<!DOCTYPE html><html><head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<p>Hi Roberto,<br>
by "singleton limitation" in JNA, I assume you refer to the fact
that, in JNA (but also JNI) you can only load a native library
once, by only one classloader. Correct?</p>
<p>If that's the limitation you are trying to workaround, then yes,
FFM allows you to load the same native library multiple times
using its SymbolLookup abstraction. Make sure to use the correct
factory -- the one that does not rely on an association with the
current classloader:</p>
<p><a class="moz-txt-link-freetext" href="https://docs.oracle.com/en/java/javase/23/docs//api/java.base/java/lang/foreign/SymbolLookup.html#libraryLookup(java.lang.String,java.lang.foreign.Arena)">https://docs.oracle.com/en/java/javase/23/docs//api/java.base/java/lang/foreign/SymbolLookup.html#libraryLookup(java.lang.String,java.lang.foreign.Arena)</a></p>
<p>This is just a very thin wrapper around dlopen, so it will take
whatever library name dlopen can resolve, and will also allow you
to open the library multiple times. Note that the library will be
unloaded when the provided arena is closed -- so ideally you could
use one arena per client.</p>
<p>Examples of Arena.ofConfined, or custom arenas can be found in
the javadoc:</p>
<p>* confined arena -
<a class="moz-txt-link-freetext" href="https://docs.oracle.com/en/java/javase/23/docs//api/java.base/java/lang/foreign/package-summary.html">https://docs.oracle.com/en/java/javase/23/docs//api/java.base/java/lang/foreign/package-summary.html</a><br>
</p>
<p>* custom arena -
<a class="moz-txt-link-freetext" href="https://docs.oracle.com/en/java/javase/22/docs//api/java.base/java/lang/foreign/SymbolLookup.html#libraryLookup(java.lang.String,java.lang.foreign.Arena)">https://docs.oracle.com/en/java/javase/22/docs//api/java.base/java/lang/foreign/SymbolLookup.html#libraryLookup(java.lang.String,java.lang.foreign.Arena)</a></p>
<p>We also have some narrative documents on how to use memory
segment and linker API here:</p>
<p><a class="moz-txt-link-freetext" href="https://github.com/openjdk/panama-foreign/blob/foreign-memaccess%2Babi/doc/panama_memaccess.md">https://github.com/openjdk/panama-foreign/blob/foreign-memaccess%2Babi/doc/panama_memaccess.md</a></p>
<p><a class="moz-txt-link-freetext" href="https://github.com/openjdk/panama-foreign/blob/foreign-memaccess%2Babi/doc/panama_ffi.md">https://github.com/openjdk/panama-foreign/blob/foreign-memaccess%2Babi/doc/panama_ffi.md</a></p>
<p>And, if you want to know more on jextract, we have a
comprehensive guide here:</p>
<p><a class="moz-txt-link-freetext" href="https://github.com/openjdk/jextract/blob/master/doc/GUIDE.md">https://github.com/openjdk/jextract/blob/master/doc/GUIDE.md</a></p>
<p><br>
Cheers<br>
Maurizio<br>
</p>
<div class="moz-cite-prefix">On 05/02/2025 00:03,
<a class="moz-txt-link-abbreviated" href="mailto:roberto.minoletti@trusthub.cloud">roberto.minoletti@trusthub.cloud</a> wrote:<br>
</div>
<blockquote type="cite" cite="mid:!&!AAAAAAAAAAAuAAAAAAAAAExtYa3gpX5HoQdE6pcyVYEBAMO2jhD3dRHOtM0AqgC7tuYAAAAAAA4AABAAAADd+TEeumaRTZk1zPeQBgVaAQAAAAA=@trusthub.cloud">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style>@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}@font-face
{font-family:Aptos;}p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
font-size:11.0pt;
font-family:"Calibri",sans-serif;
mso-ligatures:standardcontextual;
mso-fareast-language:EN-US;}span.EstiloCorreo18
{mso-style-type:personal-compose;
font-family:"Calibri",sans-serif;
color:windowtext;}.MsoChpDefault
{mso-style-type:export-only;
font-size:11.0pt;
mso-ligatures:none;
mso-fareast-language:EN-US;}div.WordSection1
{page:WordSection1;}</style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
<div class="WordSection1">
<p class="MsoNormal">Hello Maurizio,<o:p></o:p></p>
<p class="MsoNormal" style="text-indent:35.4pt">Thank you to
provide the right contact of the Panama project (I reached to
you in LinkedIn some days ago)<o:p></o:p></p>
<p class="MsoNormal">I am writing to you on behalf of a backend
development team that is trying to accomplish our
requirements.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We need to interact from our java code
(JDK21 that we can easely update to JDK23 if required and
Spring Web-Flux) to a C++ library that allow to create Slots,
generate Keypairs store Certificates simulating a real HSM
(Hardware Security Module). This is named libsofthsm2.so
(SoftHSM2).<o:p></o:p></p>
<p class="MsoNormal"><span lang="IT">As I mentioned we
customized this library as we need to store certificates and
keys in a different path for each user. One important
requirement is that we need to be able to process many
requests coming from many different users to the same
library that should operate in different paths at the same
time.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="IT">We preliminary resolved a
POC using JNA but when tried to execute many parallel treads
we faced with his singleton limitation and after a deep
reasearch we founded Panama project.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="IT"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="IT">Does Panama FFI support
multiple parallel treads? Does it have any Singleton
limitations?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="IT">What we need is to get many
objects/treads at the same time (paralley) loading its own
different instance of the same library, getting its own
memory context, variables and states, all completely
isolated but working at the same time. This was not possible
for us because JNA uses the Singleton pattern to load the
library directly into the process, making it only possible
to have a single instance of the library for the entire
process.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="IT"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="IT">The goal is that each
object/tread parallely instantiate the same library but
having isolated states, configurations and variables stored
in a dedicated memory slot for each tread, so even if the
C++ library maybe does not completely support cuncurrency
itself it should attend multiple treads as it is virtually
responding at once having one specific configuration per
user.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="IT"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="IT">What we are looking for is
that each ARENA has access to libsofthsm2.so and its
internal variables using that dedicated memory space to each
tread to calculate the operations it must perform.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="IT"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="IT">Does Panama FFI allow all
this? This is the first basic question we have. After this
we will be able to perform more specific questions.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="IT">Also if you have any sample
of code that use Arena.ofConfined() or any Custom Arena it
would be really fantastic.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="IT"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="IT">Thank you in advance for
any information and/or support impelmenting Panama in our
Project.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="IT"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="IT">Roberto Minoletti<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="IT">Trusthub LLC<o:p></o:p></span></p>
</div>
</blockquote>
</body>
</html>