Just recently a few colleagues of mine helped out with narrowing down a memory leak. One of the problems was found in Microsoft's code. This is from reflector showing that the enumerator will leak.
Here the count property calls getenumerator but never checks for Idisposable:
public int Count
{
get
{
if (this.isDisposed)
{
throw new ObjectDisposedException(name);
}
int num = 0;
IEnumerator enumerator = this.GetEnumerator();
while (enumerator.MoveNext())
{
num++;
}
return num;
}
}
This is the ManagementObjectCollection's GetEnumerator just to show the type returned is a ManagementObjectEnumerator.
public ManagementObjectEnumerator GetEnumerator()
{
if (this.isDisposed)
{
throw new ObjectDisposedException(name);
}
if (!this.options.Rewindable)
{
return new ManagementObjectEnumerator(this, this.enumWbem);
}
IEnumWbemClassObject ppEnum = null;
int errorCode = 0;
try
{
errorCode = this.scope.GetSecuredIEnumWbemClassObjectHandler(this.enumWbem).Clone_(ref ppEnum);
if ((errorCode & 0x80000000L) == 0L)
{
errorCode = this.scope.GetSecuredIEnumWbemClassObjectHandler(ppEnum).Reset_();
}
}
catch (COMException exception)
{
ManagementException.ThrowWithExtendedInfo(exception);
}
if ((errorCode & 0xfffff000L) == 0x80041000L)
{
ManagementException.ThrowWithExtendedInfo((ManagementStatus) errorCode);
}
else if ((errorCode & 0x80000000L) != 0L)
{
Marshal.ThrowExceptionForHR(errorCode);
}
return new ManagementObjectEnumerator(this, ppEnum);
}
This showing that it is disposable:
public class ManagementObjectEnumerator : IEnumerator, IDisposable
{
// Fields
private bool atEndOfCollection;
private uint cachedCount;
private IWbemClassObjectFreeThreaded[] cachedObjects;
private int cacheIndex;
private ManagementObjectCollection collectionObject;
private IEnumWbemClassObject enumWbem;
private bool isDisposed;
private static readonly string name;
// Methods
static ManagementObjectEnumerator();
internal ManagementObjectEnumerator(ManagementObjectCollection collectionObject, IEnumWbemClassObject enumWbem);
public void Dispose();
protected override void Finalize();
public bool MoveNext();
public void Reset();
// Properties
public ManagementBaseObject Current { get; }
object IEnumerator.Current { [TargetedPatchingOptOut("Performance critical to inline this type of method across NGen image boundaries")] get; }
}
Though enumerators that are disposable are disposed of properly by foreach statements (http://msdn.microsoft.com/en-us/library/aa664754(v=vs.71).aspx), this does not mean that the only case where the enumerator will be used is in a foreach loop.
I know that you can skip the count property and roll your own mechanism for getting the number of objects in the collection by using the enumerator yourself but the question I have is how much unmanaged memory does this leak?
Related
I am trying to range beacons and I am doing exactly what it is written here:
http://altbeacon.github.io/android-beacon-library/samples.html
didRangeBeaconsInRegion method is firing but always with empty collection.
I have installed "locate" by altbeacon and it located 3 beacons.
this is my code: am I missing something?
public class BeaconSingletone implements BeaconConsumer {
private static BeaconSingletone instance;
private final org.altbeacon.beacon.BeaconManager beaconManager2;
private ArrayList<BeaconThin> listNearBeacons = new ArrayList<>();
BeaconRegion region = new BeaconRegion("ranged region",
UUID.fromString("B9407F30-F5F8-466E-AFF9-25556B57FE6D"), null, null);
private List<EventInterface> listeners = new ArrayList<EventInterface>();
private BeaconSingletone()
{
beaconManager2 = org.altbeacon.beacon.BeaconManager.getInstanceForApplication(ar_activity.get());
// To detect proprietary beacons, you must add a line like below corresponding to your beacon
// type. Do a web search for "setBeaconLayout" to get the proper expression.
