> I should mention that I was using midas/examples/Triumf/c++/fevme.cxx

this is correct, the fevme frontend is written to do 100% CPU-busy polling.

there is several reasons for this:
- on our VME processors, we have 2 core CPUs, 1st core can poll the VME bus, 2nd core can run 
mfe.c and the ethernet transmitter.
- interrupts are expensive to use (in latency and in cpu use) because kernel handler has to call 
use handler, return back etc
- sub-millisecond sleep used to be expensive and unreliable (on 1-2GHz "core 1" and "core 2" 
CPUs running SL6 and SL7 era linux). As I understand, current linux and current 3+GHz CPUs can 
do reliable microsecond sleep.

K.O.

>    r->rsprintf("Expires: %s\r\n", str);

The best I can tell, none of this works in current browsers. with google-chrome,
I see it cache pretty much everything regardless of "expires", "no cache", etc
and anything else I tried.

Things like shift-<reload>, etc used to work to refresh the cache, but not any more.

So, I too, see confusing side-effects of caching, where I change something in ODB,
but "nothing happens". Then I scratch my head for 30 minutes until I remember
to open the javascript debugger where shift-<reload> (or is it ctrl-<reload>) actually works.

It seems that the only reliable way to bypass the browser cache is to add
a tag with a random number to the URL ("&ts=currenttime").

This is for HTTP GET requests. HTTP POST does not seem to be cached, so I do not worry
about this nonsense for json-rpc requests.

Perhaps we should do this random number trick for all user actions. User can
press buttons only so fast, we should be able to sustain the rate. Anything
loaded automatically or from a timer, we should allow caching.

BTW, things like midas.js are also cached, and it is common to see problems
after updating midas, where status.html is newly loaded, but midas.js is an old
stale version from cache.

Messy.

K.O.

> I am encountering a Javascript error (TypeError: client.error is undefined) when 
> I transition between run states. Does anybody have an idea of what my problem 
> might be? I have pasted an example of what MIDAS logs during such sequences.


Not enough information. Can you do this:

a) for the javascript error, if you get it every time, open the javascript debugger 
and capture the stack trace? or at least the file name, function name and line number 
where the javascript exception is thrown?

b) for the run start failure, start the run from odbedit "start now -v" or from 
"mtransition -v -d 1 START" (or "stop" as the case may be). capture the output, email 
to me directly or put in this elog here.

K.O.


> 
> Thanks for all the help!
> 
> Isaac
> 
> 
> 09:24:08.611 2021/02/10 [mhttpd,INFO] Executing script 
> "~/ANIS_20210106/scripts/start_daq.sh" from ODB "/Script/Start DAQ"
> 
> 09:24:13.833 2021/02/10 [Logger,LOG] Program Logger on host localhost started
> 
> 09:24:28.598 2021/02/10 [fevme,LOG] Program fevme on host localhost started
> 
> 09:24:33.951 2021/02/10 [mhttpd,INFO] Run #234 started
> 
> 09:26:30.970 2021/02/10 [mhttpd,ERROR] [midas.cxx:4260:cm_transition_call,ERROR] 
> Client "Logger" transition 2 aborted while waiting for client "fevme": 
> "/Runinfo/Transition in progress" was cleared
> 
> 09:26:31.015 2021/02/10 [mhttpd,ERROR] [midas.cxx:5120:cm_transition,ERROR] 
> transition STOP aborted: "/Runinfo/Transition in progress" was cleared
> 
> 09:27:27.270 2021/02/10 [mhttpd,ERROR] 
> [system.cxx:4937:ss_recv_net_command,ERROR] timeout receiving network command 
> header
> 
> 09:27:27.270 2021/02/10 [mhttpd,ERROR] [midas.cxx:12262:rpc_client_call,ERROR] 
> call to "fevme" on "localhost" RPC "rc_transition": timeout waiting for reply

midas-2020-12-a is here, see https://midas.triumf.ca/MidasWiki/index.php/Changelog#2020-12

notable change from previous midas releases:

Use of ODB "Common" by mfe.c frontends has changed. New preferred behaviour
is to have the values defined in the equipment structure in the source code
to always overwrite values in ODB /Equipment/Foo/Common, except for the value
of "Common/enabled" (equipment_common_overwrite set to TRUE).

