How to temporarily acquire lock for IntentService from Fragment

Question

I have IntentService which I use for uploading photo files to server sequentially. I have Gallery fragment showing files from upload queue and files already uploaded to server. I get list of already uploaded files using api-call to server. Local files which going to be uploaded just stored in DB.

Once next file is uploaded - IntentService sends event to Gallery fragment. After that I can hide progress-wheel for uploaded file and remove record about that file from DB. This part work well.

For synchronization reasons I want to block all events coming from upload Service (make them wait) while api-request for fetching remote files are in progress.

What I'm worry about - some file can be uploaded at the same time with requesting remote files and I will loose that event. How can I delay delivering events from Service until api-request is finish?

Answer 1

In your fragment you can do this:

boolean isRequestingAPI = false;
.
.
.

//Requesting API on server

isRequestingAPI = true

synchronize(isRequestingAPI){
   // do request API here


   //You get callback from API 
   isRequestingAPI = false;
}

.
.
.

//Getting event from Service

private void onEventFromServceListener(){

   if(isRequestingAPI){
       //Put event/data in a queue and consume it when when you get callback from API
   }
   synchronize(isRequestingAPI){
       //do whatever your want to do with event from service
   }
}

By using synchronize(isRequestingAPI) your API call and Event from service will become mutually exclusive events. Each event will wait for other to finish first.