beaconManager2.getBeaconParsers().add(new BeaconParser().
setBeaconLayout("m:2-3=beac,i:4-19,i:20-21,i:22-23,p:24-24,d:25-25"));
beaconManager2.bind(this);
public static BeaconSingletone getInstance() {
if(instance == null) {
instance = new BeaconSingletone();
}
return instance;
}
private void showNotification(Region region, final List<Beacon> list) {
listNearBeacons.clear();
listNearBeacons.add(new BeaconThin(3514,7580,-1));
for (Iterator<EventInterface> i = listeners.iterator(); i.hasNext(); ) {
EventInterface item = i.next();
//item.NewBeaconFound(list.get(0).getMajor(),list.get(0).getMinor(),Utils.computeAccuracy(list.get(0)));
item.NewBeaconsFound(listNearBeacons);
}
return;
}
#Override
public void onBeaconServiceConnect() {
beaconManager2.addRangeNotifier(new RangeNotifier() {
#Override
public void didRangeBeaconsInRegion(Collection<org.altbeacon.beacon.Beacon> beacons, org.altbeacon.beacon.Region region) {
if (beacons.size() > 0) {
Log.i("BeaconManager", "The first beacon I see is about "+beacons.iterator().next().getDistance()+" meters away.");
}
}
});
try {
beaconManager2.startRangingBeaconsInRegion(new org.altbeacon.beacon.Region("mybeacons", null, null, null));
} catch (RemoteException e) { }{
}
}
#Override
public Context getApplicationContext() {
return ar_activity.get();
}
#Override
public void unbindService(ServiceConnection serviceConnection) {
ar_activity.get().unbindService(serviceConnection);
}
#Override
public boolean bindService(Intent intent, ServiceConnection serviceConnection, int i) {
return ar_activity.get().bindService(intent, serviceConnection, i);
}
}
You need to add a beacon layout for the beacon type you are using (iBeacon?). Replace this line:
beaconManager2.getBeaconParsers().add(new BeaconParser().
setBeaconLayout("m:2-3=beac,i:4-19,i:20-21,i:22-23,p:24-24,d:25-25"));
With the proper layout from here:
https://beaconlayout.wordpress.com
My unit of work class is mentioned below and I am using Ninject and I have tried injecting IUnitOfWork per request per thread scope, transient etc. but I am still getting error which is:
"Message":"An error has occurred.","ExceptionMessage":"The context cannot be used while the model is being created. This exception may be thrown if the context is used inside the OnModelCreating method or if the same context instance is accessed by multiple threads concurrently. Note that instance members of DbContext and related classes are not guaranteed to be thread safe.","ExceptionType":"System.InvalidOperationException
I get this error when i make two web API (get) calls at the same time using angularJS and it shows error at the point _context.Set<TEntity>().FirstOrDefault(match);
public class UnitOfWork : IUnitOfWork, IDisposable
{
private My_PromotoolEntities _uowDbContext = new My_PromotoolEntities();
private Dictionary<string, object> _repositories;
// Do it like this if no specific class file
private GenericRepository<MysPerson> _personRepository;
//private GenericRepository<MysDataSource> dataSourcesRepository;
//private GenericRepository<MysCountry> countryMasterRepository;
// Or like this if with specific class file.