All mfe.c frontends will need to be modified for this change:

- for old behaviour (use ODB "Common"), add: BOOL equipment_common_overwrite = false;
- for new behaviour (use equipment values in the source code), add: BOOL equipment_common_overwrite = true;

The TMFE C++ frontend does not implement this change yet, it uses all "Common" values from ODB
and there is no way to overwrite things like the MIDAS event buffer name from C++ code. This may
change with the next version.

notable updates since midas-2020-08:

- new ODB variable /Experiment/Enable sound can be used to globally prevent mhttpd from playing sounds.
- Lazylogger now supports writing data over SFTP.
- odbvalue elements on custom pages now support an onload() callback as well as onchange(). Most elements now also 
support a data-validate callback.
- custom pages can now tie a select drop-down box to an ODB value using modbselect.
- ability to choose whether the code or the current ODB values take precendence for the "Common" settings of an 
equipment when starting a frontend. See elog thread 2014 for more details, and the "Upgrade guide" below for 
instructions.
- minor improvements to mdump program - support for 64-bit data types and ability to load larger events if needed.
- minor improvements to History plots and Buffers webpage.
- bug fixes

plans for next development: major update of mlogger to simplify channel 
configuration in odb, improvements to mhttpd multithreading, new history plot 
configuration page, more c++ification.

To obtain this release, either checkout the top of branch release/midas-2020-12 
(recommended) or checkout the tag midas-2020-12-a.

K.O.

there is a problem with mlogger between commits xxx (17 Nov 2020) and a762bb8 (12 feb 2021). because of 
confusion between seconds and milliseconds, FILE (mhf*.dat files) and SQL history are recording with 
incorrect timestamps.

- traditional MIDAS history (*.hst files) does not have this problem (because of a buglet)
- midas-2020-12 release does not have this problem (it has mlogger from midas-2020-08 release)

there are some additional changes in mlogger that we are sorting out, when ready, we will make a new 
release of midas.

K.O.

> The most recent commit (b43aef648c2f8a7e710a327d0b322751ae44afea) throws this 
> compiler error:
> src/tmfe_main.cxx:39:11: error: 'SIGPIPE' was not declared in this scope
>     signal(SIGPIPE, SIG_IGN);
> 
> It's fixed by adding #include <signal.h> to that file.

"but it works just fine on my mac!"

anyhow, thank you for reporting this problem, it already fixed. the bitbucket auto-
build also caught it. I also boogered up "make remoteonly", also fixed now.

BTW, for production use I recommend midas from the "release" branches, unless one 
needs a bug fix or new feature from the development branch.

K.O.

> Am I right in thinking that the TMFE HandlePoll function is calle once per 
> PollMidas()? And what is the difference to HandleRead()?

Actually, polled equipment is not implemented yet in TMFE, as you noted, the 
internal scheduler needs to be reworked.

Anyhow, I think with modern c++ and with threads, both "periodic" and "polled" 
equipments are not strictly necessary.

Periodic equipment is effectively this:

in a thread:
while (1) {
do stuff, read data, send events
sleep
}

Polled equipment is effectively this:

in a thread:
while (1) {
if (poll()) { read data, send events }
else { sleep for a little bit }
}

Example of such code is the "bulk" equipment in progs/fetest.cxx.

But to implement the same in a single threaded environment (eliminates
problems with data locking, race conditions, etc) and to provide additional
structure to the user code, the plan is to implement polled equipment in TMFE
frontends. (periodic equipment is already implemented).

K.O.

Clearly something goes wrong with the STARTABORT transition. Actually from your 
sceenshot, it is not clear why the STARTABORT transition was initiated.

Usually it is called after some client fails the "start run" transition to inform 
other clients that the run did not start after all. (mlogger uses this to close the 
output file, etc).

But in the screenshot, we do not see any client fail the transition (only rootana1 
was called, and it returned "green").

So, a puzzle. One possibility is that the transition code gets so confused
that it does not record correct transition data to ODB, then the web page
gets even more confused.

One way to see what happens, is to run the odbedit command "start now -v".

Can you try that? And attach all it's output here?

K.O.

> > [mhttpd,ERROR] [history.cxx:97:xread,ERROR] Error: Unexpected end-of-file when 
> > reading file "/home/wagasci-ana/Data/online/210219.hst"

I am puzzled. We can try two things:

a) look inside the "bad" hst file, maybe we can see something. run "mhdump -L 
/home/wagasci-ana/Data/online/210219.hst". If there is anything wrong with the file, it 
will be probably at the end. You can also try to run it without "-L".

b) switch from "midas" history (.hst files) to "FILE" history (mh*.dat files), the 
"FILE" history code is newer and the file format is more robust, with luck it may 
survive whatever trouble is happening in your experiment. This is controlled in ODB 
/Logger/History/XXX/Active (set to "y/n").

c) the output of "mlogger -v" may give us some clue, it usually complains if something 
is not right with definitions of history data.

