Mailing-List: contact zookeeper-user-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
Reply-To: zookeeper-user@hadoop.apache.org
Received-SPF: neutral (nike.apache.org: local policy)
DomainKey-Signature: a=rsa-sha1; s=serpent; d=yahoo-inc.com; c=nofws; q=dns;
	h=received:from:to:date:subject:thread-topic:thread-index:
	message-id:references:in-reply-to:accept-language:
	content-language:x-ms-has-attach:x-ms-tnef-correlator:acceptlanguage:
	content-type:content-transfer-encoding:mime-version;
	b=jfh4S6uyj/8OVmn7YBpPsQxDUsX8I3e7bstr1sYPD967SrNU6htWXttR33iFvfoJ
From: Benjamin Reed <breed@yahoo-inc.com>
To: "zookeeper-user@hadoop.apache.org" <zookeeper-user@hadoop.apache.org>
Date: Wed, 7 Jan 2009 09:25:47 -0800
Subject: RE: Sending data during NodeDataChanged or NodeCreated
Thread-Topic: Sending data during NodeDataChanged or NodeCreated
Thread-Index: AclwYIxr4SXA9xHcR3OdJEAGLZo6TwAi5eUo
Message-ID: 
 <6990D2A1CAF07E40A7CFE68A5FAAA15317F9B9B5BF@SP1-EX07VS02.ds.corp.yahoo.com>
References: <30c6373b0901061639s700430edj5e879e62e19adec5@mail.gmail.com>
In-Reply-To: <30c6373b0901061639s700430edj5e879e62e19adec5@mail.gmail.com>
Accept-Language: en-US
Content-Language: en-US
acceptlanguage: en-US
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0

This is the behavior we had when we first implemented the API, and in every=
 case where people used the information there was a bug. it is virtually im=
possible to use correctly. In general I'm all for giving people rope, but i=
f it always results in death, you should stop handing it out.

In your example, if the ACL changed and then the data changed, we would hav=
e a security hole if we sent the data with the watch.

ben
________________________________________
From: burtonator@gmail.com [burtonator@gmail.com] On Behalf Of Kevin Burton=
 [burton@spinn3r.com]
Sent: Tuesday, January 06, 2009 4:39 PM
To: zookeeper-user@hadoop.apache.org
Subject: Sending data during NodeDataChanged or NodeCreated

So if I understand this correctly, if I receive a NodeDataChanged event, an=
d
then attempt do do a read of that node, there's a race condition where the
server could crash and I would be disconnected and my read would hit an
Exception
Or, the ACL could change and I no longer have permission to read the file
(though I did for a short window).

..... now I have to add all this logic to retry.  Are there any other race
conditions I wonder.

Why not just send the byte[] data during the NodeDataChanged or NodeCreated
event from the server?  This would avoid all these issues.

It's almost certainly what the user wants anyway.

Kevin

--
Founder/CEO Spinn3r.com
Location: San Francisco, CA
AIM/YIM: sfburtonator
Skype: burtonator
Work: http://spinn3r.com