Author: mahadev
Date: Wed Jan 28 00:46:59 2009
New Revision: 738325
URL: http://svn.apache.org/viewvc?rev=738325&view=rev
Log:
ZOOKEEPER-253. documentation of DataWatcher state transition is misleading
regarding auto watch reset on reconnect. (phunt via mahadev)
Modified:
hadoop/zookeeper/trunk/CHANGES.txt
hadoop/zookeeper/trunk/docs/javaExample.html
hadoop/zookeeper/trunk/docs/javaExample.pdf
hadoop/zookeeper/trunk/src/docs/src/documentation/content/xdocs/javaExample.xml
Modified: hadoop/zookeeper/trunk/CHANGES.txt
URL:
http://svn.apache.org/viewvc/hadoop/zookeeper/trunk/CHANGES.txt?rev=738325&r1=738324&r2=738325&view=diff
==============================================================================
--- hadoop/zookeeper/trunk/CHANGES.txt (original)
+++ hadoop/zookeeper/trunk/CHANGES.txt Wed Jan 28 00:46:59 2009
@@ -120,6 +120,9 @@
ZOOKEEPER-210. Require Java 6. (phunt via breed)
ZOOKEEPER-177. needed: docs for JMX (phunt via mahadev)
+
+ ZOOKEEPER-253. documentation of DataWatcher state transition is misleading
+regarding auto watch reset on reconnect. (phunt via mahadev)
Release 3.0.0 - 2008-10-21
Modified: hadoop/zookeeper/trunk/docs/javaExample.html
URL:
http://svn.apache.org/viewvc/hadoop/zookeeper/trunk/docs/javaExample.html?rev=738325&r1=738324&r2=738325&view=diff
==============================================================================
--- hadoop/zookeeper/trunk/docs/javaExample.html (original)
+++ hadoop/zookeeper/trunk/docs/javaExample.html Wed Jan 28 00:46:59 2009
@@ -231,11 +231,11 @@
</li>
<li>
-<p> a znode, by name</p>
+<p>then name of a znode - the one to be watched</p>
</li>
<li>
-<p> an executable with arguments.</p>
+<p>an executable with arguments.</p>
</li>
</ul>
</li>
@@ -319,8 +319,7 @@
</p>
<pre class="code">
public class Executor implements Watcher, Runnable,
DataMonitor.DataMonitorListener {
-...
- </pre>
+...</pre>
<p>The <strong>Watcher</strong> interface is defined by the ZooKeeper Java API.
ZooKeeper uses it to communicate back to its container. It supports only
one method, <span class="codefrag command">process()</span>, and ZooKeeper uses
it to communciates generic events that the main thread would be intersted
in, such as the state of the ZooKeeper connection or the ZooKeeper session.The
Executor
@@ -516,8 +515,10 @@
// connection has changed
switch (event.getState()) {
case SyncConnected:
- // Everything is happy. Lets kick things off
- // again by checking the existence of the znode
+ // In this particular example we don't need to do anything
+ // here - watches are automatically re-registered with
+ // server and any watches triggered while the client was
+ // disconnected will be delivered (in order of course)
break;
case Expired:
// It's all over
@@ -537,9 +538,14 @@
}
</pre>
<p>
-If the client-side ZooKeeper libraries can reestablish the communication
channel to ZooKeeper, DataMonitor simply kicks
-everything off again with the call to <span class="codefrag
command">ZooKeeper.exists()</span>.
-If it gets an event for a znode, it calls <span class="codefrag
command">ZooKeeper.exists()</span> to find out what has changed.
+If the client-side ZooKeeper libraries can re-establish the
+communication channel (SyncConnected event) to ZooKeeper before
+session expiration (Expired event) all of the session's watches will
+automatically be re-established with the server (auto-reset of watches
+is new in ZooKeeper 3.0.0). See <a
href="zookeeperProgrammers.html#ch_zkWatches">ZooKeeper Watches</a>
+in the programmer guide for more on this. A bit lower down in this
+function, when DataMonitor gets an event for a znode, it calls
+<span class="codefrag command">ZooKeeper.exists()</span> to find out what has
changed.
