Android Work Manager - Difference between ExistingPeriodicWorkPolicy.KEEP and .Replace

Question

By referring to: Android WorkManager api for running daily task in Background

It uses the WorkManager.enqueueUniquePeriodicWork to ensure that PeriodicWorkRequest is not created multiple times.

example code:

val work = PeriodicWorkRequestBuilder<SyncWork>(15,TimeUnit.MINUTES).build()

WorkManager.getInstance().enqueueUniquePeriodicWork("TaskTag",
                                       ExistingPeriodicWorkPolicy.KEEP, work);

However, I found it there is 2 option of ExistingPeriodicWorkPolicy which is ExistingPeriodicWorkPolicy.KEEP and ExistingPeriodicWorkPolicy.REPLACE can be use.

I try to implement it and run the code, but it does really show any differences, and it seem both of them behave the same way.

My uncertainty:

与 的ExistingPeriodicWorkPolicy.KEEP表现有何不同ExistingPeriodicWorkPolicy.REPLACE？

Answer 1

在您的示例中，您将要排队一个新的工作请求（又名工人）。如果您之前在运行时执行过此操作，则此工作器已存在状态为 ENQUEUED。

KEEP：如果之前的工作人员存在，则您的新尝试将被简单地忽略，否则您的新工作人员将入队。

REPLACE：如果前一个worker存在，它被取消，导致它的状态为CANCELLED。否则，您的新工作人员已入队。

因此，如果您确定您的新工人与前一个工人相同（假设约束没有改变），那么 KEEP 应该是安全的，否则 REPLACE 可能是更好的选择。

Answer 2

KEEP：如果存在具有相同唯一名称的现有待处理工作，则不执行任何操作。

REPLACE：如果存在具有相同唯一名称的现有待处理工作，则取消并删除它。