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Date: Wed, 1 Oct 2014 09:53:25 -0500
From: Jordan Zimmerman <jordan@jordanzimmerman.com>
To: =?utf-8?Q?Singer=2C_Jill?= <jill.singer@pearson.com>
Cc: user <user@curator.apache.org>
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Subject: Re: revocation not working
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* Damn - looks like getLockPath() is protected. That should be corrected.=
 =46or now, create a subclass that has a new method that returns the lock=
 path.

* the=C2=A0=C2=A0InterProcessSemaphoreMutex does not allow revoking; so h=
ow will that help=3F
Damn again. Instead, you=E2=80=99ll need to=C2=A0interrupt=C2=A0the threa=
d that owns the lock.

I apologize about the lack of features here. Apparently, this hasn=E2=80=99=
t been used very much. A PR with improvements would be appreciated.

-JZ

On October 1, 2014 at 9:44:13 AM, Singer, Jill (jill.singer=40pearson.com=
) wrote:

Jordan-

=C2=A0 =C2=A0 thanks for the advice=21

Here are my follow-up questions:

* I can't find the 'getLockPath()=22 =C2=A0method on the InterProcessMute=
x or=C2=A0=C2=A0InterProcessSemaphoreMutex class
(I looked here:=C2=A0https://curator.apache.org/apidocs/index.html and co=
uldn't find a 'getLockPath()=22 method anywhere (the docs are version 2.5=
.1-snapshot, btw)
(I am using curator version=C2=A02.5.0)

* the=C2=A0=C2=A0InterProcessSemaphoreMutex does not allow revoking; so h=
ow will that help=3F

On Tue, Sep 30, 2014 at 8:46 PM, Jordan Zimmerman <jordan=40jordanzimmerm=
an.com> wrote:
There are a number of problems:

* The docs are not clear on this, but=C2=A0makeRevocable() must be called=
 BE=46ORE the lock is acquired. Please submit a Jira/PR to fix the doc.
* In your test,=C2=A0Revoker.attemptRevoke was using the incorrect path. =
It must be the path of the lock, so: =22Revoker.attemptRevoke(client2, ip=
Mutex.getLockPath());=E2=80=9D
*=C2=A0InterProcessMutex keeps track of the thread that owns the lock. So=
, the=C2=A0lock.release(); in your revoker won=E2=80=99t work. I suggest =
using=C2=A0InterProcessSemaphoreMutex instead.

-JZ


On September 30, 2014 at 4:19:58 PM, Singer, Jill (jill.singer=40pearson.=
com) wrote:

short: =C2=A0I want to create a lock with one client and release it with =
another; so I am trying to use revocation for that end.=C2=A0 It isn't wo=
rking. =C2=A0more details (and my code) are below.
any help is appreciated=21



long: =C2=A0have a system where one thread (with its own client) sets the=
 first lock (update),
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 then a second thread (with a cl=
ient that may or may not be the same as the original client)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 will set a second lock; then do=
 some work, then release that lock, and then release the first lock

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 this code simulates two threads=
 by having two different clients get locks.

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 the second client is unable to =
revoke the lock from the first client, however. =C2=A0the 'revocation lis=
tener' is never triggered.
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 I have scoured the web and not =
found examples.

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 this code assumes that you have=
 a zookeeper server running on your local host at port 2181

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 ideally, I'd also like to look =
up from somewhere else real quick to see if the lock is in place, but per=
haps=C2=A0
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 an acquire with a very short ti=
meout (5 milliseconds) would accomplish that.

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0also, is =C2=A0it a good idea to=
 reap away locks after releasing them=3F =C2=A0(to not clog up the system=
=3F)

thanks

-Jill

ps: =C2=A0also posted on stack overflow.

I'll cross-post answers if I have them.
>>>>>>>>>>>>>
import java.util.Collection;
import java.util.List;
import java.util.concurrent.TimeUnit;
import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.Curator=46ramework;
import org.apache.curator.framework.Curator=46ramework=46actory;
import org.apache.curator.framework.recipes.locks.InterProcessMutex;
import org.apache.curator.framework.recipes.locks.RevocationListener;
import org.apache.curator.framework.recipes.locks.Revoker;
import org.apache.curator.retry.ExponentialBackoffRetry;

public class MultipleClientExample =7B


=C2=A0 =C2=A0 /*entry point
=C2=A0 =C2=A0 =C2=A0*/
=C2=A0 =C2=A0 public static void main(String=5B=5D args)=7B

