Asia catch`up with U.S.exchanges

Thanks Sonny,

I could imagine that u.s. exchanges are more advanced in terms of trading rules, operational complexity, matching engine, order types … because presumably u.s. exchanges have more volume and more variations in securities. It’s like a bigger, older hospital is more sophisticated since it has treated many more patients.

On the other hand, I read more than once (over the last 7 years) that in terms of pure latency the bigger exchanges in the U.S. are often slower, but only moderately, so everything still works fine. I don’t know any capacity concerns on the horizon. Some of the smaller exchanges in Asia were aggressive to beat the bigger exchanges on latency. World #1 fastest exchange is now Bombay.

Good sharing.

Victor

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bash script show`trap,read,waiting for gdb-attach

#1 valuable feature is the wait for gdb to attach, before unleashing the data producer.

#2 signal trap. I don’t have to remember to kill off background processes.

# Better source this script. One known benefit -- q(jobs) command would now work

sigtrap(){
  echo Interrupted
  kill %1 %2 %3 %4 # q(jobs) can show the process %1 %2 etc
  set -x
  trap - INT
  trap # show active signal traps
  sleep 1
  jobs
  set +x
}

set +x
ps4 # my alias to show relevant processes
echo -e "\njobs:"
jobs
echo -en "\nContinue? [y/any_other_key] "
unset REPLY; read $REPLY
[ "$REPLY" = "y" ] || return

trap "sigtrap" INT # not sure what would happen to the current cmd and to the shell

base=/home/vtan//repo/tp/plugins/xtap/nysemkt_integrated_parser/
pushd $base
make NO_COMPILE=1 || return
echo '---------------------'
popd
/bin/rm --verbose $base/*_vtan.*log /home/vtan/nx_parser/working/CSMIParser_StaticDataMap.dat

set -x

#If our parser is a client to rebus server, then run s2o as a fake rebus server:
s2o 40490|tee $base/2rebus_vtan.bin.log | decript2 ctf -c $base/etc/cdd.cfg > $base/2rebus_vtan.txt.log 2>&1 &

#if our parser is a server outputing rtsd to VAP, then run c2o as a fake client:
c2o localhost 40492|tee $base/rtsd_vtan.bin.log | decript2 ctf -c $base/etc/cdd.cfg > $base/rtsd_vtan.txt.log 2>&1 &

# run a local xtap process:
$base/shared/tp_xtap/bin/xtap -c $base/etc/test_replay.cfg > $base/xtap_vtan.txt.log 2>&1 &
#sleep 3; echo -en "\n\n\nDebugger ready? Start pbflow? [y/any_other_key] "
#unset REPLY; read $REPLY; [ "$REPLY" = "y" ] || return

# playback some historical data, on a multicast port:
pbflow -r999 ~/captured/ax/arcabookxdp1-primary 224.0.0.7:40491 &

set +x
jobs
trap

c++variables: !always objects

Every variable that holds data is an object. Objects are created either with static duration (by defining rather than declaring the variable), with automatic duration (declaration alone) or with dynamic duration via new/malloc().

That’s the short version. Here’s the long version:

– stack variables (including function parameters) – each stack object has a name (multiple possible?) i.e. the host variable, like a door plate on the memory location. When you clone a stack variable you get a cloned object. (Advanced — You could create a reference to the stack object, when you pass the host variable by-reference into a function. You should never return a stack variable by reference)

– heap objects – have no name no “host variable” no door plate. They only have addresses. The address could be saved in a “pointer object”, which is a can of worm. (In many cases, the address is passed around without any pointer object)

– non-local static objects — are more tricky. The variable(i.e. name) is there after you declare it, but it is a door plate without a door. It only becomes a door plate on a storage location when you allocate storage i.e. create the object by “defining” the host variable. There’s a one-definition-rule for static objects, so most of the time you first declare the variable without defining it, then you define it elsewhere. See https://bintanvictor.wordpress.com/2017/05/30/declared-but-undefined-variable-in-c/

good article: epoll() illustrated n contrasted^q(SELECT)

Compared to select(), the newer linux system call epoll() is designed to be more performant.

Ticker Plant uses epoll. No select() at all.

https://banu.com/blog/2/how-to-use-epoll-a-complete-example-in-c/ is a nice article with sample code of a TCP server.

  • main() function with an event loop
  • bind()
  • listen()
  • accept()

I think this toy program is more educational than a real-world epoll server with thousands of lines of code.

No sample client but I think a standard TCP client will do.

example with/without extern-C

---- dummy8.c ----
#include <stdio.h> //without this "test", we could be using c++ compiler unknowingly 😦
int cfunc(){ return 123; }
---- dummy9.cpp ----
#include <iostream>
extern "C" // Try removing this line and see the difference
  int cfunc();
int main(){std::cout << cfunc() <<std::endl; }

Above is a complete example of a c++ application using a pre-compiled C function. It shows the need for extern-C.

/bin/rm -v *.*o *.out

gcc -v -x c -c dummy8.c # Without the -x c, we would end up with c++ compiler 😦

g++ -v dummy8.o dummy9.cpp  # link the dummy8.o into executable

./a.out

So that’s how to compile and run it. Note you need both a c compiler and a c++ compiler. If you only use a c++ compiler, then you won’t have the pre-compiled C code. You can still make the code work, but you won’t be mixing C and C++ and you won’t need extern-C.

My goal is not merely “make the code work”. It’s very easy to make the code work if you have full source code. You won’t need extern-C. You have a simpler alternative — compile every source file in c++ after trivial adjustments to #include.

c++dynamicLoading^dynamicLinking^staticLinking, basics

https://en.wikipedia.org/wiki/Dynamic_loading

*.so and *.dll files are libraries for dynamic linking.
*.a and *.lib files are libraries for static linking.

“Dynamic loading” allows an executable to start up in the absence of these libraries and integrate them at run time, rather than at link time.

You use dlopen(“path/to/some.so”) system call. In Windows it’s LoadLibrary(“path/to/some.dll”)