when I try to stop a run from odbedit I get a core dump.

[ODBEdit1,INFO] Run #31 stopped odbedit: src/system.c:1223: ss_shm_flush:
Assertion `size == mmap_size[handle]' failed. Aborted (core dumped)

midas commit 53af92a5d0...

-----

I checked what happens if I try to stop a run via the mhttpd web-page: this
works! So what is different?

-----

I placed a issue (# 47) on bitbucket as well.

What is the preferred channel to report potential bugs (elog / bitbucket issues)? 

> when I try to stop a run from odbedit I get a core dump.
> 
> [ODBEdit1,INFO] Run #31 stopped odbedit: src/system.c:1223: ss_shm_flush:
> Assertion `size == mmap_size[handle]' failed. Aborted (core dumped)
> 
> midas commit 53af92a5d0...
> 
> -----
> 
> I checked what happens if I try to stop a run via the mhttpd web-page: this
> works! So what is different?
> 
> -----
> 
> I placed a issue (# 47) on bitbucket as well.
> 
> What is the preferred channel to report potential bugs (elog / bitbucket issues)? 

I think I found the problem. Some ODB String values which are **automatically**
generated:

CSS File = STRING : [1024] mhttpd.css
Sqlite dir = STRING : [1024]
History dir = STRING : [1024]
Sound = STRING : [1000] alarm.mp3

are exceeding the MAX_STRING_LENGTH 256 (defined in msystem.h)

It looks as if this screws up quite a bit of the system! When deleting .ODB.SHM and
afterwards try to reload the ODB via a dump I previously made with odbedit, the
following is happening:

1) I get the error message that some strings are too long (exceeding
MAX_STRING_LENGTH). Unfortunately the underlying routine doesn't tell which ODB
variables this is.

2) After this reload, essentially nothing is working anymore. Any client I tried to
start just crashed.

Since it seems that the string length of MAX_STRING_LENGTH is very crucial I would
suggest that db_create_record (or whatever routine is dealing with it) checks for
STRING variables and ensures that they cannot exceed MAX_STRING_LENGTH.

When I shortened in my dump the above variables to MAX_STRING_LENGTH, regenerated the
ODB, also the 'stop' Problem in odbedit is gone.

I stumbled over an oddity which I would like to understand better. Here the
boundaries:
- Enable non-localhost RPC -> y
- Disable RPC hosts check  -> y

1) I am starting a run from ODBedit (start now -v):

07:13:11.272 2017/04/19 [ODBEdit,INFO] Run #26 started

07:13:25.516 2017/04/19 [Logger,LOG] File '/data/max/dlog/lem17_0026.root'
CRC32C checksum: 0x05ca4e7e, 1523383 bytes

On this little test experiment there is not much running, but it already shows
the effect I wanted to understand.

2) I am stopping the run from ODBedit (stop -v):

07:13:25.519 2017/04/19 [ODBEdit,INFO] Run #26 stopped

So, everything looks perfectly fine up to this point.

3) Now the 'strange' thing happens. To any point in time after this, I will stop
ODBEdit which results in the following messages:

07:13:32.335 2017/04/19 [ODBEdit,INFO] Program ODBEdit on host pc7962 stopped

07:13:32.335 2017/04/19 [Logger,ERROR] [midas.c:14079:rpc_server_receive,ERROR]
rpc check ok, abort canceled

This I do NOT understand! It looks as if the Logger (or any other client which
gets the run state transition) thinks that some Client (here ODBEdit) has a
broken connection. At least this is how I understand the comment in midas.c /
rpc_server_receive(). Is something broken in the de-registration from the RPC
server? By the way, all clients where running on the localhost, i.e. no remote
connection used here.

All this only happens if a run transition took place.

Unfortunately I do not understand the system well enough to suggest any fix to
this :-( and hence would appreciate any help. 

A handy feature of the history of the mhttpd is to export the data. However, this 
seems to be broken. It currently only works if the run marker flag is activated by 
fails otherwise.

Description of the problem (starting with 61be7a1):

When starting a new experiment, creating a fresh ODB and than adding the 
directory '/Custom', the mhttpd runs into a problem on RHEL/Fedora, but not on 
Ubuntu and macOS. When trying to open the ODB from within whatever browser I get 
the following error message in the midas message queque:

[mhttpd,ERROR] [mhttpd.cxx:563:rread,ERROR] Cannot read file '/root', read of 
4096 returned -1, errno 21 (Is a directory)

and in the browser I get a popup which tries to save a file called 'root'.

