a big update to the event buffer code was merged today.

two important bug fixes:

- a logic error in bm_receive_event() (actually bm_fill_read_cache_locked()) 
caused use of uninitialized variable to increment the read pointer and crash 
with error "read pointed points to an invalid event")
- missing bm_unlock() in bm_flush_cache() caused double-locking of event buffer 
caused a hang and a subsequent crash via the watchdog timeout.

several improvements:

- bm_receive_event_vec(std::vector<char>) with automatic memory allocation, one 
does not need to worry about providing a large event buffer to receive event 
data. For local connections MAX_EVENT_SIZE is no longer used, for remote 
connections, a buffer of MAX_EVENT_SIZE is allocated automatically, this is a 
limitation of the MIDAS RPC layer (it does not know how to allocate memory to 
receive arbitrary large data)

(MAX_EVENT_SIZE is now only used in bm_receive_event_rpc()).

- rpc_send_event_sg() - thread safe method to send events to the mserver. it 
takes an array of scatter-gather buffers, so a midas event does not have to be 
in one continious buffer.

- bm_send_event_sg() - same for local connections.

- on top of bm_send_event_sg() we now have bm_send_event_vec(std::vector<char>) 
and bm_send_event_vec(std::vector<vector<char>>). now we can move forward with 
implementing a new "event object" (the TMEvent event object from midasio.h 
already works with these new methods).

- remote connected bm_send_event() & co now always send events to the mserver 
using the event socket. (before, bm_send_event() used RPC_BM_SEND_EVENT and 
suffered from the RPC layer encoding/decoding overhead. mfe.c used 
rpc_send_event() for remote connections)

- bm_send_event(), bm_receive_event() & co now take a timeout value (in 
milliseconds) instead of an async_flag. The old async_flag values BM_WAIT and 
BM_NO_WAIT continue working as expected (wait forever and do not wait at all, 
respectively).

- following improvements are only for remote connections:

- in the case of event buffer congestion (event readers are slow, event buffers 
are close to 100% full), the bm_flush_cache() RPC will no longer timeout due to 
mserver being stuck waiting for free buffer space. (RPC is called with a 1000 
msec timeout, infinite loop waiting for flush is done on the frontend side, the 
RPC timeout will never fire)

- in the case of event buffer congestion, ODB RPC will no longer timeout. 
(previously mserver was stuck waiting for free buffer space and did not process 
any RPCs).

- at the end of run, last few events could be stuck in the event socket. now, 
frontends can flush it using bm_flush_cache(0,BM_WAIT) (use zero for the buffer 
handle). correct run transition should stop the trigger, stop generating new 
events, call bm_flush_cache(0,BM_WAIT), call bm_flush_cache("SYSTEM",BM_WAIT) 
and return success. (TMFE frontend already does this). Note that 
bm_flush_cache(BM_WAIT) can be stuck for very long time waiting for the event 
buffers to empty-out, so run transition RPC timeout is still possible.

K.O.

How does "find_package (Midas REQUIRED)" find the location of MIDAS?

The best I can tell from the current code, the package config files are installed
inside $MIDASSYS somewhere and I see "find_package MIDAS" never find them (indeed,
find_package() does not know about $MIDASSYS, so it has to use telepathy or something).

Does anybody actually use "find_package(midas)", does it actually work for anybody?

Also it appears that "the cmake way" of importing packages is to use
the install(EXPORT) method.

In this scheme, the user package does this:

include(${MIDASSYS}/lib/midas-targets.cmake)
target_link_libraries(myprogram PUBLIC midas)

this causes all the midas include directories (including mxml, etc)
and dependancy libraries (-lutil, -lpthread, etc) to be automatically
added to "myprogram" compilation and linking.

of course MIDAS has to generate a sensible targets export file,
working on it now.

K.O.

> > Does anybody actually use "find_package(midas)", does it actually work for anybody?
> 
> What we do is to include midas as a submodule and than we call find_package:
> 
>     add_subdirectory(midas)
>     list(APPEND CMAKE_PREFIX_PATH ${CMAKE_CURRENT_SOURCE_DIR}/midas)
>     find_package(Midas REQUIRED)
> 
> For us it works fine like this but we kind of always compile Midas fresh and don't use a version on our system (keeping the newest version). 
> 
> Without the find_package the build does not work for us.

