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# User API
```eval_rst
.. doxygenfile:: omnitrace/user.h
```
By default, when omnitrace detects any `omnitrace_user_start_*` or `omnitrace_user_stop_*` function, instrumentation
is disabled at start-up -- thus, `omnitrace_user_stop_trace()` is not required at the beginning of main. This is
can be manually controlled via the `OMNITRACE_INIT_ENABLED` environment variable. User-defined regions are always
recorded, regardless of whether whether `omnitrace_user_start_*` or `omnitrace_user_stop_*` has been called.
## Example
### User API Implementation
```cpp
#include <omnitrace/user.h>
#include <atomic>
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <sstream>
#include <thread>
#include <vector>
std :: atomic < long > total { 0 };
long
fib ( long n ) __attribute__ (( noinline ));
void
run ( size_t nitr , long ) __attribute__ (( noinline ));
int
custom_push_region ( const char * name );
namespace
{
int ( * omnitrace_push_region_f )( const char * ) = nullptr ;
}
int
main ( int argc , char ** argv )
{
// get the internal callback to start a user-defined region
omnitrace_user_get_callbacks ( OMNITRACE_USER_REGION , ( void ** ) & omnitrace_push_region_f ,
nullptr );
// assign the custom callback to start a user-defined region
if ( omnitrace_push_region_f )
omnitrace_user_configure ( OMNITRACE_USER_REGION , ( void * ) & custom_push_region ,
nullptr );
omnitrace_user_push_region ( argv [ 0 ]);
omnitrace_user_push_region ( "initialization" );
size_t nthread = std :: min < size_t > ( 16 , std :: thread :: hardware_concurrency ());
size_t nitr = 50000 ;
long nfib = 10 ;
if ( argc > 1 ) nfib = atol ( argv [ 1 ]);
if ( argc > 2 ) nthread = atol ( argv [ 2 ]);
if ( argc > 3 ) nitr = atol ( argv [ 3 ]);
omnitrace_user_pop_region ( "initialization" );
printf ( "[%s] Threads: %zu \n [%s] Iterations: %zu \n [%s] fibonacci(%li)... \n " , argv [ 0 ],
nthread , argv [ 0 ], nitr , argv [ 0 ], nfib );
omnitrace_user_push_region ( "thread_creation" );
std :: vector < std :: thread > threads {};
threads . reserve ( nthread );
// disable instrumentation for child threads
omnitrace_user_stop_thread_trace ();
for ( size_t i = 0 ; i < nthread ; ++ i )
{
size_t _nitr = (( i % 2 ) == 1 ) ? ( nitr - ( 0.1 * nitr )) : ( nitr + ( 0.1 * nitr ));
long _nfib = (( i % 2 ) == 1 ) ? ( nfib - ( 0.1 * nfib )) : ( nfib + ( 0.1 * nfib ));
threads . emplace_back ( & run , _nitr , _nfib );
}
// re-enable instrumentation
omnitrace_user_start_thread_trace ();
omnitrace_user_pop_region ( "thread_creation" );
omnitrace_user_push_region ( "thread_wait" );
for ( auto & itr : threads )
itr . join ();
omnitrace_user_pop_region ( "thread_wait" );
run ( nitr , nfib );
printf ( "[%s] fibonacci(%li) x %lu = %li \n " , argv [ 0 ], nfib , nthread , total . load ());
omnitrace_user_pop_region ( argv [ 0 ]);
return 0 ;
}
long
fib ( long n )
{
return ( n < 2 ) ? n : fib ( n - 1 ) + fib ( n - 2 );
}
#define RUN_LABEL \
std::string{ std::string{ __FUNCTION__ } + "(" + std::to_string(n) + ") x " + \
std::to_string(nitr) } \
.c_str()
void
run ( size_t nitr , long n )
{
omnitrace_user_push_region ( RUN_LABEL );
long local = 0 ;
for ( size_t i = 0 ; i < nitr ; ++ i )
local += fib ( n );
total += local ;
omnitrace_user_pop_region ( RUN_LABEL );
}
int
custom_push_region ( const char * name )
{
printf ( "Pushing custom region :: %s \n " , name );
return ( * omnitrace_push_region_f )( name );
}
```
### User API Output
```console
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$ omnitrace -l --min-instructions= 8 -E custom_push_region -o -- ./user-api
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...
