Dear experts,
    we have a problem when trying to run a MIDAS DAQ which worked in the past on the same PC (but on a different
network). We get the following error messages when starting a new run:

Wed Apr 26 23:03:12 2017 [mhttpd,ERROR] [midas.c:9106:rpc_client_connect,ERROR] cannot connect to host "scar
lett", port 44858: connect() returned -1, errno 113 (No route to host)
Wed Apr 26 23:03:12 2017 [mhttpd,ERROR] [midas.c:3539:cm_transition_call,ERROR] cannot connect to client "Lo
gger" on host scarlett, port 44858, status 503

(scarlett is indeed the hostname of the PC). The error occurs even if the PC is disconnected from the network.

Any suggestion?

Best Regards,
        Francesco

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

After a quick discussion with Konstantin, I changed these strings to a length of 256 chars 
(MAX_STRING_LENGTH). Actually all changes I had to made was on code introduced by KO, so I hope I 
did everything correctly. He should carefully check my changes (actually I would have preferred if he 
could change his code himself...).

I agree with KO that the preferred format for saving the ODB should be JSON, but there might be 
experiments with have some old ODB dumps in other formats, so we should not remove the possibility to 
read those formats back.

Stefan

> ODB name lengths (the name of a key) are limited to 256 characters, the length of strings in the ODB should NOT be limited.

Right, I was not ever aware of such limitation until I just now looked at the .odb and .xml writing code. Definitely string length
is truncated to MAX_STRING_LENGTH on writing, chokes or truncates on reading.

The new json reader/writer handles overlength strings correctly. I would say we should deprecate the old formats and go forward
with json. Most current software can work with json data much easier than xml or custom .odb.

> I see now that db_paste & co. is hopelessly broken. To fix it, everything should be changed to std::string which is in my opinion 
> the only 'clean' solution. That would also remove the cumbersome strlcpy and strlcat.

Yes, that's the code for reading .odb format.

>
> But looking at odb.c, replacing everything with std::string would probably take a brave programmer a couple of weeks. Not sure if we should dive into that adventure right now.
>

I agree. Too much of an adventure.

Simpler solution could be add a db_get_data(), db_get_value() that allocates a data buffer of correct size (user has to remember to free it).

> a) The strings "CSS File", "Sqlite dir" etc. reported below get reduced to 256 characters (MAX_STRING_LENGTH).

We should fix the inconsistency, my vote is it should be either MAX_STRING_LENGTH or PATH_MAX (from limits.h).

K.O.

> > Fixed a small buglet, now saving and reloading odb in the old ".odb" format will silently truncate all overlong strings to 256 bytes. (I think it always did that).
> 
> Not sure that we want that. There might be cases where people want to store long strings. I would remove the truncation completely when saving .odb or .xml files, and fix the load routines to 
> deal with overlong strings.
> 

Since I just looked at the code for reading/writing .odb format, I see that it uses fixed size buffer for reading lines from a file,
currently 2*MAX_STRING_LENGTH). I am not in the mood to rewrite and retest all that code. Never looked at the xml reader,
probably has same problem (xml writer truncates long strings via truncation in db_sprintf()).

Since we already have the json odb reader/writer that handles unlimited string length correctly (also handles unicode and
unusual odb names), perhaps we should make json as the default and be done with it.

K.O.

> Fixed a small buglet, now saving and reloading odb in the old ".odb" format will silently truncate all overlong strings to 256 bytes. (I think it always did that).

Not sure that we want that. There might be cases where people want to store long strings. I would remove the truncation completely when saving .odb or .xml files, and fix the load routines to 
deal with overlong strings.

Stefan

ODB name lengths (the name of a key) are limited to 256 characters, the length of strings in the ODB should NOT be limited. At some point we wanted to have complete web pages inside the ODB, 
which for sure are longer than 256 characters. While this was the idea, I see now that db_paste & co. is hopelessly broken. To fix it, everything should be changed to std::string which is in my opinion 
the only 'clean' solution. That would also remove the cumbersome strlcpy and strlcat.

But looking at odb.c, replacing everything with std::string would probably take a brave programmer a couple of weeks. Not sure if we should dive into that adventure right now. The quick fix would be:

a) The strings "CSS File", "Sqlite dir" etc. reported below get reduced to 256 characters (MAX_STRING_LENGTH). The value of 256 characters came from the file system limitation in linux (some many 
years ago), where a full path of a file could not exceed 256 characters. Not sure if this limit is still valid today, but having all file names in the ODB limited to 256 characters is maybe not a bad idea 
anyhow (who wants to type in file names with more than 256 characters ???).

b) Change the max string length in db_paste to 1024 to cover the few exceptions above.


