249 lines
8.5 KiB
Perl
249 lines
8.5 KiB
Perl
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######################################################################
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# HTTP connection to backend node
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# possible states: connecting, bored, sending_req, wait_res, xfer_res
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######################################################################
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package Perlbal::ReproxyManager;
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use strict;
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use warnings;
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# class storage to store 'host:ip' => $service objects, for making
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# reproxies use a service that you can then track
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our $ReproxySelf;
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our %ReproxyConnecting; # ( host:ip => $backend ); keeps track of outstanding connections to backend that
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# are in the connecting state
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our %ReproxyBored; # ( host:ip => [ $backend, ... ] ); list of our bored backends
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our %ReproxyQueues; # ( host:ip => [ $clientproxy, ... ] ); queued up requests for this backend
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our %ReproxyBackends; # ( host:ip => [ $backend, ... ] ); array of backends we have connected
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our %ReproxyMax; # ( host:ip => int ); maximum number of connections to have open at any one time
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our $ReproxyGlobalMax; # int; the global cap used if no per-host cap is specified
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our $NoSpawn = 0; # bool; when set, spawn_backend immediately returns without running
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our $LastCleanup = 0; # int; time we last ran our cleanup logic (FIXME: temp hack)
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# singleton new function; returns us if we exist, else creates us
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sub get {
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return $ReproxySelf if $ReproxySelf;
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# doesn't exist, so create it and return it
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my $class = shift;
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my $self = {};
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bless $self, $class;
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return $ReproxySelf = $self;
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}
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# given (clientproxy, primary_res_hdrs), initiate proceedings to process a
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# request for a reproxy resource
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sub do_reproxy {
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my Perlbal::ReproxyManager $self = Perlbal::ReproxyManager->get; # singleton
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my Perlbal::ClientProxy $cp = $_[0];
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return undef unless $self && $cp;
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# get data we use
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my $datref = $cp->{reproxy_uris}->[0];
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my $ipport = "$datref->[0]:$datref->[1]";
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push @{$ReproxyQueues{$ipport} ||= []}, $cp;
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# see if we should do cleanup (FIXME: temp hack)
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my $now = time();
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if ($LastCleanup < $now - 5) {
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# remove closed backends from our array. this is O(n) but n is small
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# and we're paranoid that just keeping a count would get corrupt over
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# time. also removes the backends that have clients that are closed.
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@{$ReproxyBackends{$ipport}} = grep {
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! $_->{closed} && (! $_->{client} || ! $_->{client}->{closed})
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} @{$ReproxyBackends{$ipport}};
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$LastCleanup = $now;
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}
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# now start a new backend
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$self->spawn_backend($ipport);
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return 1;
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}
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# part of the reportto interface; this is called when a backend is unable to establish
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# a connection with a backend. we simply try the next uri.
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sub note_bad_backend_connect {
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my Perlbal::ReproxyManager $self = $_[0];
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my Perlbal::BackendHTTP $be = $_[1];
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# decrement counts and undef connecting backend
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$ReproxyConnecting{$be->{ipport}} = undef;
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# if nobody waiting, doesn't matter if we couldn't get to this backend
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return unless @{$ReproxyQueues{$be->{ipport}} || []};
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# if we still have some connected backends then ignore this bad connection attempt
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return if scalar @{$ReproxyBackends{$be->{ipport}} || []};
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# at this point, we have no connected backends, and our connecting one failed
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# so we want to tell all of the waiting clients to try their next uri, because
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# this host is down.
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while (my Perlbal::ClientProxy $cp = shift @{$ReproxyQueues{$be->{ipport}}}) {
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$cp->try_next_uri;
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}
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return 1;
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}
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# called by a backend when it's ready for a request
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sub register_boredom {
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my Perlbal::ReproxyManager $self = $_[0];
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my Perlbal::BackendHTTP $be = $_[1];
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# if this backend was connecting
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my $ipport = $be->{ipport};
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if ($ReproxyConnecting{$ipport} && $ReproxyConnecting{$ipport} == $be) {
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$ReproxyConnecting{$ipport} = undef;
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$ReproxyBackends{$ipport} ||= [];
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push @{$ReproxyBackends{$ipport}}, $be;
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}
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# sometimes a backend is closed but it tries to register with us anyway... ignore it
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# but since this might have been our only one, spawn another
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if ($be->{closed}) {
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$self->spawn_backend($ipport);
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return;
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}
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# find some clients to use
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while (my Perlbal::ClientProxy $cp = shift @{$ReproxyQueues{$ipport} || []}) {
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# safety checks
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next if $cp->{closed};
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# give backend to client
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$cp->use_reproxy_backend($be);
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return;
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}
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# no clients if we get here, so push onto bored backend list
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push @{$ReproxyBored{$ipport} ||= []}, $be;
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# clean up the front of our list if we can (see docs above)
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if (my Perlbal::BackendHTTP $bbe = $ReproxyBored{$ipport}->[0]) {
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if ($bbe->{alive_time} < time() - 5) {
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$NoSpawn = 1;
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$bbe->close('have_newer_bored');
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shift @{$ReproxyBored{$ipport}};
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$NoSpawn = 0;
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}
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}
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return 0;
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}
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# backend closed, decrease counts, etc
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sub note_backend_close {
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my Perlbal::ReproxyManager $self = $_[0];
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my Perlbal::BackendHTTP $be = $_[1];
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# remove closed backends from our array. this is O(n) but n is small
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# and we're paranoid that just keeping a count would get corrupt over
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# time.
