• On-wiki documentation, probably at https://www.mediawiki.org/wiki/Excimer. Can probably refer to the docbook or doxygen documentation for most details.
• Phpdoc stubs, for phan and IDEs and doc.wikimedia.org.
• Docbook documentation, for php.net (once this is in pecl).

Things to remember to mention in the documentation for various methods:

• Which ExcimerProfiler and ExcimerTimer property-setter methods take effect immediately versus only after start() is re-called.
  • Immediately: setMaxDepth, setFlushCallback, setCallback
  • After restart: setPeriod, setInterval, setEventType
• ExcimerLog::offsetExists() will warn if passed a string, contrary to the interface's documentation.
• ExcimerLog::offsetSet() and ExcimerLog::offsetUnset() are unusable and raise errors.
• ExcimerLogEntry::getTimestamp() always returns wall time, or more specifically "unsuspended seconds since the ExcimerProfiler was created". This is intentional, see details in T205059.