1Terminology • Shared Library: • Shared Object, Dynamic Object, Dynamic Shared Object (DSO), Dynamic Load Library (DLL), Dynamic Shared Library • Binary: • Executable / Shared Library , Component cause ODR violation errors. • Speculated motivation: • In the elden days the canonical example of shared-lib was libc. Users may reasonably wish to override implementations. 15foo Library Search Order After exe, before any lib 16 exe lib1 lib2 lib3 lib4 lib5 preload_lib1C++ Implication #1: Can a shared-library symbol be overridden from an executable? • Windows: • No. • Linux: • Yes. • Mac: •

Shared Libraries and Where to Find Them R&D Team Lead, JFrogIntroduction From the point of view of a C++ developer, compiled code typically ends up in either: ● The executables themselves ● Static Static libraries ● Shared libraries Libraries* are a vehicle for “reusable” code code that can be invoked by other libraries or applications (even from other languages) * libraries: not defined by the standard meanings…How developers deal with shared librariesAbout this talk ● What this talk covers: ○ WHEN shared libraries are needed ○ WHICH programs needs to locate shared libraries ○ TOOLS to query, troubleshoot

danielanderson.net What we’ll learn today • How shared_ptr is implemented under the hood • Atomics and concurrency patterns • How existing atomic<shared_ptr> are implemented (the split reference count used for • You’ve heard of shared_ptr Things we won’t cover • Alias pointers, weak pointers4 Daniel Anderson -- danielanderson.net What we’ll learn today • How shared_ptr is implemented under the the hood • Atomics and concurrency patterns • How existing atomic<shared_ptr> are implemented (the split reference count technique) • Deferred reclamation, i.e., garbage collection in C++ Some assumed

set_map_service( const std::shared_ptr request, std::shared_ptr response); void generate_path_service( const std::shared_ptr request, std::shared_ptr response); bool set_costmap(const std_msgs::msg::UInt8MultiArray& costmap); Path generate_global_path(Position set_map_service( const std::shared_ptr request, std::shared_ptr response); void generate_path_service( const std::shared_ptr

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ModernesCpp.netSmart Pointer A First Overview std::unique_ptr – Exclusive Ownership std::shared_ptr – Shared Ownership std::weak_ptr – Break of Cyclic References Performance Concurrency Function Return ValuesSmart Pointer A First Overview std::unique_ptr – Exclusive Ownership std::shared_ptr – Shared Ownership std::weak_ptr – Break of Cyclic References Performance Concurrency Function ▪ Can not be copied ▪ Deals with non-copy objects std::shared_ptr C++11 ▪ Shares a resource ▪ Supports an reference counter to the shared resource and manages it ▪ Deletes the resource if the reference

custom generator with generator packages . . . . . . . . . . . . . . . . . . 193 13.11 How to manage shared libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 13.12 How CMakeLists.txt with SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -m32"), and the same to CMAKE_C_FLAGS, CMAKE_SHARED_LINK_FLAGS and CMAKE_EXE_LINKER_FLAGS. This can also be done more easily, automatically with Conan [requires] Poco/1.9.0@pocoproject/stable [generators] cmake [options] Poco:shared=True # PACKAGE:OPTION=VALUE OpenSSL:shared=True Install the requirements and compile from the build folder (change the

custom generator with generator packages . . . . . . . . . . . . . . . . . . 183 12.11 How to manage shared libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 12.12 How CMakeLists.txt with SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -m32"), and the same to CMAKE_C_FLAGS, CMAKE_SHARED_LINK_FLAGS and CMAKE_EXE_LINKER_FLAGS. This can also be done more easily, automatically with Conan [requires] Poco/1.9.0@pocoproject/stable [generators] cmake [options] Poco:shared=True # PACKAGE:OPTION=VALUE OpenSSL:shared=True Install the requirements and compile from the build folder (change the

custom generator with generator packages . . . . . . . . . . . . . . . . . . 193 12.11 How to manage shared libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 12.12 How running SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -m32"), and the same applies to CMAKE_C_FLAGS, CMAKE_SHARED_LINK_FLAGS and CMAKE_EXE_LINKER_FLAGS. This can also be done more easily, by automatically using [requires] Poco/1.9.0@pocoproject/stable [generators] cmake [options] Poco:shared=True # PACKAGE:OPTION=VALUE OpenSSL:shared=True Install the requirements and compile from the build folder (change the

custom generator with generator packages . . . . . . . . . . . . . . . . . . 191 12.11 How to manage shared libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 12.12 How CMakeLists.txt with SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -m32"), and the same to CMAKE_C_FLAGS, CMAKE_SHARED_LINK_FLAGS and CMAKE_EXE_LINKER_FLAGS. This can also be done more easily, automatically with Conan [requires] Poco/1.9.0@pocoproject/stable [generators] cmake [options] Poco:shared=True # PACKAGE:OPTION=VALUE OpenSSL:shared=True Install the requirements and compile from the build folder (change the

custom generator with generator packages . . . . . . . . . . . . . . . . . . 195 13.11 How to manage shared libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 13.12 How CMakeLists.txt with SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -m32"), and the same to CMAKE_C_FLAGS, CMAKE_SHARED_LINK_FLAGS and CMAKE_EXE_LINKER_FLAGS. This can also be done more easily, automatically with Conan [requires] Poco/1.9.0@pocoproject/stable [generators] cmake [options] Poco:shared=True # PACKAGE:OPTION=VALUE OpenSSL:shared=True Install the requirements and compile from the build folder (change the