If we go with a), KO has to change his ODB file names, in case of b) I can do the change.

So what is your opinion?

Best regards,
Stefan

> > 
> > I shall check on the use of MAX_STRING_LENGTH at least in odb itself...
> > 
> 
> Ok, I looked at the use of MAX_STRING_LENGTH in ODB (odb.c):
> 
> a) it is not used in any critical places for the database itself, so it is not a limit on maximum length of TID_STRING data. good.
> b) it is used in the code for saving/loading odb from .odb files (old format), not sure how it works against overlong strings, but probably 
> truncates/corrupts/crashes.
> c) it is used in the code for saving odb to odb.xml files. Overlong strings are truncated (I added a message about it).
> d) code for loading/saving to json files handles overlong strings okey.
> e) odbedit "ls" truncates overlong strings, mhttpd has some oddities against overlong strings.
> f) db_sprintf() truncates string text to MAX_STRING_LENGTH to avoid output buffer overflow (should use db_snprintf() instead).
> 
> Conclusion, overlong strings should be okey, but do not use the old .odb and .xml save files. (mlogger saves odb to output .mid file in xml 
> format, we should switch it to use json format).
> 
> > > 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)
> 
> So these should not cause any corruption or problem unless actual content length exceeds 255 bytes,
> even then they are okey if odb is only saved and loaded into json files.
> 
> > > 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.
> 
> this is in db_check_record(), where it compares odb content with user-supplied data descriptions (there is no system-supplied
> data descriptions with strings longer than MAX_STRING_LENGTH).
> 
> so I think what happened is you created a data structure with overlong strings, passed it to db_paste() or something,
> db_check_record() complained about it, and db_paste() corrupted memory.
> 
> > > 
> > > 2) After this reload, essentially nothing is working anymore. Any client I tried to start just crashed.
> > > 
> 
> Somebody corrupted some shared memory, most likely it was db_paste() corrupted odb shared memory.
> 
> K.O.

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. 

> > 
> > I shall check on the use of MAX_STRING_LENGTH at least in odb itself...
> > 
> 
> Ok, I looked at the use of MAX_STRING_LENGTH in ODB (odb.c):
> 

Fixed a small buglet, now saving and reloading odb in the old ".odb" format will silently truncate all overlong strings to 256 bytes. (I think it always did that).

K.O.

> 
> I shall check on the use of MAX_STRING_LENGTH at least in odb itself...
> 

Ok, I looked at the use of MAX_STRING_LENGTH in ODB (odb.c):

a) it is not used in any critical places for the database itself, so it is not a limit on maximum length of TID_STRING data. good.
b) it is used in the code for saving/loading odb from .odb files (old format), not sure how it works against overlong strings, but probably 
truncates/corrupts/crashes.
c) it is used in the code for saving odb to odb.xml files. Overlong strings are truncated (I added a message about it).
d) code for loading/saving to json files handles overlong strings okey.
e) odbedit "ls" truncates overlong strings, mhttpd has some oddities against overlong strings.
f) db_sprintf() truncates string text to MAX_STRING_LENGTH to avoid output buffer overflow (should use db_snprintf() instead).

Conclusion, overlong strings should be okey, but do not use the old .odb and .xml save files. (mlogger saves odb to output .mid file in xml 
format, we should switch it to use json format).

> > 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)

So these should not cause any corruption or problem unless actual content length exceeds 255 bytes,
even then they are okey if odb is only saved and loaded into json files.

> > 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.

this is in db_check_record(), where it compares odb content with user-supplied data descriptions (there is no system-supplied
data descriptions with strings longer than MAX_STRING_LENGTH).

so I think what happened is you created a data structure with overlong strings, passed it to db_paste() or something,
db_check_record() complained about it, and db_paste() corrupted memory.

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

Somebody corrupted some shared memory, most likely it was db_paste() corrupted odb shared memory.

K.O.

> 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)
> 

I am puzzled. The crash is at the very end of everything (save odb shared memory to odb.shm),
does the run actually stop, or the crash is before the run is fully stopped? (I guess if you want
to run more odbedit commands after stopping the run, so you care about not crashing).

K.O.

> For an unknown reason, Logger died few days ago while writing the history. The
> file mhf_1489577446_20170315_system.dat was created, but was empty.

