IOS memory leak because of WWW object

Hi there,

I have a nifty memory leak when I run my project on the IOS platform. I have checked it using instruments leak tool and debug using Xcode 6. In some cases it looks like the WWW object is never disposed.

---

I°) Here is the part of code that handle sending WWW requests:

 private void issueRequestWithoutQueuing(string url, Dictionary<string, string> parameters = null, Callback<ServerData> successCallback = null, Callback<string> apiFailureCallback = null, Callback<string> layerFailureCallback = null, bool showSpinner = false)
 {
     QueuedWWWObject queueWWW = new QueuedWWWObject();
     queueWWW.url = url;
     queueWWW.successCB = successCallback;
     queueWWW.apiFailureCB = apiFailureCallback;
     queueWWW.layerFailureCB = layerFailureCallback;
     if (parameters != null)
     {
         queueWWW.parameters = parameters;
     }
     issueRequest(queueWWW, showSpinner);
 }
 
     private void issueRequest(QueuedWWWObject queueWWW, bool showSpinner = false)
     {
         numberRequestInProgress ++;
 
         WWW www;
         if (queueWWW.parameters != null && queueWWW.parameters.Count != 0)
         {
             WWWForm form = new WWWForm();
             foreach (KeyValuePair<string, string> pair in queueWWW.parameters)
             {
                 form.AddField(pair.Key, pair.Value);
             }
             www = new WWW(queueWWW.url, form);
         }
         else
         {
             www = new WWW(queueWWW.url);
         }
 
         NetworkManager.instance.StartCoroutine(WaitForRequest(www, queueWWW, queueWWW.successCB, queueWWW.apiFailureCB, queueWWW.layerFailureCB));
     }

We are waiting for request until we receive either that the request is done, there has been an error, or the request has timed out

     private IEnumerator<WWW> WaitForRequest(WWW www, Callback<ServerData> successCallback = null, Callback<string> apiFailureCallback = null, Callback<string> layerFailureCallback = null)
     {
         
         int startLaunchRequestTime = ServerTime.instance.getRealGameTime();
         while (!www.isDone && www.error == null && ((ServerTime.instance.getRealGameTime() - startLaunchRequestTime) < REQUEST_TIMEOUT))
         {
             yield return www;
         }
         
         LaunchCallback cb = new LaunchCallback();
         cb.www = www;
         cb.successCB = successCallback;
         cb.apiFailureCB = apiFailureCallback;
         cb.layerFailureCB = layerFailureCallback;
         
         if ((ServerTime.instance.getRealGameTime() - startLaunchRequestTime) >= REQUEST_TIMEOUT)
         {
             cb.timeOutError = true;
         }
         
         _launchCallbacks.Add(cb);
     }

---

II°) And then, in the update function, where we request the results for the launchcallback, handle the callbacks, and dispose the WWW object:

     public void update()
     {
         int len = _launchCallbacks.Count;
         List<LaunchCallback> callbackToDelete = new List<LaunchCallback>();
         for (int i=0; i<len; i++)
         {
             LaunchCallback cb = _launchCallbacks[i];
             RequestResult(cb.www, cb.hasTransaction,  cb.successCB, cb.apiFailureCB, cb.layerFailureCB, cb.timeOutError);
             callbackToDelete.Add(cb);
         }
         foreach(LaunchCallback call in callbackToDelete)
         {
             _launchCallbacks.Remove(call);
             call.dispose();
         }
     }


     private void RequestResult(WWW www, bool hasTransaction, Callback<ServerData> successCallback, Callback<string> apiFailureCallback , Callback<string> layerFailureCallback, bool timeOutError)
     {
         // handles success/ failure callbacks, not relevant here
         numberRequestInProgress --;
     }

---

III°) The LauncCcallback class is just a container for the WWW object and its callbacks:

     public class LaunchCallback
     {
         public Callback<ServerData> successCB;
         public Callback<string> apiFailureCB;
         public Callback<string> layerFailureCB;
         public WWW www;
         public bool hasTransaction;
         public bool timeOutError = false;
     
     
         public void dispose()
         {
             Debug.Log (" DISPOSING WWW object " + www.url );
             www.Dispose();
             successCB = null;
             apiFailureCB = null;
             layerFailureCB = null;
         }
     }
     

---

When I run the project on IOS, I get the debug output of DISPOSING WWW object " + www.url, but the leak instrument tells me that the issueRequest function has leaked several strings, dictionary etc etc, as if the WWW has not been disposed:

http://imgur.com/RWBbYwH

When I put a breakpoint in Xcode, we pass in the destroy function for every request:

 extern "C" void UnityDestroyWWWConnection(void* connection)
 {
     UnityWWWConnectionDelegate* delegate = (UnityWWWConnectionDelegate*)connection;
 
     [delegate cleanup];
     [delegate release];
 }

which calls this:

 - (void)cleanup
 {
     [_connection cancel];
     _connection = nil;
 
     [_data release];
     _data = nil;
 }

I really don't know what's going on, because I do pass in the dispose function of the launchcallback. Is there any references that could lead the WWW object to not be disposed?

