<html>
<body>
<div style="font-family: Verdana, Arial, Helvetica, Sans-Serif;">
<table bgcolor="#f9f3c9" width="100%" cellpadding="12" style="border: 1px #c9c399 solid; border-radius: 6px; -moz-border-radius: 6px; -webkit-border-radius: 6px;">
<tr>
<td>
This is an automatically generated e-mail. To reply, visit:
<a href="https://git.reviewboard.kde.org/r/121710/">https://git.reviewboard.kde.org/r/121710/</a>
</td>
</tr>
</table>
<br />
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: 10px;">
<p style="margin-top: 0;">On December 30th, 2014, 2:06 p.m. UTC, <b>Daniel Vrátil</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: 10px;">
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">I guess the code is note perfect and there are still race conditions, but this is a good step in the right direction, so let's ship it. I'll think about the lockfile solution, or some other and try to implement it (once I'm back at work).</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">The one-service-multiple-objects solution would not work, since you can't have multiple processes owning the same DBus service name, and I don't want to run multiple backends in one process.</p></pre>
</blockquote>
</blockquote>
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">Why would you ever want to run multiple backends at the same time?
(outside of testing, which could be done on a private DBus session)</p></pre>
<br />
<p>- David</p>
<br />
<p>On December 28th, 2014, 10:33 a.m. UTC, David Edmundson wrote:</p>
<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="12" style="border: 1px #888a85 solid; border-radius: 6px; -moz-border-radius: 6px; -webkit-border-radius: 6px;">
<tr>
<td>
<div>Review request for Plasma, Solid and Daniel Vrátil.</div>
<div>By David Edmundson.</div>
<p style="color: grey;"><i>Updated Dec. 28, 2014, 10:33 a.m.</i></p>
<div style="margin-top: 1.5em;">
<b style="color: #575012; font-size: 10pt;">Repository: </b>
libkscreen
</div>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: 1px solid #b8b5a0">
<tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">Avoid risk of starting two kscreen_launchers at the same having a race condition.</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">There were three possible bugs:
CheckIsAlreadyRunning tried to register a service and check if it worked.
This could clash with another process checking at the same time. Causing them both to fail saying another is running
Similarly, a daemon doing actual registering could clash with another daemon just checking if the name is free, and then it would fail saying we can't init()</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">There was also a risk that two launchers pass the check that nothing is running, then both try to activate a session. DBus server handles this fine and one will gracefully fail. Without this patch the second launcher would just die without returning the path of the service that was activated causing the relevant app to do nothing.</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">--</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">IMHO, you'd be better off having a fixed service name and using DBus activation for exactly these reasons.
You could put the different backends at different object paths, and have a method on the root object that says which object path to use rather than using the stdout of a launcher. That's a discussion for another day though.</p></pre>
</td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: 1px solid #b8b5a0">
<tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">Send it to bshah. Plasmashell started for him. Previously it didn't.</p></pre>
</td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">
<li>src/backendlauncher/backendloader.cpp <span style="color: grey">(e7da8cd)</span></li>
<li>src/backendlauncher/main.cpp <span style="color: grey">(f8bf323)</span></li>
</ul>
<p><a href="https://git.reviewboard.kde.org/r/121710/diff/" style="margin-left: 3em;">View Diff</a></p>
</td>
</tr>
</table>
</div>
</body>
</html>