I got a service that generate the user location.
I got also a thread with the service instance that takes the location from the service and send it to the db.
The thread is sleeping for 1 min and the asking again for the address from the service and sending it to the db.
My question is should I create instead of this thread a service and the second service will be started every 1 min?
The advantage is that the service won't run when he doesn't needs to like the thread but the disadvantage is that I will have to create a new connection every 1 min.
What is better? Who is more efficient?
I'm usually from a line of thought that says that the best is always to not use Thread.sleep();
Said that, there're several options you can approach:
. Request location only every 1 minute, but that might have a weird battery impact as the GPS radio will be kept on during the non-working time.
. create a PendingIntent of your service and ask the AlarmManager to call it again in 1 min. This won't be keeping your GPS on all the time (if u program right), but it will need to fix the position again
. you also can in the same service (without destroying and re-starting it) use a ScheduledExecutorService to run the thread every 1 min. (GPS ON or OFF depend on programming)
Why do you need a thread or second service to insert the location updates inserted into the database. Why you cant you configure the locationupdates for every 1 minute in requestLocationUpdates method and onLocationChanged event, why cant you directly insert the records into the table. Running a second service or thread every minute might impact your battery performance. I have seen in one of my project.
Related
I need to running thread every one second. But when application killed, the thread must be still alive.
My thread task is used for increment Unix Timestamp (that synchronized when the first time application running from our server time) by one every second. I need to create this task because in some device, date time can changed unpredictable (maybe low on battery, hard reset, dropped or something else).
My Activity must be get that Unix Timestamp value when it needed.
From SO, Alarm Manager is not a good choice,
I would recommend you not to use an AlarmManager for 30 seconds, as some have suggested. Because 30 seconds is too short. it will drain the battery. For AlarmManager use a minimum 1 minute with RTC.
Other people suggest using Timer Task or ScheduledExecutorService, what the best thread to fit my need?
Thanks.
You would never achieve that. Any process could be killed by System. And task running every seconds is horrible (like AlarmManager said).
One idea is: save your server time and device time such as SystemClock.elapsedRealtime() . (do not use System.currentTimeMillis() for this purpose. ... this is display time for user and can be changed by user or something).
When you need time later, get elapsedRealtime() again and compare with stored elapsedRealtime(), and add this diff to stored server time. You will get desired time.
Or simply ask current time to your server , depends on needs :).
If you want to care hard reset I think that you should have database on your server to manage the first time when user launches app.
I want to run some kind of Thread continuously in app engine. What the thread does is
checks a hashmap and updates entries as per some business continuously.
My hashmap is a public memeber variable of class X. And X is a singleton class.
Now I know that appengine do not support Thread and it has somethinking called backend.
Now my question is: If I run backend continiously for 24*7 will I be charged?
There is no heavy processing in backend. It just updates a hashmap based on some condition.
Can I apply some trick so that am not charged? My webapp is not for commercial use and is for fun.
Yes, backends are billed per hour. It does not matter how much they are used: https://developers.google.com/appengine/docs/billing#Billable_Resource_Unit_Costs
Do you need this calculation to happen immediatelly? You could run a cron job, say ever 5 min and perform the task.
Or you can too enqueue a 10 minutes task and re-enqueue when is near to arrive to its 10 minutes limit time. For that you can use the task parameters to pass the state of the process to the next task or also you can use datastore.
I have an application that checks a resource on the internet for new mails. If there is are new mails it does some processing on them. This means that depending on the amount of mails it might take just a few seconds to hours of processing.
Now the object/program that does the processing is already a singleton. So right now I already took care of there really only being 1 instance that's handling the checking and processing.
However I only have it running once now and I'd like to have it continuously running, checking for new mails more or less every 10 minutes or so to handle them in a timely manner.
I understand I can take care of this with Timer/Timertask or even better I found a resource here: http://www.ibm.com/developerworks/java/library/j-schedule/index.html that uses Scheduler/SchedulerTask. But what I am afraid of.. is if I set it to run every 10 minutes and a previous session is already processing data it will put the new task in a stack waiting to be executed once the previous one is done. So what I'm afraid of is for instance the first run running for 5 hours and then, because it was busy all the time, after that it will launch 5*6-1=29 runs immediately after each other checking for mails and/do some processing without giving the server a break.