I track this down to the following: in mhttpd, interprete (line 18046) it is 
check if a custom page file exists (ss_file_exist) and if yes, it tries to 'load' 
it. Now, at this stage the variable dec_path contains '/root'.

Here now what goes wrong: ss_file_exist tries to open the given path, and if a 
valid file descriptor is returned it assumes the file exists. This is not 
perfectly correct since it also will get a valid file descriptor is path is an 
accessible directory!

Now for whatever reason, on RHEL/Fedora '/root' will return a valid file 
descriptor, but not on macOS and Ubuntu. Others I haven't tested. A possible fix 
would be to check explicitly if path is a directory and if yes return 0 in 
ss_file_exist (see attached diff).

Perhaps there is cleaner way to deal with this issue?! 

> > In any case, IMO, mhttpd has no business serving the contents of /root,
> > or serving any files outside of the mhttpd user $HOME directory. (but also
> > should not serve files from ~user/.ssh, or any other "secret" files, good
> > luck making a complete axhuastive list of all secret files that should not be
> > served).
> 
> I fully agree with Konstantin. mhttpd should only serve files under certain directories. One is the 
> midas/resources directory, another is the one defined in the ODB under /Custom/Path. I plan to modify 
> mhttpd to only serve these files (and also prevent tricks like putting "../../../" into the URL). This will then 
> also fix Andreas' problem.
> 
> Stefan

Yes, I think this is a good idea as well. But just to make sure that you get the problem: it's not the custom page call by itself! If you currently type e.g. <midas-server>/root it will open the ODB html-page.

There is a bug in the string handling when changing ODB string entries via the
mhttpd (git sha 07dfb83). It truncates the string length in the ODB.

For instance I create a string with length 32 and set it with odbedit to 'a'.
Then the string length stays 32, as expected. If the same is done through the
web-interface, the string length will be truncated to 2.

This can lead to problems if some frontend has a hotlink to a structure
containing this string since it will complain about structure size mismatch. 

> > There is a bug in the string handling when changing ODB string entries via the
> > mhttpd (git sha 07dfb83). It truncates the string length in the ODB.
> > 
> > For instance I create a string with length 32 and set it with odbedit to 'a'.
> > Then the string length stays 32, as expected. If the same is done through the
> > web-interface, the string length will be truncated to 2.
> > 
> > This can lead to problems if some frontend has a hotlink to a structure
> > containing this string since it will complain about structure size mismatch. 
> 
> I know about this problem since last summer. I mentioned it to KO, since it's deep down in his 
> JSONRPC code. We had a long discussion, where he kind of insisted that this is not a bug but a 
> feature. The ODB should store strings with variable lengths, and thus adapt it according to the 
> current string length. This makes some sense, since in the future we plan to put C++ string 
> support for the ODB, where strings have dynamically varying lengths. But this will take a while, so 
> I asked KO to change the truncation of the strings though the web interface, because this breaks 
> many experiments. He did not react so far. Several people complained. Maybe your request will 
> help now.
> 
> Stefan

Well I appreciate the direction towards more C++ string handling, yet it must not break the hotlink
functionality which is very important at many places.

Is there a simple way from the javascript side to check if a fontend is running?
Currently one would need to go through the /System/Client list to find out if a
frontend/client is running. Wouldn't it be nice to have this centralized, either
in the mhttpd.cxx or mhttpd.js part? 

> > Is there a simple way from the javascript side to check if a fontend is running?
> > Currently one would need to go through the /System/Client list to find out if a
> > frontend/client is running. Wouldn't it be nice to have this centralized, either
> > in the mhttpd.cxx or mhttpd.js part? 
> 
> Hi,
> 
> I think that this option already exists with the cm_exist method for the mjsonrpc calls.  For instance, you can use a 
> call like 
> 
> curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","id":null,"method":"cm_exist","params":
> {"name":"Logger"}}' 'http://localhost:8081?mjsonrpc'
> 
> to get the status of the logger program.  There is a description of the cm_exist parameters on this page:
> 
> https://midas.triumf.ca/MidasWiki/index.php/Mjsonrpc

Thanks a lot for the info. I just simply missed it :-|

A feature I always missed (or just missed to find in the docu) is the following:
1) It would be nice to have a command in odbedit which allows to check how full
the ODB currently is.
2) Even more important: I would like to have an ODB routine which allows me to
check the fill level of the ODB, and/or a routine which tells me if I would
create a structure of given size that it still fits in the current ODB or not. 
The use case is that some clients create on the fly ODB entries and I would like
to make sure before hand the ODB's remaining space in order not to crash things
by overfilling the ODB. 