PS: I am using unity 4.5.5 & monodevelop 4.0.1

Many thanks,

Down

---

UPDATE 1:

A little update:

After reviewing the code generated by unity in xcode and analyzing it: xcode tells me that there is a potential leak in the WWWConnection.mm, particulary here, the delegate.connection is never cleaned:

 extern "C" void* UnityStartWWWConnectionGet(void* udata, const void* headerDict, const char* url)
 {
     UnityWWWConnectionDelegate*    delegate = [UnityWWWConnectionDelegate newDelegateWithCStringURL:url udata:udata];
 
     NSMutableURLRequest* request =
         [UnityWWWConnectionDelegate newRequestForHTTPMethod:@"GET" url:delegate.url headers:(NSDictionary*)headerDict];
 
     delegate.connection = [NSURLConnection connectionWithRequest:request delegate:delegate];
     return delegate;
 }

the same occurs for POST methods:

 extern "C" void* UnityStartWWWConnectionPost(void* udata, const void* headerDict, const char* url, const void* data, unsigned length)
 {
     UnityWWWConnectionDelegate*    delegate = [UnityWWWConnectionDelegate newDelegateWithCStringURL:url udata:udata];
 
     NSMutableURLRequest* request =
         [UnityWWWConnectionDelegate newRequestForHTTPMethod:@"POST" url:delegate.url headers:(NSDictionary*)headerDict];
     [request setHTTPBody:[NSData dataWithBytes:data length:length]];
     [request setValue:[NSString stringWithFormat:@"%d", length] forHTTPHeaderField:@"Content-Length"];
 
     delegate.connection = [NSURLConnection connectionWithRequest:request delegate:delegate];
     return delegate;
 }

Which correlates nicely with what I see:

http://imgur.com/vIdeg54

I don't really know what to do, as it looks like its related to the unity code. Any help would be appreciated.

---

UPDATE 2

I have a similar leak when I call this function:

     private void OnEnable()
     {
      StartCoroutine(doGet(facebookURL, onGetFacebookAvatar));
     }

     public IEnumerator doGet(string url, Callback<WWW> callback = null) 
     {
         using (WWW www = new WWW(url))
         {
             yield return www;
             if (callback != null)
             {
                 callback(www);
                 callback = null;
             }
         }
     }

     private void onGetFacebookAvatar(WWW result)
     {
         if (!string.IsNullOrEmpty (result.error))
         {
             ErrorManager.instance.logWarning (ErrorManager.ERROR_FACEBOOK_API,  "Get facebook avatar failed : " + result.error, "AvatarBehaviour");
         }
         else
         {
             Texture2D texture = new Texture2D(frame.width-20, frame.height-20);
             if (!_facebookAvatar.ContainsKey(_userID))
             {
                 // Never use www.texture as it cause memory leak (WWW object is never released)
                 result.LoadImageIntoTexture(texture);
                 _facebookAvatar.Add(_userID, texture);
             }
             avatarTexture.mainTexture = texture;
             avatarTexture.width = frame.width - 20;
             avatarTexture.height = frame.height - 20;
             NGUITools.SetActiveSelf(avatarSprite.gameObject, false);
             NGUITools.SetActiveSelf(avatarTexture.gameObject, true);
         }
     }

see http://imgur.com/vIdeg54

---

UPDATE 3:

After some investigation, adding the line:

 [request release];

here

 extern "C" void* UnityStartWWWConnectionGet(void* udata, const void* headerDict, const char* url)
 {
     UnityWWWConnectionDelegate*    delegate = [UnityWWWConnectionDelegate newDelegateWithCStringURL:url udata:udata];
 
     NSMutableURLRequest* request =
         [UnityWWWConnectionDelegate newRequestForHTTPMethod:@"GET" url:delegate.url headers:(NSDictionary*)headerDict];
 
     delegate.connection = [NSURLConnection connectionWithRequest:request delegate:delegate];
     [request release];
     return delegate;
 }
 

Does helps, but still some leak, maybe because what's inside the request is not fully released (string and stuff), still investigating

  while (!www.isDone && www.error == null && ((ServerTime.instance.getRealGameTime() - startLaunchRequestTime) < REQUEST_TI$$anonymous$$EOUT))
 {
 yield return www;
 }

 yield return null;