chore: add sync backoff mechanism checks (#2786)

packages/services/src/Domain/Sync/SyncBackoffService.spec.ts

@@ -0,0 +1,55 @@
+import { AnyItemInterface } from '@standardnotes/models'
+import { SyncBackoffService } from './SyncBackoffService'
+
+describe('SyncBackoffService', () => {
+  const createService = () => new SyncBackoffService()
+
+  it('should not be in backoff if no backoff was set', () => {
+    const service = createService()
+
+    expect(service.isItemInBackoff({ uuid: '123' } as jest.Mocked<AnyItemInterface>)).toBe(false)
+  })
+
+  it('should be in backoff if backoff was set', () => {
+    const service = createService()
+
+    service.backoffItem({ uuid: '123' } as jest.Mocked<AnyItemInterface>)
+
+    expect(service.isItemInBackoff({ uuid: '123' } as jest.Mocked<AnyItemInterface>)).toBe(true)
+  })
+
+  it('should not be in backoff if backoff expired', () => {
+    const service = createService()
+
+    jest.spyOn(Date, 'now').mockReturnValueOnce(1_000_000)
+
+    service.backoffItem({ uuid: '123' } as jest.Mocked<AnyItemInterface>)
+
+    jest.spyOn(Date, 'now').mockReturnValueOnce(2_000_000)
+
+    expect(service.isItemInBackoff({ uuid: '123' } as jest.Mocked<AnyItemInterface>)).toBe(false)
+  })
+
+  it('should double backoff penalty on each backoff', () => {
+    const service = createService()
+
+    jest.spyOn(Date, 'now').mockReturnValueOnce(1_000_000)
+
+    service.backoffItem({ uuid: '123' } as jest.Mocked<AnyItemInterface>)
+
+    jest.spyOn(Date, 'now').mockReturnValueOnce(1_000_000)
+    expect(service.isItemInBackoff({ uuid: '123' } as jest.Mocked<AnyItemInterface>)).toBe(true)
+
+    jest.spyOn(Date, 'now').mockReturnValueOnce(1_000_000)
+    service.backoffItem({ uuid: '123' } as jest.Mocked<AnyItemInterface>)
+
+    jest.spyOn(Date, 'now').mockReturnValueOnce(1_001_000)
+    expect(service.isItemInBackoff({ uuid: '123' } as jest.Mocked<AnyItemInterface>)).toBe(true)
+
+    jest.spyOn(Date, 'now').mockReturnValueOnce(1_000_000)
+    service.backoffItem({ uuid: '123' } as jest.Mocked<AnyItemInterface>)
+
+    jest.spyOn(Date, 'now').mockReturnValueOnce(1_003_000)
+    expect(service.isItemInBackoff({ uuid: '123' } as jest.Mocked<AnyItemInterface>)).toBe(true)
+  })
+})

packages/services/src/Domain/Sync/SyncBackoffService.ts

@@ -0,0 +1,37 @@
+import { AnyItemInterface } from '@standardnotes/models'
+import { SyncBackoffServiceInterface } from './SyncBackoffServiceInterface'
+
+export class SyncBackoffService implements SyncBackoffServiceInterface {
+  private backoffPenalties: Map<string, number>
+  private backoffStartTimestamps: Map<string, number>
+
+  constructor() {
+    this.backoffPenalties = new Map<string, number>()
+    this.backoffStartTimestamps = new Map<string, number>()
+  }
+
+  isItemInBackoff(item: AnyItemInterface): boolean {
+    const backoffStartingTimestamp = this.backoffStartTimestamps.get(item.uuid)
+    if (!backoffStartingTimestamp) {
+      return false
+    }
+
+    const backoffPenalty = this.backoffPenalties.get(item.uuid)
+    if (!backoffPenalty) {
+      return false
+    }
+
+    const backoffEndTimestamp = backoffStartingTimestamp + backoffPenalty
+
+    return backoffEndTimestamp > Date.now()
+  }
+
+  backoffItem(item: AnyItemInterface): void {
+    const backoffPenalty = this.backoffPenalties.get(item.uuid) || 0
+
+    const newBackoffPenalty = backoffPenalty === 0 ? 1_000 : backoffPenalty * 2
+
+    this.backoffPenalties.set(item.uuid, newBackoffPenalty)
+    this.backoffStartTimestamps.set(item.uuid, Date.now())
+  }
+}

packages/services/src/Domain/Sync/SyncBackoffServiceInterface.ts

@@ -0,0 +1,6 @@
+import { AnyItemInterface } from '@standardnotes/models'
+
+export interface SyncBackoffServiceInterface {
+  isItemInBackoff(item: AnyItemInterface): boolean
+  backoffItem(item: AnyItemInterface): void
+}