java - Calling subject.onNext() inside doOnSubscribe -


why calling subject.onnext(o) inside doonsubscribe not effect, calling subject.oncomplete() causes stream terminate!?

final publishsubject<integer> subject = publishsubject.create();      final observable<integer> observable = subject.doonsubscribe(new consumer<disposable>() {         @override         public void accept(@nonnull disposable disposable) throws exception {             system.out.println("disposable = [" + disposable + "]");             subject.onnext(1);             //or             observable.just(2, 3).subscribe(subject);         }     });      observable.subscribe(new observer<integer>() {         @override         public void onsubscribe(disposable d) {             system.out.println("d = [" + d.isdisposed() + "]");         }          @override         public void onnext(integer integer) {             system.out.println("item = [" + integer + "]");         }          @override         public void onerror(throwable e) {             system.out.println("e = [" + e + "]");         }          @override         public void oncomplete() {             system.out.println("oncomplete");         }     });/*     expected:     disposable = [false]     d = [false]     item = 1     item = 2     item = 3     oncomplete     received :     disposable = [false]     d = [false]     oncomplete     */

when subscribing subject in 2.x, disposable representing connection traversing onsubscribe() chain before particular observer becomes visible onnext. can see if call hasobservers onsubscribe return false until onsubscribe returns.

this required observable protocol not allowed run onsubscribe , onnext concurrently , onsubscribe must happen before onnext. if rule wasn't held, concurrent call subject.onnext run before or @ same time observer.onsubscribe call , find unprepared consumer.

since publishsubject doesn't retain onnext calls, unobserved onnext items dropped. depending on use case, should instead use behaviorsubject or yoursubject.startwith(initialvalue).subscribe() value before other onnext subject.


Comments

Post a Comment

Popular posts from this blog

inversion of control - Autofac named registration constructor injection -

does autofac support specifying registration name in components' constructors? example: ninject's namedattribute . you need use autofac.extras.attributed package on top achieve this so let's have 1 interface , 2 classes: public interface ihello { string sayhello(); } public class englishhello : ihello { public string sayhello() { return "hello"; } } public class frenchhello : ihello { public string sayhello() { return "bonjour"; } } then have consumer class, in want select instance injected: public class helloconsumer { private readonly ihello helloservice; public helloconsumer([withkey("en")] ihello helloservice) { if (helloservice == null) { throw new argumentnullexception("helloservice"); } this.helloservice = helloservice; } public string sayhello() { return this.helloservice.sayhello()...
Read more

ios - Change Storyboard View using Seague -

i have following code checks connection server, , depending on want change views if no connection found. nsstring *connect = [nsstring stringwithcontentsofurl:[nsurl urlwithstring:@"http://myserver.com"] encoding:nsutf8stringencoding error:nil]; if (connect == null) { [self performseguewithidentifier:@"network_failure" sender:self]; } else { // other code here } my problem not change views. have added storyboard segue between 2 views identifier of network_failure . not have navigation controller or that, problem? thanks help! no not problem. first of all, in objectivec exists nil object oriented null . must use that. so: if(connect == nil) or better: if(!connect) so due fact nil not same of null , probably code does't enter in if scope . you have been able discover breakpoint. anyway: be sure set trigger segue (line) 2 view controller , , name network_failure (that not best name. should instead view1toview2 ) as, m...
Read more

verilog - Systemverilog dynamic casting issues -

i've code snippet following in testbench function void write_to_port( my_data_type_base data ); my_data_type_extended data_ext; if(!$cast(data_ext, data)); `uvm_error(get_type_name(), "failed cast"); `uvm_info(get_name(), $psprintf("data_ext :\n%s", data_ext.sprint()), uvm_medium) // write data_ext out port.... endfunction when run it, i'm getting uvm_error "failed cast." i'm not quire sure why $cast not returning 1. can see, i'm printing out extended class data item after casting uvm_info. can see it's being cast properly. if don't use $cast if condition, don't runtime error. isn't coding practice use if dynamic cast check if $cast returning 1 ? what might reason behind cast not returning 1 in above case? i think semicolon on line 'if' not belong? i think consumes if statement, , uvm_error executes regardless of how if evaluates: if(!$cast(data_ext, data)); <- no semico...
Read more