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[BUG] Blob Storage's downloadToFile deletes files after `toFuture` is called

See original GitHub issue

Describe the bug After calling downloadToFile (with or without overwrite = true), the operation succeeds, and the file, for a brief moment, is successfully downloaded and persisted on disk. However, if a toFuture subscriber is attached and then subsequently converted to a Scala Future (using either Scala’s built in compat, or via Reactor’s Scala extensions), a cancel signal is fired, and the handler here fires and deletes the file: https://github.com/Azure/azure-sdk-for-java/blob/b59f999110e7a12004b51918b04b7ede444824a5/sdk/storage/azure-storage-blob/src/main/java/com/azure/storage/blob/specialized/BlobAsyncClientBase.java#L1039

edit - quick update - Mono’s toFuture does indeed fire off a cancel: https://github.com/reactor/reactor-core/blob/c6b75f2578ee5f201ac06add2239322cc5b7bfcd/reactor-core/src/main/java/reactor/core/publisher/MonoToCompletableFuture.java#L59, which makes the downloadToFile methods impossible to use if a CompletableFuture is desired. May I suggest loosening the check for deletion? 😄

I’m not very familiar with Reactor, and would be happy to find out if I’m doing something wrong, or if there’s a workaround. We are on a Scala codebase that relies heavily on Futures, so not using a Future is not quite an option.

Exception or Stack Trace N/A

To Reproduce Steps to reproduce the behavior: See the following snippet

Code Snippet

blobContainerClient
  .getBlobAsyncClient(myBlobKey)
  .downloadToFile("my/path")
  .onComplete { ...file is fine here... }
  .doFinally { ... eventually `cancel` is fired instead of `complete` ... }
  .toFuture.asScala.map { ... file disappears ... }

Expected behavior Don’t delete my file 😦

Screenshots N/A

Setup (please complete the following information):

OS: macOS Catalina
IDE : Intellij Ultimate
Version of the Library used: 12.4.0

Additional context Could be related to https://github.com/spring-projects/spring-framework/issues/22952, even though this appears to be fixed?

Information Checklist Kindly make sure that you have added all the following information above and checkoff the required fields otherwise we will treat the issuer as an incomplete report