Release v2.3.0

Changes

Entries can now be stamped by a clock of your choice instead of always std::chrono::system_clock: a calibrated TSC, a backtest's simulated time, or a fixed clock in tests. Code that calls LOG_* needs no changes, the default output is unchanged, and a 2.3.0 process can share a segment with a 2.2.x one.

• Configurable timestamper. The new ITimestamper interface (uint64_t now() noexcept, returning nanoseconds since the Unix epoch) decides the time stored in LogEntry::timestamp. TimestampFormatter and the pattern flags still decide how that time is printed
  • Three ways to set one: derive from ITimestamper and pass it to Logger::set_timestamper(); pass any callable, including a lambda with captures; or name a chrono-style clock type with set_timestamper<Clock>(). LogConfig::timestamper sets it at init(), before the version banner is logged
  • set_timestamper(nullptr) and reset() go back to system_clock. A null LogConfig::timestamper keeps the current one, the same rule as an empty LogConfig::pattern, and shutdown() leaves it alone
  • timestamper() returns the one in use (null while the default is), and current_timestamp() reads the logger's clock directly
• Safe to swap while logging. Logging threads read the timestamper through one atomic pointer, so set_timestamper() takes no lock and blocks no one. A replaced timestamper is kept alive until reset(), because a thread may still be inside its now(). As with set_pattern(), call it from one thread at a time
• Cost. The timestamper runs on every log call, on every logging thread, so it must be cheap and thread-safe, and it must not throw: now() is noexcept, so a throwing callable terminates the program. Measured on Windows/MSVC /O2 (minimum of 40 rounds), the default path adds under 1 ns to the ~52 ns system_clock read it wraps, and a timestamper returning a stored value costs about 3.5 ns
• LogStats::timestamp_ns follows the timestamper, so statistics rows keep lining up with the log lines they describe. DailyFileSink still takes the date in its file name from the wall clock
• Compatibility. LogEntry is unchanged, so 2.3.0 and 2.2.x processes can share a segment; each producer stamps its entries with its own timestamper. Logger itself gained members, so a plugin that routes its LOG_* calls to the host through set_instance() must be rebuilt against the same version as the host
  • timestamper is the last member of LogConfig, so positional (aggregate) initializers written for 2.2.x keep compiling and keep their meaning. A test pins the member order
• Documentation and CI. The README opens with an overview, navigation and benchmark highlights, and its installation section now leads with vcpkg. A new CI job builds and runs the README's vcpkg example in both classic and manifest mode
• New tests cover each way to set a timestamper, LogConfig handling, the statistics timestamp, and swapping the timestamper while four threads log

Downloads

The library is header-only: take slick-logger-2.3.0.zip
or .tar.gz and add include/ to your include path. The archive is
self-contained - alongside slick/logger.hpp it bundles the
slick/queue.h and slick/shm/ headers it includes, from
slick-queue and
slick-shm, so there is no
separate dependency to install. Their licences are in licenses/.

slick-log-collector-* contains the prebuilt standalone collector for
multi-process logging.
It is optional; you only need it to collect log entries from several
processes into one set of sinks.