Re: [Jython-dev] Buffer protocol - direct vs. JVM ByteBuffers

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<div>Just an add-on to my recent post:</div>

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<div>&gt;It may depend on <tt>storage.hasArray()</tt>, but <tt>storage.isDirect()</tt> seems to make no difference.</div>

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<div>I think it is likely the JVM does not offer a backing array, if the buffer is created as direct (i.e. these flags likely exclude each other), because this would imply array pinning and all the restrictions coming with it. I didn&#39;t test it though, but anyway we cannot rely on the one or other behavior, as doc explicitly does not guarantee a backing array for direct buffers, saying this is &quot;implementation specific&quot;.</div>

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<div style="margin:0 0 10px 0;"><b>Gesendet:</b>&nbsp;Sonntag, 15. Mai 2016 um 11:57 Uhr<br/>
<b>Von:</b>&nbsp;&quot;Jeff Allen&quot; &lt;ja...@fa...&gt;<br/>
<b>An:</b>&nbsp;&quot;Stefan Richthofer&quot; &lt;Ste...@gm...&gt;, &quot;Jython Developers&quot; &lt;jyt...@li...&gt;<br/>
<b>Betreff:</b>&nbsp;[Jython-dev] Buffer protocol - direct vs. JVM ByteBuffers</div>

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<p>Stefan:</p>

<p><a class="moz-txt-link-freetext" href="https://github.com/jythontools/jython/pull/39" target="_blank">https://github.com/jythontools/jython/pull/39</a></p>

<p>What difference does it make in your use case whether a NIO ByteBuffer is direct or non-direct? I can see why a client might want to know which it had been given, but not why it might want an exception raised in one or other case.</p>

<p>Nothing I&#39;m doing seems to depend on what kind of memory the exporting object has, therefore on the implementation type of <tt>ByteBuffer storage</tt>. It may depend on <tt>storage.hasArray()</tt>, but <tt>storage.isDirect()</tt> seems to make no difference.</p>
Jeff

<pre class="moz-signature">-- 
Jeff Allen</pre>
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