=C2=A0 =C2=A0 =C2=A0 =C2=A0 RetryPolicy retryPolicy =3D new ExponentialBa=
ckoffRetry(1000, 3);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 String zookeeperConnectionString =3D =22127.0=
.0.1:2181=22;
=C2=A0 =C2=A0 =C2=A0 =C2=A0 Curator=46ramework client =3D Curator=46ramew=
ork=46actory.newClient(zookeeperConnectionString, retryPolicy);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 client.start();

=C2=A0 =C2=A0 =C2=A0 =C2=A0 try =7B
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 System.out.println(=22testing l=
ocks....=22);

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 InterProcessMutex ipMutex =3D n=
ew InterProcessMutex(client, =22/mpx-updates/guid123/update=22);

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 boolean acquired =3D ipMutex.ac=
quire(3, TimeUnit.SECONDS);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 System.out.println(=22got the l=
ock(update)=3F=22 + acquired);

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 RevocationListener<InterProcess=
Mutex> rl =3D new MyRevocationListener();

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 ipMutex.makeRevocable(rl);

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 InterProcessMutex ipMutex2 =3D =
new InterProcessMutex(client, =22/mpx-updates/guid123/swap=22);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 boolean a2 =3D ipMutex2.acquire=
(3, TimeUnit.SECONDS);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 System.out.println(=22got the l=
ock(swap)=3F=22 + a2);

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 System.out.println(=22got the f=
irst lock in this process=3F =22 + ipMutex.isAcquiredInThisProcess());

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 // make a new client; see if it=
 can get the lock=21
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 Curator=46ramework client2 =3D =
Curator=46ramework=46actory.newClient(zookeeperConnectionString, retryPol=
icy);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 client2.start();

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 InterProcessMutex ipMutex1Retry=
 =3D new InterProcessMutex(client2, =22/mpx-updates/guid123/update=22);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 boolean a3 =3D ipMutex1Retry.ac=
quire(3, TimeUnit.SECONDS);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 System.out.println(=22got the l=
ock(retry/update) =3F=22 + a3);

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 System.out.println(=22got the f=
irst lock in this process=3F =22 + ipMutex1Retry.isAcquiredInThisProcess(=
));

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 Revoker.attemptRevoke(client2, =
=22/mpx-updates/guid123/update=22);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 a3 =3D ipMutex1Retry.acquire(3,=
 TimeUnit.SECONDS);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 System.out.println(=22AGAIN: go=
t the lock(retry/update) =3F=22 + a3);

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =7D catch (Exception e) =7B
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 // TODO Auto-generated catch bl=
ock
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 e.printStackTrace();
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =7D

=C2=A0 =C2=A0 =7D

=C2=A0 =C2=A0 public class MyRevocationListener implements RevocationList=
ener<InterProcessMutex> =7B

=C2=A0 =C2=A0 =C2=A0 =C2=A0 /*
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0* (non-Javadoc)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0*=C2=A0
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0* =40see org.apache.curator.framework.r=
ecipes.locks.RevocationListener=23revocationRequested(java.lang.Object)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0*/
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =40Override
=C2=A0 =C2=A0 =C2=A0 =C2=A0 public void revocationRequested(InterProcessM=
utex lock) =7B

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 //this seems to never be called=
=C2=A0

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 Collection<String> participantN=
odes =3D null;

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 try =7B
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 System.out.printl=
n(=22revocation was requested....=22);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 System.out.printl=
n(=22ick ick revocation requested....=22);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 participantNodes =
=3D lock.getParticipantNodes();
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 lock.release();
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 System.out.printl=
n(=22revoked lock at path: =22 + participantNodes);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =7D catch (Exception e) =7B
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 System.out.printl=
n(=22problem revoking lock with path: =22 + participantNodes + =22; it wa=
s not revoked=22);
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =7D

