@actions/cache: using concurrent download whenever server supported (via `Accept-Ranges` header)

packages/cache/src/internal/cacheHttpClient.ts

@@ -13,12 +13,12 @@ import * as utils from './cacheUtils'
 import {CompressionMethod} from './constants'
 import {
   ArtifactCacheEntry,
-  InternalCacheOptions,
+  ArtifactCacheList,
   CommitCacheRequest,
-  ReserveCacheRequest,
-  ReserveCacheResponse,
+  InternalCacheOptions,
   ITypedResponseWithError,
-  ArtifactCacheList
+  ReserveCacheRequest,
+  ReserveCacheResponse
 } from './contracts'
 import {
   downloadCacheHttpClient,
@@ -27,9 +27,9 @@ import {
 } from './downloadUtils'
 import {
   DownloadOptions,
-  UploadOptions,
   getDownloadOptions,
-  getUploadOptions
+  getUploadOptions,
+  UploadOptions
 } from '../options'
 import {
   isSuccessStatusCode,
@@ -179,22 +179,45 @@ export async function downloadCache(
   if (archiveUrl.hostname.endsWith('.blob.core.windows.net')) {
     if (downloadOptions.useAzureSdk) {
       // Use Azure storage SDK to download caches hosted on Azure to improve speed and reliability.
-      await downloadCacheStorageSDK(
+      return await downloadCacheStorageSDK(
         archiveLocation,
         archivePath,
         downloadOptions
       )
-    } else if (downloadOptions.concurrentBlobDownloads) {
+    }
+  }
+
+  let acceptRange = false
+  let contentLength = -1
+  // Determine partial file downloads is supported by server
+  // via `Accept-Ranges: bytes` response header.
+  try {
+    const httpClient = new HttpClient('actions/cache', undefined, {
+      socketTimeout: downloadOptions.timeoutInMs,
+      keepAlive: true
+    })
+
+    const res = await retryHttpClientResponse(
+      'downloadCacheMetadata',
+      async () => await httpClient.request('HEAD', archiveLocation, null, {})
+    )
+
+    acceptRange = res.message.headers['Accept-Ranges'] === 'bytes'
+
+    const lengthHeader = res.message.headers['Content-Length']
+    contentLength = parseInt(lengthHeader)
+  } catch {
+    // ignore
+  }
+
+  if (acceptRange && contentLength > 0) {
     // Use concurrent implementation with HttpClient to work around blob SDK issue
     await downloadCacheHttpClientConcurrent(
       archiveLocation,
       archivePath,
+      contentLength,
       downloadOptions
     )
-    } else {
-      // Otherwise, download using the Actions http-client.
-      await downloadCacheHttpClient(archiveLocation, archivePath)
-    }
   } else {
     await downloadCacheHttpClient(archiveLocation, archivePath)
   }

packages/cache/src/internal/downloadUtils.ts

@@ -208,10 +208,13 @@ export async function downloadCacheHttpClient(
  *
  * @param archiveLocation the URL for the cache
  * @param archivePath the local path where the cache is saved
+ * @param contentLength
+ * @param options
  */
 export async function downloadCacheHttpClientConcurrent(
   archiveLocation: string,
   archivePath: fs.PathLike,
+  contentLength: number,
   options: DownloadOptions
 ): Promise<void> {
   const archiveDescriptor = await fs.promises.open(archivePath, 'w')
@@ -220,29 +223,14 @@ export async function downloadCacheHttpClientConcurrent(
     keepAlive: true
   })
   try {
-    const res = await retryHttpClientResponse(
-      'downloadCacheMetadata',
-      async () => await httpClient.request('HEAD', archiveLocation, null, {})
-    )
-
-    const lengthHeader = res.message.headers['content-length']
-    if (lengthHeader === undefined || lengthHeader === null) {
-      throw new Error('Content-Length not found on blob response')
-    }
-
-    const length = parseInt(lengthHeader)
-    if (Number.isNaN(length)) {
-      throw new Error(`Could not interpret Content-Length: ${length}`)
-    }
-
     const downloads: {
       offset: number
       promiseGetter: () => Promise<DownloadSegment>
     }[] = []
     const blockSize = 4 * 1024 * 1024
 
-    for (let offset = 0; offset < length; offset += blockSize) {
-      const count = Math.min(blockSize, length - offset)
+    for (let offset = 0; offset < contentLength; offset += blockSize) {
+      const count = Math.min(blockSize, contentLength - offset)
       downloads.push({
         offset,
         promiseGetter: async () => {
@@ -260,7 +248,7 @@ export async function downloadCacheHttpClientConcurrent(
     downloads.reverse()
     let actives = 0
     let bytesDownloaded = 0
-    const progress = new DownloadProgress(length)
+    const progress = new DownloadProgress(contentLength)
     progress.startDisplayTimer()
     const progressFn = progress.onProgress()