NAME

       "IO::Async::Debug" - debugging control and support for IO::Async

DESCRIPTION

       The following methods and behaviours are still experimental and may change or even be
       removed in future.

       Debugging support is enabled by an environment variable called "IO_ASYNC_DEBUG" having a
       true value.

       When debugging is enabled, the "make_event_cb" and "invoke_event" methods on
       IO::Async::Notifier (and their "maybe_" variants) are altered such that when the event is
       fired, a debugging line is printed, using the "debug_printf" method. This identifes the
       name of the event.

       By default, the line is only printed if the caller of one of these methods is the same
       package as the object is blessed into, allowing it to print the events of the most-derived
       class, without the extra verbosity of the lower-level events of its parent class used to
       create it. All calls regardless of caller can be printed by setting a number greater than
       1 as the value of "IO_ASYNC_DEBUG".

       By default the debugging log goes to "STDERR", but two other environment variables can
       redirect it. If "IO_ASYNC_DEBUG_FILE" is set, it names a file which will be opened for
       writing, and logging written into it. Otherwise, if "IO_ASYNC_DEBUG_FD" is set, it gives a
       file descriptor number that logging should be written to. If opening the named file or
       file descriptor fails then the log will be written to "STDERR" as normal.

       Extra debugging flags can be set in a comma-separated list in an environment variable
       called "IO_ASYNC_DEBUG_FLAGS". The presence of these flags can cause extra information to
       be written to the log. Full details on these flags will be documented by the implementing
       classes. Typically these flags take the form of one or more capital letters indicating the
       class, followed by one or more lowercase letters enabling some particular feature within
       that class.

AUTHOR

       Paul Evans <leonerd@leonerd.org.uk>