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pcas/documentation/RELEASE_NOTES.html
2016-03-30 12:39:36 -05:00

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<title>EPICS Base R3.16.0.2 Release Notes</title>
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<h1 align="center">EPICS Base Release 3.16.0.2</h1>
<p style="color:red">This version of EPICS Base has not been released yet.</p>
<h2 align="center">Changes made on the 3.16 branch since 3.15.3</h2>
<!-- Insert new items immediately below this template ...
<h3>Title...</h3>
<p>Description</p>
-->
<h3>Echoless comments in iocsh</h3>
<p>The way comments are parsed by the iocsh interpreter has changed. The
interpreter can be selectively disabled from echoing comments coming from
a script by starting those lines with '#-' rather than just '#'.</p>
<hr>
<h2 align="center">Changes in 3.16.0.1 made since 3.15.3</h2>
<h3>Build support for CapFast and dbst removed</h3>
<p>The build rules associated with the CapFast-related tools <tt>sch2edif</tt>
and <tt>e2db</tt> and the <q>database optimization</q> tool <tt>dbst</tt> have
been removed, along with the <tt>DB_OPT</tt> build configuration variable.</p>
<h3>compressRecord buffering order</h3>
<p>The compressRecord has a new field <tt>BALG</tt> which can select between
FIFO (append) and LIFO (prepend) ordering for insertion of new elements. FIFO
ordering is the default, matching the behviour of previous versions.</p>
<h3>Valgrind Instrumentation</h3>
<p>Valgrind is a software debugging suite provided by many Linux distributions.
The header valgrind/valgrind.h is now included in, and installed by, Base.
When included by a C or C++ source file this header defines some macros which
expand to provide hints to the Valgrind runtime.
These have no effect on normal operation of the software, but when run using the
valgrind tool they can help to find memory leaks and buffer overflows.
Suitable hints have been added to several free-lists within libCom, including
freeListLib, allowing valgrind to provide more accurate information about the
source of potential leaks.</p>
<p>valgrind.h automatically disables itself when the build target is not
supported by the valgrind tool.
It can also explicitly be disabled by defining the macro <em>NVALGRIND</em>.
See <em>src/libCom/Makefile</em> for a commented-out example.</p>
<p>As a matter of policy valgrind.h will never be included by any header file
installed by Base, so its use will remain purely an implementation
detail hidden from application software.
Support modules which choose to use valgrind.h are advised to do
likewise.</p>
<h3>Database Multi-locking</h3>
<p>The IOC record locking code has been re-written with an expanded API; global
locks are no longer required by the IOC database implementation.</p>
<p>The new API functions center around dbScanLockMany(), which behaves like
dbScanLock() applied to an arbitrary group of records. dbLockerAlloc() is used
to prepare a list or record pointers, then dbScanLockMany() is called. When it
returns, all of the records listed may be accessed (in any order) until
dbScanUnlockMany() is called.</p>
<p>The Application Developer's Guide has been updated to describe the API and
implementation is more detail.</p>
<p>Previously a global mutex 'lockSetModifyLock' was locked and unlocked during
dbScanLock(), acting as a sequencing point for otherwise unrelated calls. The
new dbLock.c implementation does not include any global mutex in dbScanLock() or
dbScanLockMany(). Locking/unlocking of unrelated lock sets is now completely
concurrent.</p>
<h3>Generate Version Header</h3>
<p>A Perl script and Makefile rules have been added to allow modules to generate
a C header file with a macro defined with an automatically updated identifier.
This is a VCS revision ID (Darcs, Git, Mercurial, Subversion, and Bazaar are
supported) or the date/time of the build if no VCS system is in use.</p>
<p>The makeBaseApp example template has been updated with a new device support
which makes this identifier visible via a lsi (long string input) record.</p>
<h3>epicsTime API return status</h3>
<p>The epicsTime routines that used to return epicsTimeERROR now return a
specific S_time_ status value, allowing the caller to discover the reason for
any failure. The identifier <tt>epicsTimeERROR</tt> is no longer defined, so any
references to it in source code will no longer compile. The identifier
epicsTimeOK still exists and has the value 0 as before, so most code that uses
these APIs can be changed in a way that is backwards-compatible with the
previous return status.</p>
<p>Time providers that have to return a status value and still need to be built
with earlier versions of Base can define the necessary status symbols like
this:</p>
<blockquote><pre>
#include "epicsTime.h"
#ifndef M_time
/* S_time_... status values were not provided before Base 3.16 */
#define S_time_unsynchronized epicsTimeERROR
#define S_time_...whatever... epicsTimeERROR
#endif
</pre></blockquote>
<h3>Refactoring of epicsReadline</h3>
<p>The epicsReadline code has been reorganized to allow the commandline history
editor to be disabled at runtime. The EPICS_COMMANDLINE_LIBRARY build setting
still selects the preferred editor, but the new <tt>IOCSH_HISTEDIT_DISABLE</tt>