$ export OMNITRACE_USE_TIMEMORY = ON
$ export OMNITRACE_USE_PID = OFF
$ export OMNITRACE_TIME_OUTPUT = OFF
$ export OMNITRACE_OUTPUT_PATH = omnitrace-example-output
$ ./user-api.inst 20 4 100
Pushing custom region :: ./user-api.inst
[omnitrace][omnitrace_init_tooling] Instrumentation mode: Trace
______ .___ ___. .__ __. __ .___________..______ ___ ______ _______
/ __ \ | \/ | | \ | | | | | || _ \ / \ / || ____|
| | | | | \ / | | \| | | | `---| |----`| |_) | / ^ \ | ,----'| |__
| | | | | |\/| | | . ` | | | | | | / / /_\ \ | | | __|
| `--' | | | | | | |\ | | | | | | |\ \----./ _____ \ | `----.| |____
\______/ |__| |__| |__| \__| |__| |__| | _| `._____/__/ \__\ \______||_______|
Pushing custom region :: initialization
[./user-api.inst] Threads: 4
[./user-api.inst] Iterations: 100
[./user-api.inst] fibonacci(20)...
Pushing custom region :: thread_creation
Pushing custom region :: thread_wait
Pushing custom region :: run(20) x 100
Pushing custom region :: run(20) x 100
Pushing custom region :: run(20) x 100
Pushing custom region :: run(20) x 100
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Pushing custom region :: run(20) x 100
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[./user-api.inst] fibonacci(20) x 4 = 3382500
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[omnitrace][86267][0][omnitrace_finalize] finalizing...
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[omnitrace][86267][0] omnitrace : 5.190895 sec wall_clock, 2.748 mb peak_rss, 6.330000 sec cpu_clock, 121.9 % cpu_util [laps: 1]
[omnitrace][86267][0] user-api.inst/thread-0 : 5.078713 sec wall_clock, 4.722415 sec thread_cpu_clock, 93.0 % thread_cpu_util, 1.276 mb peak_rss [laps: 1]
[omnitrace][86267][0] user-api.inst/thread-1 : 0.322248 sec wall_clock, 0.322191 sec thread_cpu_clock, 100.0 % thread_cpu_util, 1.000 mb peak_rss [laps: 1]
[omnitrace][86267][0] user-api.inst/thread-2 : 0.323255 sec wall_clock, 0.323194 sec thread_cpu_clock, 100.0 % thread_cpu_util, 0.000 mb peak_rss [laps: 1]
[omnitrace][86267][0] user-api.inst/thread-3 : 0.323569 sec wall_clock, 0.323484 sec thread_cpu_clock, 100.0 % thread_cpu_util, 1.092 mb peak_rss [laps: 1]
[omnitrace][86267][0] user-api.inst/thread-4 : 0.324178 sec wall_clock, 0.324057 sec thread_cpu_clock, 100.0 % thread_cpu_util, 1.184 mb peak_rss [laps: 1]
[omnitrace][86267][0] Post-processing 51 cpu frequency and memory usage entries...
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[omnitrace][wall_clock]|0> Outputting 'omnitrace-user-api.inst-output/wall_clock.json'...
[omnitrace][wall_clock]|0> Outputting 'omnitrace-user-api.inst-output/wall_clock.tree.json'...
[omnitrace][wall_clock]|0> Outputting 'omnitrace-user-api.inst-output/wall_clock.txt'...
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[omnitrace][manager::finalize][metadata]> Outputting 'omnitrace-user-api.inst-output/metadata.json' and 'omnitrace-user-api.inst-output/functions.json'...
