Menu
▾
▴
Re: [xmlvm-users] Bug in NSData?
|
From: Paul P. <bay...@gm...> - 2011-06-20 14:48:36
|
FYI - I implemented the C version of wait/notify/sleep/interrupt a few days
ago, so you may use Thread.sleep(long) now.
Thanks,
Paul
On Thu, May 19, 2011 at 1:38 PM, Alex Lewis <ale...@gm...> wrote:
> Ah yes, take out the sleep and finished flag. Sorry that was mistakenly
> left in from other tests I had been trying. Without the sleep and finished
> flag the system output is still (when using the google url)...
>
> Received data [<!doctype html><html><head]
> Finish loading
>
> So looking at the implementation of NSURLConnection calling
> "connectionWithRequest" starts a new thread so the method calls should be
> asynchronous back to the delegate? So I would expect the
> "applicationDidFinishLaunching" method to finish quickly but whilst the
> NSURLConnection thread is running to get the output generated by the
> delegate. Looking at the code again I see there should be just the one
> "Received data" message followed by the "Finish Loading" message but there
> should be a lot more data in NSData's byte array.
>
> Thanks,
> Alex
>
>
> Just in case here's the modified code...
>
> @Override
> public void applicationDidFinishLaunching(UIApplication app) {
> try {
> final NSURL url = NSURL.URLWithString("http://www.google.com");
> final NSMutableURLRequest req = new NSMutableURLRequest(url);
>
> NSURLConnectionDelegate delegate = new NSURLConnectionDelegate() {
> @Override
> public void connectionDidFailWithError(
> NSURLConnection connection, NSError error) {
> super.connectionDidFailWithError(connection, error);
> System.out.println("Error [" + error + "]");
> }
>
> @Override
> public void connectionDidFinishLoading(
> NSURLConnection connection) {
> super.connectionDidFinishLoading(connection);
> System.out.println("Finish loading");
> }
>
> @Override
> public void connectionDidReceiveData(
> NSURLConnection connection, NSData data) {
> super.connectionDidReceiveData(connection, data);
> System.out.println("Received data [" + new String(data.getBytes())
> + "]");
> }
> };
>
> NSURLConnection.connectionWithRequest(req, delegate);
> }
> catch (Exception e) {
> System.err.println("Exception doing HTTP" + e);
> }
> }
>
> On 19 May 2011 18:05, Arno Puder <ar...@pu...> wrote:
>
>>
>> I'm not sure if you should do that sleep() in your code. The
>> NSURLConnection delegate will most likely be executed in the context of
>> the same thread that created it, but if you put that thread to sleep,
>> problems will occur. Basically you implemented a busy wait which is
>> never a good idea. This in not an XMLVM problem, IMHO.
>>
>> Arno
>>
>>
>> On 5/19/11 6:53 AM, Alex Lewis wrote:
>> > Hi,
>> > I wrote a very simple Java->iPhone application to open a connection
>> > and read the data in the response, but I found I only ever got back 26
>> > bytes of data. Here's the simplest code I could put together which
>> > exhibits the problem...
>> >
>> > private boolean finished = false;
>> > @Override
>> > public void applicationDidFinishLaunching(UIApplication app) {
>> > try {
>> > final NSURL url = NSURL.URLWithString("http://www.google.com");
>> > final NSMutableURLRequest req = new NSMutableURLRequest(url);
>> > NSURLConnectionDelegate delegate = new NSURLConnectionDelegate() {
>> > @Override
>> > public void connectionDidFailWithError(
>> > NSURLConnection connection, NSError error) {
>> > super.connectionDidFailWithError(connection, error);
>> > System.out.println("Error [" + error + "]");
>> > }
>> > @Override
>> > public void connectionDidFinishLoading(
>> > NSURLConnection connection) {
>> > super.connectionDidFinishLoading(connection);
>> > finished = true;
>> > System.out.println("Finish loading");
>> > }
>> > @Override
>> > public void connectionDidReceiveData(
>> > NSURLConnection connection, NSData data) {
>> > super.connectionDidReceiveData(connection, data);
>> > System.out.println("Received data [" + new String(data.getBytes()) +
>> "]");
>> > }
>> > };
>> > NSURLConnection.connectionWithRequest(req, delegate);
>> > // Wait until all the data has been received or we hit a
>> > 20s limit.
>> > int i = 0;
>> > while (!finished && i < 20) {
>> > Thread.sleep(1000);
>> > i++;
>> > }
>> > }
>> > catch (Exception e) {
>> > System.err.println("Exception doing HTTP" + e);
>> > }
>> > }
>> >
>> > I would have expected multiple "Received Data[.......]" messages but I
>> > only ever get one of 26 characters. I took a look at the NSData java
>> > class, specifically the readData method and I can see why it is failing.
>> > The do/while loop in there only continues to read data if its buffer has
>> > been filled and assumes that if the read() method returns a read count
>> > of less than the buffer size that all the data has been read. Using the
>> > code above the response contains an initial 26 bytes and consequently
>> > stops as the buffer in NSData has not been completely filled. I wrote an
>> > equivalent pure java application and it exhibits the same behaviour
>> > using the readData code. Rewriting the readData method so it keeps
>> > reading until -1 is returned and buffering the code appropriately
>> > retrieves all the data which is approximately 9k bytes.
>> >
>> > Is this a bug or have I done something wrong? Would the code work
>> > properly if the application were running on an iPhone rather than in the
>> > Emulator?
>> >
>> > Thanks,
>> > Alex
>> >
>> >
>> >
>> >
>> ------------------------------------------------------------------------------
>> > What Every C/C++ and Fortran developer Should Know!
>> > Read this article and learn how Intel has extended the reach of its
>> > next-generation tools to help Windows* and Linux* C/C++ and Fortran
>> > developers boost performance applications - including clusters.
>> > http://p.sf.net/sfu/intel-dev2devmay
>> >
>> >
>> >
>> > _______________________________________________
>> > xmlvm-users mailing list
>> > xml...@li...
>> > https://lists.sourceforge.net/lists/listinfo/xmlvm-users
>>
>>
>> ------------------------------------------------------------------------------
>> What Every C/C++ and Fortran developer Should Know!
>> Read this article and learn how Intel has extended the reach of its
>> next-generation tools to help Windows* and Linux* C/C++ and Fortran
>> developers boost performance applications - including clusters.
>> http://p.sf.net/sfu/intel-dev2devmay
>> _______________________________________________
>> xmlvm-users mailing list
>> xml...@li...
>> https://lists.sourceforge.net/lists/listinfo/xmlvm-users
>>
>
>
>
> ------------------------------------------------------------------------------
> What Every C/C++ and Fortran developer Should Know!
> Read this article and learn how Intel has extended the reach of its
> next-generation tools to help Windows* and Linux* C/C++ and Fortran
> developers boost performance applications - including clusters.
> http://p.sf.net/sfu/intel-dev2devmay
> _______________________________________________
> xmlvm-users mailing list
> xml...@li...
> https://lists.sourceforge.net/lists/listinfo/xmlvm-users
>
>
|
