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lib/Plack/Middleware/Cache/CHI.pm  view on Meta::CPAN

use strict;
package Plack::Middleware::Cache::CHI;
our $AUTHORITY = 'cpan:PNU';
# ABSTRACT: Caching Reverse Proxy for Plack

use warnings;
use parent qw/Plack::Middleware/;

use Plack::Util::Accessor qw( chi rules scrub cachequeries trace );
use Data::Dumper;
use Plack::Request;
use Plack::Response;
use Time::HiRes qw( gettimeofday );

our $VERSION = '0.102'; # VERSION

our @trace;
our $timer_call;
our $timer_pass;

sub _uinterval {
    my ( $t0, $t1 ) = ( @_, [gettimeofday] );
    ($t1->[0] - $t0->[0]) * 1_000_000 + $t1->[1] - $t0->[1];
}

sub call {
    my ($self,$env) = @_;

    ## Pass-thru streaming responses
    return $self->app->($env)
        if ( ref $env eq 'CODE' );

    ## Localize trace for this request
    local @trace = ();
    local $timer_pass = undef;
    local $timer_call = [gettimeofday];

    my $req = Plack::Request->new($env);
    my $r = $self->handle($req);
    my $res = Plack::Response->new(@$r);

    ## Add trace and cache key to response headers
    $timer_call = _uinterval($timer_call);
    my $trace = join q{, }, @trace;
    my $key = $self->cachekey($req);

    ## The subrequest is timed separately
    if ( $timer_pass ) {
        $timer_call -= $timer_pass;
        $res->headers->push_header(
            'X-Plack-Cache-Time-Pass' => "$timer_pass us",
        );
    }

    $res->headers->push_header(
        'X-Plack-Cache' => $trace,
        'X-Plack-Cache-Key' => $key,
        'X-Plack-Cache-Time' => "$timer_call us",
    );

    $res->finalize;
}

sub handle {
    my ($self,$req) = @_;

    if ( $req->method eq 'GET' or $req->method eq 'HEAD' ) {
        if ( $req->headers->header('Expect') ) {
            push @trace, 'expect';
            $self->pass($req);
        } else {
            $self->lookup($req);
        }
    } else {
        $self->invalidate($req);
    }
}

sub pass {
    my ($self,$req) = @_;
    push @trace, 'pass';
    $timer_pass = [gettimeofday];

    my $res = $self->app->($req->env);

    $timer_pass = _uinterval($timer_pass);
    return $res;
}