[omnitrace][86267][0][omnitrace_finalize] Finalized
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$ cat omnitrace-example-output/wall_clock.txt
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| REAL-CLOCK TIMER (I.E. WALL-CLOCK TIMER) |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| LABEL | COUNT | DEPTH | METRIC | UNITS | SUM | MEAN | MIN | MAX | VAR | STDDEV | % SELF |
|---------------------------------------------------------------------------------|--------|--------|------------|--------|----------|----------|----------|----------|----------|----------|--------|
| |0>>> ./user-api.inst | 1 | 0 | wall_clock | sec | 5.078521 | 5.078521 | 5.078521 | 5.078521 | 0.000000 | 0.000000 | 0.0 |
| |0>>> |_initialization | 1 | 1 | wall_clock | sec | 0.000004 | 0.000004 | 0.000004 | 0.000004 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_thread_creation | 1 | 1 | wall_clock | sec | 0.000159 | 0.000159 | 0.000159 | 0.000159 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_thread_wait | 1 | 1 | wall_clock | sec | 0.355307 | 0.355307 | 0.355307 | 0.355307 | 0.000000 | 0.000000 | 0.0 |
| |0>>> |_std::vector<std::thread, std::allocator<std::thread> >::begin | 1 | 2 | wall_clock | sec | 0.000001 | 0.000001 | 0.000001 | 0.000001 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_std::vector<std::thread, std::allocator<std::thread> >::end | 1 | 2 | wall_clock | sec | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_pthread_join | 4 | 2 | wall_clock | sec | 0.355257 | 0.088814 | 0.000001 | 0.333144 | 0.026559 | 0.162970 | 100.0 |
| |2>>> |_start_thread | 1 | 3 | wall_clock | sec | 0.000032 | 0.000032 | 0.000032 | 0.000032 | 0.000000 | 0.000000 | 100.0 |
| |1>>> |_start_thread | 1 | 3 | wall_clock | sec | 0.000036 | 0.000036 | 0.000036 | 0.000036 | 0.000000 | 0.000000 | 100.0 |
| |3>>> |_start_thread | 1 | 3 | wall_clock | sec | 0.000034 | 0.000034 | 0.000034 | 0.000034 | 0.000000 | 0.000000 | 100.0 |
| |4>>> |_start_thread | 1 | 3 | wall_clock | sec | 0.000039 | 0.000039 | 0.000039 | 0.000039 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_run | 1 | 1 | wall_clock | sec | 4.722993 | 4.722993 | 4.722993 | 4.722993 | 0.000000 | 0.000000 | 0.0 |
| |0>>> |_std::char_traits<char>::length | 1 | 2 | wall_clock | sec | 0.000001 | 0.000001 | 0.000001 | 0.000001 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_std::distance<char const*> | 1 | 2 | wall_clock | sec | 0.000001 | 0.000001 | 0.000001 | 0.000001 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_std::operator+<char, std::char_traits<char>, std::allocator<char> > | 2 | 2 | wall_clock | sec | 0.000002 | 0.000001 | 0.000001 | 0.000001 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_run(20) x 100 | 1 | 2 | wall_clock | sec | 4.722951 | 4.722951 | 4.722951 | 4.722951 | 0.000000 | 0.000000 | 0.0 |
| |0>>> |_run [{94,25}-{96,25}] | 1 | 3 | wall_clock | sec | 4.722925 | 4.722925 | 4.722925 | 4.722925 | 0.000000 | 0.000000 | 0.0 |
| |0>>> |_fib | 100 | 4 | wall_clock | sec | 4.722718 | 0.047227 | 0.046713 | 0.051987 | 0.000000 | 0.000625 | 0.0 |
| |0>>> |_fib | 200 | 5 | wall_clock | sec | 4.722302 | 0.023612 | 0.017827 | 0.034091 | 0.000032 | 0.005627 | 0.0 |
| |0>>> |_fib | 400 | 6 | wall_clock | sec | 4.721485 | 0.011804 | 0.006790 | 0.023003 | 0.000016 | 0.004024 | 0.0 |
| |0>>> |_fib | 800 | 7 | wall_clock | sec | 4.719858 | 0.005900 | 0.002564 | 0.016078 | 0.000006 | 0.002498 | 0.1 |
| |0>>> |_fib | 1600 | 8 | wall_clock | sec | 4.716572 | 0.002948 | 0.000977 | 0.011849 | 0.000002 | 0.001465 | 0.1 |