Ok, I see. I now think that for us, this "find_package" business an unnecessary complication:

since one has to know where midas is in order to add it to CMAKE_PREFIX_PATH,
one might as well import the midas targets directly by include(.../midas/lib/midas-targets.cmake).

From what I see now, the cmake file is much simplifed by converting
it from "find_package(midas)" style MIDAS_INCLUDES & co to more cmake-ish
target_link_libraries(myexe midas) - all the compiler switches, include paths,
dependant libraires and gunk are handled by cmake automatically.

I am not touching the "find_package(midas)" business, so it should continue to work, then.

K.O.

> MidasConfig.cmake might at some point get included in the standard Cmake installation (or some add-on). It will then reside in the Cmake system path 
> and you don't have to explicitly know where this is. Just the find_package(Midas) will then be enough.

Hi, Stefan, can you say more about this? If MidasConfig.cmake is part of the cmake distribution,
(did I understand you right here?) and is installed into a system-wide directory,
how can it know to use midas from /home/agmini/packages/midas or from /home/olchansk/git/midas?

Certainly we do not do system wide install of midas (into /usr/local/bin or whatever) because
typically different experiments running on the same computer use different versions of midas.

For ROOT, it looks as if for find_package(ROOT) to work, one has to add $ROOTSYS to the Cmake package
search path. This is what we do in our cmake build.

As for find_package() vs install(EXPORT), we may have the same situation as with my "make cmake",
where my one line solution is no good for people who prefer to type 3 lines of commands.

Specifically, the install(EXPORT) method defines the "midas" target which brings with it
all it's dependent include paths, libraries and compile flags. So to link midas you need
two lines:

include(.../midas/lib/midas-targets.cmake)
target_link_libraries(myexe midas)
target_link_libraries(myfrontend mfe)

whereas find_package() defines a bunch of variables (the best I can tell) and one has
to add them to the include paths and library paths and compile flags "by hand".

I do not know how find_package() handles the separate libmidas, libmfe and librmana. (and
the separate libmanalyzer and libmanalyzer_main).

K.O.

> A simple program to forward MIDAS messages to Discord, Slack and or Mattermost
> 
> (Python 3 required)
> 
> Pull request accepted! Documentation can be found on the wiki
> 
> https://midas.triumf.ca/MidasWiki/index.php/Mmessenger

This sounds like a very useful and welcome addition to MIDAS.

But from documentation provided, I have clue how to activate it.

Perhaps it would help if you could write up the basic steps on how to go about it, i.e.
- go to discord
- push these buttons
- cut and paste this thingy from the web page to ODB

K.O.

https://bitbucket.org/tmidas/midas/issues/305/log_history_periodic-doesnt-account-for

this problem is a blocker for the next midas release.

the best I can tell, current development version of midas writes history data incorrectly,
but I do not have time to look at it at this moment.

I recommend that people use the latest released version, midas-2020-12. (this is what we have on alphag and 
should have in alpha2).

midas-2020-12 uses mlogger from midas-2020-08.

If I cannot find time to figure out what is going on in the mlogger,
the next release may have to be done the same way (with mlogger from midas-2020-08).

K.O.

> This list of responsible being attached to alarm message strings ...

This is a great idea. But I think we do not need to artificially limit ourselves
to string and array lengths.

The code in alarm.c should be changes to use std::string and std::vector<std::string> (STRING_LIST 
#define), db_get_record() should be replaced with individual ODB reads (that's what it does behind 
the scenes, but in a non-type and -size safe way).

I think the web page code will work correctly, it does not care about string lengths.

K.O.

> % mariadb_config --cflags
> -I/usr/include/mariadb -I/usr/include/mariadb/mysql

I get similar, both .../include and .../include/mysql are in my include path,
so both #include "mysql/mysql.h" and #include "mysql.h" work.

I added a message to cmake to report the MySQL CFLAGS and libraries, so next time
this is a problem, we can see what happened from the cmake output:

4ed0:midas olchansk$ make cmake | grep MySQL
...
-- MIDAS: Found MySQL version 10.4.16
-- MIDAS: MySQL CFLAGS: -I/opt/local/include/mariadb-10.4/mysql;-I/opt/local/include/mariadb-
10.4/mysql/mysql and libs: -L/opt/local/lib/mariadb-10.4/mysql/ -lmariadb

K.O.