I ran into same problem installing new midas in the alpha experiment at cern. It should be fixed now:
https://bitbucket.org/tmidas/midas/commits/788021d9cb39a348a40e36f1b35b1440e06aa744

K.O.

> 
> When trying to restart Logger, I would get a seg fault without any special error
> message.
> 
> I tracked the issue to the "read_file_schema" function in history_schema.cxx
> 
> * L4731, a pointer to HsFileSchema *s is declared.
> * L4747, We enter a while(1) loop.
> * L4749, get char on the filename.
> In our case, the file was empty, so the variable "b" gets NULL and the loop breaks.
> 
> Problem: the memory allocation for "s" is later in the loop, L4768.
> Upon exiting the loop, L4854, we try to access record_size on a NULL pointer ==>
> SegFault. 
> 
> It would be nice to at least have a message before breaking the loop...

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

I prefer that bugs be reported on this forum here. Most bugs affect every midas user, so best to notify the 
whole community.

Bitbucket have a nice bug tracking system, but there is a couple of problems:
a) only a couple of people see the bug reports for midas, minimizing probability of fix.
b) bug reports on bitbucket stay on bitbucket, we do not have backups and archives
of bug reports, if tomorrow bitbucket goes belly-up, our bug database goes poof! with them.
c) I can search the bug report on this forum using "grep" (i am sure there is a "find" button
on the bitbucket web page and it finds what I am looking for right away).

So if you have a bug report that others should know about (i.e. the "+" button on the status page does 
not work), I say use this forum.

If you have a bug that you think is unique to you, not interesting to others (i.e. my midas crashes when I 
do X), file it on bitbucket. If you see no activity on the bitbucket for a week or two, repost it here.

K.O.

> > > 
> > > We have recently been experiencing a lot of lag with our midas control webpage,
> > > which is making it very frustrating to use. Has anyone experienced this, and do
> > > you have any advice to speed it up? Are there particular web browsers that work
> > > better than others, or certain settings that can make respond more quickly?
> > > 

Wes, you provided excessive information. Who is "we", what is your location (internet in africa is different from internet in canada),
what is your computer (rpi3 is different from mac mini), what is your os (fedora-1 is different from centos-7), what
is your browser (netscape is different from google-chrome).

As to "what browser should work", on MacOS, google-chrome and firefox should be ok (that's what I test), on Linux,
stock firefox (usually an oldish esr version) should work, on el7 and ubuntu google-chrome works. On windows, google-chrome
and firefox should be ok. microsoft browsers probably not ok (no testing). cellphone browsers also not tested (but google-chrome and firefox 
should be ok).

K.O.

> > Hi everyone, 
> > 
> > We have recently been experiencing a lot of lag with our midas control webpage,
> > which is making it very frustrating to use. Has anyone experienced this, and do
> > you have any advice to speed it up? Are there particular web browsers that work
> > better than others, or certain settings that can make respond more quickly?
> > 
> > Thanks!
> > Wes
> 
> We saw this happening as well. In our case, we could track this down to mhttpd
> taking a lot of CPU. A kill/restart of mhttpd is usually doing the trick (without
> disturbing data taking). We did not find an obvious reason for this happening.

One place where mhttpd can be stalled (and even go into infornite loop) is making history plots.

If you ask for a history plot of 10 variables across 1 year, nobody can access any midas web page
until mhttpd finishes grinding through the history data. (with the old .hst history format is was exceedingly 
slow, with the new "file" format, it is pretty quick, but everybody still has to wait). If you leave this page 
open, it will autorefresh every so many minutes ensuring continuing delays for other mhttpd users.

The other place for stalling mhttpd was in the run transitions (mhttpd was unresponsive while executing a 
run transition), this was fixed by the multithreaded transitions.

To fix the unresponsive history requests, you can try to setup a separate "history mhttpd", run a second 
mhttpd on a different port (with "-H" if desired), put this URL of this mhttpd in ODB "/history/url". (if you 
are using my instructions for setting up the apache httpd proxy, you can see provisions for this. 
/history/url will be set to "https://proxy.host.net/history/").

If neither of the above, there is the usual culprits of bad networking somewhere, etc.

Best way to test if delays are in midas or elsewhere is to stand in front of your midas computer, run a 
current version of google-chrome or firefox right on it, there should be no delays.

K.O.

> > 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)
> > 


I am quite puzzled by this situation. We have seen the above error before, tried to track it down, failed. I was 
always thinking this is some kind of strange size mismatch between odb size and shared memory size and 
shared memory save file odb.shm size.

