Worker Chaining Problems

Currently, the ContentObserverWork triggers FilesSyncWork, which in turn triggers FileUploadWorker, which finally calls UploadFileOperation.

This chained architecture introduces fragility to the Auto Upload mechanism. If any call in the chain such as FileUploadWorker or UploadFileOperation fails or behaves unexpectedly due to some code changes in any of it, it can disrupt the entire auto upload process. This tightly coupled workflow increases the risk of failure and makes debugging more complex.

Additionally, deep worker chaining can cause this edge case, especially on Android 12 and above, where the system limits each app to 100 scheduled jobs. Exceeding this limit can lead to runtime exceptions, redundant executions, and premature worker terminations.

To improve reliability and maintainability, a single source of truth approach should be adopted. Ideally, there should be one worker responsible for handling the auto upload logic, and this worker should internally manage the execution of file upload operations, rather than delegating through chained workers.

FilesSyncWork Internal Logic Problems

Early Exit Logic (canExitEarly()):

The canExitEarly() method is used to exit the auto upload process early. However, its current implementation, combined with scan interval logic, can lead to premature exits, causing uploads to be skipped. This logic should be reviewed and potentially moved outside the worker. e.g., handled via PeriodicWorkRequest.Builder.

Lack of Failure Handling:

FilesSyncWork currently does not return failure or retry results. This suppresses visibility into failed executions and prevents proper application of retry or backoff policies.

Missing Backoff Policy:

In cases of failure (e.g., due to poor network connectivity), the worker should automatically retry using a defined BackoffPolicy, either EXPONENTIAL or LINEAR.

Missing Constraints:

FilesSyncWork does not currently utilize Constraints (e.g., requiring internet, charging status, or sufficient battery). These constraints should be configured externally before scheduling the periodic worker.

File Skipping (changedFiles logic):

Files are sometimes incorrectly skipped due to issues with the changedFiles logic. This logic should be reviewed, as it may cause the auto upload to end prematurely or skip files that actually need to be uploaded.

Suggestions

Use single, consolidated Worker that file uploads internally.

Introduce proper failure and retry handling in FilesSyncWork.

Apply appropriate BackoffPolicy and Constraints to improve reliability.

Move scan interval out of the worker to a higher-level scheduler.

Investigate and correct the file-skipping issue caused by changedFiles logic.

Check app storage permissions and inform user - #15240

Check & Prompt to Disable Battery Optimization - #15039 (comment)

Uh oh!

Deep dive Auto Upload #15214

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