[kVinsom]

Summary

CyberRT's timing wheel uses Rate to pace its ticks. Rate currently measures cycles using wall time and waits on a system-clock deadline, so changing the system clock can disrupt timer execution and produce incorrect cycle durations.

Use Time::MonoTime() in all Rate constructors, Sleep() and Reset(), and wait on the corresponding std::chrono::steady_clock deadline. Keep the existing cycle-overrun resynchronization behaviour and update its diagnostic. Time::SleepUntil() retains its wall-clock semantics for other callers.

Add a rate_test target and seven tests covering constructor periods, successive waits, cycle overruns, and forward/backward one-hour clock jumps before sleeping and resetting. The tests interpose clock reads in the test executable; they do not change the machine's clock or require clock-setting privileges. Include Doxygen documentation and comments explaining the clock domains.

Fixes #15763.

Validation

• Compiled the actual Rate, Time, Duration and binary sources on Ubuntu/WSL with GCC 15, C++14 and -Wall -Wextra -Werror.
• Used GoogleTest 1.10.0 pinned by Apollo, with its archive checksum verified. Building this older GoogleTest with GCC 15 required locally adding -include cstdint to its compilation; no dependency sources or repository build settings were changed.
• All 15 tests passed: 7 new Rate tests plus 8 existing Time/Duration tests.
• Against the original Rate implementation, 5 of the new tests failed, including the forward/backward jump cases.
• clang-format --dry-run --Werror, Apollo's pinned cpplint 1.5.2, and git diff --check passed for the changed C++ files/diff.

Full Apollo/Bazel and timer integration validation remains outstanding: this machine does not have the Apollo development container/Bazel environment configured. The Windows checkout also has CRLF shell scripts, so the attempted apollo.sh check could not run. The results above are direct C++ compilation/tests, not a successful full Apollo build.

AI assistance

Codex assisted with implementation, test development, documentation and local validation.

[CLAassistant]

All committers have signed the CLA.