> is there any way to order the labels in the history plot legend? In the old 
> system there was the “order” column in the config panel, but I can not find it 
> in the new system. Thanks in advance for the support.

correct, for reasons unknown, the function to reorder and to delete individual 
entries was removed from the history panel editor.

K.O.

> > is there any way to order the labels in the history plot legend? In the old 
> > system there was the “order” column in the config panel, but I can not find it 
> > in the new system. Thanks in advance for the support.
> 
> correct, for reasons unknown, the function to reorder and to delete individual 
> entries was removed from the history panel editor.
> 
> K.O.

https://bitbucket.org/tmidas/midas/issues/284/history-panel-editor-reordering-of

K.O.

> Hi,
> 
> I am running a simple FE executable that is supposed to define a PRAW DWORD bank.
> The issue is that, right after the start of the run, the logger crashes without messages.
> Then the FE reports this error, which is rather confusing.
> ```
> 12:59:29.140 2021/05/24 [feTestDatastruct,ERROR] [odb.cxx:6986:db_set_data1,ERROR] "/Equipment/Trigger/Variables/PRAW" is of type UINT32, not UINT32
> ```

I think this is fixed in latest midas. There was a typo in this message, the same tid was printed twice,
with result you report "mismatch UINT32 and UINT32", instead of "mismatch of UINT32 vs what is actually there".

This fixes the message, after that you have to manually fix the mismatch in the data type in ODB (delete old one, I guess).

K.O.

> > Thanks a lot, this solved my issue!
> 
> ... or we should turn IPv6 off by default, since not many people use this right now.

IPv6 certainly works and is used at CERN.

But I am not sure why people see this message. I do not see it on any machines at 
TRIUMF, even those with IPv6 turned off.

K.O.

> OS: OSX 10.14.6 Mojave
> MIDAS: Downloaded from repo on April 2021.
> 
> I have a slow control frontend doing the command/readout of a MPOD HV/LV. Since I am reading out the current that are in nA (after updating snmp), I wanted to multiply the number by 1e9.
> 
> I noticed the new "Formula" field (introduced in 2019 it seems) instead of the "Factor/Offset" I was used to. None of my entries seems to be accepted (after hitting save, when coming back thee field is empty).
> 
> Looking in ODB in "/History/Display/MPOD/HV (Current)/", the field "Formula" is a string of size 32 (even if I have multiple plots in that display). I noticed that the fields "Factor" and "Offset" are still existing and they are arrays with the correct size. However, changing the values does not seem to do anything.
> 
> Deleting "Formula" by hand and creating a new field as an array of string (of correct length) seems to do the trick: the formula is displayed in the History display config, and correctly used.

I see this, too. Problem is that the history plot code must be compatible with both
the old scheme (factor/offset) and the new scheme (formula). But something goes wrong somewhere.

https://bitbucket.org/tmidas/midas/issues/307/history-plot-config-incorrect-in-odb

Why?

- new code cannot to "3 year" plots, old code has no problem with it
- old experiments (alpha1, etc) have only the old-style history plot definitions,
and both old and new plotting code should be able to show them (there is nobody
to convert this old stuff to the "new way", but we still desire to be able to look at it!)

K.O.

I truncated the bitbucket build to only build on ubuntu LTS 20.04.

Somehow all the other build targets - centos-7, centos-8, ubuntu-18 - have
an obsolete version of cmake. I do not know where the bitbucket os images
get these obsolete versions of cmake - my centos-7 and centos-8 have much
more recent versions of cmake.

If somebody has time to figure it out, please go at it, I would like very
much to have centos-7 and centos-8 builds restored (with ROOT), also
to have a ubuntu LTS 20.04 build with ROOT. (For me, debugging bitbucket
builds is extremely time consuming).

Right now many midas cmake files require cmake 3.12 (released in late 2018).

I do not know why that particular version of cmake (I took the number
from the tutorials I used).

I do not know what is the actual version of cmake that MIDAS (and ROOTANA) 
require/depend on.

I wish there were a tool that would look at a cmake file, examine all the 
features it uses and report the lowest version of cmake that supports them.

K.O.

> cmake ../ -DCMAKE_INSTALL_PREFIX=/usr/local/midas

good timing, I am working on cmake for manalyzer and rootana and I have not tested
the install prefix business.

now I know to test it for all 3 packages.

I will also change find_package(Midas) slightly, (see my other message here),
I hope you can confirm that I do not break it for you.

K.O.