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =7D

=C2=A0 =C2=A0 =7D
=7D



--542c1565_79e2a9e3_117
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<html><head><style>body=7Bfont-family:Helvetica,Arial;font-size:13px=7D</=
style></head><body style=3D=22word-wrap: break-word; -webkit-nbsp-mode: s=
pace; -webkit-line-break: after-white-space;=22><div id=3D=22bloop=5Fcust=
omfont=22 style=3D=22font-family:Helvetica,Arial;font-size:13px; color: r=
gba(0,0,0,1.0); margin: 0px; line-height: auto;=22>* Damn - looks like ge=
tLockPath() is protected. That should be corrected. =46or now, create a s=
ubclass that has a new method that returns the lock path.</div> <div id=3D=
=22bloop=5Fsign=5F1412175091921436928=22 class=3D=22bloop=5Fsign=22><div =
style=3D=22font-family:helvetica,arial;font-size:13px=22><br></div><div><=
blockquote type=3D=22cite=22 class=3D=22clean=5Fbq=22 style=3D=22font-fam=
ily: Helvetica, Arial; font-size: 13px;=22><div dir=3D=22ltr=22><span sty=
le=3D=22font-size: 12.8000001907349px;=22>* the&nbsp;</span><span style=3D=
=22font-size: 12.8000001907349px;=22>&nbsp;</span><span style=3D=22font-s=
ize: 12.8000001907349px;=22>InterProcessSemaphoreMutex does not allow rev=
oking; so how will that help=3F</span></div></blockquote><div><div dir=3D=
=22ltr=22><font face=3D=22helvetica, arial=22><span style=3D=22font-size:=
 12.8000001907349px;=22>Damn again. Instead, you</span>=E2=80=99<span sty=
le=3D=22font-size: 12.8000001907349px;=22>ll need to&nbsp;</span>interrup=
t<span style=3D=22font-size: 12.8000001907349px;=22>&nbsp;the thread that=
 owns the lock.</span></font></div></div></div><div dir=3D=22ltr=22><font=
 face=3D=22helvetica, arial=22><span style=3D=22font-size: 12.80000019073=
49px;=22><br></span></font></div><div dir=3D=22ltr=22><font face=3D=22hel=
vetica, arial=22><span style=3D=22font-size: 12.8000001907349px;=22>I apo=
logize about the lack of features here. Apparently, this hasn</span>=E2=80=
=99<span style=3D=22font-size: 12.8000001907349px;=22>t been used very mu=
ch. A PR with improvements would be appreciated.</span></font></div><div =
dir=3D=22ltr=22><font face=3D=22helvetica, arial=22><span style=3D=22font=
-size: 12.8000001907349px;=22><br></span></font></div><div dir=3D=22ltr=22=
><font face=3D=22helvetica, arial=22><span style=3D=22font-size: 12.80000=
01907349px;=22>-JZ</span></font></div></div> <br><p style=3D=22color:=230=
00;=22>On October 1, 2014 at 9:44:13 AM, Singer, Jill (<a href=3D=22mailt=
o:jill.singer=40pearson.com=22>jill.singer=40pearson.com</a>) wrote:</p> =
<blockquote type=3D=22cite=22 class=3D=22clean=5Fbq=22><span><div><div></=
div><div>