private DataSourceRepository _dataSourcesRepository;
private CustomerRepository _customerRepository;
private DeviceRepository _deviceRepository;
private DeviceRegistrationRepository _deviceRegistrationRepository;
private EmailQueueRepository _emailQueueRepository;
public void SetContext(My_PromotoolEntities context)
{
_uowDbContext = context;
}
public void CacheThis(object cacheThis, string keyName, TimeSpan howLong)
{
Cacheing.StaticData.CacheStaticData(cacheThis, keyName, howLong);
}
public object GetFromCache(string keyName)
{
return Cacheing.StaticData.GetFromCache(keyName);
}
public GenericRepository<T> GenericRepository<T>() where T : BaseEntity
{
if (_repositories == null)
{
_repositories = new Dictionary<string, object>();
}
var type = typeof(T).Name;
if (!_repositories.ContainsKey(type))
{
var repositoryType = typeof(GenericRepository<>);
var repositoryInstance = Activator.CreateInstance(repositoryType.MakeGenericType(typeof(T)), _uowDbContext);
_repositories.Add(type, repositoryInstance);
}
return (GenericRepository<T>)_repositories[type];
}
public GenericRepository<MysPerson> PersonRepository
{
get
{
if (this._personRepository == null)
{
this._personRepository = new GenericRepository<MysPerson>(_uowDbContext);
}
return _personRepository;
}
}
public DataSourceRepository DataSourcesRepository
{
get
{
if (this._dataSourcesRepository == null)
{
this._dataSourcesRepository = new DataSourceRepository(_uowDbContext);
}
return _dataSourcesRepository;
}
}
public CustomerRepository CustomerRepository
{
get
{
if (this._customerRepository == null)
{
this._customerRepository = new CustomerRepository(_uowDbContext);
}
return _customerRepository;
}
}
public DeviceRepository DeviceRepository
{
get
{
if (this._deviceRepository == null)
{
this._deviceRepository = new DeviceRepository(_uowDbContext);
}
return _deviceRepository;
}
}
public DeviceRegistrationRepository DeviceRegistrationRepository
{
get
{
if (this._deviceRegistrationRepository == null)
{
this._deviceRegistrationRepository = new DeviceRegistrationRepository(_uowDbContext);
}
return _deviceRegistrationRepository;
}
}
public EmailQueueRepository emailQueueRepository
{
get
{
if (this._emailQueueRepository == null)
{
this._emailQueueRepository = new EmailQueueRepository(_uowDbContext);
}
return _emailQueueRepository;
}
}
/// <summary>
/// Commits all changes to the db. Throws exception if fails. Call should be in a try..catch.
/// </summary>
public void Save()
{
try
{
_uowDbContext.SaveChanges();
}
catch (DbEntityValidationException dbevex)
{
// Entity Framework specific errors:
StringBuilder sb = new StringBuilder();
var eve = GetValidationErrors();
if (eve.Count() > 0)
{
eve.ForEach(error => sb.AppendLine(error));
}
ClearContext();
// Throw a new exception with original as inner.
var ex = new Exception(sb.ToString(), dbevex);
ex.Source = "DbEntityValidationException";
throw ex;
}
catch (Exception)
{
ClearContext();
throw;
}
}
private void ClearContext()
{
DetachAll();
}
private void DetachAll()
{
foreach (DbEntityEntry dbEntityEntry in _uowDbContext.ChangeTracker.Entries())
{
if (dbEntityEntry.Entity != null)
{
dbEntityEntry.State = EntityState.Detached;
}
}
}
/// <summary>
/// Checks for EF DbEntityValidationException(s).
/// </summary>
/// <returns>Returns a List of string containing the EF DbEntityValidationException(s).</returns>
public List<string> GetValidationErrors()
{
if (_uowDbContext.GetValidationErrors().Count() != 0)
{
return _uowDbContext.GetValidationErrors().Select(e => string.Join(Environment.NewLine, e.ValidationErrors.Select(v => string.Format("{0} - {1}", v.PropertyName, v.ErrorMessage)))).ToList();
}
return null;
}
private bool disposed = false;
protected virtual void Dispose(bool disposing)
{
if (!this.disposed)
{
if (disposing)
{
_uowDbContext.Dispose();
}
}
this.disposed = true;
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
}
You should never use a context in 2 places at the same time, that's exactly why you are getting this error. From the MSDN documentation:
Thread Safety: Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
It is a little hard to make suggestions without a repro but there is a brute force approach that should resolve the issue. If you have an interception point before/during DI setup then you can cause all the context initialization etc to happen by creating an instance of your context and calling ctx.Database.Initialize(force: false); Passing 'force: false' will ensure that the initialization still only happens once per AppDomain
I need to create an extension to do some custom activity, on File Save Event in visual studio. How to achieve this using VS Package.