Now with your information, it looks like it is memory corruption.

I always thought there is no length limit to odb strings, except for the odb api problem where you have to 
know the maximum string length for db_get_value() & co otherwise long strings will be corrupted. Today
nobody uses fixed size buffers, either db_get_value() allocates the string of correct size (replacing buffer
overflow errors with memory leak errors), or return std::string.

I shall check on the use of MAX_STRING_SIZE at least in odb itself...

The default value 256 seems to be too small for today's use. (if you want to store json data, web page 
fragments, etc).


K.O.




> > 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'd liked very much the possibility to hide away Equipment on the main page. It
> > > is also nice to have the '+' to get it quickly back when needed. However, this
> > > seems not to work anymore (git c9d9d604803). Is this a feature or something went
> > > wrong?
> > 
> > The expansion of the equipment list is handled by a Cookie ("expeq" being 1 or 0). When Konstantin 
> > implemented the mongoose server instead of the internal mhttp server, he neglected to evaluate 
> > this cookie. I fixed this now (also renamed the cookie to "midas_expeq") in the current development 
> > branch. Please check if it's working.
> > 
> > Stefan
> 
> Tested it on two machines and expansion is back and working! Thanks a lot!
> 

Confirmed fixed. Thanks. Not sure how this got lost.

K.O.

> In my opinion this makes sense. If KO agrees, you should commit your change.

Please go ahead (sorry for slow reply). I have no idea what this change does. A screenshot of "before" 
and "after" would be nice. The reason I ask is:

note that I am getting rid of the css hell in mhttpd.css. all the new pages will be using the simplified css 
rules in midas.css.

the main change is: the new css rules only change the appearance of html elements that request the 
"midas look" and one can still use the normal html formatting if desired. The old css changed all (and I 
do mean *all*) html elements, making it impossible to write custom web pages using common examples 
from the web - the insane formatting from mhttpd.css was applied to everything indiscriminantly, i.e. h1, 
h2, h3 all look the same.

K.O.


> 
> Stefan
> 
> > We use the customHeader to display some useful information. Currently I do not
> > like its style. What about to make it more alike the footer?
> > 
> > I just changed in resources/mhttpd.css
> > 
> > diff --git a/resources/mhttpd.css b/resources/mhttpd.css
> > index fb0070d..f3264c8 100644
> > --- a/resources/mhttpd.css
> > +++ b/resources/mhttpd.css
> > @@ -280,6 +280,15 @@ table.headerTable td{
> >         border: none;
> >  }
> >  
> > +div.headerDiv{
> > +       background-color: #6F6F6F;
> > +       text-align: center;
> > +       padding:1em;
> > +       color:#EEEEEE;
> > +       border-bottom:1px solid #000000;
> > +       height:3em;
> > +}
> > +
> >  div.footerDiv{
> >         background-color: #808080;
> >         text-align: center;
> > 
> > and
> > 
> > diff --git a/resources/mhttpd.js b/resources/mhttpd.js
> > index de8bc6c..972c261 100644
> > --- a/resources/mhttpd.js
> > +++ b/resources/mhttpd.js
> > @@ -172,7 +172,7 @@ function mhttpd_goto_page(page) {
> >  
> >  function mhttpd_navigation_bar(current_page, path)
> >  {
> > -   document.write("<div id=\"customHeader\">\n");
> > +   document.write("<div class=\"headerDiv\" id=\"customHeader\">\n");
> >     document.write("</div>\n");
> >  
> >     document.write("<div class=\"mnavcss\">\n");
> > 
> > What do you think?

> Hi everyone, 
> 
> We have recently been experiencing a lot of lag with our midas control webpage,
> which is making it very frustrating to use. Has anyone experienced this, and do
> you have any advice to speed it up? Are there particular web browsers that work
> better than others, or certain settings that can make respond more quickly?
> 
> Thanks!
> Wes

We saw this happening as well. In our case, we could track this down to mhttpd
taking a lot of CPU. A kill/restart of mhttpd is usually doing the trick (without
disturbing data taking). We did not find an obvious reason for this happening.

Hi everyone, 

We have recently been experiencing a lot of lag with our midas control webpage,
which is making it very frustrating to use. Has anyone experienced this, and do
you have any advice to speed it up? Are there particular web browsers that work
better than others, or certain settings that can make respond more quickly?

Thanks!
Wes

> 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.