> > A feature I always missed (or just missed to find in the docu) is the following:
> > 1) It would be nice to have a command in odbedit which allows to check how full
> > the ODB currently is.
> > 2) Even more important: I would like to have an ODB routine which allows me to
> > check the fill level of the ODB, and/or a routine which tells me if I would
> > create a structure of given size that it still fits in the current ODB or not. 
> > The use case is that some clients create on the fly ODB entries and I would like
> > to make sure before hand the ODB's remaining space in order not to crash things
> > by overfilling the ODB. 
> 
> If you do "mem" in odbedit, you see the currently free areas, one for the keys themselves, one for 
> the data of the keys. The corresponding C function is db_show_mem. At the moment it outputs the 
> list of free blocks as a long ASCII string, but if necessary I can write a variant which returns the 
> number of free bytes.
> 
> Stefan

Thanks for the info, and yes a variant of db_show_mem returning the number of free bytes would be just
prefect!

For us it would be a handy feature if history data could be requested directly
from a custom page (time range or run based intervals) . Here I am not talking
about history plots but I am talking about recorded time series data. This way
we could easily generate useful graphs. For instance, if we measure the voltage
(constant current) while cooling, we could instantly get the resistance versus
temperature. Often we would like to 'correlate' recorded slow control data.

Is it already possible to extract history data the way suggested?

When using a slowcontrol frontend which operates a device using the multi class
driver the current midas version (ec3225902d6) has the following issue:

There is a row labeled with: All Input Output

So far by clicking e.g. on Input, only the Input related part was displayed, etc.

Currently this leads to the following error message: 

Error: cannot find key LS336/Variables/Input

where LS336 is my DD.

I like the new history system very much, but I stumbled over a couple of issues.
I used the version "Thu Aug 29 08:24:29 2019 +0200 -
midas-2019-06-b-244-gdd6585bb on branch develop":

1) it would be nice to have an option to format the label output (see attachment 1)

2) the background of a history plot is very handy if you only show one measure.
If you have multiple ones (see attachment 2), this is not the case anymore. It
would be nice if the background could be enabled/disabled.

> During my visit at TRIUMF we rewrote the history plotting functionality of
midas. Instead of 
> static GIF images, we have now interactive JavaScript panels where we can
scroll, zoom, 
> inspect values and much more (example is attached). We are now in a state
where this is still 
> work in progress, but already at this stage it might be useful for others to
report any 
> feedback.
> 
> Simply upgrade the the newest develop branch of midas, and you will see two
menu items 
> "OldHistory" which is the old system and "History" which is the new system. In
the new 
> system, you can drag with the mouse to scroll, use the mouse wheel to zoom in
and out the 
> time axis, and hover with your mouse over data points to see its value. If you
zoom out, 
> old data is loaded automatically in the background.
> 
> Following items are planned, but not yet implemented:
> 
> - Printing of run markers as in the old history
> 
> - Delete old data in the buffer to limit memory consumption if the browser
window is 
>    open for very long (weeks)
> 
> - Implement time interval selector (clock icon, select "last day", "last 8
hours" etc.)
> 
> - New settings dialog as a floating dialog box. At the moment, the setting
page of the 
>    old history system is used
> 
> - Export / Printing / Sending to ELOG any history plot
> 
> - Implement a formula for plotting data, such as "y = 12 * (x-14) +32". This
will replace 
>    the old "offset" and "factor" and is more flexible. The formula can be
passed directly 
>    to the JavaScript engine and will be executed on the web page. It should be
also 
>    possible to combine different channels, like the difference of two history
values.
> 
> - Determine the number of digits for variable display from the axis limits.
Like if a value 
>    changes between 520001 and 520002 only, we need more digits than the usual 6.
> 
> Many of these things will be implemented in the next weeks. If you have any
more idea 
> or find some bugs, please report back to me.
> 
> Best,
> Stefan for the midas team

> > 2) the background of a history plot is very handy if you only show one measure.
> > If you have multiple ones (see attachment 2), this is not the case anymore. It
> > would be nice if the background could be enabled/disabled.
> 
> Looking at your plot, even without the background things look messy. Please note
> that you can display only a single curve by double clicking on it (and back with Escape).
> If all curves are on top of each other, you can get them apart a bit by zooming
> in to the vertical axis, then double click. Let ma know if that works for you.