> find_package(Midas)

I am testing find_package(Midas). There is a number of problems:

1) ${MIDAS_LIBRARIES} is set to "midas;midas-shared;midas-c-compat;mfe".

This seem to be an incomplete list of all libraries build by midas (rmana is missing).

This means ${MIDAS_LIBRARIES} should not be used for linking midas programs (unlike ${ROOT_LIBRARIES}, etc):

- we discourage use of midas shared library because it always leads to problems with shared library version mismatch (static linking is preferred)
- midas-c-compat is for building python interfaces, not for linking midas programs
- mfe contains a main() function, it will collide with the user main() function

So I think this should be changed to just "midas" and midas linking dependancy
libraries (-lutil, -lrt, -lpthread) should also be added to this list.

Of course the "install(EXPORT)" method does all this automatically. (so my fixing find_package(Midas) is a waste of time)

2) ${MIDAS_INCLUDE_DIRS} is missing the mxml, mjson, mvodb, midasio submodule directories

Again, install(EXPORT) handles all this automatically, in find_package(Midas) it has to be done by hand.

Anyhow, this is easy to add, but it does me no good in the rootana cmake if I want to build against old versions
of midas. So in the rootana cmake, I still have to add $MIDASSYS/mvodb & co by hand. Messy.

I do not know the history of cmake and why they have two ways of doing things (find_package and install(EXPORT)),
this second method seems to be much simpler, everything is exported automatically into one file,
and it is much easier to use (include the export file and say target_link_libraries(rootana PUBLIC midas)).

So how much time should I spend in fixing find_package(Midas) to make it generally usable?

- include path is incomplete
- library list is nonsense
- compiler flags are not exported (we do not need -DOS_LINUX, but we do need -DHAVE_ZLIB, etc)
- dependency libraries are not exported (-lz, -lutil, -lrt, -lpthread, etc)

K.O.

> cmake ../ -DCMAKE_INSTALL_PREFIX=/usr/local/midas
> Is the cmake setup not relocatable? This is new and was working until recently:

Indeed. Not relocatable. This is because we do not install the header files.

When you use the CMAKE_INSTALL_PREFIX, you get MIDAS "installed" in:

prefix/lib
prefix/bin
$MIDASSYS/include <-- this is the source tree and so not "relocatable"!

Before, this was kludged and cmake did not complain about it.

Now I changed cmake to handle the include path "the cmake way", and now it knows to complain about it.

I am not sure how to fix this: we have a conflict between:

- our normal way of using midas (include $MIDASSYS/include, link $MIDASSYS/lib, run $MIDASSYS/bin)
- the cmake way (packages *must be installed* or else! but I do like install(EXPORT)!)
- and your way (midas include files are in $MIDASSYS/include, everything else is in your special location)

I think your case is strange. I am curious why you want midas libraries to be in prefix/lib instead of in 
$MIDASSYS/lib (in the source tree), but are happy with header files remaining in the source tree.

K.O.

> > find_package(Midas)
> 
> So how much time should I spend in fixing find_package(Midas) to make it generally usable?
> 
> - include path is incomplete
> - library list is nonsense
> - compiler flags are not exported (we do not need -DOS_LINUX, but we do need -DHAVE_ZLIB, etc)
> - dependency libraries are not exported (-lz, -lutil, -lrt, -lpthread, etc)
> 

I think I give up on find_package(Midas). It seems like a lot of work to straighten
all this out, when install(EXPORT) does it all automatically and is easier to use
for building user frontends and analyzers.

K.O.

> > > cmake ../ -DCMAKE_INSTALL_PREFIX=/usr/local/midas
> > > Is the cmake setup not relocatable? This is new and was working until recently:
> > Not relocatable. This is because we do not install the header files.
> 
> We do it this way, since the lib and bin needs to be in a place where standard users have no access to. 

hmm... i did not get this. "needs to be in a place where standard users have no access to". what do you
mean by this? you install midas in a secret location to prevent somebody from linking to it?

> If I think an all other packages I am working with, e.g. ROOT, the includes are also installed under CMAKE_INSTALL_PREFIX.

cmake and other frameworks tend to be like procrustean beds (https://en.wikipedia.org/wiki/Procrustes),
pre-cmake packages never quite fit perfectly, and either the legs or the heads get cut off. post-cmake packages
are constructed to fit the bed, whether it makes sense or not.

given how this situation is known since antiquity, I doubt we will solve it today here.