I am struck with below code, any advise?
#region Package Members
FileEventsListener listener = null;
protected override void Initialize()
{
Debug.WriteLine (string.Format(CultureInfo.CurrentCulture, "Entering Initialize() of: {0}", this.ToString()));
base.Initialize();
listener = new FileEventsListener();
}
#endregion
}
public class FileEventsListener : IPersistFileFormat, IDisposable
{
private IVsSolution solution;
private uint solutionEventsCookie;
private bool isDirty;
private string fileName;
private const uint MyFormat = 0;
private const string MyExtension = ".edmx";
public FileEventsListener()
{
//solution = Package.GetGlobalService(typeof(SPersistFileFormat)) as IVsSolution;
//if (solution != null)
//{
// solution.AdviseSolutionEvents(this, out solutionEventsCookie);
//}
}
#region IDisposable Members
public void Dispose()
{
}
#endregion
public int GetClassID(out Guid pClassID)
{
ErrorHandler.ThrowOnFailure(((IPersist)this).GetClassID(out pClassID));
return VSConstants.S_OK;
}
public int GetCurFile(out string ppszFilename, out uint pnFormatIndex)
{
pnFormatIndex = MyFormat;
ppszFilename = fileName;
return VSConstants.S_OK;
}
public int GetFormatList(out string ppszFormatList)
{
char Endline = (char)'\n';
string FormatList = string.Format(CultureInfo.InvariantCulture, "My Editor (*{0}){1}*{0}{1}{1}", MyExtension, Endline);
ppszFormatList = FormatList;
return VSConstants.S_OK;
}
public int InitNew(uint nFormatIndex)
{
if (nFormatIndex != MyFormat)
{
return VSConstants.E_INVALIDARG;
}
// until someone change the file, we can consider it not dirty as
// the user would be annoyed if we prompt him to save an empty file
isDirty = false;
return VSConstants.S_OK;
}
public int IsDirty(out int pfIsDirty)
{
pfIsDirty = 0;
return VSConstants.S_OK;
}
public int Load(string pszFilename, uint grfMode, int fReadOnly)
{
fileName = pszFilename;
return VSConstants.S_OK;
}
public int Save(string pszFilename, int fRemember, uint nFormatIndex)
{
return VSConstants.S_OK;
}
public int SaveCompleted(string pszFilename)
{
return VSConstants.S_OK;
}
}
}
You can subscribe to the DTE.Events.DocumentEvents.DocumentSaved event.
I am trying to implement a busy waiting mechanism, using 2 flags. I get a deadlock, but just can't understand why... it looks to me as if it should work...
sorry for the long code, That's the shortest I succeeded to make it.
package pckg1;
public class MainClass {
public static void main(String[] args) {
Buffer b = new Buffer();
Producer prod = new Producer(b);
Consumer cons = new Consumer(b);
cons.start();
prod.start();
}
}
class Producer extends Thread {
private Buffer buffer;
public Producer(Buffer buffer1) {
buffer = buffer1;
}
public void run() {
for (int i = 0; i < 60; i++) {
while (!buffer.canUpdate)
;
buffer.updateX();
buffer.canUpdate = false;
buffer.canUse = true;
}
}
}
class Consumer extends Thread {
private Buffer buffer;
public Consumer(Buffer buffer1) {
buffer = buffer1;
}
public void run() {
for (int i = 0; i < 60; i++) {
while (!buffer.canUse)
;
buffer.consumeX();
buffer.canUse = false;
buffer.canUpdate = true;
}
}
}
class Buffer {
private int x;
public boolean canUpdate;
public boolean canUse;
public Buffer() {
x = 0;
canUpdate = true;
}
public void updateX() {
x++;
System.out.println("updated to " + x);
}
public void consumeX() {
System.out.println("used " + x);
}
}
I recommend that all the logic concerning Buffer should go into that class.
