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lib/Algorithm/ToNumberMunger.pm  view on Meta::CPAN

        "munger": "datetime", "from": "timestamp",
        "format": "%Y-%m-%dT%H:%M:%S",
        "parts":  [ "sin_week", "cos_week" ],
        "into":   [ "time_sin", "time_cos" ]
    }

The timestamp is parsed once and both columns are filled together, so they can
never drift apart or be half-configured. C<parts> and C<into> must be the same
length. (Using C<parts> without C<into>, or C<part> with C<into>, is an error.)

B<Performance.> Two transparent accelerations, both value-identical to the plain
path: a one-slot memo returns the previous result when the same stamp string
repeats (the common case in bursty event streams); and when the format is built
from only the six numeric codes C<%Y %m %d %H %M %S> (once each, e.g.
C<%Y-%m-%dT%H:%M:%S>), parsing skips C<strptime> for a compiled regex plus
integer date math, falling back to C<strptime> for any value the regex does not
match B<or whose fields are out of range> (a month C<13>, an hour C<24>, a
C<Feb 30>) -- so an invalid stamp croaks or normalizes exactly as C<strptime>
would, never silently feeding nonsense to the date math. Like C<strptime>
without a zone code, stamps are treated as UTC.

lib/Algorithm/ToNumberMunger.pm  view on Meta::CPAN

=item * C<timeout> - per-operation socket timeout in seconds (default 5,
best-effort via C<SO_RCVTIMEO>/C<SO_SNDTIMEO>), so a wedged daemon cannot hang a
writer forever.

=back

Semantics worth knowing: a marked read B<includes the event just marked>; keys
have whitespace/control bytes replaced with C<_> to satisfy the daemon's key
rules; connections are made lazily on first use and kept open (reconnecting
transparently after a fork or an error), so compiling a plan -- including the
eager validation in C<write_info> -- needs no running daemon. Each eps column
costs one unix-socket round trip per row; the multi-output form exists so
rate+count of the same key costs one round trip, not two.

=cut

# Default socket path of the iqbi-damiq daemon.
our $EPS_SOCKET = '/var/run/iqbi-damiq.sock';

# Persistent daemon connections, keyed by socket path, shared by every eps
# munger in the process. Entries record the pid that opened them so a forked
# writer transparently reopens instead of sharing a socket with its parent.
# Connections are made lazily on first use -- never at munger build time, so a
# plan can compile (eager validation) with no daemon running.
my %EPS_CONN;

sub _eps_conn {
	my ( $path, $timeout ) = @_;
	my $c = $EPS_CONN{$path};
	return $c->{fh} if $c && $c->{pid} == $$;

	require Socket;