<title></title>


<div dir=3D=22ltr=22>Jordan-
<div><br></div>
<div>&nbsp; &nbsp; thanks for the advice=21</div>
<div><br></div>
<div>Here are my follow-up questions:</div>
<div><br></div>
<div>* I can't find the 'getLockPath()=22 &nbsp;method on the
InterProcessMutex or&nbsp;<span style=3D=22font-size:12.8000001907349px;c=
olor:rgb(0,0,0);font-family:Helvetica,Arial=22>&nbsp;</span><span style=3D=
=22font-size:12.8000001907349px;color:rgb(0,0,0);font-family:Helvetica,Ar=
ial=22>InterProcessSemaphoreMutex
class</span></div>
<div><span style=3D=22font-size:12.8000001907349px;color:rgb(0,0,0);font-=
family:Helvetica,Arial=22>
(I looked here:&nbsp;</span><font color=3D=22=23000000=22 face=3D=22Helve=
tica, Arial=22><a href=3D=22https://curator.apache.org/apidocs/index.html=
=22>https://curator.apache.org/apidocs/index.html</a>
and couldn't find a 'getLockPath()=22 method anywhere (the docs are
version 2.5.1-snapshot, btw)</font></div>
<div><font color=3D=22=23000000=22 face=3D=22Helvetica, Arial=22>(I am us=
ing
curator version&nbsp;2.5.0)</font></div>
<div><font color=3D=22=23000000=22 face=3D=22Helvetica, Arial=22><br></fo=
nt></div>
<div><span style=3D=22font-size:12.8000001907349px;color:rgb(0,0,0);font-=
family:Helvetica,Arial=22>
* the&nbsp;</span><span style=3D=22font-size:12.8000001907349px;color:rgb=
(0,0,0);font-family:Helvetica,Arial=22>&nbsp;</span><span style=3D=22font=
-size:12.8000001907349px;color:rgb(0,0,0);font-family:Helvetica,Arial=22>=
InterProcessSemaphoreMutex
does not allow revoking; so how will that help=3F</span></div>
</div>
<div class=3D=22gmail=5Fextra=22><br>
<div class=3D=22gmail=5Fquote=22>On Tue, Sep 30, 2014 at 8:46 PM, Jordan
Zimmerman <span dir=3D=22ltr=22>&lt;<a href=3D=22mailto:jordan=40jordanzi=
mmerman.com=22 target=3D=22=5Fblank=22>jordan=40jordanzimmerman.com</a>&g=
t;</span> wrote:<br>
<blockquote class=3D=22gmail=5Fquote=22 style=3D=22margin:0 0 0 .8ex;bord=
er-left:1px =23ccc solid;padding-left:1ex=22>
<div style=3D=22word-wrap:break-word=22>
<div style=3D=22font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0=
,0,1.0);margin:0px;line-height:auto=22>
There are a number of problems:</div>
<div style=3D=22font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0=
,0,1.0);margin:0px;line-height:auto=22>
<br></div>
<div style=3D=22font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0=
,0,1.0);margin:0px;line-height:auto=22>
* The docs are not clear on this, but&nbsp;makeRevocable() must be
called BE=46ORE the lock is acquired. Please submit a Jira/PR to fix
the doc.</div>
<div style=3D=22font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0=
,0,1.0);margin:0px;line-height:auto=22>
* In your test,&nbsp;Revoker.attemptRevoke was using the incorrect
path. It must be the path of the lock, so:
=22Revoker.attemptRevoke(client2, ipMutex.getLockPath());=E2=80=9D</div>
<div style=3D=22font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0=
,0,1.0);margin:0px;line-height:auto=22>
*&nbsp;InterProcessMutex keeps track of the thread that owns the
lock. So, the&nbsp;lock.release(); in your revoker won=E2=80=99t work. I
suggest using&nbsp;InterProcessSemaphoreMutex instead.</div>
<div style=3D=22font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0=
,0,1.0);margin:0px;line-height:auto=22>
<span class=3D=22HOEnZb=22><font color=3D=22=23888888=22><br></font></spa=
n></div>
<div style=3D=22font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0=
,0,1.0);margin:0px;line-height:auto=22>
<span class=3D=22HOEnZb=22><font color=3D=22=23888888=22>-JZ</font></span=
></div>
<div>
<div class=3D=22h5=22>
<div>
<div style=3D=22font-family:helvetica,arial;font-size:13px=22>
<br></div>
</div>
<br>
<p style=3D=22color:=23000=22>On September 30, 2014 at 4:19:58 PM, Singer=
,
Jill (<a href=3D=22mailto:jill.singer=40pearson.com=22 target=3D=22=5Fbla=
nk=22>jill.singer=40pearson.com</a>) wrote:</p>
<blockquote type=3D=22cite=22>
<div>
<div>
<div dir=3D=22ltr=22>
<div>
<div><span>short: &nbsp;I want to create a lock with one client and
release it with another; so I am trying to use revocation for that
end.&nbsp; It isn't working. &nbsp;more details (and my code) are
below.</span></div>
<div><span>any help is appreciated=21</span></div>
<div><span><br></span></div>
<div><span><br></span></div>
<div><span><br></span></div>
<div><span>long: &nbsp;have a system where one thread (with its own
client) sets the first lock (update),</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; then a second
thread (with a client that may or may not be the same as the
original client)</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; will set a
second lock; then do some work, then release that lock, and then
release the first lock</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; this code
simulates two threads by having two different clients get
locks.</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; the second
client is unable to revoke the lock from the first client, however.
&nbsp;the 'revocation listener' is never triggered.</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; I have scoured
the web and not found examples.</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; this code
assumes that you have a zookeeper server running on your local host
at port 2181</span></div>
</div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ideally, I'd
also like to look up from somewhere else real quick to see if the
lock is in place, but perhaps&nbsp;</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; an acquire
with a very short timeout (5 milliseconds) would accomplish
that.</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;also, is
&nbsp;it a good idea to reap away locks after releasing them=3F
&nbsp;(to not clog up the system=3F)</span></div>
<div><span><br></span></div>
<div><span>thanks</span></div>
<div><span><br></span></div>
<div><span>-Jill</span></div>
<div><span><br></span></div>
<div><span>ps: &nbsp;also posted on stack overflow.</span></div>
<div><span><br></span></div>
<div><span>I'll cross-post answers if I have them.</span></div>
<div>
<span>&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;</span></div>
<div>
<div><span>import java.util.Collection;</span></div>
<div><span>import java.util.List;</span></div>
<div><span>import java.util.concurrent.TimeUnit;</span></div>
<div><span>import org.apache.curator.RetryPolicy;</span></div>
<div><span>import