Also, accessing (and modifying) the flags must be protected, if 2 or more have access to it. That's why I put synchronised to the 2 methods.
class Buffer {
private int x;
private boolean canUpdate;
private boolean canUse;
public Buffer() {
x = 0;
canUpdate = true;
}
public synchronised void updateX() {
x++;
System.out.println("updated to " + x);
canUpdate = false;
canUse = true;
}
public synchronised void consumeX() {
System.out.println("used " + x);
canUpdate = true;
canUse = false;
}
public synchronised boolean canUse() {
return canUse;
}
public synchronised boolean canUpdate() {
return canUpdate;
}
}
Also, remove the canUpdate and canUse writes from the Producer and Consumer classes, and replace the reads (in the conditons) with the methods.
Also, it would be useful to introduce some Thread.sleep(100) in the waiting loops.
How can I cancel a thread from another class fetching/refreshing location. I am able to cancel a thread from within the same class. But I am unable to do this across classes. Declaring the GPSThread static did not help. Can anyone please guide?
Class1:
public class GPSListener {
/* Other instantiation code */
Dialog busyDialog1 = new Dialog("Refreshing Location...",
new String [] { "Cancel" },
new int [] { Dialog.CANCEL},
Dialog.CANCEL,
Bitmap.getPredefinedBitmap(Bitmap.HOURGLASS))
{
public void fieldChanged(Field field1, int context1)
{
GPSHandler.requestStop();
busyDialog1.cancel();
}
};
public String refreshCoordinates() {
String test = "nothing";
if (GPSHandler.isStopRequested())
{
GPSHandler.stopRequested = false;
return null;
}
GPSHandler.getInstance().setListener(this);
GPSHandler.getInstance().requestLocationUpdates();
if (GPSHandler.isStopRequested())
{
GPSHandler.stopRequested = false;
return null;
}
busyDialog1.setEscapeEnabled(false);
busyDialog1.show();
return test;
}
public void onLocationReceived(Coordinates location) {
lblLatitude.setText(Double.toString(location.getLatitude()));
lblLongitude.setText(Double.toString(location.getLongitude()));
busyDialog1.cancel();
}
}
Class 2:
public class GPSHandler {
private GPSThread _gpsThread;
private Coordinates _location;
private boolean _gotLocation;
private GPSListener _listener;
/** this class will be a Singleton, as the device only has one GPS system */
private static GPSHandler _instance;
/** #return the Singleton instance of the GPSHandler */
public static GPSHandler getInstance() {
if (_instance == null) {
_instance = new GPSHandler();
}
return _instance;
}
public static boolean stopRequested = false;
public synchronized static void requestStop() {
stopRequested = true;
}
public synchronized static boolean isStopRequested() {
return stopRequested;
}
/** not publicly accessible ... use getInstance() */
private GPSHandler() {
}
/** call this to trigger a new location fix */
public void requestLocationUpdates() {
if (_gpsThread == null || !_gpsThread.isAlive()) {
_gpsThread = new GPSThread();
_gpsThread.start();
}
}
public void setListener(GPSListener listener) {
// only supports one listener this way
_listener = listener;
}
private void setLocation(final Coordinates value) {
_location = value;
if (value.getLatitude() != 0.0 || value.getLongitude() != 0.0) {
_gotLocation = true;
if (_listener != null) {
// this assumes listeners are UI listeners, and want callbacks on the UI thread:
UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run() {
_listener.onLocationReceived(value);
}
});
}
}
}
private class GPSThread extends Thread {
private void getLocationFromGoogle() {
try {
int cellID = GPRSInfo.getCellInfo().getCellId();
int lac = GPRSInfo.getCellInfo().getLAC();
String urlString2 = "http://www.google.com/glm/mmap";
// Open a connection to Google Maps API