| |0>>> |_fib | 3200 | 9 | wall_clock | sec | 4.709918 | 0.001472 | 0.000371 | 0.008246 | 0.000001 | 0.000831 | 0.3 |
| |0>>> |_fib | 6400 | 10 | wall_clock | sec | 4.696775 | 0.000734 | 0.000140 | 0.005111 | 0.000000 | 0.000461 | 0.6 |
| |0>>> |_fib | 12800 | 11 | wall_clock | sec | 4.670093 | 0.000365 | 0.000050 | 0.003166 | 0.000000 | 0.000253 | 1.1 |
| |0>>> |_fib | 25600 | 12 | wall_clock | sec | 4.617496 | 0.000180 | 0.000017 | 0.001959 | 0.000000 | 0.000137 | 2.3 |
| |0>>> |_fib | 51200 | 13 | wall_clock | sec | 4.512671 | 0.000088 | 0.000004 | 0.001212 | 0.000000 | 0.000074 | 4.6 |
| |0>>> |_fib | 102400 | 14 | wall_clock | sec | 4.304142 | 0.000042 | 0.000000 | 0.000752 | 0.000000 | 0.000039 | 9.6 |
| |0>>> |_fib | 202600 | 15 | wall_clock | sec | 3.892580 | 0.000019 | 0.000000 | 0.000469 | 0.000000 | 0.000021 | 19.0 |
| |0>>> |_fib | 363200 | 16 | wall_clock | sec | 3.151143 | 0.000009 | 0.000000 | 0.000293 | 0.000000 | 0.000011 | 33.2 |
| |0>>> |_fib | 502000 | 17 | wall_clock | sec | 2.105217 | 0.000004 | 0.000000 | 0.000183 | 0.000000 | 0.000006 | 49.1 |
| |0>>> |_fib | 476000 | 18 | wall_clock | sec | 1.071652 | 0.000002 | 0.000000 | 0.000114 | 0.000000 | 0.000004 | 63.6 |
| |0>>> |_fib | 294200 | 19 | wall_clock | sec | 0.390193 | 0.000001 | 0.000000 | 0.000071 | 0.000000 | 0.000003 | 75.3 |
| |0>>> |_fib | 115200 | 20 | wall_clock | sec | 0.096190 | 0.000001 | 0.000000 | 0.000043 | 0.000000 | 0.000002 | 84.4 |
| |0>>> |_fib | 27400 | 21 | wall_clock | sec | 0.015020 | 0.000001 | 0.000000 | 0.000025 | 0.000000 | 0.000001 | 91.1 |
| |0>>> |_fib | 3600 | 22 | wall_clock | sec | 0.001336 | 0.000000 | 0.000000 | 0.000013 | 0.000000 | 0.000001 | 96.3 |
| |0>>> |_fib | 200 | 23 | wall_clock | sec | 0.000050 | 0.000000 | 0.000000 | 0.000001 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_std::char_traits<char>::length | 1 | 3 | wall_clock | sec | 0.000001 | 0.000001 | 0.000001 | 0.000001 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_std::distance<char const*> | 1 | 3 | wall_clock | sec | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_std::operator+<char, std::char_traits<char>, std::allocator<char> > | 2 | 3 | wall_clock | sec | 0.000001 | 0.000001 | 0.000000 | 0.000001 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_std::operator& | 1 | 1 | wall_clock | sec | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 100.0 |
| |0>>> std::vector<std::thread, std::allocator<std::thread> >::~vector | 1 | 0 | wall_clock | sec | 0.000045 | 0.000045 | 0.000045 | 0.000045 | 0.000000 | 0.000000 | 32.7 |
| |0>>> |_std::thread::~thread | 4 | 1 | wall_clock | sec | 0.000030 | 0.000007 | 0.000007 | 0.000009 | 0.000000 | 0.000001 | 31.2 |
| |0>>> |_std::thread::joinable | 4 | 2 | wall_clock | sec | 0.000021 | 0.000005 | 0.000005 | 0.000006 | 0.000000 | 0.000001 | 89.4 |
| |0>>> |_std::thread::id::id | 4 | 3 | wall_clock | sec | 0.000001 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_std::operator== | 4 | 3 | wall_clock | sec | 0.000001 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_std::allocator_traits<std::allocator<std::thread> >::deallocate | 1 | 1 | wall_clock | sec | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 100.0 |
| |0>>> |_std::allocator<std::thread>::~allocator | 1 | 1 | wall_clock | sec | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 0.000000 | 100.0 |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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```