Hi Markus,
On 2015-12-14 21:53, Markus Gronlund wrote:
Hi Marcus,
Thanks for updating the patch.
I think you could also move the lock representation, i.e the Semaphore to
become a (static) field inside the ConfigurationLocker class - this since you
want all entry/exits to go through instances of this object.
Sounds good, I'll move it.
I know that the other MutexLocker's don't aggregate their lock resource but rather take
them as pointer in their constructors. However, I don’t think emulating that behavior is
paramount here, so if the semaphore moves into the ConfigurationLocker, another name (for
discernment against the other *Lockers) could possibly be used - for example:
"ConfigurationLock" which is generic enough for the abstraction letting you
change how locking is done underneath should you need to.
Also sounds like a good idea.
Thanks for looking at this!
Marcus
Thanks
Markus
-----Original Message-----
From: Marcus Larsson
Sent: den 14 december 2015 16:31
To: serviceability-dev@openjdk.java.net
Cc: hotspot-runtime-...@openjdk.java.net
Subject: Re: RFR: 8145083: Use semaphore instead of mutex for synchronization
of Unified Logging configuration
Hi again,
Made some changes to the patch after feedback from Markus Grönlund. The
ConfigurationLocker and the semaphore have been moved out of the
LogConfiguration.hpp and into the .cpp instead. The lock is only used
internally by the LogConfiguration so this makes sense. It simplifies the
LogConfiguration interface and hides the details of the locking under the hood.
New webrev:
http://cr.openjdk.java.net/~mlarsson/8145083/webrev.02/
Incremental:
http://cr.openjdk.java.net/~mlarsson/8145083/webrev.01-02/
Thanks,
Marcus
On 2015-12-14 15:53, Marcus Larsson wrote:
Hi,
New webrev:
http://cr.openjdk.java.net/~mlarsson/8145083/webrev.01/
Incremental:
http://cr.openjdk.java.net/~mlarsson/8145083/webrev.00-01/
Changes:
* Introduced the ConfigurationLocker class for automatic wait/signal
in constructor/destructor just like a MutexLocker.
* Added an assert to verify that the "lock" is held by the current
thread when calling configure_output.
* Made the config-string functions in LogOutput protected and
LogConfiguration a friend of LogOutput to prevent incorrect usage of
these functions. These functions should typically only be used inside
configure_output, which now ensures that the lock is held.
Thanks,
Marcus
On 2015-12-14 11:13, Marcus Larsson wrote:
Hi,
Please review the following patch to use a semaphore instead of a
mutex for the synchronization of log configuration. Using a mutex
requires some parts of the VM to be initialized, whereas the
semaphores can be used right from the start. This simplifies the code
and allows very early log configuration without special cases for
early configuration vs reconfiguration after VM init.
Webrev:
http://cr.openjdk.java.net/~mlarsson/8145083/webrev.00/
Issue:
https://bugs.openjdk.java.net/browse/JDK-8145083
Thanks,
Marcus