ConnectionFactory connFact = new ConnectionFactory();
ConnectionDescriptor connDesc;
connDesc = connFact.getConnection(urlString2);
HttpConnection httpConn2;
httpConn2 = (HttpConnection)connDesc.getConnection();
httpConn2.setRequestMethod("POST");
// Write some custom data to Google Maps API
OutputStream outputStream2 = httpConn2.openOutputStream();//getOutputStream();
writeDataGoogleMaps(outputStream2, cellID, lac);
// Get the response
InputStream inputStream2 = httpConn2.openInputStream();//getInputStream();
DataInputStream dataInputStream2 = new DataInputStream(inputStream2);
// Interpret the response obtained
dataInputStream2.readShort();
dataInputStream2.readByte();
final int code = dataInputStream2.readInt();
UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run() {
Dialog.alert(code + "");
}
});
if (code == 0) {
final double latitude = dataInputStream2.readInt() / 1000000D;
final double longitude = dataInputStream2.readInt() / 1000000D;
setLocation(new Coordinates(latitude, longitude, 0.0f));
UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run() {
Dialog.alert(latitude+"-----"+longitude);
}
});
dataInputStream2.readInt();
dataInputStream2.readInt();
dataInputStream2.readUTF();
} else {
System.out.println("Error obtaining Cell Id ");
}
outputStream2.close();
inputStream2.close();
} catch (Exception e) {
System.out.println("Error: " + e.getMessage());
}
}
private void tryGetLocationFromDevice() {
_gotLocation = false;
try {
Criteria myCriteria = new Criteria();
myCriteria.setCostAllowed(false);
LocationProvider myLocationProvider = LocationProvider.getInstance(myCriteria);
try {
Location myLocation = myLocationProvider.getLocation(300);
setLocation(myLocation.getQualifiedCoordinates());
} catch ( InterruptedException iex ) {
System.out.println(iex.getMessage());
} catch ( LocationException lex ) {
System.out.println(lex.getMessage());
}
} catch ( LocationException lex ) {
System.out.println(lex.getMessage());
}
if (!_gotLocation) {
getLocationFromGoogle();
}
}
public void run() {
int bbMapsHandle = CodeModuleManager.getModuleHandle("net_rim_bb_lbs"); // OS 4.5 - 6.0
int bbMapsHandle60 = CodeModuleManager.getModuleHandle("net_rim_bb_maps"); // OS 6.0
if (bbMapsHandle > 0 || bbMapsHandle60 > 0) {
tryGetLocationFromDevice();
} else {
getLocationFromGoogle();
}
}
}
private void writeDataGoogleMaps(OutputStream out, int cellID, int lac) throws IOException {
DataOutputStream dataOutputStream = new DataOutputStream(out);
dataOutputStream.writeShort(21);
dataOutputStream.writeLong(0);
dataOutputStream.writeUTF("en");
dataOutputStream.writeUTF("Android");
dataOutputStream.writeUTF("1.0");
dataOutputStream.writeUTF("Web");
dataOutputStream.writeByte(27);
dataOutputStream.writeInt(0);
dataOutputStream.writeInt(0);
dataOutputStream.writeInt(3);
dataOutputStream.writeUTF("");
dataOutputStream.writeInt(cellID);
dataOutputStream.writeInt(lac);
dataOutputStream.writeInt(0);
dataOutputStream.writeInt(0);
dataOutputStream.writeInt(0);
dataOutputStream.writeInt(0);
dataOutputStream.flush();
}
}
Your GPSThread object is currently declared as a private inner class within GPSHandler. If you want to stop execution (or indeed do anything with it) from outside the scope of GPSHandler you will need to mark it as public. You will also need to provide some public mechanism (e.g. a stop() method) to cancel the thread execution.
The most common way of doing this is to have a boolean flag inside your thread (e.g shouldStop) which is checked within your main execution loop inside run() to see if it should stop. When the stop() method is called shouldStop is set to true and your Thread will stop.
Here's a good example: How to stop threads in Java?
There's two groups of changes you should make.