environment variable can be set at runtime to disable history editing and make
the IOC or other program use the basic editor instead. This is useful when
starting and controlling an IOC from another program through its stdin and
stdout streams since history editors often insert invisible escape codes into
the stdout stream, making it hard to parse.</p>
<h3>Callback subsystem API</h3>
<p>Added a new macro <tt>callbackGetPriority(prio, callback)</tt> to the
callback.h header and removed the need for dbScan.c to reach into the internals
of its CALLBACK objects.</p>
<h2 align="center">Changes pulled from the 3.15 branch since 3.15.3</h2>
<h3>CA server configuration changes</h3>
<p>RSRV now honors EPICS_CAS_INTF_ADDR_LIST and binds only to the provided list
of network interfaces. Name searches (UDP and TCP) on other network interfaces
are ignored. For example on a computer with interfaces 10.5.1.1/24, 10.5.2.1/24,
and 10.5.3.1/24, setting "EPICS_CAS_INTF_ADDR_LIST='10.5.1.1 10.5.2.1'" will
accept traffic on the .1.1 and .2.1, but ignore from .3.1</p>
<p>RSRV now honors EPICS_CAS_IGNORE_ADDR_LIST and ignores UDP messages received
from addresses in this list.</p>
<p>Previously, CA servers (RSRV and PCAS) would build the beacon address list
using EPICS_CA_ADDR_LIST if EPICS_CAS_BEACON_ADDR_LIST was no set. This is no
longer done. Sites depending on this should set both envronment variables to the
same value.</p>
<h3>IPv4 multicast for name search and beacons</h3>
<p>libca, RSRV, and PCAS may now use IPv4 multicasting for UDP traffic (name
search and beacons). This is disabled by default. To enable multicast address(s)
must be listed in EPICS_CA_ADDR_LIST for clients and EPICS_CAS_INTF_ADDR_LIST
for servers (IOCs should set both). For example:
"EPICS_CAS_INTF_ADDR_LIST='224.0.2.9' EPICS_CA_ADDR_LIST=224.0.2.9".</p>
<p>Please note that no IPv4 multicast address is officially assigned for Channel
Access by IANA. The example 224.0.2.9 is taken from the AD-HOC Block I range.<p>
<h3>Moved <tt>mlockall()</tt> into its own epicsThread routine</h3>
<p>Since EPICS Base 3.15.0.2 on Posix OSs the initialization of the epicsThread
subsystem has called <tt>mlockall()</tt> when the OS supports it and thread
priority scheduling is enabled. Doing so has caused problems in third-party
applications that call the CA client library, so the functionality has been
moved to a separate routine <tt>epicsThreadRealtimeLock()</tt> which will be
called by the IOC at iocInit (unless disabled by setting the global variable
<tt>dbThreadRealtimeLock</tt> to zero).</p>
<h3>Added dbQuietMacroWarnings control</h3>
<p>When loading database files, macros get expanded even on comment lines. If a
comment contains an undefined macro, the load still continues but an error
message gets printed. For this release the error message has been changed to a
warning, but even this warning can be made less verbose by setting this new
variable to a non-zero value before loading the file, like this:</p>
<blockquote><pre>
var dbQuietMacroWarnings 1 <i>iocsh</i>
dbQuietMacroWarnings=1 <i>VxWorks</i>
</pre></blockquote>
<p>This was <a href="https://bugs.launchpad.net/bugs/541119">Launchpad bug
541119</a>.</p>
<h2 align="center">Changes pulled from the 3.14 branch since 3.15.3</h2>
<h3>String field buffer overflows</h3>
<p>Two buffer overflow bugs that can crash the IOC have been fixed, caused by
initializing a string field with a value larger than the field size
(<a href="https://bugs.launchpad.net/bugs/1563191">Launchpad bug
#1563191</a>).</p>
<h3>Fixed stack corruption bug in epicsThread C++ API</h3>
<p>The C++ interface to the epicsThread API could corrupt the stack on thread
exit in some rare circumstances, usually at program exit. This bug has been
fixed (<a href="https://bugs.launchpad.net/bugs/1558206">Launchpad bug
#1558206</a>).</p>
<h3>RTEMS NTP Support Issue</h3>
<p>On RTEMS the NTP Time Provider could in some circumstances get out of sync
with the server because the osdNTPGet() code wasn't clearing its input socket
before sending out a new request. This
(<a href="https://bugs.launchpad.net/bugs/1549908">Launchpad bug 1549908</a>)
has now been fixed.</p>
<h3>CALC engine bitwise operator fixes</h3>
<p>The bitwise operators in the CALC engine have been modified to work properly
with values that have bit 31 (0x80000000) set. This modification involved
back-porting some earlier changes from the 3.15 branch, and fixes
<a href="https://code.launchpad.net/bugs/1514520">Launchpad bug
#1514520</a>.</p>
<h3>Fix <tt>ipAddrToAsciiAsync()</tt>: Don't try to join the daemon thread</h3>
<p>On process exit, don't try to stop the worker thread that makes DNS lookups
asynchronous. Previously this would wait for any lookups still in progress,
delaying the exit unnecessarily. This was most obvious with catools (eg.
cainfo).
<a href="https://bugs.launchpad.net/bugs/1527636">lp:1527636</a></p>
<h3>Fix <tt>epicsTime_localtime()</tt> on Windows</h3>
<p>Simpler versions of the epicsTime_gmtime() and epicsTime_localtime()
routines have been included in the Windows implementations, and a new test
program added. The original versions do not report DST status properly. Fixes
<a href="https://bugs.launchpad.net/bugs/1528284">Launchpad bug 1528284</a>.</p>
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