Timeout and retry for backend requests

src/config.ts

@@ -6,6 +6,8 @@ export const defaultEndpoint =
 export const currentConfig: Config = {
   japaneseAddressesApi: defaultEndpoint,
   cacheSize: 1_000,
+  backendTimeout: 600,
+  backendTries: 3,
 }
 
 export type FetchOptions = {
@@ -24,6 +26,37 @@ export type FetchLike = (
   options?: FetchOptions,
 ) => Promise<FetchResponseLike>
 
+const timeoutableFetch = async (
+  fetch: (input: RequestInfo, init?: RequestInit) => Promise<Response>,
+  input: RequestInfo,
+  init: RequestInit | undefined,
+  timeout: number,
+) => {
+  const controller = new AbortController()
+  const timeoutId = setTimeout(() => controller.abort(), timeout)
+  const response = await fetch(input, { ...init, signal: controller.signal })
+  clearTimeout(timeoutId)
+  return response
+}
+
+export async function fetchWithTimeoutRetry(
+  fetch: (input: RequestInfo, init?: RequestInit) => Promise<Response>,
+  input: RequestInfo,
+  init?: RequestInit,
+) {
+  let tries = 0
+  while (true) {
+    try {
+      return timeoutableFetch(fetch, input, init, currentConfig.backendTimeout)
+    } catch (error) {
+      tries++
+      if (tries >= currentConfig.backendTries) {
+        throw error
+      }
+    }
+  }
+}
+
 /**
  * @internal
  */
@@ -41,7 +74,7 @@ export const __internals: { fetch: FetchLike } = {
     if (typeof o.length !== 'undefined' && typeof o.offset !== 'undefined') {
       headers['Range'] = `bytes=${o.offset}-${o.offset + o.length - 1}`
     }
-    return window.fetch(url, {
+    return fetchWithTimeoutRetry(window.fetch, url, {
       headers,
     })
   },

src/main-node.ts

@@ -1,5 +1,10 @@
 import * as Normalize from './normalize'
-import { __internals, FetchOptions, FetchResponseLike } from './config'
+import {
+  __internals,
+  fetchWithTimeoutRetry,
+  FetchOptions,
+  FetchResponseLike,
+} from './config'
 import { promises as fs } from 'node:fs'
 import { fetch } from 'undici'
 
@@ -43,9 +48,14 @@ export const requestHandlers = {
     if (typeof o.length !== 'undefined' && typeof o.offset !== 'undefined') {
       headers['Range'] = `bytes=${o.offset}-${o.offset + o.length - 1}`
     }
-    return fetch(fileURL.toString(), {
-      headers,
-    })
+    return fetchWithTimeoutRetry(
+      // 私達が使う場所の undici fetch インタフェースはDOMのfetchと同等なので、型キャストしても問題ない
+      fetch as (typeof Window.prototype)['fetch'],
+      fileURL.toString(),
+      {
+        headers,
+      },
+    )
   },
 }
 

src/normalize.ts

@@ -52,6 +52,15 @@ export interface Config {
   /** 内部キャッシュの最大サイズ。デフォルトでは 1,000 件 */
   cacheSize: number
 
+  /**
+   * バックエンドへのリクエストのタイムアウト。
+   * デフォルト 600ms
+   * タイムアウトした場合、数回リトライを行います。
+   * リトライ回数は {@link backendTries} で設定します。
+   */
+  backendTimeout: number
+  backendTries: number
+
   geoloniaApiKey?: string
 }
 export const config: Config = currentConfig