   expect(newSession.sampled).toBe(false);
 });
 
 it('samples using `sessionSampleRate`', function () {
-  const newSession = new Session(undefined, {
-    sessionSampleRate: 1.0,
-    errorSampleRate: 0.0,
-  });
+  const newSession = makeSession(
+    {},
+    {
+      sessionSampleRate: 1.0,
+      errorSampleRate: 0.0,
+    },
+  );
 
   expect(newSession.sampled).toBe('session');
 });
 
 it('samples using `errorSampleRate`', function () {
-  const newSession = new Session(undefined, {
-    sessionSampleRate: 0,
-    errorSampleRate: 1.0,
-  });
+  const newSession = makeSession(
+    {},
+    {
+      sessionSampleRate: 0,
+      errorSampleRate: 1.0,
+    },
+  );
 
   expect(newSession.sampled).toBe('error');
 });
 
 it('does not run sampling function if existing session was sampled', function () {
-  const newSession = new Session(
+  const newSession = makeSession(
     {
       sampled: 'session',
     },

packages/replay/test/unit/session/fetchSession.test.ts

@@ -1,6 +1,5 @@
 import { REPLAY_SESSION_KEY, WINDOW } from '../../../src/constants';
 import { fetchSession } from '../../../src/session/fetchSession';
-import { sessionToJSON } from '../../utils/sessionToJson';
 
 const oldSessionStorage = WINDOW.sessionStorage;
 
@@ -27,7 +26,7 @@ it('fetches a valid and sampled session', function () {
     '{"id":"fd09adfc4117477abc8de643e5a5798a","sampled": true,"started":1648827162630,"lastActivity":1648827162658}',
   );
 
-  expect(sessionToJSON(fetchSession(SAMPLE_RATES)!)).toEqual({
+  expect(fetchSession(SAMPLE_RATES)).toEqual({
     id: 'fd09adfc4117477abc8de643e5a5798a',
     lastActivity: 1648827162658,
     segmentId: 0,

packages/replay/test/unit/session/getSession.test.ts

@@ -3,8 +3,7 @@ import * as CreateSession from '../../../src/session/createSession';
 import * as FetchSession from '../../../src/session/fetchSession';
 import { getSession } from '../../../src/session/getSession';
 import { saveSession } from '../../../src/session/saveSession';
-import { Session } from '../../../src/session/Session';
-import { sessionToJSON } from '../../utils/sessionToJson';
+import { makeSession } from '../../../src/session/Session';
 
 jest.mock('@sentry/utils', () => {
   return {
@@ -19,7 +18,7 @@ const SAMPLE_RATES = {
 };
 
 function createMockSession(when: number = new Date().getTime()) {
-  return new Session(
+  return makeSession(
     {
       id: 'test_session_id',
       segmentId: 0,
@@ -53,7 +52,7 @@ it('creates a non-sticky session when one does not exist', function () {
   expect(FetchSession.fetchSession).not.toHaveBeenCalled();
   expect(CreateSession.createSession).toHaveBeenCalled();
 
-  expect(sessionToJSON(session)).toEqual({
+  expect(session).toEqual({
     id: 'test_session_id',
     segmentId: 0,
     lastActivity: expect.any(Number),
@@ -85,7 +84,7 @@ it('creates a non-sticky session, when one is expired', function () {
     expiry: 1000,
     stickySession: false,
     ...SAMPLE_RATES,
-    currentSession: new Session(
+    currentSession: makeSession(
       {
         id: 'old_session_id',
         lastActivity: new Date().getTime() - 1001,
@@ -116,7 +115,7 @@ it('creates a sticky session when one does not exist', function () {
   expect(FetchSession.fetchSession).toHaveBeenCalled();
   expect(CreateSession.createSession).toHaveBeenCalled();
 
-  expect(sessionToJSON(session)).toEqual({
+  expect(session).toEqual({
     id: 'test_session_id',
     segmentId: 0,
     lastActivity: expect.any(Number),
@@ -125,7 +124,7 @@ it('creates a sticky session when one does not exist', function () {
   });
 
   // Should not have anything in storage
-  expect(sessionToJSON(FetchSession.fetchSession(SAMPLE_RATES)!)).toEqual({
+  expect(FetchSession.fetchSession(SAMPLE_RATES)).toEqual({
     id: 'test_session_id',
     segmentId: 0,
     lastActivity: expect.any(Number),
@@ -148,7 +147,7 @@ it('fetches an existing sticky session', function () {
   expect(FetchSession.fetchSession).toHaveBeenCalled();
   expect(CreateSession.createSession).not.toHaveBeenCalled();
 
-  expect(sessionToJSON(session)).toEqual({
+  expect(session).toEqual({
     id: 'test_session_id',
     segmentId: 0,
     lastActivity: now,
@@ -181,7 +180,7 @@ it('fetches a non-expired non-sticky session', function () {
     expiry: 1000,
     stickySession: false,
     ...SAMPLE_RATES,
-    currentSession: new Session(
+    currentSession: makeSession(
       {
         id: 'test_session_id_2',
         lastActivity: +new Date() - 500,

packages/replay/test/unit/session/saveSession.test.ts

@@ -1,6 +1,6 @@
 import { REPLAY_SESSION_KEY, WINDOW } from '../../../src/constants';
 import { saveSession } from '../../../src/session/saveSession';
-import { Session } from '../../../src/session/Session';
+import { makeSession } from '../../../src/session/Session';
 
 beforeAll(() => {
   WINDOW.sessionStorage.clear();
@@ -11,7 +11,7 @@ afterEach(() => {
 });
 
 it('saves a valid session', function () {
-  const session = new Session(
+  const session = makeSession(
     {
       id: 'fd09adfc4117477abc8de643e5a5798a',
       segmentId: 0,

packages/replay/test/unit/util/isSessionExpired.test.ts

@@ -1,8 +1,8 @@
-import { Session } from '../../../src/session/Session';
+import { makeSession } from '../../../src/session/Session';
 import { isSessionExpired } from '../../../src/util/isSessionExpired';
 
 function createSession(extra?: Record<string, any>) {
-  return new Session(
+  return makeSession(
     {
       started: 0,
       lastActivity: 0,