K.O.

> I see this mhttpd error starting MSL-script: 
> Uncaught (in promise) ReferenceError: m is not defined
> at mhttpd_message (VM2848 mhttpd.js:2304)
> at VM2848 mhttpd.js:2122

your line numbers do not line up with my copy of mhttpd.js. what version of midas 
do you run?

please give me the output of odbedit "ver" command (GIT revision, looks like this: 
IT revision:       Wed Feb 3 11:47:02 2021 -0800 - midas-2020-08-a-84-g78d18b1c on 
branch feature/midas-2020-12).

same info is in the midas "help" page (GIT revision).

to decipher the git revision string:

midas-2020-08-a-84-g78d18b1c means:
is commit 78d18b1c
which is 84 commits after git tag midas-2020-08-a

"on branch feature/midas-2020-12" confirms that I have the midas-2020-12 pre-
release version without having to do all the decoding above.

if you also have "-dirty" it means you changed something in the source code 
 and warranty is voided. (just joking! we can debug even modified midas source 
code)

K.O.

> 
> I have also attached a screen capture of the output.
> 

so the error is gone?


> Thanks for your help as always.
> 
> Isaac
> 
> > K.O.
> > 
> > 
> > > 
> > > Thanks for all the help!
> > > 
> > > Isaac
> > > 
> > > 
> > > 09:24:08.611 2021/02/10 [mhttpd,INFO] Executing script 
> > > "~/ANIS_20210106/scripts/start_daq.sh" from ODB "/Script/Start DAQ"
> > > 
> > > 09:24:13.833 2021/02/10 [Logger,LOG] Program Logger on host localhost started
> > > 
> > > 09:24:28.598 2021/02/10 [fevme,LOG] Program fevme on host localhost started
> > > 
> > > 09:24:33.951 2021/02/10 [mhttpd,INFO] Run #234 started
> > > 
> > > 09:26:30.970 2021/02/10 [mhttpd,ERROR] [midas.cxx:4260:cm_transition_call,ERROR] 
> > > Client "Logger" transition 2 aborted while waiting for client "fevme": 
> > > "/Runinfo/Transition in progress" was cleared
> > > 
> > > 09:26:31.015 2021/02/10 [mhttpd,ERROR] [midas.cxx:5120:cm_transition,ERROR] 
> > > transition STOP aborted: "/Runinfo/Transition in progress" was cleared
> > > 
> > > 09:27:27.270 2021/02/10 [mhttpd,ERROR] 
> > > [system.cxx:4937:ss_recv_net_command,ERROR] timeout receiving network command 
> > > header
> > > 
> > > 09:27:27.270 2021/02/10 [mhttpd,ERROR] [midas.cxx:12262:rpc_client_call,ERROR] 
> > > call to "fevme" on "localhost" RPC "rc_transition": timeout waiting for reply

> 
> I have also attached a screen capture of the output.
> 

so the error is gone?

K.O.

> 
> I have also attached a screen capture of the output.
> 

so the error is gone?

K.O.

So there is no error on run start anymore? To debug the stuck run stop, please use "stop -v" 
to see where it got stuck. You can also play with the RPC timeouts (the connect timeout and 
the response timeout), to make it get "unstuck" quicker. Definitely it should not be stuck 
forever, it should timeout at maximum of "rpc timeout * number of clients". K.O.

since I am implementing a polled equipment, I was curious what is the smallest possible sleep time on current computers.

in current UNIX, there are 2 system calls available for sleeping: select() (with microsecond granularity) and nanosleep() (with nanosecond granularity).

So I wrote a little test program to check it out (progs/test_sleep).