</p>
</div>
@@ -779,8 +785,10 @@
// connection has changed
switch (event.getState()) {
case SyncConnected:
- // Everything is happy. Lets kick things off
- // again by checking the existence of the znode
+ // In this particular example we don't need to do anything
+ // here - watches are automatically re-registered with
+ // server and any watches triggered while the client was
+ // disconnected will be delivered (in order of course)
break;
case Expired:
// It's all over
Modified: hadoop/zookeeper/trunk/docs/javaExample.pdf
URL:
http://svn.apache.org/viewvc/hadoop/zookeeper/trunk/docs/javaExample.pdf?rev=738325&r1=738324&r2=738325&view=diff
==============================================================================
Binary files - no diff available.
Modified:
hadoop/zookeeper/trunk/src/docs/src/documentation/content/xdocs/javaExample.xml
URL:
http://svn.apache.org/viewvc/hadoop/zookeeper/trunk/src/docs/src/documentation/content/xdocs/javaExample.xml?rev=738325&r1=738324&r2=738325&view=diff
==============================================================================
---
hadoop/zookeeper/trunk/src/docs/src/documentation/content/xdocs/javaExample.xml
(original)
+++
hadoop/zookeeper/trunk/src/docs/src/documentation/content/xdocs/javaExample.xml
Wed Jan 28 00:46:59 2009
@@ -54,8 +54,8 @@
<itemizedlist><listitem><para>It takes as parameters:</para>
<itemizedlist>
<listitem><para>the address of the ZooKeeper
service</para></listitem>
- <listitem> <para> a znode, by name</para></listitem>
- <listitem><para> an executable with
arguments.</para></listitem></itemizedlist></listitem>
+ <listitem> <para>then name of a znode - the one to be
watched</para></listitem>
+ <listitem><para>an executable with
arguments.</para></listitem></itemizedlist></listitem>
<listitem><para>It fetches the data associated with the znode and
starts the executable.</para></listitem>
<listitem><para>If the znode changes, the client refetches the contents
and restarts the executable.</para></listitem>
<listitem><para>If the znode disappears, the client kills the
executable.</para></listitem></itemizedlist>
@@ -134,8 +134,7 @@
<programlisting>
public class Executor implements Watcher, Runnable,
DataMonitor.DataMonitorListener {
-...
- </programlisting>
+...</programlisting>
<para>The <emphasis role="bold">Watcher</emphasis> interface is defined by
the ZooKeeper Java API.
ZooKeeper uses it to communicate back to its container. It supports only
one method, <command>process()</command>, and ZooKeeper uses
@@ -334,8 +333,10 @@
// connection has changed
switch (event.getState()) {
case SyncConnected:
- // Everything is happy. Lets kick things off
- // again by checking the existence of the znode
+ // In this particular example we don't need to do anything
+ // here - watches are automatically re-registered with
+ // server and any watches triggered while the client was
+ // disconnected will be delivered (in order of course)
break;
case Expired:
// It's all over
@@ -355,9 +356,15 @@
}
</programlisting>
<para>
-If the client-side ZooKeeper libraries can reestablish the communication
channel to ZooKeeper, DataMonitor simply kicks
-everything off again with the call to <command>ZooKeeper.exists()</command>.
-If it gets an event for a znode, it calls
<command>ZooKeeper.exists()</command> to find out what has changed.
+If the client-side ZooKeeper libraries can re-establish the
+communication channel (SyncConnected event) to ZooKeeper before
+session expiration (Expired event) all of the session's watches will
+automatically be re-established with the server (auto-reset of watches
+is new in ZooKeeper 3.0.0). See <ulink
+url="zookeeperProgrammers.html#ch_zkWatches">ZooKeeper Watches</ulink>
+in the programmer guide for more on this. A bit lower down in this
+function, when DataMonitor gets an event for a znode, it calls
+<command>ZooKeeper.exists()</command> to find out what has changed.
</para>
</section>
@@ -586,8 +593,10 @@
// connection has changed
switch (event.getState()) {
case SyncConnected:
- // Everything is happy. Lets kick things off
- // again by checking the existence of the znode
+ // In this particular example we don't need to do anything
+ // here - watches are automatically re-registered with
+ // server and any watches triggered while the client was
+ // disconnected will be delivered (in order of course)
break;
case Expired:
// It's all over
