FirebaseRemoteConfig.fetch() does not trigger OnCompleteListener every time

问题

I'm trying to implement Firebase Remote Config :

override fun onCreate(savedInstanceState: Bundle?) {

    val configSettings = FirebaseRemoteConfigSettings.Builder().setDeveloperModeEnabled(BuildConfig.DEBUG).build()

    mFirebaseRemoteConfig = FirebaseRemoteConfig.getInstance()
    mFirebaseRemoteConfig.setConfigSettings(configSettings)
    mFirebaseRemoteConfig.setDefaults(R.xml.remote_config_defaults)
    fetchRemoteConfig()
}

private fun fetchRemoteConfig() {
    var cacheExpiration = 3600L
    if (mFirebaseRemoteConfig.info.configSettings.isDeveloperModeEnabled) {
        cacheExpiration = 0L
    }

    mFirebaseRemoteConfig.fetch(cacheExpiration)
        .addOnCompleteListener { task ->
                if (task.isSuccessful) {
                    Log.d(TAG, "Remote config fetch succeeded")
                    mFirebaseRemoteConfig.activateFetched()
                } else {
                    Log.d(TAG, "Remote config fetch failed - ${task.exception?.message}")
                }

                setupView()
            }
}

private fun setupView() {
    val text = mFirebaseRemoteConfig.getString("my_text")
    //...
}

My problem is that the OnCompleteListener is not always called. If I close/open my app several times, the setupView() is not always triggered.

The OnCompleteListener should always be called right? Even if I'm hitting cache?

EDIT: Even if I disable the developper mode the behavior is the same. Sometimes the callback is triggered, sometimes not.

回答1:

I was facing the same issue and contacted the firebase support. They replied the following:

There currently is a bug that has been reported where onComplete, onSuccess, and onFailure listeners doesn't get called if fetch() is called too early. [...] Currently there is a work around where you can put the fetch() inside a postResume. You can try using this in the meantime before a solution has been released.

I implemented the workaround accordingly

protected void onPostResume() {
    super.onPostResume();

    mFirebaseRemoteConfig.fetch(cacheExpiration)
            .addOnSuccessListener(new OnSuccessListener<Void>() {
                @Override
                public void onSuccess(Void aVoid) {
                    Log.d(TAG, "Fetch Succeeded");
                    // Once the config is successfully fetched it must be activated before newly fetched values are returned.
                    mFirebaseRemoteConfig.activateFetched();
                    // Do whatever should be done on success
                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception exception) {
                    Log.d(TAG, "Fetch failed");
                    // Do whatever should be done on failure
                }
            });
}

So far it seems their proposed workaround has resolved the issue.

UPDATE:

I just got notice from the firebase support. According to them the issue is resolved with the latest Google Play Services update.

A fix to Remote Config not calling listeners after fetching has been released in the newest Google play services update. I'll be closing this case for now. However if you are still experiencing issues, feel free to reach out and let me know.

回答2:

If your device run an old Google Play Service and incompatible version, you should see in logs:

GooglePlayServicesUtil: Google Play services out of date. Requires 11020000 but found 10930470

One solution is to upgrade your device Google Play services, but if you cannot, you can also simply downgrade firebase version to match the expected version (here change 11.0.2 to 10.9.3). Not ideal, but still a solution if you cannot upgrade your device (for instance the simulator is running 10.9.3 as of today):

compile 'com.google.firebase:firebase-core:10.2.6'
compile 'com.google.firebase:firebase-messaging:10.2.6'
compile 'com.google.firebase:firebase-config:10.2.6'

回答3:

For those of you who cannot make it by simply calling fetch() onPostResume (and really willing to make this work better), you may try calling fetch method inside Handler.postDelayed() to delay your fetch timing. For our team it increased the chance of fetch method working correctly. Of course this solution does not work reliably just like calling fetch onPostResume though.

@Override
public void onPostResume() {
   new Handler().postDelayed(new Runnable() {
      @Override
      public void run() {
         mFirebaseRemoteConfig.fetch(cacheExpiration)...
         ...
      }
   }, 500L);
}

回答4:

UPDATE version 9.2.0 of firebase works as one would expect and this hack is no longer needed.

I got this "working" reliably... but you may not like my solution. In order to get the config fetch to happen when firebase is ready I had to do this:

FirebaseAuth.getInstance()
   // I don't actually want to or need to sign in..(and this actually throws an error for us.. but we ignore it)
  .signInAnonymously()
  // when it completes (error or no error) we can do our business
  .addOnCompleteListener(new OnCompleteListener<AuthResult>() {
      @Override
      public void onComplete(@NonNull Task<AuthResult> task) {
        // do the remote config fetch you were doing before
        remoteConfig.fetch(...).addOnComplete(...);
      }
  });

This ensures that the firebase internals are ready to do that initial config fetch... on first app open this seems to take about 6-10 seconds on my crappy test device (the entire thing including the auth and config fetch). On subsequent opens the entire thing takes like 2-5 seconds. Obviously that's all arbitrary depending on device/network and YMMV.

I would love to know why this is required.. seems like remote config should be able to manage this internally and not expose this to us.

p.s. you will need this dependency in addition to the firebase-config

compile 'com.google.firebase:firebase-auth:9.0.1'

来源：https://stackoverflow.com/questions/37501124/firebaseremoteconfig-fetch-does-not-trigger-oncompletelistener-every-time