First, Linux result using select(). Typical run on AMD 3700X CPU (4.1 GHz turbo boost) with Ubuntu LTS 20, linux kernel 5.8:

daq13:midas$ ./bin/test_sleep 
sleep      10 loops, 0.100000 sec per loop, 1.000000 sec total,  1003368.855 usec actual, 100336.885 usec actual per loop, oversleep 336.885 usec, 0.3%
sleep     100 loops, 0.010000 sec per loop, 1.000000 sec total,  1008512.020 usec actual, 10085.120 usec actual per loop, oversleep 85.120 usec, 0.9%
sleep    1000 loops, 0.001000 sec per loop, 1.000000 sec total,  1062137.842 usec actual, 1062.138 usec actual per loop, oversleep 62.138 usec, 6.2%
sleep   10000 loops, 0.000100 sec per loop, 1.000000 sec total,  1528650.999 usec actual, 152.865 usec actual per loop, oversleep 52.865 usec, 52.9%
sleep   99999 loops, 0.000010 sec per loop, 0.999990 sec total,  6250898.123 usec actual, 62.510 usec actual per loop, oversleep 52.510 usec, 525.1%
sleep 1000000 loops, 0.000001 sec per loop, 1.000000 sec total, 54056918.144 usec actual, 54.057 usec actual per loop, oversleep 53.057 usec, 5305.7%
sleep 1000000 loops, 0.000000 sec per loop, 0.100000 sec total,   210875.988 usec actual, 0.211 usec actual per loop, oversleep 0.111 usec, 110.9%
sleep 1000000 loops, 0.000000 sec per loop, 0.010000 sec total,   204804.897 usec actual, 0.205 usec actual per loop, oversleep 0.195 usec, 1948.0%
daq13:midas$ 

How to read this:

First line is 10 sleeps of 100 ms, for a total of 1 sec. this actually sleeps for a bit longer,
average over-sleep is 300 usec out of 100 ms is 0.3%.

Next few lines use progressively shorter sleep, 10 ms, 1 ms and 0.1 ms. over-sleep is consistently around 50-60 usec,
which I conclude to be this linux sleep granularity.

Last two lines try sleep for 0.1 usec and 0.01 usec, resulting in a zero-time sleep of select(),
so we just measure the average time cost of a linux syscall, around 200 ns in this machine.

Going to different machines:

Intel E-2236 (4.8 GHz tutboboost), Ubuntu LTS 20, linux kernel 5.8: over-sleep is 60 usec, zero-sleep is 400 ns.
Intel E-2226G (same, see arc.intel.com), CentOS-7, linux kernel 3.10: over-sleep is 60 usec, zero-sleep is 600 ns.
VME processor (2 GHz Intel T7400), Ubuntu 20, linux kernel 5.8: over-sleep is 60 usec, zero-sleep is 1700 ns.

This is pretty consistent, select() over-sleep is 60 usec on all hardware, zero-sleep tracks CPU GHz ratings.

Next, MacOS result, MacBookAir2020, MacOS 10.15.7, CPU 1.2 GHz i7-1060G7:

4ed0:midas olchansk$ ./bin/test_sleep 
sleep      10 loops, 0.100000 sec per loop, 1.000000 sec total,  1031108.856 usec actual, 103110.886 usec actual per loop, oversleep 3110.886 usec, 3.1%
sleep     100 loops, 0.010000 sec per loop, 1.000000 sec total,  1091104.984 usec actual, 10911.050 usec actual per loop, oversleep 911.050 usec, 9.1%
sleep    1000 loops, 0.001000 sec per loop, 1.000000 sec total,  1270800.829 usec actual, 1270.801 usec actual per loop, oversleep 270.801 usec, 27.1%
sleep   10000 loops, 0.000100 sec per loop, 1.000000 sec total,  1370345.116 usec actual, 137.035 usec actual per loop, oversleep 37.035 usec, 37.0%
sleep   99999 loops, 0.000010 sec per loop, 0.999990 sec total,  1706473.112 usec actual, 17.065 usec actual per loop, oversleep 7.065 usec, 70.6%
sleep 1000000 loops, 0.000001 sec per loop, 1.000000 sec total,  5150341.034 usec actual, 5.150 usec actual per loop, oversleep 4.150 usec, 415.0%
sleep 1000000 loops, 0.000000 sec per loop, 0.100000 sec total,   595654.011 usec actual, 0.596 usec actual per loop, oversleep 0.496 usec, 495.7%
sleep 1000000 loops, 0.000000 sec per loop, 0.010000 sec total,   591560.125 usec actual, 0.592 usec actual per loop, oversleep 0.582 usec, 5815.6%
4ed0:midas olchansk$ 

things are quite different here, OS is Mach microkernel with an oldish FreeBSD UNIX single-server (from NextSTEP),
so the sleep granularity is different, better than linux. zero-sleep still measures the syscall time, 600 ns on this machine.

