NPE of decryptCallbackResultInfo in GetBlobOperation

[zzmao]

There is case causing NPE in GetBlobOperation. An instance of stack is as follow:

2019/01/17 15:42:37.472 ERROR [NettyResponseChannel] [RequestResponseHandlerThread-0] [ambry-frontend] [] Internal error handling request /xxxxxxxx.pdf/BlobInfo with method GET
com.github.ambry.rest.RestServiceException: com.github.ambry.router.RouterException: Get poll encountered unexpected error Error: UnexpectedInternalError
at com.github.ambry.frontend.AmbryBlobStorageService.submitResponse(AmbryBlobStorageService.java:385)
at com.github.ambry.frontend.AmbryBlobStorageService$GetCallback.onCompletion(AmbryBlobStorageService.java:901)
at com.github.ambry.frontend.AmbryBlobStorageService$GetCallback.onCompletion(AmbryBlobStorageService.java:814)
at com.github.ambry.router.NonBlockingRouter$1.onCompletion(NonBlockingRouter.java:155)
at com.github.ambry.router.NonBlockingRouter$1.onCompletion(NonBlockingRouter.java:149)
at com.github.ambry.router.NonBlockingRouter.completeOperation(NonBlockingRouter.java:501)
at com.github.ambry.router.NonBlockingRouter.completeOperation(NonBlockingRouter.java:478)
at com.github.ambry.router.GetBlobOperation.abort(GetBlobOperation.java:154)
at com.github.ambry.router.GetManager.removeAndAbort(GetManager.java:282)
at com.github.ambry.router.GetManager.poll(GetManager.java:199)
at com.github.ambry.router.NonBlockingRouter$OperationController.pollForRequests(NonBlockingRouter.java:783)
at com.github.ambry.router.NonBlockingRouter$OperationController.run(NonBlockingRouter.java:840)
at java.lang.Thread.run(Thread.java:748)
Caused by: com.github.ambry.router.RouterException: Get poll encountered unexpected error Error: UnexpectedInternalError
... 4 more
Caused by: java.lang.NullPointerException
at com.github.ambry.router.GetBlobOperation$FirstGetChunk.maybeProcessCallbacks(GetBlobOperation.java:1009)
at com.github.ambry.router.GetBlobOperation$GetChunk.poll(GetBlobOperation.java:580)
at com.github.ambry.router.GetBlobOperation.poll(GetBlobOperation.java:265)
at com.github.ambry.router.GetManager.poll(GetManager.java:194)
... 3 more
2019/01/17 15:42:37.472 ERROR [RouterUtils] [RequestResponseHandlerThread-0] [ambry-frontend] [] Router operation met with a system health error:
com.github.ambry.router.RouterException: Get poll encountered unexpected error Error: UnexpectedInternalError
at com.github.ambry.router.GetManager.poll(GetManager.java:199)
at com.github.ambry.router.NonBlockingRouter$OperationController.pollForRequests(NonBlockingRouter.java:783)
at com.github.ambry.router.NonBlockingRouter$OperationController.run(NonBlockingRouter.java:840)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
at com.github.ambry.router.GetBlobOperation$FirstGetChunk.maybeProcessCallbacks(GetBlobOperation.java:1009)
at com.github.ambry.router.GetBlobOperation$GetChunk.poll(GetBlobOperation.java:580)
at com.github.ambry.router.GetBlobOperation.poll(GetBlobOperation.java:265)
at com.github.ambry.router.GetManager.poll(GetManager.java:194)
... 3 more