From 70d4bba4dd89a534488965aa6dcb978ef3a99631 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Eduardo=20Bou=C3=A7as?= <mail@eduardoboucas.com>
Date: Thu, 27 Jul 2023 16:21:25 +0100
Subject: [PATCH] feat: add retry logic

---
 src/main.test.ts | 53 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.ts      |  4 +++-
 src/retry.ts     | 48 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 104 insertions(+), 1 deletion(-)
 create mode 100644 src/retry.ts

diff --git a/src/main.test.ts b/src/main.test.ts
index a340616..ed1422e 100644
--- a/src/main.test.ts
+++ b/src/main.test.ts
@@ -369,6 +369,59 @@ describe('set', () => {
       `The blob store is unavailable because it's missing required configuration properties`,
     )
   })
+
+  test('Retries failed operations', async () => {
+    let attempts = 0
+
+    const fetcher = async (...args: Parameters<typeof globalThis.fetch>) => {
+      const [url, options] = args
+      const headers = options?.headers as Record<string, string>
+
+      expect(options?.method).toBe('put')
+
+      if (url === `https://api.netlify.com/api/v1/sites/${siteID}/blobs/${key}?context=production`) {
+        const data = JSON.stringify({ url: signedURL })
+
+        expect(headers.authorization).toBe(`Bearer ${apiToken}`)
+
+        return new Response(data)
+      }
+
+      if (url === signedURL) {
+        attempts += 1
+
+        expect(options?.body).toBe(value)
+
+        if (attempts === 1) {
+          return new Response(null, { status: 500 })
+        }
+
+        if (attempts === 2) {
+          throw new Error('Some network problem')
+        }
+
+        if (attempts === 3) {
+          return new Response(null, { headers: { 'X-RateLimit-Reset': '10' }, status: 429 })
+        }
+
+        return new Response(value)
+      }
+
+      throw new Error(`Unexpected fetch call: ${url}`)
+    }
+
+    const blobs = new Blobs({
+      authentication: {
+        token: apiToken,
+      },
+      fetcher,
+      siteID,
+    })
+
+    await blobs.set(key, value)
+
+    expect(attempts).toBe(4)
+  })
 })
 
 describe('setJSON', () => {
diff --git a/src/main.ts b/src/main.ts
index 9619ca8..6b05151 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1,3 +1,5 @@
+import { fetchAndRetry } from './retry.ts'
+
 interface APICredentials {
   apiURL?: string
   token: string
@@ -127,7 +129,7 @@ export class Blobs {
       headers['cache-control'] = 'max-age=0, stale-while-revalidate=60'
     }
 
-    const res = await this.fetcher(url, { body, headers, method })
+    const res = await fetchAndRetry(this.fetcher, url, { body, method, headers })
 
     if (res.status === 404 && method === HTTPMethod.Get) {
       return null
diff --git a/src/retry.ts b/src/retry.ts
new file mode 100644
index 0000000..288cd74
--- /dev/null
+++ b/src/retry.ts
@@ -0,0 +1,48 @@
+const DEFAULT_RETRY_DELAY = 5000
+const MIN_RETRY_DELAY = 1000
+const MAX_RETRY = 5
+const RATE_LIMIT_HEADER = 'X-RateLimit-Reset'
+
+export const fetchAndRetry = async (
+  fetcher: typeof globalThis.fetch,
+  url: string,
+  options: RequestInit,
+  attemptsLeft = MAX_RETRY,
+): ReturnType<typeof globalThis.fetch> => {
+  try {
+    const res = await fetcher(url, options)
+
+    if (attemptsLeft > 0 && (res.status === 429 || res.status >= 500)) {
+      const delay = getDelay(res.headers.get(RATE_LIMIT_HEADER))
+
+      await sleep(delay)
+
+      return fetchAndRetry(fetcher, url, options, attemptsLeft - 1)
+    }
+
+    return res
+  } catch (error) {
+    if (attemptsLeft === 0) {
+      throw error
+    }
+
+    const delay = getDelay()
+
+    await sleep(delay)
+
+    return fetchAndRetry(fetcher, url, options, attemptsLeft - 1)
+  }
+}
+
+const getDelay = (rateLimitReset?: string | null) => {
+  if (!rateLimitReset) {
+    return DEFAULT_RETRY_DELAY
+  }
+
+  return Math.max(Number(rateLimitReset) * 1000 - Date.now(), MIN_RETRY_DELAY)
+}
+
+const sleep = (ms: number) =>
+  new Promise((resolve) => {
+    setTimeout(resolve, ms)
+  })