Next we measure the same using the nansleep() syscall.

daq13:midas$ ./bin/test_sleep 
sleep      10 loops, 0.100000 sec per loop, 1.000000 sec total,  1004133.940 usec actual, 100413.394 usec actual per loop, oversleep 413.394 usec, 0.4%
sleep     100 loops, 0.010000 sec per loop, 1.000000 sec total,  1046117.067 usec actual, 10461.171 usec actual per loop, oversleep 461.171 usec, 4.6%
sleep    1000 loops, 0.001000 sec per loop, 1.000000 sec total,  1096894.979 usec actual, 1096.895 usec actual per loop, oversleep 96.895 usec, 9.7%
sleep   10000 loops, 0.000100 sec per loop, 1.000000 sec total,  1526744.843 usec actual, 152.674 usec actual per loop, oversleep 52.674 usec, 52.7%
sleep   99999 loops, 0.000010 sec per loop, 0.999990 sec total,  6250154.018 usec actual, 62.502 usec actual per loop, oversleep 52.502 usec, 525.0%
sleep 1000000 loops, 0.000001 sec per loop, 1.000000 sec total, 53344123.125 usec actual, 53.344 usec actual per loop, oversleep 52.344 usec, 5234.4%
sleep 1000000 loops, 0.000000 sec per loop, 0.100000 sec total, 52641665.936 usec actual, 52.642 usec actual per loop, oversleep 52.542 usec, 52541.7%
sleep 1000000 loops, 0.000000 sec per loop, 0.010000 sec total, 52637501.001 usec actual, 52.638 usec actual per loop, oversleep 52.628 usec, 526275.0%
daq13:midas$ 

Here everything is simple. sleep longer than 1000 usec works the same as select(), sleep for shorter than 100 usec sleeps for 52 usec, regardless of what 
we ask for.

MacOS does no better, long sleeps are same as select(), sleeps is 1 usec or less sleep for too long. no improvement over select().

4ed0:midas olchansk$ ./bin/test_sleep 
sleep      10 loops, 0.100000 sec per loop, 1.000000 sec total,  1023327.827 usec actual, 102332.783 usec actual per loop, oversleep 2332.783 usec, 2.3%
sleep     100 loops, 0.010000 sec per loop, 1.000000 sec total,  1130330.086 usec actual, 11303.301 usec actual per loop, oversleep 1303.301 usec, 13.0%
sleep    1000 loops, 0.001000 sec per loop, 1.000000 sec total,  1333846.807 usec actual, 1333.847 usec actual per loop, oversleep 333.847 usec, 33.4%
sleep   10000 loops, 0.000100 sec per loop, 1.000000 sec total,  1402330.160 usec actual, 140.233 usec actual per loop, oversleep 40.233 usec, 40.2%
sleep   99999 loops, 0.000010 sec per loop, 0.999990 sec total,  2034706.831 usec actual, 20.347 usec actual per loop, oversleep 10.347 usec, 103.5%
sleep 1000000 loops, 0.000001 sec per loop, 1.000000 sec total,  6646192.074 usec actual, 6.646 usec actual per loop, oversleep 5.646 usec, 564.6%
sleep 1000000 loops, 0.000000 sec per loop, 0.100000 sec total,  7556284.189 usec actual, 7.556 usec actual per loop, oversleep 7.456 usec, 7456.3%
sleep 1000000 loops, 0.000000 sec per loop, 0.010000 sec total, 15720005.035 usec actual, 15.720 usec actual per loop, oversleep 15.710 usec, 157100.1%
4ed0:midas olchansk$ 

On Linux, strace tells us that the actual syscall behind nanosleep() is this:
clock_nanosleep(CLOCK_REALTIME, 0, {tv_sec=0, tv_nsec=10000}, 0x7fffc159e200) = 0

Let's try it directly... result is the same.
Let's try it with CLOCK_MONOTONIC... result is the same.

The man page of clock_nanosleep() specifies that this syscall always suspends the calling thread,
so what we see here is the Linux scheduler tick size.

Bottom line.

On current linux, shortest sleep is around 100 usec both select() and nanosleep().
On MacOS, shortest sleep is down to 5 usec using select(), but I cannot tell if CPU sleeps or busy-loops.

select() is still the best syscall for sleeping.

K.O.

> Why do you need that?

UNIX/POSIX advertises functions for sleeping in microseconds and nanoseconds,
for sure it is interesting to know what they actually do and what happens
when you ask them to sleep for 1 microsecond or 1 nanosecond.

To sleep or not to sleep that is a question.

But if I do decide to sleep, and I call the sleep function, I want to know what actually happens.

