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Re: Library for Escalable Locks, Slimmest API?

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Robert Klemme schrieb:
>>  if ( resourceNeedsLoading() ) {
>>     acquire w-l
>>     if ( resourceNeedsLoading() ) {
>>        loadFromFile()
>>        updateResource()
>>     }
>>     release w-l
>>  }
>
> That is not optimal.  That is slow and error prone.  Slow, because you
> call the method for checking at most three times while my code only
> calls it at most two times per execution.  Wrong, because you invoke the
> check method without holding a lock.  That is precisely the reason why
> my suggested code remembers the state when obtained inside the lock and
> reevaluates when holding the read lock.

Yes, maybe this is a good approach, to use a read lock
for the resourceNeedsLoading().

Since we have learnt that if a thread holds a write lock
he is also entitled to acquire a read lock, the whole
thing could be coded more modular:

boolean resourceNeedsLoading() {
     aquire r-l
     res=checkResource();
     release r-l
     return res;
}

But my problems are not refacroring problems. The issue
is that checkResouce() das a URL get() with if_modified_since,
how can I reduce the number of URL() get?

(BTW: I am not only using if_modified_since , I am also
checking the expiration against last modified , and some
more stuff )

I was already thinking about:

   if ( "URL head()" ) {
      acquire w-l
      if ( "URL get()" ) {
         loadFromFile()
         updateResource()
      }
      release w-l
   }

But I have not yet experimented with 304 in HEAD,
I am only able to handle 304 in GET for the moment,
lets see.

(BTW: Don't worry, also some further caching is possible,
so I can also reduce the number of URL head(), since there
are import maps)

Bye

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Library for Escalable Locks, Slimmest API? Jan Burse <janburse@fastmail.fm> - 2016-08-07 18:55 +0200
  Re: Library for Escalable Locks, Slimmest API? Andreas Leitgeb <avl@logic.at> - 2016-08-08 01:10 +0000
    Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-08 09:38 +0200
      Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-08 09:47 +0200
      Re: Library for Escalable Locks, Slimmest API? Andreas Leitgeb <avl@logic.at> - 2016-08-10 14:39 +0000
        Re: Library for Escalable Locks, Slimmest API? Jan Burse <janburse@fastmail.fm> - 2016-08-10 18:05 +0200
          Re: Library for Escalable Locks, Slimmest API? Lew <lewbloch@gmail.com> - 2016-08-10 17:44 -0700
            Re: Library for Escalable Locks, Slimmest API? Jan Burse <janburse@fastmail.fm> - 2016-08-11 12:43 +0200
              Re: Library for Escalable Locks, Slimmest API? Robert Klemme <shortcutter@googlemail.com> - 2016-08-12 22:18 +0200
                Re: Library for Escalable Locks, Slimmest API? Andreas Leitgeb <avl@logic.at> - 2016-08-13 05:56 +0000
                Re: Library for Escalable Locks, Slimmest API? Robert Klemme <shortcutter@googlemail.com> - 2016-08-13 11:08 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-13 11:37 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-13 11:39 +0200
                Re: Library for Escalable Locks, Slimmest API? Jan Burse <janburse@fastmail.fm> - 2016-08-13 12:27 +0200
                Re: Library for Escalable Locks, Slimmest API? Robert Klemme <shortcutter@googlemail.com> - 2016-08-13 23:21 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 11:42 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 11:50 +0200
                Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-14 12:06 +0200
                Re: Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-14 13:08 +0200
                Re: Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?) Robert Klemme <shortcutter@googlemail.com> - 2016-08-14 13:45 +0200
                Re: Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-14 14:01 +0200
                Re: Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-14 14:01 +0200
                Re: Jumping to false Conclusions [Robert Klemme] (Was: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-14 14:07 +0200
                Re: Library for Escalable Locks, Slimmest API? Robert Klemme <shortcutter@googlemail.com> - 2016-08-14 12:13 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 12:25 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 12:36 +0200
                Re: Library for Escalable Locks, Slimmest API? Robert Klemme <shortcutter@googlemail.com> - 2016-08-14 13:41 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 12:45 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 12:49 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 13:45 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 13:48 +0200
                Re: Library for Escalable Locks, Slimmest API? Robert Klemme <shortcutter@googlemail.com> - 2016-08-14 14:29 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 14:56 +0200
                Re: Library for Escalable Locks, Slimmest API? j4n bur53 <janburse@fastmail.fm> - 2016-08-14 14:59 +0200
                Re: Library for Escalable Locks, Slimmest API? Jan Burse <janburse@fastmail.fm> - 2016-08-14 18:10 +0200
  Simpler requirements on the horizon! (Re: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-14 13:18 +0200
  I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-31 01:23 +0200
    Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) bursejan@gmail.com - 2016-08-30 16:35 -0700
      Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) bursejan@gmail.com - 2016-08-30 16:45 -0700
        Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) Andreas Leitgeb <avl@logic.at> - 2016-08-31 09:23 +0000
          Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) Andreas Leitgeb <avl@logic.at> - 2016-08-31 10:13 +0000
          Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-31 14:00 +0200
        Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-08-31 07:49 -0400
          Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) j4n bur53 <janburse@fastmail.fm> - 2016-08-31 14:13 +0200
            Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-08-31 12:55 -0400
    Re: I dont see a deadlock (Re: Library for Escalable Locks, Slimmest API?) Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-08-31 07:54 -0400

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