Change the Stop Requested Flag
First, remember that encapsulation is a good thing in Object-Oriented languages. The isStopRequested() method, or stopRequested variable of the GPSHandler should not be used outside of that class. Your UI's GPSListener should not attempt to use either of those. I would change your GPSHandler to use this:
private static boolean stopRequested = false;
public synchronized static void requestStop() {
stopRequested = true;
}
private synchronized static boolean isStopRequested() {
return stopRequested;
}
Only requestStop() should be public. It looks like you made stopRequested public to allow the GPSListener to reset it. If it needs resetting, let the class that owns that variable do the resetting. For example, in GPSHandler:
/** call this to trigger a new location fix */
public void requestLocationUpdates() {
if (_gpsThread == null || !_gpsThread.isAlive()) {
// reset this stop flag:
stopRequested = false;
_gpsThread = new GPSThread();
_gpsThread.start();
}
}
requestLocationUpdates() is really the method that starts the thread, so it should be where stopRequested gets reset to false.
Also, another reason that you should not make stopRequested public and allow other classes to use it is that this is not generally thread-safe. One of the reasons to wrap stopRequested with the requestStop() and isStopRequested() methods is to add thread-safety. There's many ways to do that, but those two methods achieve thread-safety by being marked with the synchronized keyword.
Change How/Where You Check the Flag
After you make these fixes, you need to change where you check if a stop has been requested. You don't really want to check isStopRequested() in the refreshCoordinates() method. That method involves almost no work. Even though it starts the process of getting a location fix, that only starts a thread, but the actual work of getting the location is done on a background thread (your GPSThread). If requestStop() is called, it's very unlikely that it will be called in the middle of refreshCoordinates(), so that's not where you should check it.
Check isStopRequested() multiple times within the GPSHandler class's methods tryGetLocationFromDevice() and getLocationFromGoogle(). Those are the methods that perform slow processing. Those are the ones you might want to interrupt in the middle. So, something like this:
private void getLocationFromGoogle() {
try {
int cellID = GPRSInfo.getCellInfo().getCellId();
int lac = GPRSInfo.getCellInfo().getLAC();
String urlString2 = "http://www.google.com/glm/mmap";
if (isStopRequested()) return;
// Open a connection to Google Maps API
ConnectionFactory connFact = new ConnectionFactory();
ConnectionDescriptor connDesc;
connDesc = connFact.getConnection(urlString2);
HttpConnection httpConn2;
httpConn2 = (HttpConnection)connDesc.getConnection();
httpConn2.setRequestMethod("POST");
// Write some custom data to Google Maps API
OutputStream outputStream2 = httpConn2.openOutputStream();//getOutputStream();
writeDataGoogleMaps(outputStream2, cellID, lac);
if (isStopRequested()) return;
// Get the response
InputStream inputStream2 = httpConn2.openInputStream();//getInputStream();
DataInputStream dataInputStream2 = new DataInputStream(inputStream2);
// Interpret the response obtained
dataInputStream2.readShort();
dataInputStream2.readByte();
if (isStopRequested()) return;
final int code = dataInputStream2.readInt();
UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run() {
Dialog.alert(code + "");
}
});
And in tryGetLocationFromDevice(), you could do this (make sure to add the member variable and new method below):
private LocationProvider _locationProvider; // must be a member variable!
public void requestStop() {
if (_locationProvider != null) {
// this will interrupt the _locationProvider.getLocation(300) call
_locationProvider.reset();
}
}
private void tryGetLocationFromDevice() {
_gotLocation = false;
try {
Criteria myCriteria = new Criteria();
myCriteria.setCostAllowed(false);
_locationProvider = LocationProvider.getInstance(myCriteria);
try {
Location myLocation = _locationProvider.getLocation(300);
setLocation(myLocation.getQualifiedCoordinates());
} catch ( InterruptedException iex ) {
// this may be caught if stop requested!!!!
System.out.println(iex.getMessage());
} catch ( LocationException lex ) {
System.out.println(lex.getMessage());
}
} catch ( LocationException lex ) {
System.out.println(lex.getMessage());
}
if (!_gotLocation && !isStopRequested()) {
getLocationFromGoogle();
}
}
Then, call the GPSThread.requestStop() method from the outer GPSHandler.requestStop() method:
public synchronized static void requestStop() {
stopRequested = true;
if (_gpsThread != null) {
_gpsThread.requestStop();
}
}