Now I do and I share it with all.

On current Linux, shortest sleep is around 60 usec. select() with sleep
shorter than that will not sleep at all, nanosleep() will always sleep for
the shortest amount.

P.S. For fans of interrupts ("because they are fast"), sleep waiting for interrupt
probably has same latency/granularity as above (60 usec), so if I drive a DMA engine
and I except the DMA transfer to complete under 60 usec, I should use a busy loop
to poll the "DMA done" bit instead of going to sleep and wait for the DMA interrupt.

K.O.

> 
> I am currently trying to access a ROOT file produced by manalyzer. By calling JSROOT.openFile("MIDAS_DOMAIN/outputRUN.root"). I can download the rootfile via MIDAS_DOMAIN/outputRUN.root. Using JSROOT.openFile results in an 501 error, 
> since the request feature is not provided. Using a simple API and uploading outputRUN.root there worked fine (when the run finised). 
> 
> Is there a way to use JSROOT.openFile with the current analyzed root file in Midas (so during the run)? I know that one can access histograms of the THttpServer via JSON but I need to get the full root tree.
> 

Good questions. Right now in manalyzer I do not do anything more than starting the ROOT web server (so whatever
they support should work) and providing two "standard" location: one in the output file for histograms
and other permanent output and one in memory for transient objects, such as waveform plots, etc.

At some point I would like to provide a function to "get" TAFlowEvent objects so you can do things
like event displays in javascript. But I need a c++ to json serializer and standard c++ does not have it.
So I will have to use the clang serializer (also used by ROOT) and it will take me a few days
to figure it out.

Back to "openFile".

If you figure out the missing bits that need to be added to our code,
please post them here or submit them as a pull request or a bug report in bitbucket.

Also it would be good if you can provide a code example of "openFile" working elsewhere
but not with manalyzer, if I can run it, maybe I can figure out what's missing. But lacking
some example code, there is nothing for me to hack at.

K.O.

> It does not get stuck if I run my DAQ using the odbedit commands (start/stop).

Interesting. Run start/stop from odbedit works but from mhttpd gets stuck.

I think they do not run the transition quite the same way. mhttpd uses the multithreaded transition.

So we can debug this using the "mtransition" program. Try:

- mtransition -v -d 1 START/STOP -- this should be same as odbedit
- mtransition -m -v -d 1 START/STOP -- this should be same as mhttpd

The "-v" and "-d 1" flags should cause lots of output, for failed transitions,
cut-and-paste it all into this elog here, should give us plenty of meat to debug.

K.O.

well, if this is something in ROOT, perhaps you can pursue it with the ROOT crowd,
they are quite friendly.

on my side, if all you need is to pull event data banks, this is easy to add
in mhttpd.

the jsonrpc request will look something like this:

get_event {
"buffer":"system",
"get_type":"GET_LATEST", (or whatever bm_receive_event() can do)
"include_banks":["AAAA","BBBB"],
"exclude_banks":["CCCC","DDDD"]
}

and return something like this:

event {
"header":{"event_id":1,...},
"banks":{
"AAAA":[1,2,3,4],
"BBBB":NULL (you asked for it, so you always get it, but it is NULL if bank does not exist)
}
}

would this work for what you are doing?

(this is not good enough if data has to be pre-digested by c++ analysis in rootana)

K.O.

> We have to request of a 64-bit integer data type to be included in MIDAS banks.
> Since 64-bit integers are on some systems "long" and on other systems "long long",
> I decided to create the two new data types
> 
> TID_INT64
> TID_UINT64
> 

These 64-bit data types do not work with ODB and they do not work with the MIDAS history.

As of commits on 30 March 2021, mlogger will refuse to write them to the history and 
db_create_key() will refuse to create them in ODB.

Why these limitations:

a1) all reading of history is done using the "double" data type, IEEE-754 double precision 
floating point numbers have around 53 bits of precision and are too small to represent all 
possible values of 64-bit integers.
a2) SQL, SQLite and FILE history know nothing about reading and writing 64-bit integer data 
types (this should be easy to fix, as long as MySQL/MariaDB and PostgresQL support it)

b1) in ODB, odbedit and mhttd web pages do not display INT64/UINT64/QWORD data
b2) ODB save and restore from odb, xml and json formats most likely does not work for these 
data types

Fixing all this is possible, with a medium amount of work. As long as somebody needs it. 
Display of INT64/UINT64/QWORD on history plots will probably forever be truncated to 
"double" precision.

K.O.