Does anyone know how I can solve this?
P.S. the way I have my application set up right now is I'm using a Java Servlet on my tomcat server that's launched upon server start where it creates a Singleton instance of my main program, then calls some method to do the fetching/processing. And what I want is to repeat that fetching/processing every "x" amount of time (10 minutes or so), making sure that really only 1 instance is doing this and that really after each run 10 minutes or so are given to rest.
Actually, Timer + TimerTask can deal with this pretty cleanly. If you schedule something with Timer.scheduleAtFixedRate() You will notice that the docs say that it will attempt to "make up" late events to maintain the long-term period of execution. However, this can be overcome by using TimerTask.scheduledExecutionTime(). The example therein lets you figure out if the task is too tardy to run, and you can just return instead of doing anything. This will, in effect, "clear the queue" of TimerTask.
Of note: TimerTask uses a single thread to execute, so it won't spawn two copies of your task side-by-side.
On the side note part, you don't have to process all 10k emails in the queue in a single run. I would suggest processing for a fixed amount of time using TimerTask.scheduledExecutionTime() to figure out how long you have, then returning. That keeps your process more limber, cleans up the stack between runs, and if you are doing aggregates, ensures that you don't have to rebuild too much data if, for example, the server is restarted in the middle of the task. But this recommendation is based on generalities, since I don't know what you're doing in the task :)
how can i start/stop a specific service based on the following:
user A call user B ( the trigger is user B answer the phone and service stopped when call is ended )
user B call user A ( the trigger is user A answer the phone and service stopped when call is ended )
i want to calculate the call duration of the call and store the result in database.
regards
The calculation of the call duration is already done for you. Use the CallLog content provider, please.
Even if for some strange reason using the official call log is not what you want, you do not need a service. Set up a manifest-registered BroadcastReceiver for ACTION_PHONE_STATE_CHANGED and store the start/stop times in the database. Do not have a Service hanging out in memory for the sole purpose of watching time tick by.
But, please, just use the CallLog, since the OS is doing this work for you, and you don't waste the user's battery doing duplicate work.
I am a complete newbie to Android development;
Basically, I am about to write an application, that will let the user to take photo, which (with a bunch of extra data) will be submitted to the remote webservice.
So I'm guessing I will need:
A Photo-taking application (Activity) that will gather all the extra data and put in the SQLite DB.
A background service looking up the DB in time intervals and sending the data over the Internet, optionally making web requests with current GPS location (I'm trying to keep in mind, that sometimes network would not be accessible).
A receiver object that will run the service at boot, and optionally check if the service needs to be restarted.
My concerns are:
Do I really need to monitor the service and care about anything bad that could kill it.
Will the battery last for at least 12 hours with a non-stop running service, making some networking/GPS actions in, let's say, 30-minute intervals. (G1/Dream)
What else should I be careful about?
Any ideas/suggestions will be appreciated.
a word of advice needed
Rutabaga.
Oh, wait. You're probably looking for something related to Android. OK, carry on.
A receiver object that will run the
service at boot, and optionally check
if the service needs to be restarted.
Yuck. Use AlarmManager and have your service behave more like a cron job/Windows scheduled task.
Do I really need to monitor the
service and care about anything bad
that could kill it.
Not if you use AlarmManager and have your service behave more like a cron job.
Will the battery last for at least 12
hours with a non-stop running service,
making some networking/GPS actions in,
let's say, 30-minute intervals.
(G1/Dream)
If you use AlarmManager and have your service behave more like a cron job, a 30-minute interval should be OK. Just make sure you shut down the GPS radio when you are done with it. Note that using the GPS radio from a cron job sort of task is a bit tricky, since it takes a while to get its first fix. You will also want to take a look at using PowerManager.WakeLock to keep the device awake until your work is completed.
What else should I be careful about?
Mynd you, moose bites kan be pretti nasti.
Beyond that and what I wrote above, you should be in OK shape. Note that what you are diving into is not exactly "newbie" material.