Library Integration Guidelines

This document defines the supported integration contract for consuming Time Shield as a header-only dependency.

Canonical Language

English is the canonical version of this document.

Russian localization:

• docs/library-integration-guidelines-RU.md

Supported Integration Shapes

Time Shield is a header-only library. The normal supported integration paths are:

• CMake find_package(TimeShield CONFIG REQUIRED)
• CMake add_subdirectory(...)
• manual include-path integration for non-CMake builds

Link the exported target when CMake is available:

target_link_libraries(app PRIVATE time_shield::time_shield)

Multiple Static Libraries

It is valid for multiple static libraries in the same final program to depend on time_shield::time_shield.

This does not create a source-duplication problem as long as consumers:

• include the public Time Shield headers normally
• do not compile private copies of the library internals as separate .cpp files
• do not mix incompatible compile-time configuration for the same final program

NTP Service Contract

NtpTimeService is header-only and supports C++11, C++14, and C++17.

• the service uses an immortal singleton internally to avoid static destruction order problems
• during normal runtime the singleton getters keep their lazy-start behavior
• during process teardown the service stops restarting background work and falls back to realtime plus the last cached offset
• in general, C++17+ allows a simpler singleton-storage pattern with inline variables, and the public usage contract for NtpTimeService is the same in C++11/C++14/C++17

Windows Linking

When TIME_SHIELD_ENABLE_NTP_CLIENT=ON on Windows, the NTP stack requires the platform socket system library.

Supported behavior:

• if you use the exported CMake target time_shield::time_shield, the required Windows socket library is linked transitively
• if you integrate manually without the CMake target, you must link the platform socket library yourself (for Windows, ws2_32)

Configuration Consistency

Do not mix incompatible compile-time configuration for the same final program.

In particular:

• all consumers in one program should agree on whether TIME_SHIELD_ENABLE_NTP_CLIENT is enabled
• public behavior that depends on compile-time configuration must stay consistent across static libraries and the final executable

Practical Checklist

Before finalizing integration, verify:

• the program links time_shield::time_shield through CMake when possible
• multiple static libraries only include public Time Shield headers and do not build private copies of internals
• NtpTimeService is used without ownership macros or a special owning TU
• Windows builds with NTP enabled resolve the socket library transitively, or link it manually in non-CMake builds
• all targets in the final program use compatible Time Shield compile-time configuration