This I found out, yet the attachment here shows another case where it would be useful to be
able to disable the background, namely if you have positive and negative measures in one
plot. Somehow it suggests that CH1 and CH2 show very different values, whereas it is only a
difference in the sign of this variables.

It's not all the important but I would like to mention this is the early stage before
everything is fully frozen.

Our typical use case is that a lot of people are connected to the experiment
having some history tabs open most of the time. Hence, I setup a test system and
connect to it from all kind of systems/browsers. What I see currently quite
often is the error hs_read_arraybuffer (see the attachement).

For firefox 60.8.0esr this can result into a full freeze of the tab and only
closing it is possible.

For chromium based browsers you eventually get a popup informing that it is not
responsive anymore.

The worst though is safari 12.1.2 which not only freezes the tab, but
reproducibly crashes the mhttpd on the server side.

Are there ways to get a log which would document where the problems start?  

> On the mhttpd side, please capture the stack trace from the crash: enable 
> core dumps (ODB "/experiment/enable core dumps" set to "y", after the crash, 
> run "ls -l core.*; gdb mhttpd core.9999") or run mhttpd inside gdb or attach 
> gdb to a running mhttpd (gdb -p 9999). Once in gdb, run "info thr" to list all 
> threads, "thr 0; bt", "thr 1; bt", etc to get stack traces from all threads, only 
> one of them contains the crash (tedious!).
> 
> Email me the stack trace (or post here), in case we want to look at values
> of any variables from the crash, keep the core dump and do not rebuild 
> mhttpd.
> 
> K.O.

here comes the stack trace (only happens when using safari 12.1.2 macOS 10.14.6):