(I exercise my freedom of speech rights to state that I object being put into
such situations. And I would like to have it clear that I hate cmake (ask me why)).

>
> Up until recently there was no issue to work with CMAKE_INSTALL_PREFIX, accepting that the includes stay under 
> $MIDASSYS/include, even though this is not quite the standard way, but no problem here.
>

I think a solution would be to add install rules for include files. There will be a bit of trouble,
normal include path is $MIDASSYS/include,$MIDASSYS/mxml,$MIDASSYS/mjson,etc, after installing
it will be $CMAKE_INSTALL_PREFIX/include (all header files from different git submodules all
dumped into one directory). I do not know what problems will show up from that.

I think if midas is used as a subproject of a bigger project, this is pretty much required
(and I have seen big experiments, like STAR and ND280, do this type of stuff with CMT,
another horror and the historical precursor of cmake)

The problem is that we do not have any super-project like this here, so I cannot ever
be sure that I have done everything correctly. cmake itself can be helpful, like
in the current situation where it told us about a problem. but I will never trust
cmake completely, I see cmake do crazy and unreasonable things way too often.

One solution would be for you or somebody else to contribute such a cmake super-project,
that would build midas as a subproject, install it with a CMAKE_INSTALL_PREFIX and
try to link some trivial frontend or analyzer to check that everything is installed
correctly. It would become an example for "how to use midas as a subproject").
Ideally, it should be usable in a bitbucket automatic build (assuming bitbucket
has correct versions of cmake, which it does not half the time).

P.S. I already spent half-a-week tinkering with cmake rules, only to discover
that I broke a kludge that allows you to do something strange (if I have it right,
the CMAKE_PREFIX_INSTALL code is your contribution). This does not encourage
 me to tinker with cmake even more. who knows against what other
kludge I bump into. (oh, yes, I know, I already bumped into the nonsense
find_package(Midas) implementation).

K.O.

> > > > > cmake ../ -DCMAKE_INSTALL_PREFIX=/usr/local/midas
> > > > > Is the cmake setup not relocatable? This is new and was working until recently:
> > > > Not relocatable. This is because we do not install the header files.
> > > 
> > > We do it this way, since the lib and bin needs to be in a place where standard users have no access to. 
> > 
> > hmm... i did not get this. "needs to be in a place where standard users have no access to". what do you
> > mean by this? you install midas in a secret location to prevent somebody from linking to it?
> > 
> 
> This was a wrong wording from my side. We do not want the the users have write access to the midas installation libs and bins.
> I have submitted the pull request which should resolve this without interfere with your usage.
> Hope this will resolve the issue.

Excellent. I think it is good to have midas "install" in a sane manner.

But I still struggle to understand what you do. Presumably you can "install" midas
in the "midas account", which is not writable by the experiment and user accounts.
Then it does not matter if you "install" it in it's build directory (like we do)
or in some other location (like you do now).

This does not work of course if you only have one account, so do you build midas
as root? or install it as root?

I do ask because in the current computing world, doing things as root requires
a certain amount of trust, which may not be there anymore, see the recent "supply side" attacks
against python packages, solar winds hack, linux kernel malicious patches from umn, etc.

Personally, I do not want to answer questions "is midas safe to run as root?",
"can I trust the midas install scripts to run as root?" and certainly I do not want to hear
about "I installed midas and 100 other packages as root and got hacked 7 days later".

(and running midas as root was never safe. neither mhttpd nor mserver will pass
a security audit).

Anyhow, looks like I will look at cmake again next week. Right now I have a major
breakthrough in the ALPHA-g experiment, my big 96-port Juniper switch suddenly
has working ethernet flow control and I can record data at 600 Mbytes/sec without
any UDP packet loss. Above that, my event builder explodes. I want to fix it and get
it up to 1000 Mbytes/sec, the limit of my 10gige network link. (In this system I do not
have the disk subsystem to record data at this rate, but I have build 8-disk ZFS arrays
that would sink it, no problem). And the day has come when I ran out of CPU cores.
The UDP packet receivers are multithreaded, the event builder is multithreaded and I am using
all 4 of the available cores (intel cpu). As soon as I can get a rackmounted AMD Ryzen
or Threadripper machine, we will likely upgrade. (need at least one more CPU core to run
the online analyzer!). Exciting.

K.O.