(10) (M) RFR: 8174231: Factor out and share PlatformEvent and Parker code for POSIX systems (original) (raw)

David Holmes david.holmes at oracle.com
Thu May 18 07:35:09 UTC 2017

On 18/05/2017 5:32 PM, Magnus Ihse Bursie wrote:

On 2017-05-18 08:25, David Holmes wrote:

Bug: https://bugs.openjdk.java.net/browse/JDK-8174231

webrevs: Build-related: http://cr.openjdk.java.net/~dholmes/8174231/webrev.top/ Build changes look good.

Thanks Magnus! I just realized I left in the AC_MSG_NOTICE debugging prints outs - do you want me to remove them? I suppose they may be useful if something goes wrong on some platform.

David

/Magnus

hotspot: http://cr.openjdk.java.net/~dholmes/8174231/webrev.hotspot/

First a big thank you to Thomas Stuefe for testing various versions of this on AIX. This is primarily a refactoring and cleanup exercise (ie lots of deleted duplicated code!). I have taken the PlatformEvent, PlatformParker and Parker::* code, out of oslinux and moved it into osposix for use by Linux, OSX, BSD, AIX and perhaps one day Solaris (more on that later). The Linux code was the most functionally complete, dealing with correct use of CLOCKMONOTONIC for relative timed waits, and the default wall-clock for absolute timed waits. That functionality is not, unfortunately, supported by all our POSIX platforms so there are some configure time build checks to set some #defines, and then some dynamic lookup at runtime**. We allow for the runtime environment to be less capable than the build environment, but not the other way around (without build time support we don't know the runtime types needed to make library calls). ** There is some duplication of dynamic lookup code on Linux but this can be cleaned up in future work if we refactor the time/clock code into osposix as well. The cleanup covers a number of things: - removal of linux anachronisms that got "ported" into the other platforms - eg EINTR can not be returned from the wait methods - removal of solaris anachronisms that got ported into the linux code and then on to other platforms - eg ETIMEDOUT is what we expect never ETIME - removal of the ancient/obsolete os::*::allowdebugblockedsignals() from the Parker methods - consolidation of unpackTime and computeabstime into one utility function - use statics for things completely private to the implementation rather than making them part of the os* API (eg access to condAttr objects) - cleanup up commentary and style within methods of the same class - clean up coding style in places eg not using Names that start with capitals. I have not tried to cleanup every single oddity, nor tried to reconcile differences between the very similar in places PlatformEvent and Park methods. For example PlatformEvent still examines the FilterSpuriousWakeups** flag, and Parker still ignores it. ** Perhaps a candidate for deprecation and future removal. There is one mini "enhancement" slipped in this. I now explicitly initialize mutexes with a mutexAttr object with its type set to PTHREADMUTEXNORMAL, instead of relying on the definition of PTHREADMUTEXDEFAULT. On FreesBSD the default is not "normal" but "error checking" and so is slow. On all other current platforms there is no effective change. Finally, Solaris is excluded from all this (other than the debug signal blocking cleanup) because it potentially supports three different low-level sync subsystems: UI thr*, Pthread, and direct LWP sync. Solaris cleanup would be a separate RFE. No doubt I've overlooked mentioning something that someone will spot. :) Thanks, David

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