ClickHouse/base/base/phdr_cache.h
Alexey Milovidov 35cce03125 Remove dlopen
2022-09-17 03:02:34 +02:00

21 lines
989 B
C++

#pragma once
/// This code was based on the code by Fedor Korotkiy https://www.linkedin.com/in/fedor-korotkiy-659a1838/
/** Collects all dl_phdr_info items and caches them in a static array.
* Also rewrites dl_iterate_phdr with a lock-free version which consults the above cache
* thus eliminating scalability bottleneck in C++ exception unwinding.
* As a drawback, this only works if no dynamic object unloading happens after this point.
* This function is thread-safe. You should call it to update cache after loading new shared libraries.
* Otherwise exception handling from dlopened libraries won't work (will call std::terminate immediately).
* NOTE: dlopen is forbidden in our code.
*
* NOTE: It is disabled with Thread Sanitizer because TSan can only use original "dl_iterate_phdr" function.
*/
void updatePHDRCache();
/** Check if "dl_iterate_phdr" will be lock-free
* to determine if some features like Query Profiler can be used.
*/
bool hasPHDRCache();