(gdb) thr 1
[Switching to thread 1 (Thread 0x7f57ceffd700 (LWP 3538))]
#0  0x00007f57f29fe377 in raise () from /lib64/libc.so.6
(gdb) bt
#0  0x00007f57f29fe377 in raise () from /lib64/libc.so.6
#1  0x00007f57f29ffa68 in abort () from /lib64/libc.so.6
#2  0x00007f57f330e7d5 in __gnu_cxx::__verbose_terminate_handler() () from
/lib64/libstdc++.so.6
#3  0x00007f57f330c746 in ?? () from /lib64/libstdc++.so.6
#4  0x00007f57f330c773 in std::terminate() () from /lib64/libstdc++.so.6
#5  0x00007f57f330c993 in __cxa_throw () from /lib64/libstdc++.so.6
#6  0x00007f57f330cf2d in operator new(unsigned long) () from /lib64/libstdc++.so.6
#7  0x00007f57f336ba19 in std::string::_Rep::_S_create(unsigned long, unsigned long,
std::allocator<char> const&)
    () from /lib64/libstdc++.so.6
#8  0x00007f57f336c62b in std::string::_Rep::_M_clone(std::allocator<char> const&,
unsigned long) ()
   from /lib64/libstdc++.so.6
#9  0x00007f57f336ccfc in std::basic_string<char, std::char_traits<char>,
std::allocator<char> >::basic_string(std::string const&) () from /lib64/libstdc++.so.6
#10 0x000000000041ce0f in check_digest_auth (hm=hm@entry=0x7f57ceffc520, auth=0x74b060
<auth_mg>)
    at /home/nemu/nemu/tmidas/midas/progs/mhttpd.cxx:17143
#11 0x0000000000452a61 in handle_http_message (msg=0x7f57ceffc520, nc=0x2019ca0,
this=<optimized out>, 
    this=<optimized out>, this=<optimized out>) at
/home/nemu/nemu/tmidas/midas/progs/mhttpd.cxx:17703
#12 handle_http_event_mg (nc=nc@entry=0x2019ca0, ev=ev@entry=100,
ev_data=ev_data@entry=0x7f57ceffc520)
    at /home/nemu/nemu/tmidas/midas/progs/mhttpd.cxx:17753
#13 0x0000000000464c4b in mg_call (nc=nc@entry=0x2019ca0, 
    ev_handler=0x4521f0 <handle_http_event_mg(mg_connection*, int, void*)>, ev=100, 
    ev_data=ev_data@entry=0x7f57ceffc520) at
/home/nemu/nemu/tmidas/midas/progs/mongoose6.cxx:2120
#14 0x000000000046790e in mg_http_call_endpoint_handler (nc=nc@entry=0x2019ca0,
ev=<optimized out>, 
    hm=hm@entry=0x7f57ceffc520) at /home/nemu/nemu/tmidas/midas/progs/mongoose6.cxx:4946
#15 0x0000000000467e3f in mg_http_handler (nc=nc@entry=0x2019ca0, ev=ev@entry=3, 
    ev_data=ev_data@entry=0x7f57ceffcb2c) at
/home/nemu/nemu/tmidas/midas/progs/mongoose6.cxx:5139
#16 0x0000000000464c4b in mg_call (nc=nc@entry=0x2019ca0, 
    ev_handler=0x467a20 <mg_http_handler(mg_connection*, int, void*)>,
ev_handler@entry=0x0, ev=ev@entry=3, 
    ev_data=ev_data@entry=0x7f57ceffcb2c) at
/home/nemu/nemu/tmidas/midas/progs/mongoose6.cxx:2120
#17 0x0000000000464fb7 in mg_recv_common (nc=nc@entry=0x2019ca0,
buf=buf@entry=0x7f57c0000cd0, len=len@entry=279)
    at /home/nemu/nemu/tmidas/midas/progs/mongoose6.cxx:2676
#18 0x00000000004659c8 in mg_if_recv_tcp_cb (len=279, buf=0x7f57c0000cd0, nc=0x2019ca0)
    at /home/nemu/nemu/tmidas/midas/progs/mongoose6.cxx:2680
#19 mg_read_from_socket (conn=0x2019ca0) at
/home/nemu/nemu/tmidas/midas/progs/mongoose6.cxx:3378
#20 mg_mgr_handle_conn (nc=0x2019ca0, fd_flags=1, now=now@entry=1568705761.3290441)
    at /home/nemu/nemu/tmidas/midas/progs/mongoose6.cxx:3511
#21 0x0000000000465ee0 in mg_mgr_poll (mgr=mgr@entry=0x7f57ceffcda0,
timeout_ms=timeout_ms@entry=1000)
    at /home/nemu/nemu/tmidas/midas/progs/mongoose6.cxx:3687
#22 0x0000000000466085 in per_connection_thread_function (param=0x2019ca0)
    at /home/nemu/nemu/tmidas/midas/progs/mongoose6.cxx:3805
#23 0x00007f57f39c7ea5 in start_thread () from /lib64/libpthread.so.0
#24 0x00007f57f2ac68cd in clone () from /lib64/libc.so.6

I am currently testing the new history system on the mhttpd side and stumbled over the following issue: typically our user open a lot of midas web-page tabs and keep them open. With the current version this leads after a night typically to a state where the browser is busy with itself and not reacting anymore.

One important reason seems to be that ALL tabs trying to communicate all the time which is totally unnecessary, since I think a hidden tab should stay in a sleeping mode. 

I was browsing if there is a way to find out if a tab is active or not, and found the following API which exactly does this:

https://developer.mozilla.org/en-US/docs/Web/API/Page_Visibility_API

Furthermore, the simple

document.hidden 

tag, could be used to find out if the page is currently active.

Wouldn't it a good idea to send all midas tabs which are not active into a sleep mode and only reactivate them if they come into focus?

I had a quick look at the JavaScript libs of midas, but I am not quite certain where to best inject this. 

Dear All,

At our experiment we write ROOT files. When starting/stopping runs we get the following error messages:

[Logger,ERROR] [mlogger.cxx:3358:root_write,ERROR] Cannot write system event into ROOT file, event_id 0xffff8000

[Logger,ERROR] [mlogger.cxx:3358:root_write,ERROR] Cannot write system event into ROOT file, event_id 0xffff8001

Looking into the source code I found that log_write (line 4248) sends these Midas System Events (BOR,EOR) to root_write without filtering them. root_write() checks in a first step if it gets such Midas System Events and if yes, moans.

Wouldn't it be better just to filter these events in log_write, before calling root_write, avoiding unnecessary error messages?

Is there something I miss?

Thanks,
  Andreas