Better offline support in AWS implementation

s3buildcache/src/main/kotlin/androidx/build/gradle/s3buildcache/S3BuildCacheService.kt

@@ -69,6 +69,7 @@ class S3BuildCacheService(
  }
 
  override fun store(key: BuildCacheKey, writer: BuildCacheEntryWriter) {
+ if (writer.size == 0L) return // do not store empty entries into the cache
  logger.info("Storing ${key.blobKey()}")
  val cacheKey = key.blobKey()
  val output = ByteArrayOutputStream()

s3buildcache/src/main/kotlin/androidx/build/gradle/s3buildcache/S3StorageService.kt

@@ -100,9 +100,13 @@ class S3StorageService(
  }
 
  override fun validateConfiguration() {
- val buckets = client.listBuckets().buckets()
- if (buckets.none { bucket -> bucket.name() == bucketName }) {
- throw Exception("Bucket $bucketName under project $region cannot be found or it is not accessible using the provided credentials")
+ try {
+ val buckets = client.listBuckets().buckets()
+ if (buckets.none { bucket -> bucket.name() == bucketName }) {
+ throw Exception("Bucket $bucketName under project $region cannot be found or is not accessible using the provided credentials")
+ }
+ } catch (e: Exception) {
+ logger.warn("Couldn't validate S3 client config: ${e.message}")
  }
  }
 
@@ -127,6 +131,7 @@ class S3StorageService(
  return try {
  val inputStream = client.getObject(request)
  val blob = inputStream.response() ?: return null
+ if (blob.contentLength() == 0L) return null // return empty entries as a cache miss
  if (blob.contentLength() > sizeThreshold) {
  val path = FileHandleInputStream.create()
  val outputStream = path.outputStream()
@@ -162,7 +167,12 @@ class S3StorageService(
  }
 
  private fun delete(client: S3Client, request: DeleteObjectRequest): Boolean {
- return client.deleteObject(request).deleteMarker()
+ return try {
+ client.deleteObject(request).deleteMarker()
+ } catch (e: Exception) {
+ logger.debug("Unable to delete $request", e)
+ false
+ }
  }
  }
 }