(feat) Add a network status listener to restart DataStore after the network comes online

[mikepschneider]

Add a network status listener to restart DataStore after the network comes online. This brings Android closer in line with ios and js behavior.

• [x ] PR title and description conform to Pull Request guidelines.

Issue #, if available:

Description of changes:

This change adds a ReachabilityMonitor that listens to the state of the network and publishes an event when the network is gained or lost. AWSDataStorePlugin listens to these events and calls start() and stop() when the network is gained or lost.

How did you test these changes?
Unit tests, manual tests

• [ x] Added Unit Tests
• Added Integration Tests

Documentation update required?

• [ x] No
• Yes (Please include a PR link for the documentation update)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

Merging #2148 (5840f86) into main (178138f) will decrease coverage by 0.00%.
The diff coverage is 62.50%.

@@             Coverage Diff              @@
##               main    #2148      +/-   ##
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- Coverage     43.33%   43.33%   -0.01%     
- Complexity     2566     2572       +6     
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  Files           739      740       +1     
  Lines         24761    24796      +35     
  Branches       2753     2753              
============================================
+ Hits          10731    10746      +15     
- Misses        12956    12974      +18     
- Partials       1074     1076       +2     

[manueliglesias]

Can you elaborate a little on why is the ReachabilityMonitor used in the plugin and not in the orchestrator?

[mikepschneider]

Can you elaborate a little on why is the ReachabilityMonitor used in the plugin and not in the orchestrator?

I originally was calling stop/start in the Orchestrator. But that was not the right place to do it, it caused everything to get messed up. I realized that the Stop/Start methods of the plugin are meant to be called externally unlike Orchestrator and that's the right place to stop and start the datastore. When I tried it out it works correctly.

[manueliglesias]

LGTM 👍

[tylerjroach]

Is configure needed, or can this just be done in the init of the ReachabilityMonitor? Side effect right now of forgetting configure is a crash, and I don't see too much of a reason not just to allow class to configure itself since it holds on to the current network status to pass to a newly attached observer.

[joekiller]

@mikepschneider while working on a new PR for #1876 (comment) I noticed this new functionality is causing issues with the tests and potentially can cause unneeded orchestrator thrashing.

As a user I expect the data store to not be triggered unless operated upon and not the be activated during configuration. Actual behavior: reachabilityMonitor will start the datastore when it detect network even if the datastore is supposed to be stopped, cleared, or is supposed to be inactive.

This breach of contract manifests primarily in datastore crashes during tests. It will also cause the datastore to start/stop unintentionally.

I understand the point is to have this closer in implementation to the iOS/js stuff however this is really brute force thrashing for the orchestrator as is and introduces denial of service whenever the network transitions while the orchestrator does all its overhead.

[joekiller]

I guess it's really just hitting hard in the tests at random times. When I try to make stopStopsSyncUntilNextInteraction exhibit what I was worried about, ie starting back up after stopped, it seemed okay.

I tried slapping the following on

amplify-android/aws-datastore/src/test/java/com/amplifyframework/datastore/AWSDataStorePluginTest.java

Line 360 in dfb5b55

but could not get the error so perhaps no worries.

Completable.timer(10, TimeUnit.SECONDS).blockingAwait();

[joekiller]

mmm. I feel like I'm hitting it though. will look a little more.