How to remove duplicate intent from JobIntentService

Question

I have a JobIntentService that is launched every time a push notification comes in to tell the service to go fetch more data. While the app is in the foreground everything works as it should.

When the app is in the background and multiple push notifications come in, the intent gets queued up and it executes the same intent multiple times putting unneeded stress on the server because the first call to the server will get all the information it needs making the other queued intent's from the push notifications unnecessary.

Is there anyway to cancel or not add the same intent to the queue or some other way to prevent the extra calls to the server?

Answer 1

So first a couple of already similar questions with lots of good knowledge: question1 and question2. Maybe your question even duplicates those similar.

The cleanest would be to get your hands on JobIntentService's jobs queue in your MyOwnJobIntentService extends JobIntentService.

In androidx.core.app.JobIntentService.java there is:

final ArrayList<CompatWorkItem> mCompatQueue;

And in your MyOwnJobIntentService extends JobIntentService:

if(mCompatQueue.isEmpty()){
  //only in this case enqueue new job   
}

But unfortunately mCompatQueue is not public field.

And 10 minutes later we're getting with working solution -> SingleJobIntentService a JobIntentService which will not queue jobs if it's already working.

import android.content.Context;
import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.v4.app.JobIntentService;
import android.util.Log;

public class SingleJobIntentService extends JobIntentService {

    private static final String TAG = "SingleJobIntentService";

    private Intent theOnlyJobIhave = null;

    public static void enqueue(Context context, Intent work) {
        Log.d(TAG, "enqueue: someone tries to add me work " + work.hashCode());
        JobIntentService.enqueueWork(
                context,
                SingleJobIntentService.class,
                SingleJobIntentService.class.hashCode(),
                work);
    }

    @Override
    protected void onHandleWork(@NonNull final Intent theWorkIgot) {
        Log.d(TAG, "onHandleWork: " + this.hashCode());
        if (theOnlyJobIhave == null) {
            theOnlyJobIhave = theWorkIgot;
            final int extraValue = theOnlyJobIhave.getIntExtra(MainActivity.KEY, -500);
            Log.d(TAG, "onHandleWork: " + extraValue);
            try {
                Thread.sleep(7000); //this simulates fetch to server
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        } else {
            Log.d(TAG, "onHandleWork I'm already busy, refuse to work >:(");
        }
        Log.d(TAG, "onHandleWork end");
    }
}

You may want test it with simple activity with a button:

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;

public class MainActivity extends AppCompatActivity {

    public static final String KEY = "KEYKEY";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        findViewById(R.id.button).setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(final View v) {
                final Intent theIntent = new Intent();
                theIntent.putExtra(KEY, 666);
                SingleJobIntentService.enqueue(MainActivity.this, theIntent);
            }
        });
    }
}

Notice: you must be careful with threading as the solution I gave is not thread-safe. For example in androidx.core.app.JobIntentService.java touching mCompatQueue is synchronized. EDIT: after thinking about it -> since onHandleWork is called from JobIntentService from single thread there is no thread issue and the solution is thread safe!