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Groups > comp.lang.java.programmer > #35330

Re: Library for Escalable Locks, Slimmest API?

From Robert Klemme <shortcutter@googlemail.com>
Newsgroups comp.lang.java.programmer
Subject Re: Library for Escalable Locks, Slimmest API?
Date 2016-08-14 13:41 +0200
Message-ID <e1b3mdFe732U1@mid.individual.net> (permalink)
References (8 earlier) <nompol$fqt$1@news.albasani.net> <e19h9vF37j0U1@mid.individual.net> <nopee6$efa$1@news.albasani.net> <e1auj7Fcvt6U1@mid.individual.net> <nopguv$j81$1@news.albasani.net>

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On 14.08.2016 12:25, j4n bur53 wrote:
>> Alternatively the algorithm without any need for lock
>> escalation could be like this (pseudo code):
>
> I need a library where additionaly to that:
>
>   acquire w-l
>   if ( resourceNeedsLoading() ) {
>     loadFromFile()
>     updateResource()
>   }
>   release w-l
>
> Inside loadFromFile() the loading thread can also do an
> acquire r-l and then a release r-l.

You can do that with Java's ReentrantReadWriteLock:

"Additionally, a writer can acquire the read lock, but not vice-versa."

But you do not need to because the thread has an exclusive lock already 
(the write lock) and the write lock excludes read locks.  You do not 
gain anything from that unless you want to do lock downgrading.

> Robert Klemme schrieb:
>> I do not know though how consistency requirements are in your
>> application on a larger scale - especially since you mention
>> "re-loading".  Under which circumstances is a file reloaded?
>
> When it has been changed.

Well, yes.  Then see my suggestion.

Regards

	robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

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Thread

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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