cppcms-users

[Cppcms-users] Q&A: async gzip and mount

[Markus R. <us...@ma...>]

Hi users!

Here are some questions (with answers) which could be of interest:

1.) Is it possible to use gzip compression on async connections?

Artyom Beilis wrote:
> No you can't, for two reasons:
> 
> 1. You can't really do streaming with gzip compression
>    as the stream becomes buffered.
> 2. The compression process costs a lot so it not wise
>    to use it in the single event-loop's thread.


2.) What is the difference between
booster::intrusive_ptr<App> c=new App(service);
service.applications_pool().mount(c);
and:
service.applications_pool().mount(cppcms::applications_factory<App>());


Artyom Beilis wrote:
> in the first case you have a single application
> instance that only being executed in a single thread
> of the event loop, in the second case multiple applications
> are created on demand and run in the thread pool.

See:
http://cppcms.com/cppcms_ref/1.0.2/classcppcms_1_1applications__pool.html



3.) Are there some examples how to mount multiple applications (both sync 
and async; with dispatcher and using main; mounting the same application 
twice) using mount_points?

Now there is:
cppcms::service app(argc,argv);
app.applications_pool().mount(cppcms::applications_factory<myapp>(), 	
    cppcms::mount_point("/myapp(/(.*))?", 1));
app.applications_pool().mount(cppcms::applications_factory<numbers>(),
    cppcms::mount_point("/numbers(/(.*))?", 1));
app.applications_pool().mount(cppcms::applications_factory<letters>(), 
    cppcms::mount_point("/letters(/(.*))?", 1));
booster::intrusive_ptr<async> c (new async(app));
app.applications_pool().mount(c, cppcms::mount_point("/async(/(.*))?", 1));
app.applications_pool().mount(cppcms::applications_factory<sync>(), 
    cppcms::mount_point("/sync(/(.*))?", 1));
app.run();

See attached file for full example, there are small issues with double 
mounting in the example: the URL mapper does not always work correctly.

See also http://cppcms.com/cppcms_ref/1.0.2/classcppcms_1_1mount__point.html

Best regards
Markus

Re: [Cppcms-users] Q&A: async gzip and mount

[Artyom B. <art...@ya...>]

> 

> See attached file for full example, there are small issues with double 
> mounting in the example: the URL mapper does not always work correctly.
> 

Can you explain what is the problem?

Artyom

Re: [Cppcms-users] Q&A: async gzip and mount

[Markus R. <us...@ma...>]

Hello!

Artyom Beilis wrote:

>> See attached file for full example, there are small issues with double
>> mounting in the example: the URL mapper does not always work correctly.

> Can you explain what is the problem?
 
The problem is within the example mount.cpp
(urls with scriptname /hello, config is attached)

When you go to:
http://localhost:8080/hello/myapp/numbers
or
http://localhost:8080/myapp/numbers

the URL for odd is correct (works):
http://localhost:8080/myapp/numbers/odd


But when you go to:
http://localhost:8080/hello/numbers
or
http://localhost:8080/numbers

the generated URL for odd numbers is
http://localhost:8080/odd
which does not work (404 - Not found).


best regards
Markus Raab

Re: [Cppcms-users] Q&A: async gzip and mount

[Markus R. <us...@ma...>]

Hello!

Btw, this code (also seen in many other examples floating around):
> booster::intrusive_ptr<async> c (new async(app));
>  app.applications_pool().mount(c, cppcms::mount_point("/async(/(.*))?",
>  1));

typically crashes here at shutdown because intrusive_ptr holds the async 
object longer then the app itself which may lead to shutdown crashes like:
#0  0x00007f5028e9e624 in cppcms::application::root() () from 
/usr/lib/libcppcms.so.1
#1  0x00007f5028e9ea93 in 
booster::intrusive_ptr_release(cppcms::application*) () from 
/usr/lib/libcppcms.so.1
#2  0x0000000000404a1d in booster::intrusive_ptr<async>::~intrusive_ptr() ()
#3  0x000000000040263b in main ()


or 

#0  0xb7a71587 in cppcms::applications_pool::put(cppcms::application*) () 
from /usr/lib/libcppcms.so.1
#1  0xb7a73c4e in booster::intrusive_ptr_release(cppcms::application*) () 
from /usr/lib/libcppcms.so.1
#2  0x08494f40 in 
booster::intrusive_ptr<LVDC_service::Scan_data_service>::~intrusive_ptr 
(this=0xb4f2c21c, __in_chrg=<optimized out>) at 
/home/markus/LVDC/dev/lvdc/lvdc_pp/../../libs/booster/include/booster/intrusive_ptr.h:68

also wrong would be to put above two lines in a scope, or having
booster::intrusive_ptr<async> c (new async(app));

because then the application would not be mounted correctly and it would 
lead to a 404 Not found.


Intrusive ptr is hardly documented (neither in booster nor in boost),
so here would be a (imho) correct version:
145         cppcms::service app(argc,argv);
146         {
147             
app.applications_pool().mount(cppcms::applications_factory<myapp>(), 
cppcms::mount_point("/myapp(/(.*))?", 1));
148             
app.applications_pool().mount(cppcms::applications_factory<numbers>(), 
cppcms::mount_point("/numbers(/(.*))?", 1));
149             
app.applications_pool().mount(cppcms::applications_factory<letters>(), 
cppcms::mount_point("/letters(/(.*))?", 1));
150 
151             booster::intrusive_ptr<async> c (new async(app));
152             app.applications_pool().mount(c, 
cppcms::mount_point("/async(/(.*))?", 1));
153             
app.applications_pool().mount(cppcms::applications_factory<sync>(), 
cppcms::mount_point("/sync(/(.*))?", 1));
154             app.run();
155         }

That would terminate the async object after app.run() but before service is 
deallocated. Please correct me if I am wrong.

best regards
Markus Raab

P.s. sorry for missing debug symbols, I could not find a libcppcms-dbg 
debian package?
And what is http://apt.cppcms.com/dists/squeezy? Do you mean wheezy?