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@{$ReproxyBackends{$be->{ipport}}} = grep {
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! $_->{closed}
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} @{$ReproxyBackends{$be->{ipport}}};
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# spawn more if needed
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$self->spawn_backend($be->{ipport});
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}
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sub spawn_backend {
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return if $NoSpawn;
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my Perlbal::ReproxyManager $self = $_[0];
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my $ipport = $_[1];
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# if we're already connecting, we don't want to spawn another one
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if (my Perlbal::BackendHTTP $be = $ReproxyConnecting{$ipport}) {
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# see if this one is too old?
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if ($be->{create_time} < (time() - 5)) { # older than 5 seconds?
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$self->note_bad_backend_connect($be);
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$be->close("connection_timeout");
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# we return here instead of spawning because closing the backend calls
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# note_backend_close which will call spawn_backend again, and at that
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# point we won't have a pending connection and can spawn
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return;
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} else {
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# don't spawn more if we're already connecting
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return;
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}
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}
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# if nobody waiting, don't spawn extra connections
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return unless @{$ReproxyQueues{$ipport} || []};
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# don't spawn if we have a bored one already
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while (my Perlbal::BackendHTTP $bbe = pop @{$ReproxyBored{$ipport} || []}) {
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# don't use keep-alive connections if we know the server's
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# just about to kill the connection for being idle
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my $now = time();
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if ($bbe->{disconnect_at} && $now + 2 > $bbe->{disconnect_at} ||
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$bbe->{alive_time} < $now - 5)
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{
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$NoSpawn = 1;
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$bbe->close("too_close_disconnect");
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$NoSpawn = 0;
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next;
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}
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# it's good, give it to someone
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$self->register_boredom($bbe);
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return;
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}
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# see if we have too many already?
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my $max = $ReproxyMax{$ipport} || $ReproxyGlobalMax || 0;
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my $count = scalar @{$ReproxyBackends{$ipport} || []};
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return if $max && ($count >= $max);
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# start one connecting and enqueue
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my $be = Perlbal::BackendHTTP->new(undef, split(/:/, $ipport), { reportto => $self })
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or return 0;
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$ReproxyConnecting{$ipport} = $be;
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}
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sub backend_response_received {
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my Perlbal::ReproxyManager $self = $_[0];
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my Perlbal::BackendHTTP $be = $_[1];
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my Perlbal::ClientProxy $cp = $be->{client};
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# if no client, close backend and return 1
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unless ($cp) {
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$be->close("lost_client");
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return 1;
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}
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# pass on to client
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return $cp->backend_response_received($be);
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}
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sub dump_state {
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my $out = shift;
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return unless $out;
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# spits out what we have connecting
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while (my ($hostip, $dat) = each %ReproxyConnecting) {
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$out->("connecting $hostip 1") if defined $dat;
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}
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while (my ($hostip, $dat) = each %ReproxyBored) {
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$out->("bored $hostip " . scalar(@$dat));
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}
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while (my ($hostip, $dat) = each %ReproxyQueues) {
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$out->("clients_queued $hostip " . scalar(@$dat));
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}
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while (my ($hostip, $dat) = each %ReproxyBackends) {
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$out->("backends $hostip " . scalar(@$dat));
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foreach my $be (@$dat) {
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$out->("... " . $be->as_string);
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}
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}
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while (my ($hostip, $dat) = each %ReproxyMax) {
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$out->("SERVER max_reproxy_connections($hostip) = $dat");
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}
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$out->("SERVER max_reproxy_connections = " . ($ReproxyGlobalMax || 0));
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$out->('.');
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}
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1;
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