org.apache.curator.framework.Curator=46ramework;</span></div>
<div><span>import
org.apache.curator.framework.Curator=46ramework=46actory;</span></div>
<div><span>import
org.apache.curator.framework.recipes.locks.InterProcessMutex;</span></div=
>
<div><span>import
org.apache.curator.framework.recipes.locks.RevocationListener;</span></di=
v>
<div><span>import
org.apache.curator.framework.recipes.locks.Revoker;</span></div>
<div><span>import
org.apache.curator.retry.ExponentialBackoffRetry;</span></div>
<div><span><br></span></div>
<div><span>public class MultipleClientExample =7B</span></div>
<div><span><br></span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; /*entry point</span></div>
<div><span>&nbsp; &nbsp; &nbsp;*/</span></div>
<div><span>&nbsp; &nbsp; public static void main(String=5B=5D
args)=7B</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; RetryPolicy retryPolicy =3D
new ExponentialBackoffRetry(1000, 3);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; String
zookeeperConnectionString =3D =22<a href=3D=22http://127.0.0.1:2181=22 ta=
rget=3D=22=5Fblank=22>127.0.0.1:2181</a>=22;</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; Curator=46ramework client =3D
Curator=46ramework=46actory.newClient(zookeeperConnectionString,
retryPolicy);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; client.start();</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; try =7B</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
System.out.println(=22testing locks....=22);</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
InterProcessMutex ipMutex =3D new InterProcessMutex(client,
=22/mpx-updates/guid123/update=22);</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; boolean
acquired =3D ipMutex.acquire(3, TimeUnit.SECONDS);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
System.out.println(=22got the lock(update)=3F=22 +
acquired);</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
RevocationListener&lt;InterProcessMutex&gt; rl =3D new
MyRevocationListener();</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
ipMutex.makeRevocable(rl);</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
InterProcessMutex ipMutex2 =3D new InterProcessMutex(client,
=22/mpx-updates/guid123/swap=22);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; boolean a2 =3D
ipMutex2.acquire(3, TimeUnit.SECONDS);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
System.out.println(=22got the lock(swap)=3F=22 + a2);</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
System.out.println(=22got the first lock in this process=3F =22 +
ipMutex.isAcquiredInThisProcess());</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; // make a new
client; see if it can get the lock=21</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
Curator=46ramework client2 =3D
Curator=46ramework=46actory.newClient(zookeeperConnectionString,
retryPolicy);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
client2.start();</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
InterProcessMutex ipMutex1Retry =3D new InterProcessMutex(client2,
=22/mpx-updates/guid123/update=22);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; boolean a3 =3D
ipMutex1Retry.acquire(3, TimeUnit.SECONDS);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
System.out.println(=22got the lock(retry/update) =3F=22 +
a3);</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
System.out.println(=22got the first lock in this process=3F =22 +
ipMutex1Retry.isAcquiredInThisProcess());</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
Revoker.attemptRevoke(client2,
=22/mpx-updates/guid123/update=22);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; a3 =3D
ipMutex1Retry.acquire(3, TimeUnit.SECONDS);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
System.out.println(=22AGAIN: got the lock(retry/update) =3F=22 +
a3);</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; =7D catch (Exception e)
=7B</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; // TODO
Auto-generated catch block</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
e.printStackTrace();</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; =7D</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; =7D</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; public class MyRevocationListener
implements RevocationListener&lt;InterProcessMutex&gt;
=7B</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; /*</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;*
(non-Javadoc)</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;*&nbsp;</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;* =40see
org.apache.curator.framework.recipes.locks.RevocationListener=23revocatio=
nRequested(java.lang.Object)</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;*/</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; =40Override</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; public void
revocationRequested(InterProcessMutex lock) =7B</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; //this seems
to never be called&nbsp;</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
Collection&lt;String&gt; participantNodes =3D null;</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; try
=7B</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
System.out.println(=22revocation was requested....=22);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
System.out.println(=22ick ick revocation
requested....=22);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
participantNodes =3D lock.getParticipantNodes();</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
lock.release();</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
System.out.println(=22revoked lock at path: =22 +
participantNodes);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; =7D catch
(Exception e) =7B</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
System.out.println(=22problem revoking lock with path: =22 +
participantNodes + =22; it was not revoked=22);</span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; =7D</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; &nbsp; &nbsp; =7D</span></div>
<div><span><br></span></div>
<div><span>&nbsp; &nbsp; =7D</span></div>
<div><span>=7D</span></div>
</div>
<div><span><br></span></div>
</div>
</div>
</div>
</blockquote>
</div>
</div>
</div>
</blockquote>
</div>
<br></div>


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